Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/kernel/sched.c b/kernel/sched.c
new file mode 100644
index 0000000..f69c4a5
--- /dev/null
+++ b/kernel/sched.c
@@ -0,0 +1,5004 @@
+/*
+ * kernel/sched.c
+ *
+ * Kernel scheduler and related syscalls
+ *
+ * Copyright (C) 1991-2002 Linus Torvalds
+ *
+ * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
+ * make semaphores SMP safe
+ * 1998-11-19 Implemented schedule_timeout() and related stuff
+ * by Andrea Arcangeli
+ * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
+ * hybrid priority-list and round-robin design with
+ * an array-switch method of distributing timeslices
+ * and per-CPU runqueues. Cleanups and useful suggestions
+ * by Davide Libenzi, preemptible kernel bits by Robert Love.
+ * 2003-09-03 Interactivity tuning by Con Kolivas.
+ * 2004-04-02 Scheduler domains code by Nick Piggin
+ */
+
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/nmi.h>
+#include <linux/init.h>
+#include <asm/uaccess.h>
+#include <linux/highmem.h>
+#include <linux/smp_lock.h>
+#include <asm/mmu_context.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/kernel_stat.h>
+#include <linux/security.h>
+#include <linux/notifier.h>
+#include <linux/profile.h>
+#include <linux/suspend.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/smp.h>
+#include <linux/threads.h>
+#include <linux/timer.h>
+#include <linux/rcupdate.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/percpu.h>
+#include <linux/kthread.h>
+#include <linux/seq_file.h>
+#include <linux/syscalls.h>
+#include <linux/times.h>
+#include <linux/acct.h>
+#include <asm/tlb.h>
+
+#include <asm/unistd.h>
+
+/*
+ * Convert user-nice values [ -20 ... 0 ... 19 ]
+ * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
+ * and back.
+ */
+#define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
+#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
+#define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
+
+/*
+ * 'User priority' is the nice value converted to something we
+ * can work with better when scaling various scheduler parameters,
+ * it's a [ 0 ... 39 ] range.
+ */
+#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
+#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
+#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
+
+/*
+ * Some helpers for converting nanosecond timing to jiffy resolution
+ */
+#define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
+#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
+
+/*
+ * These are the 'tuning knobs' of the scheduler:
+ *
+ * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
+ * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
+ * Timeslices get refilled after they expire.
+ */
+#define MIN_TIMESLICE max(5 * HZ / 1000, 1)
+#define DEF_TIMESLICE (100 * HZ / 1000)
+#define ON_RUNQUEUE_WEIGHT 30
+#define CHILD_PENALTY 95
+#define PARENT_PENALTY 100
+#define EXIT_WEIGHT 3
+#define PRIO_BONUS_RATIO 25
+#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
+#define INTERACTIVE_DELTA 2
+#define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
+#define STARVATION_LIMIT (MAX_SLEEP_AVG)
+#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
+
+/*
+ * If a task is 'interactive' then we reinsert it in the active
+ * array after it has expired its current timeslice. (it will not
+ * continue to run immediately, it will still roundrobin with
+ * other interactive tasks.)
+ *
+ * This part scales the interactivity limit depending on niceness.
+ *
+ * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
+ * Here are a few examples of different nice levels:
+ *
+ * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
+ * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
+ * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
+ * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
+ * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
+ *
+ * (the X axis represents the possible -5 ... 0 ... +5 dynamic
+ * priority range a task can explore, a value of '1' means the
+ * task is rated interactive.)
+ *
+ * Ie. nice +19 tasks can never get 'interactive' enough to be
+ * reinserted into the active array. And only heavily CPU-hog nice -20
+ * tasks will be expired. Default nice 0 tasks are somewhere between,
+ * it takes some effort for them to get interactive, but it's not
+ * too hard.
+ */
+
+#define CURRENT_BONUS(p) \
+ (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
+ MAX_SLEEP_AVG)
+
+#define GRANULARITY (10 * HZ / 1000 ? : 1)
+
+#ifdef CONFIG_SMP
+#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
+ (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
+ num_online_cpus())
+#else
+#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
+ (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
+#endif
+
+#define SCALE(v1,v1_max,v2_max) \
+ (v1) * (v2_max) / (v1_max)
+
+#define DELTA(p) \
+ (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA)
+
+#define TASK_INTERACTIVE(p) \
+ ((p)->prio <= (p)->static_prio - DELTA(p))
+
+#define INTERACTIVE_SLEEP(p) \
+ (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
+ (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
+
+#define TASK_PREEMPTS_CURR(p, rq) \
+ ((p)->prio < (rq)->curr->prio)
+
+/*
+ * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
+ * to time slice values: [800ms ... 100ms ... 5ms]
+ *
+ * The higher a thread's priority, the bigger timeslices
+ * it gets during one round of execution. But even the lowest
+ * priority thread gets MIN_TIMESLICE worth of execution time.
+ */
+
+#define SCALE_PRIO(x, prio) \
+ max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
+
+static inline unsigned int task_timeslice(task_t *p)
+{
+ if (p->static_prio < NICE_TO_PRIO(0))
+ return SCALE_PRIO(DEF_TIMESLICE*4, p->static_prio);
+ else
+ return SCALE_PRIO(DEF_TIMESLICE, p->static_prio);
+}
+#define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \
+ < (long long) (sd)->cache_hot_time)
+
+/*
+ * These are the runqueue data structures:
+ */
+
+#define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long))
+
+typedef struct runqueue runqueue_t;
+
+struct prio_array {
+ unsigned int nr_active;
+ unsigned long bitmap[BITMAP_SIZE];
+ struct list_head queue[MAX_PRIO];
+};
+
+/*
+ * This is the main, per-CPU runqueue data structure.
+ *
+ * Locking rule: those places that want to lock multiple runqueues
+ * (such as the load balancing or the thread migration code), lock
+ * acquire operations must be ordered by ascending &runqueue.
+ */
+struct runqueue {
+ spinlock_t lock;
+
+ /*
+ * nr_running and cpu_load should be in the same cacheline because
+ * remote CPUs use both these fields when doing load calculation.
+ */
+ unsigned long nr_running;
+#ifdef CONFIG_SMP
+ unsigned long cpu_load;
+#endif
+ unsigned long long nr_switches;
+
+ /*
+ * This is part of a global counter where only the total sum
+ * over all CPUs matters. A task can increase this counter on
+ * one CPU and if it got migrated afterwards it may decrease
+ * it on another CPU. Always updated under the runqueue lock:
+ */
+ unsigned long nr_uninterruptible;
+
+ unsigned long expired_timestamp;
+ unsigned long long timestamp_last_tick;
+ task_t *curr, *idle;
+ struct mm_struct *prev_mm;
+ prio_array_t *active, *expired, arrays[2];
+ int best_expired_prio;
+ atomic_t nr_iowait;
+
+#ifdef CONFIG_SMP
+ struct sched_domain *sd;
+
+ /* For active balancing */
+ int active_balance;
+ int push_cpu;
+
+ task_t *migration_thread;
+ struct list_head migration_queue;
+#endif
+
+#ifdef CONFIG_SCHEDSTATS
+ /* latency stats */
+ struct sched_info rq_sched_info;
+
+ /* sys_sched_yield() stats */
+ unsigned long yld_exp_empty;
+ unsigned long yld_act_empty;
+ unsigned long yld_both_empty;
+ unsigned long yld_cnt;
+
+ /* schedule() stats */
+ unsigned long sched_switch;
+ unsigned long sched_cnt;
+ unsigned long sched_goidle;
+
+ /* try_to_wake_up() stats */
+ unsigned long ttwu_cnt;
+ unsigned long ttwu_local;
+#endif
+};
+
+static DEFINE_PER_CPU(struct runqueue, runqueues);
+
+#define for_each_domain(cpu, domain) \
+ for (domain = cpu_rq(cpu)->sd; domain; domain = domain->parent)
+
+#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
+#define this_rq() (&__get_cpu_var(runqueues))
+#define task_rq(p) cpu_rq(task_cpu(p))
+#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
+
+/*
+ * Default context-switch locking:
+ */
+#ifndef prepare_arch_switch
+# define prepare_arch_switch(rq, next) do { } while (0)
+# define finish_arch_switch(rq, next) spin_unlock_irq(&(rq)->lock)
+# define task_running(rq, p) ((rq)->curr == (p))
+#endif
+
+/*
+ * task_rq_lock - lock the runqueue a given task resides on and disable
+ * interrupts. Note the ordering: we can safely lookup the task_rq without
+ * explicitly disabling preemption.
+ */
+static inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
+ __acquires(rq->lock)
+{
+ struct runqueue *rq;
+
+repeat_lock_task:
+ local_irq_save(*flags);
+ rq = task_rq(p);
+ spin_lock(&rq->lock);
+ if (unlikely(rq != task_rq(p))) {
+ spin_unlock_irqrestore(&rq->lock, *flags);
+ goto repeat_lock_task;
+ }
+ return rq;
+}
+
+static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags)
+ __releases(rq->lock)
+{
+ spin_unlock_irqrestore(&rq->lock, *flags);
+}
+
+#ifdef CONFIG_SCHEDSTATS
+/*
+ * bump this up when changing the output format or the meaning of an existing
+ * format, so that tools can adapt (or abort)
+ */
+#define SCHEDSTAT_VERSION 11
+
+static int show_schedstat(struct seq_file *seq, void *v)
+{
+ int cpu;
+
+ seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
+ seq_printf(seq, "timestamp %lu\n", jiffies);
+ for_each_online_cpu(cpu) {
+ runqueue_t *rq = cpu_rq(cpu);
+#ifdef CONFIG_SMP
+ struct sched_domain *sd;
+ int dcnt = 0;
+#endif
+
+ /* runqueue-specific stats */
+ seq_printf(seq,
+ "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
+ cpu, rq->yld_both_empty,
+ rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt,
+ rq->sched_switch, rq->sched_cnt, rq->sched_goidle,
+ rq->ttwu_cnt, rq->ttwu_local,
+ rq->rq_sched_info.cpu_time,
+ rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);
+
+ seq_printf(seq, "\n");
+
+#ifdef CONFIG_SMP
+ /* domain-specific stats */
+ for_each_domain(cpu, sd) {
+ enum idle_type itype;
+ char mask_str[NR_CPUS];
+
+ cpumask_scnprintf(mask_str, NR_CPUS, sd->span);
+ seq_printf(seq, "domain%d %s", dcnt++, mask_str);
+ for (itype = SCHED_IDLE; itype < MAX_IDLE_TYPES;
+ itype++) {
+ seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu",
+ sd->lb_cnt[itype],
+ sd->lb_balanced[itype],
+ sd->lb_failed[itype],
+ sd->lb_imbalance[itype],
+ sd->lb_gained[itype],
+ sd->lb_hot_gained[itype],
+ sd->lb_nobusyq[itype],
+ sd->lb_nobusyg[itype]);
+ }
+ seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu\n",
+ sd->alb_cnt, sd->alb_failed, sd->alb_pushed,
+ sd->sbe_pushed, sd->sbe_attempts,
+ sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance);
+ }
+#endif
+ }
+ return 0;
+}
+
+static int schedstat_open(struct inode *inode, struct file *file)
+{
+ unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32);
+ char *buf = kmalloc(size, GFP_KERNEL);
+ struct seq_file *m;
+ int res;
+
+ if (!buf)
+ return -ENOMEM;
+ res = single_open(file, show_schedstat, NULL);
+ if (!res) {
+ m = file->private_data;
+ m->buf = buf;
+ m->size = size;
+ } else
+ kfree(buf);
+ return res;
+}
+
+struct file_operations proc_schedstat_operations = {
+ .open = schedstat_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+# define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
+# define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
+#else /* !CONFIG_SCHEDSTATS */
+# define schedstat_inc(rq, field) do { } while (0)
+# define schedstat_add(rq, field, amt) do { } while (0)
+#endif
+
+/*
+ * rq_lock - lock a given runqueue and disable interrupts.
+ */
+static inline runqueue_t *this_rq_lock(void)
+ __acquires(rq->lock)
+{
+ runqueue_t *rq;
+
+ local_irq_disable();
+ rq = this_rq();
+ spin_lock(&rq->lock);
+
+ return rq;
+}
+
+#ifdef CONFIG_SCHED_SMT
+static int cpu_and_siblings_are_idle(int cpu)
+{
+ int sib;
+ for_each_cpu_mask(sib, cpu_sibling_map[cpu]) {
+ if (idle_cpu(sib))
+ continue;
+ return 0;
+ }
+
+ return 1;
+}
+#else
+#define cpu_and_siblings_are_idle(A) idle_cpu(A)
+#endif
+
+#ifdef CONFIG_SCHEDSTATS
+/*
+ * Called when a process is dequeued from the active array and given
+ * the cpu. We should note that with the exception of interactive
+ * tasks, the expired queue will become the active queue after the active
+ * queue is empty, without explicitly dequeuing and requeuing tasks in the
+ * expired queue. (Interactive tasks may be requeued directly to the
+ * active queue, thus delaying tasks in the expired queue from running;
+ * see scheduler_tick()).
+ *
+ * This function is only called from sched_info_arrive(), rather than
+ * dequeue_task(). Even though a task may be queued and dequeued multiple
+ * times as it is shuffled about, we're really interested in knowing how
+ * long it was from the *first* time it was queued to the time that it
+ * finally hit a cpu.
+ */
+static inline void sched_info_dequeued(task_t *t)
+{
+ t->sched_info.last_queued = 0;
+}
+
+/*
+ * Called when a task finally hits the cpu. We can now calculate how
+ * long it was waiting to run. We also note when it began so that we
+ * can keep stats on how long its timeslice is.
+ */
+static inline void sched_info_arrive(task_t *t)
+{
+ unsigned long now = jiffies, diff = 0;
+ struct runqueue *rq = task_rq(t);
+
+ if (t->sched_info.last_queued)
+ diff = now - t->sched_info.last_queued;
+ sched_info_dequeued(t);
+ t->sched_info.run_delay += diff;
+ t->sched_info.last_arrival = now;
+ t->sched_info.pcnt++;
+
+ if (!rq)
+ return;
+
+ rq->rq_sched_info.run_delay += diff;
+ rq->rq_sched_info.pcnt++;
+}
+
+/*
+ * Called when a process is queued into either the active or expired
+ * array. The time is noted and later used to determine how long we
+ * had to wait for us to reach the cpu. Since the expired queue will
+ * become the active queue after active queue is empty, without dequeuing
+ * and requeuing any tasks, we are interested in queuing to either. It
+ * is unusual but not impossible for tasks to be dequeued and immediately
+ * requeued in the same or another array: this can happen in sched_yield(),
+ * set_user_nice(), and even load_balance() as it moves tasks from runqueue
+ * to runqueue.
+ *
+ * This function is only called from enqueue_task(), but also only updates
+ * the timestamp if it is already not set. It's assumed that
+ * sched_info_dequeued() will clear that stamp when appropriate.
+ */
+static inline void sched_info_queued(task_t *t)
+{
+ if (!t->sched_info.last_queued)
+ t->sched_info.last_queued = jiffies;
+}
+
+/*
+ * Called when a process ceases being the active-running process, either
+ * voluntarily or involuntarily. Now we can calculate how long we ran.
+ */
+static inline void sched_info_depart(task_t *t)
+{
+ struct runqueue *rq = task_rq(t);
+ unsigned long diff = jiffies - t->sched_info.last_arrival;
+
+ t->sched_info.cpu_time += diff;
+
+ if (rq)
+ rq->rq_sched_info.cpu_time += diff;
+}
+
+/*
+ * Called when tasks are switched involuntarily due, typically, to expiring
+ * their time slice. (This may also be called when switching to or from
+ * the idle task.) We are only called when prev != next.
+ */
+static inline void sched_info_switch(task_t *prev, task_t *next)
+{
+ struct runqueue *rq = task_rq(prev);
+
+ /*
+ * prev now departs the cpu. It's not interesting to record
+ * stats about how efficient we were at scheduling the idle
+ * process, however.
+ */
+ if (prev != rq->idle)
+ sched_info_depart(prev);
+
+ if (next != rq->idle)
+ sched_info_arrive(next);
+}
+#else
+#define sched_info_queued(t) do { } while (0)
+#define sched_info_switch(t, next) do { } while (0)
+#endif /* CONFIG_SCHEDSTATS */
+
+/*
+ * Adding/removing a task to/from a priority array:
+ */
+static void dequeue_task(struct task_struct *p, prio_array_t *array)
+{
+ array->nr_active--;
+ list_del(&p->run_list);
+ if (list_empty(array->queue + p->prio))
+ __clear_bit(p->prio, array->bitmap);
+}
+
+static void enqueue_task(struct task_struct *p, prio_array_t *array)
+{
+ sched_info_queued(p);
+ list_add_tail(&p->run_list, array->queue + p->prio);
+ __set_bit(p->prio, array->bitmap);
+ array->nr_active++;
+ p->array = array;
+}
+
+/*
+ * Put task to the end of the run list without the overhead of dequeue
+ * followed by enqueue.
+ */
+static void requeue_task(struct task_struct *p, prio_array_t *array)
+{
+ list_move_tail(&p->run_list, array->queue + p->prio);
+}
+
+static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array)
+{
+ list_add(&p->run_list, array->queue + p->prio);
+ __set_bit(p->prio, array->bitmap);
+ array->nr_active++;
+ p->array = array;
+}
+
+/*
+ * effective_prio - return the priority that is based on the static
+ * priority but is modified by bonuses/penalties.
+ *
+ * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
+ * into the -5 ... 0 ... +5 bonus/penalty range.
+ *
+ * We use 25% of the full 0...39 priority range so that:
+ *
+ * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
+ * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
+ *
+ * Both properties are important to certain workloads.
+ */
+static int effective_prio(task_t *p)
+{
+ int bonus, prio;
+
+ if (rt_task(p))
+ return p->prio;
+
+ bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
+
+ prio = p->static_prio - bonus;
+ if (prio < MAX_RT_PRIO)
+ prio = MAX_RT_PRIO;
+ if (prio > MAX_PRIO-1)
+ prio = MAX_PRIO-1;
+ return prio;
+}
+
+/*
+ * __activate_task - move a task to the runqueue.
+ */
+static inline void __activate_task(task_t *p, runqueue_t *rq)
+{
+ enqueue_task(p, rq->active);
+ rq->nr_running++;
+}
+
+/*
+ * __activate_idle_task - move idle task to the _front_ of runqueue.
+ */
+static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
+{
+ enqueue_task_head(p, rq->active);
+ rq->nr_running++;
+}
+
+static void recalc_task_prio(task_t *p, unsigned long long now)
+{
+ /* Caller must always ensure 'now >= p->timestamp' */
+ unsigned long long __sleep_time = now - p->timestamp;
+ unsigned long sleep_time;
+
+ if (__sleep_time > NS_MAX_SLEEP_AVG)
+ sleep_time = NS_MAX_SLEEP_AVG;
+ else
+ sleep_time = (unsigned long)__sleep_time;
+
+ if (likely(sleep_time > 0)) {
+ /*
+ * User tasks that sleep a long time are categorised as
+ * idle and will get just interactive status to stay active &
+ * prevent them suddenly becoming cpu hogs and starving
+ * other processes.
+ */
+ if (p->mm && p->activated != -1 &&
+ sleep_time > INTERACTIVE_SLEEP(p)) {
+ p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG -
+ DEF_TIMESLICE);
+ } else {
+ /*
+ * The lower the sleep avg a task has the more
+ * rapidly it will rise with sleep time.
+ */
+ sleep_time *= (MAX_BONUS - CURRENT_BONUS(p)) ? : 1;
+
+ /*
+ * Tasks waking from uninterruptible sleep are
+ * limited in their sleep_avg rise as they
+ * are likely to be waiting on I/O
+ */
+ if (p->activated == -1 && p->mm) {
+ if (p->sleep_avg >= INTERACTIVE_SLEEP(p))
+ sleep_time = 0;
+ else if (p->sleep_avg + sleep_time >=
+ INTERACTIVE_SLEEP(p)) {
+ p->sleep_avg = INTERACTIVE_SLEEP(p);
+ sleep_time = 0;
+ }
+ }
+
+ /*
+ * This code gives a bonus to interactive tasks.
+ *
+ * The boost works by updating the 'average sleep time'
+ * value here, based on ->timestamp. The more time a
+ * task spends sleeping, the higher the average gets -
+ * and the higher the priority boost gets as well.
+ */
+ p->sleep_avg += sleep_time;
+
+ if (p->sleep_avg > NS_MAX_SLEEP_AVG)
+ p->sleep_avg = NS_MAX_SLEEP_AVG;
+ }
+ }
+
+ p->prio = effective_prio(p);
+}
+
+/*
+ * activate_task - move a task to the runqueue and do priority recalculation
+ *
+ * Update all the scheduling statistics stuff. (sleep average
+ * calculation, priority modifiers, etc.)
+ */
+static void activate_task(task_t *p, runqueue_t *rq, int local)
+{
+ unsigned long long now;
+
+ now = sched_clock();
+#ifdef CONFIG_SMP
+ if (!local) {
+ /* Compensate for drifting sched_clock */
+ runqueue_t *this_rq = this_rq();
+ now = (now - this_rq->timestamp_last_tick)
+ + rq->timestamp_last_tick;
+ }
+#endif
+
+ recalc_task_prio(p, now);
+
+ /*
+ * This checks to make sure it's not an uninterruptible task
+ * that is now waking up.
+ */
+ if (!p->activated) {
+ /*
+ * Tasks which were woken up by interrupts (ie. hw events)
+ * are most likely of interactive nature. So we give them
+ * the credit of extending their sleep time to the period
+ * of time they spend on the runqueue, waiting for execution
+ * on a CPU, first time around:
+ */
+ if (in_interrupt())
+ p->activated = 2;
+ else {
+ /*
+ * Normal first-time wakeups get a credit too for
+ * on-runqueue time, but it will be weighted down:
+ */
+ p->activated = 1;
+ }
+ }
+ p->timestamp = now;
+
+ __activate_task(p, rq);
+}
+
+/*
+ * deactivate_task - remove a task from the runqueue.
+ */
+static void deactivate_task(struct task_struct *p, runqueue_t *rq)
+{
+ rq->nr_running--;
+ dequeue_task(p, p->array);
+ p->array = NULL;
+}
+
+/*
+ * resched_task - mark a task 'to be rescheduled now'.
+ *
+ * On UP this means the setting of the need_resched flag, on SMP it
+ * might also involve a cross-CPU call to trigger the scheduler on
+ * the target CPU.
+ */
+#ifdef CONFIG_SMP
+static void resched_task(task_t *p)
+{
+ int need_resched, nrpolling;
+
+ assert_spin_locked(&task_rq(p)->lock);
+
+ /* minimise the chance of sending an interrupt to poll_idle() */
+ nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
+ need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED);
+ nrpolling |= test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
+
+ if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id()))
+ smp_send_reschedule(task_cpu(p));
+}
+#else
+static inline void resched_task(task_t *p)
+{
+ set_tsk_need_resched(p);
+}
+#endif
+
+/**
+ * task_curr - is this task currently executing on a CPU?
+ * @p: the task in question.
+ */
+inline int task_curr(const task_t *p)
+{
+ return cpu_curr(task_cpu(p)) == p;
+}
+
+#ifdef CONFIG_SMP
+enum request_type {
+ REQ_MOVE_TASK,
+ REQ_SET_DOMAIN,
+};
+
+typedef struct {
+ struct list_head list;
+ enum request_type type;
+
+ /* For REQ_MOVE_TASK */
+ task_t *task;
+ int dest_cpu;
+
+ /* For REQ_SET_DOMAIN */
+ struct sched_domain *sd;
+
+ struct completion done;
+} migration_req_t;
+
+/*
+ * The task's runqueue lock must be held.
+ * Returns true if you have to wait for migration thread.
+ */
+static int migrate_task(task_t *p, int dest_cpu, migration_req_t *req)
+{
+ runqueue_t *rq = task_rq(p);
+
+ /*
+ * If the task is not on a runqueue (and not running), then
+ * it is sufficient to simply update the task's cpu field.
+ */
+ if (!p->array && !task_running(rq, p)) {
+ set_task_cpu(p, dest_cpu);
+ return 0;
+ }
+
+ init_completion(&req->done);
+ req->type = REQ_MOVE_TASK;
+ req->task = p;
+ req->dest_cpu = dest_cpu;
+ list_add(&req->list, &rq->migration_queue);
+ return 1;
+}
+
+/*
+ * wait_task_inactive - wait for a thread to unschedule.
+ *
+ * The caller must ensure that the task *will* unschedule sometime soon,
+ * else this function might spin for a *long* time. This function can't
+ * be called with interrupts off, or it may introduce deadlock with
+ * smp_call_function() if an IPI is sent by the same process we are
+ * waiting to become inactive.
+ */
+void wait_task_inactive(task_t * p)
+{
+ unsigned long flags;
+ runqueue_t *rq;
+ int preempted;
+
+repeat:
+ rq = task_rq_lock(p, &flags);
+ /* Must be off runqueue entirely, not preempted. */
+ if (unlikely(p->array || task_running(rq, p))) {
+ /* If it's preempted, we yield. It could be a while. */
+ preempted = !task_running(rq, p);
+ task_rq_unlock(rq, &flags);
+ cpu_relax();
+ if (preempted)
+ yield();
+ goto repeat;
+ }
+ task_rq_unlock(rq, &flags);
+}
+
+/***
+ * kick_process - kick a running thread to enter/exit the kernel
+ * @p: the to-be-kicked thread
+ *
+ * Cause a process which is running on another CPU to enter
+ * kernel-mode, without any delay. (to get signals handled.)
+ *
+ * NOTE: this function doesnt have to take the runqueue lock,
+ * because all it wants to ensure is that the remote task enters
+ * the kernel. If the IPI races and the task has been migrated
+ * to another CPU then no harm is done and the purpose has been
+ * achieved as well.
+ */
+void kick_process(task_t *p)
+{
+ int cpu;
+
+ preempt_disable();
+ cpu = task_cpu(p);
+ if ((cpu != smp_processor_id()) && task_curr(p))
+ smp_send_reschedule(cpu);
+ preempt_enable();
+}
+
+/*
+ * Return a low guess at the load of a migration-source cpu.
+ *
+ * We want to under-estimate the load of migration sources, to
+ * balance conservatively.
+ */
+static inline unsigned long source_load(int cpu)
+{
+ runqueue_t *rq = cpu_rq(cpu);
+ unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+
+ return min(rq->cpu_load, load_now);
+}
+
+/*
+ * Return a high guess at the load of a migration-target cpu
+ */
+static inline unsigned long target_load(int cpu)
+{
+ runqueue_t *rq = cpu_rq(cpu);
+ unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+
+ return max(rq->cpu_load, load_now);
+}
+
+#endif
+
+/*
+ * wake_idle() will wake a task on an idle cpu if task->cpu is
+ * not idle and an idle cpu is available. The span of cpus to
+ * search starts with cpus closest then further out as needed,
+ * so we always favor a closer, idle cpu.
+ *
+ * Returns the CPU we should wake onto.
+ */
+#if defined(ARCH_HAS_SCHED_WAKE_IDLE)
+static int wake_idle(int cpu, task_t *p)
+{
+ cpumask_t tmp;
+ struct sched_domain *sd;
+ int i;
+
+ if (idle_cpu(cpu))
+ return cpu;
+
+ for_each_domain(cpu, sd) {
+ if (sd->flags & SD_WAKE_IDLE) {
+ cpus_and(tmp, sd->span, cpu_online_map);
+ cpus_and(tmp, tmp, p->cpus_allowed);
+ for_each_cpu_mask(i, tmp) {
+ if (idle_cpu(i))
+ return i;
+ }
+ }
+ else break;
+ }
+ return cpu;
+}
+#else
+static inline int wake_idle(int cpu, task_t *p)
+{
+ return cpu;
+}
+#endif
+
+/***
+ * try_to_wake_up - wake up a thread
+ * @p: the to-be-woken-up thread
+ * @state: the mask of task states that can be woken
+ * @sync: do a synchronous wakeup?
+ *
+ * Put it on the run-queue if it's not already there. The "current"
+ * thread is always on the run-queue (except when the actual
+ * re-schedule is in progress), and as such you're allowed to do
+ * the simpler "current->state = TASK_RUNNING" to mark yourself
+ * runnable without the overhead of this.
+ *
+ * returns failure only if the task is already active.
+ */
+static int try_to_wake_up(task_t * p, unsigned int state, int sync)
+{
+ int cpu, this_cpu, success = 0;
+ unsigned long flags;
+ long old_state;
+ runqueue_t *rq;
+#ifdef CONFIG_SMP
+ unsigned long load, this_load;
+ struct sched_domain *sd;
+ int new_cpu;
+#endif
+
+ rq = task_rq_lock(p, &flags);
+ old_state = p->state;
+ if (!(old_state & state))
+ goto out;
+
+ if (p->array)
+ goto out_running;
+
+ cpu = task_cpu(p);
+ this_cpu = smp_processor_id();
+
+#ifdef CONFIG_SMP
+ if (unlikely(task_running(rq, p)))
+ goto out_activate;
+
+#ifdef CONFIG_SCHEDSTATS
+ schedstat_inc(rq, ttwu_cnt);
+ if (cpu == this_cpu) {
+ schedstat_inc(rq, ttwu_local);
+ } else {
+ for_each_domain(this_cpu, sd) {
+ if (cpu_isset(cpu, sd->span)) {
+ schedstat_inc(sd, ttwu_wake_remote);
+ break;
+ }
+ }
+ }
+#endif
+
+ new_cpu = cpu;
+ if (cpu == this_cpu || unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
+ goto out_set_cpu;
+
+ load = source_load(cpu);
+ this_load = target_load(this_cpu);
+
+ /*
+ * If sync wakeup then subtract the (maximum possible) effect of
+ * the currently running task from the load of the current CPU:
+ */
+ if (sync)
+ this_load -= SCHED_LOAD_SCALE;
+
+ /* Don't pull the task off an idle CPU to a busy one */
+ if (load < SCHED_LOAD_SCALE/2 && this_load > SCHED_LOAD_SCALE/2)
+ goto out_set_cpu;
+
+ new_cpu = this_cpu; /* Wake to this CPU if we can */
+
+ /*
+ * Scan domains for affine wakeup and passive balancing
+ * possibilities.
+ */
+ for_each_domain(this_cpu, sd) {
+ unsigned int imbalance;
+ /*
+ * Start passive balancing when half the imbalance_pct
+ * limit is reached.
+ */
+ imbalance = sd->imbalance_pct + (sd->imbalance_pct - 100) / 2;
+
+ if ((sd->flags & SD_WAKE_AFFINE) &&
+ !task_hot(p, rq->timestamp_last_tick, sd)) {
+ /*
+ * This domain has SD_WAKE_AFFINE and p is cache cold
+ * in this domain.
+ */
+ if (cpu_isset(cpu, sd->span)) {
+ schedstat_inc(sd, ttwu_move_affine);
+ goto out_set_cpu;
+ }
+ } else if ((sd->flags & SD_WAKE_BALANCE) &&
+ imbalance*this_load <= 100*load) {
+ /*
+ * This domain has SD_WAKE_BALANCE and there is
+ * an imbalance.
+ */
+ if (cpu_isset(cpu, sd->span)) {
+ schedstat_inc(sd, ttwu_move_balance);
+ goto out_set_cpu;
+ }
+ }
+ }
+
+ new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
+out_set_cpu:
+ new_cpu = wake_idle(new_cpu, p);
+ if (new_cpu != cpu) {
+ set_task_cpu(p, new_cpu);
+ task_rq_unlock(rq, &flags);
+ /* might preempt at this point */
+ rq = task_rq_lock(p, &flags);
+ old_state = p->state;
+ if (!(old_state & state))
+ goto out;
+ if (p->array)
+ goto out_running;
+
+ this_cpu = smp_processor_id();
+ cpu = task_cpu(p);
+ }
+
+out_activate:
+#endif /* CONFIG_SMP */
+ if (old_state == TASK_UNINTERRUPTIBLE) {
+ rq->nr_uninterruptible--;
+ /*
+ * Tasks on involuntary sleep don't earn
+ * sleep_avg beyond just interactive state.
+ */
+ p->activated = -1;
+ }
+
+ /*
+ * Sync wakeups (i.e. those types of wakeups where the waker
+ * has indicated that it will leave the CPU in short order)
+ * don't trigger a preemption, if the woken up task will run on
+ * this cpu. (in this case the 'I will reschedule' promise of
+ * the waker guarantees that the freshly woken up task is going
+ * to be considered on this CPU.)
+ */
+ activate_task(p, rq, cpu == this_cpu);
+ if (!sync || cpu != this_cpu) {
+ if (TASK_PREEMPTS_CURR(p, rq))
+ resched_task(rq->curr);
+ }
+ success = 1;
+
+out_running:
+ p->state = TASK_RUNNING;
+out:
+ task_rq_unlock(rq, &flags);
+
+ return success;
+}
+
+int fastcall wake_up_process(task_t * p)
+{
+ return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
+ TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
+}
+
+EXPORT_SYMBOL(wake_up_process);
+
+int fastcall wake_up_state(task_t *p, unsigned int state)
+{
+ return try_to_wake_up(p, state, 0);
+}
+
+#ifdef CONFIG_SMP
+static int find_idlest_cpu(struct task_struct *p, int this_cpu,
+ struct sched_domain *sd);
+#endif
+
+/*
+ * Perform scheduler related setup for a newly forked process p.
+ * p is forked by current.
+ */
+void fastcall sched_fork(task_t *p)
+{
+ /*
+ * We mark the process as running here, but have not actually
+ * inserted it onto the runqueue yet. This guarantees that
+ * nobody will actually run it, and a signal or other external
+ * event cannot wake it up and insert it on the runqueue either.
+ */
+ p->state = TASK_RUNNING;
+ INIT_LIST_HEAD(&p->run_list);
+ p->array = NULL;
+ spin_lock_init(&p->switch_lock);
+#ifdef CONFIG_SCHEDSTATS
+ memset(&p->sched_info, 0, sizeof(p->sched_info));
+#endif
+#ifdef CONFIG_PREEMPT
+ /*
+ * During context-switch we hold precisely one spinlock, which
+ * schedule_tail drops. (in the common case it's this_rq()->lock,
+ * but it also can be p->switch_lock.) So we compensate with a count
+ * of 1. Also, we want to start with kernel preemption disabled.
+ */
+ p->thread_info->preempt_count = 1;
+#endif
+ /*
+ * Share the timeslice between parent and child, thus the
+ * total amount of pending timeslices in the system doesn't change,
+ * resulting in more scheduling fairness.
+ */
+ local_irq_disable();
+ p->time_slice = (current->time_slice + 1) >> 1;
+ /*
+ * The remainder of the first timeslice might be recovered by
+ * the parent if the child exits early enough.
+ */
+ p->first_time_slice = 1;
+ current->time_slice >>= 1;
+ p->timestamp = sched_clock();
+ if (unlikely(!current->time_slice)) {
+ /*
+ * This case is rare, it happens when the parent has only
+ * a single jiffy left from its timeslice. Taking the
+ * runqueue lock is not a problem.
+ */
+ current->time_slice = 1;
+ preempt_disable();
+ scheduler_tick();
+ local_irq_enable();
+ preempt_enable();
+ } else
+ local_irq_enable();
+}
+
+/*
+ * wake_up_new_task - wake up a newly created task for the first time.
+ *
+ * This function will do some initial scheduler statistics housekeeping
+ * that must be done for every newly created context, then puts the task
+ * on the runqueue and wakes it.
+ */
+void fastcall wake_up_new_task(task_t * p, unsigned long clone_flags)
+{
+ unsigned long flags;
+ int this_cpu, cpu;
+ runqueue_t *rq, *this_rq;
+
+ rq = task_rq_lock(p, &flags);
+ cpu = task_cpu(p);
+ this_cpu = smp_processor_id();
+
+ BUG_ON(p->state != TASK_RUNNING);
+
+ /*
+ * We decrease the sleep average of forking parents
+ * and children as well, to keep max-interactive tasks
+ * from forking tasks that are max-interactive. The parent
+ * (current) is done further down, under its lock.
+ */
+ p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
+ CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
+
+ p->prio = effective_prio(p);
+
+ if (likely(cpu == this_cpu)) {
+ if (!(clone_flags & CLONE_VM)) {
+ /*
+ * The VM isn't cloned, so we're in a good position to
+ * do child-runs-first in anticipation of an exec. This
+ * usually avoids a lot of COW overhead.
+ */
+ if (unlikely(!current->array))
+ __activate_task(p, rq);
+ else {
+ p->prio = current->prio;
+ list_add_tail(&p->run_list, ¤t->run_list);
+ p->array = current->array;
+ p->array->nr_active++;
+ rq->nr_running++;
+ }
+ set_need_resched();
+ } else
+ /* Run child last */
+ __activate_task(p, rq);
+ /*
+ * We skip the following code due to cpu == this_cpu
+ *
+ * task_rq_unlock(rq, &flags);
+ * this_rq = task_rq_lock(current, &flags);
+ */
+ this_rq = rq;
+ } else {
+ this_rq = cpu_rq(this_cpu);
+
+ /*
+ * Not the local CPU - must adjust timestamp. This should
+ * get optimised away in the !CONFIG_SMP case.
+ */
+ p->timestamp = (p->timestamp - this_rq->timestamp_last_tick)
+ + rq->timestamp_last_tick;
+ __activate_task(p, rq);
+ if (TASK_PREEMPTS_CURR(p, rq))
+ resched_task(rq->curr);
+
+ /*
+ * Parent and child are on different CPUs, now get the
+ * parent runqueue to update the parent's ->sleep_avg:
+ */
+ task_rq_unlock(rq, &flags);
+ this_rq = task_rq_lock(current, &flags);
+ }
+ current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
+ PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
+ task_rq_unlock(this_rq, &flags);
+}
+
+/*
+ * Potentially available exiting-child timeslices are
+ * retrieved here - this way the parent does not get
+ * penalized for creating too many threads.
+ *
+ * (this cannot be used to 'generate' timeslices
+ * artificially, because any timeslice recovered here
+ * was given away by the parent in the first place.)
+ */
+void fastcall sched_exit(task_t * p)
+{
+ unsigned long flags;
+ runqueue_t *rq;
+
+ /*
+ * If the child was a (relative-) CPU hog then decrease
+ * the sleep_avg of the parent as well.
+ */
+ rq = task_rq_lock(p->parent, &flags);
+ if (p->first_time_slice) {
+ p->parent->time_slice += p->time_slice;
+ if (unlikely(p->parent->time_slice > task_timeslice(p)))
+ p->parent->time_slice = task_timeslice(p);
+ }
+ if (p->sleep_avg < p->parent->sleep_avg)
+ p->parent->sleep_avg = p->parent->sleep_avg /
+ (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
+ (EXIT_WEIGHT + 1);
+ task_rq_unlock(rq, &flags);
+}
+
+/**
+ * finish_task_switch - clean up after a task-switch
+ * @prev: the thread we just switched away from.
+ *
+ * We enter this with the runqueue still locked, and finish_arch_switch()
+ * will unlock it along with doing any other architecture-specific cleanup
+ * actions.
+ *
+ * Note that we may have delayed dropping an mm in context_switch(). If
+ * so, we finish that here outside of the runqueue lock. (Doing it
+ * with the lock held can cause deadlocks; see schedule() for
+ * details.)
+ */
+static inline void finish_task_switch(task_t *prev)
+ __releases(rq->lock)
+{
+ runqueue_t *rq = this_rq();
+ struct mm_struct *mm = rq->prev_mm;
+ unsigned long prev_task_flags;
+
+ rq->prev_mm = NULL;
+
+ /*
+ * A task struct has one reference for the use as "current".
+ * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
+ * calls schedule one last time. The schedule call will never return,
+ * and the scheduled task must drop that reference.
+ * The test for EXIT_ZOMBIE must occur while the runqueue locks are
+ * still held, otherwise prev could be scheduled on another cpu, die
+ * there before we look at prev->state, and then the reference would
+ * be dropped twice.
+ * Manfred Spraul <manfred@colorfullife.com>
+ */
+ prev_task_flags = prev->flags;
+ finish_arch_switch(rq, prev);
+ if (mm)
+ mmdrop(mm);
+ if (unlikely(prev_task_flags & PF_DEAD))
+ put_task_struct(prev);
+}
+
+/**
+ * schedule_tail - first thing a freshly forked thread must call.
+ * @prev: the thread we just switched away from.
+ */
+asmlinkage void schedule_tail(task_t *prev)
+ __releases(rq->lock)
+{
+ finish_task_switch(prev);
+
+ if (current->set_child_tid)
+ put_user(current->pid, current->set_child_tid);
+}
+
+/*
+ * context_switch - switch to the new MM and the new
+ * thread's register state.
+ */
+static inline
+task_t * context_switch(runqueue_t *rq, task_t *prev, task_t *next)
+{
+ struct mm_struct *mm = next->mm;
+ struct mm_struct *oldmm = prev->active_mm;
+
+ if (unlikely(!mm)) {
+ next->active_mm = oldmm;
+ atomic_inc(&oldmm->mm_count);
+ enter_lazy_tlb(oldmm, next);
+ } else
+ switch_mm(oldmm, mm, next);
+
+ if (unlikely(!prev->mm)) {
+ prev->active_mm = NULL;
+ WARN_ON(rq->prev_mm);
+ rq->prev_mm = oldmm;
+ }
+
+ /* Here we just switch the register state and the stack. */
+ switch_to(prev, next, prev);
+
+ return prev;
+}
+
+/*
+ * nr_running, nr_uninterruptible and nr_context_switches:
+ *
+ * externally visible scheduler statistics: current number of runnable
+ * threads, current number of uninterruptible-sleeping threads, total
+ * number of context switches performed since bootup.
+ */
+unsigned long nr_running(void)
+{
+ unsigned long i, sum = 0;
+
+ for_each_online_cpu(i)
+ sum += cpu_rq(i)->nr_running;
+
+ return sum;
+}
+
+unsigned long nr_uninterruptible(void)
+{
+ unsigned long i, sum = 0;
+
+ for_each_cpu(i)
+ sum += cpu_rq(i)->nr_uninterruptible;
+
+ /*
+ * Since we read the counters lockless, it might be slightly
+ * inaccurate. Do not allow it to go below zero though:
+ */
+ if (unlikely((long)sum < 0))
+ sum = 0;
+
+ return sum;
+}
+
+unsigned long long nr_context_switches(void)
+{
+ unsigned long long i, sum = 0;
+
+ for_each_cpu(i)
+ sum += cpu_rq(i)->nr_switches;
+
+ return sum;
+}
+
+unsigned long nr_iowait(void)
+{
+ unsigned long i, sum = 0;
+
+ for_each_cpu(i)
+ sum += atomic_read(&cpu_rq(i)->nr_iowait);
+
+ return sum;
+}
+
+#ifdef CONFIG_SMP
+
+/*
+ * double_rq_lock - safely lock two runqueues
+ *
+ * Note this does not disable interrupts like task_rq_lock,
+ * you need to do so manually before calling.
+ */
+static void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
+ __acquires(rq1->lock)
+ __acquires(rq2->lock)
+{
+ if (rq1 == rq2) {
+ spin_lock(&rq1->lock);
+ __acquire(rq2->lock); /* Fake it out ;) */
+ } else {
+ if (rq1 < rq2) {
+ spin_lock(&rq1->lock);
+ spin_lock(&rq2->lock);
+ } else {
+ spin_lock(&rq2->lock);
+ spin_lock(&rq1->lock);
+ }
+ }
+}
+
+/*
+ * double_rq_unlock - safely unlock two runqueues
+ *
+ * Note this does not restore interrupts like task_rq_unlock,
+ * you need to do so manually after calling.
+ */
+static void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
+ __releases(rq1->lock)
+ __releases(rq2->lock)
+{
+ spin_unlock(&rq1->lock);
+ if (rq1 != rq2)
+ spin_unlock(&rq2->lock);
+ else
+ __release(rq2->lock);
+}
+
+/*
+ * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
+ */
+static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest)
+ __releases(this_rq->lock)
+ __acquires(busiest->lock)
+ __acquires(this_rq->lock)
+{
+ if (unlikely(!spin_trylock(&busiest->lock))) {
+ if (busiest < this_rq) {
+ spin_unlock(&this_rq->lock);
+ spin_lock(&busiest->lock);
+ spin_lock(&this_rq->lock);
+ } else
+ spin_lock(&busiest->lock);
+ }
+}
+
+/*
+ * find_idlest_cpu - find the least busy runqueue.
+ */
+static int find_idlest_cpu(struct task_struct *p, int this_cpu,
+ struct sched_domain *sd)
+{
+ unsigned long load, min_load, this_load;
+ int i, min_cpu;
+ cpumask_t mask;
+
+ min_cpu = UINT_MAX;
+ min_load = ULONG_MAX;
+
+ cpus_and(mask, sd->span, p->cpus_allowed);
+
+ for_each_cpu_mask(i, mask) {
+ load = target_load(i);
+
+ if (load < min_load) {
+ min_cpu = i;
+ min_load = load;
+
+ /* break out early on an idle CPU: */
+ if (!min_load)
+ break;
+ }
+ }
+
+ /* add +1 to account for the new task */
+ this_load = source_load(this_cpu) + SCHED_LOAD_SCALE;
+
+ /*
+ * Would with the addition of the new task to the
+ * current CPU there be an imbalance between this
+ * CPU and the idlest CPU?
+ *
+ * Use half of the balancing threshold - new-context is
+ * a good opportunity to balance.
+ */
+ if (min_load*(100 + (sd->imbalance_pct-100)/2) < this_load*100)
+ return min_cpu;
+
+ return this_cpu;
+}
+
+/*
+ * If dest_cpu is allowed for this process, migrate the task to it.
+ * This is accomplished by forcing the cpu_allowed mask to only
+ * allow dest_cpu, which will force the cpu onto dest_cpu. Then
+ * the cpu_allowed mask is restored.
+ */
+static void sched_migrate_task(task_t *p, int dest_cpu)
+{
+ migration_req_t req;
+ runqueue_t *rq;
+ unsigned long flags;
+
+ rq = task_rq_lock(p, &flags);
+ if (!cpu_isset(dest_cpu, p->cpus_allowed)
+ || unlikely(cpu_is_offline(dest_cpu)))
+ goto out;
+
+ /* force the process onto the specified CPU */
+ if (migrate_task(p, dest_cpu, &req)) {
+ /* Need to wait for migration thread (might exit: take ref). */
+ struct task_struct *mt = rq->migration_thread;
+ get_task_struct(mt);
+ task_rq_unlock(rq, &flags);
+ wake_up_process(mt);
+ put_task_struct(mt);
+ wait_for_completion(&req.done);
+ return;
+ }
+out:
+ task_rq_unlock(rq, &flags);
+}
+
+/*
+ * sched_exec(): find the highest-level, exec-balance-capable
+ * domain and try to migrate the task to the least loaded CPU.
+ *
+ * execve() is a valuable balancing opportunity, because at this point
+ * the task has the smallest effective memory and cache footprint.
+ */
+void sched_exec(void)
+{
+ struct sched_domain *tmp, *sd = NULL;
+ int new_cpu, this_cpu = get_cpu();
+
+ /* Prefer the current CPU if there's only this task running */
+ if (this_rq()->nr_running <= 1)
+ goto out;
+
+ for_each_domain(this_cpu, tmp)
+ if (tmp->flags & SD_BALANCE_EXEC)
+ sd = tmp;
+
+ if (sd) {
+ schedstat_inc(sd, sbe_attempts);
+ new_cpu = find_idlest_cpu(current, this_cpu, sd);
+ if (new_cpu != this_cpu) {
+ schedstat_inc(sd, sbe_pushed);
+ put_cpu();
+ sched_migrate_task(current, new_cpu);
+ return;
+ }
+ }
+out:
+ put_cpu();
+}
+
+/*
+ * pull_task - move a task from a remote runqueue to the local runqueue.
+ * Both runqueues must be locked.
+ */
+static inline
+void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p,
+ runqueue_t *this_rq, prio_array_t *this_array, int this_cpu)
+{
+ dequeue_task(p, src_array);
+ src_rq->nr_running--;
+ set_task_cpu(p, this_cpu);
+ this_rq->nr_running++;
+ enqueue_task(p, this_array);
+ p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
+ + this_rq->timestamp_last_tick;
+ /*
+ * Note that idle threads have a prio of MAX_PRIO, for this test
+ * to be always true for them.
+ */
+ if (TASK_PREEMPTS_CURR(p, this_rq))
+ resched_task(this_rq->curr);
+}
+
+/*
+ * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
+ */
+static inline
+int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
+ struct sched_domain *sd, enum idle_type idle)
+{
+ /*
+ * We do not migrate tasks that are:
+ * 1) running (obviously), or
+ * 2) cannot be migrated to this CPU due to cpus_allowed, or
+ * 3) are cache-hot on their current CPU.
+ */
+ if (task_running(rq, p))
+ return 0;
+ if (!cpu_isset(this_cpu, p->cpus_allowed))
+ return 0;
+
+ /*
+ * Aggressive migration if:
+ * 1) the [whole] cpu is idle, or
+ * 2) too many balance attempts have failed.
+ */
+
+ if (cpu_and_siblings_are_idle(this_cpu) || \
+ sd->nr_balance_failed > sd->cache_nice_tries)
+ return 1;
+
+ if (task_hot(p, rq->timestamp_last_tick, sd))
+ return 0;
+ return 1;
+}
+
+/*
+ * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
+ * as part of a balancing operation within "domain". Returns the number of
+ * tasks moved.
+ *
+ * Called with both runqueues locked.
+ */
+static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
+ unsigned long max_nr_move, struct sched_domain *sd,
+ enum idle_type idle)
+{
+ prio_array_t *array, *dst_array;
+ struct list_head *head, *curr;
+ int idx, pulled = 0;
+ task_t *tmp;
+
+ if (max_nr_move <= 0 || busiest->nr_running <= 1)
+ goto out;
+
+ /*
+ * We first consider expired tasks. Those will likely not be
+ * executed in the near future, and they are most likely to
+ * be cache-cold, thus switching CPUs has the least effect
+ * on them.
+ */
+ if (busiest->expired->nr_active) {
+ array = busiest->expired;
+ dst_array = this_rq->expired;
+ } else {
+ array = busiest->active;
+ dst_array = this_rq->active;
+ }
+
+new_array:
+ /* Start searching at priority 0: */
+ idx = 0;
+skip_bitmap:
+ if (!idx)
+ idx = sched_find_first_bit(array->bitmap);
+ else
+ idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
+ if (idx >= MAX_PRIO) {
+ if (array == busiest->expired && busiest->active->nr_active) {
+ array = busiest->active;
+ dst_array = this_rq->active;
+ goto new_array;
+ }
+ goto out;
+ }
+
+ head = array->queue + idx;
+ curr = head->prev;
+skip_queue:
+ tmp = list_entry(curr, task_t, run_list);
+
+ curr = curr->prev;
+
+ if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle)) {
+ if (curr != head)
+ goto skip_queue;
+ idx++;
+ goto skip_bitmap;
+ }
+
+#ifdef CONFIG_SCHEDSTATS
+ if (task_hot(tmp, busiest->timestamp_last_tick, sd))
+ schedstat_inc(sd, lb_hot_gained[idle]);
+#endif
+
+ pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
+ pulled++;
+
+ /* We only want to steal up to the prescribed number of tasks. */
+ if (pulled < max_nr_move) {
+ if (curr != head)
+ goto skip_queue;
+ idx++;
+ goto skip_bitmap;
+ }
+out:
+ /*
+ * Right now, this is the only place pull_task() is called,
+ * so we can safely collect pull_task() stats here rather than
+ * inside pull_task().
+ */
+ schedstat_add(sd, lb_gained[idle], pulled);
+ return pulled;
+}
+
+/*
+ * find_busiest_group finds and returns the busiest CPU group within the
+ * domain. It calculates and returns the number of tasks which should be
+ * moved to restore balance via the imbalance parameter.
+ */
+static struct sched_group *
+find_busiest_group(struct sched_domain *sd, int this_cpu,
+ unsigned long *imbalance, enum idle_type idle)
+{
+ struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
+ unsigned long max_load, avg_load, total_load, this_load, total_pwr;
+
+ max_load = this_load = total_load = total_pwr = 0;
+
+ do {
+ unsigned long load;
+ int local_group;
+ int i;
+
+ local_group = cpu_isset(this_cpu, group->cpumask);
+
+ /* Tally up the load of all CPUs in the group */
+ avg_load = 0;
+
+ for_each_cpu_mask(i, group->cpumask) {
+ /* Bias balancing toward cpus of our domain */
+ if (local_group)
+ load = target_load(i);
+ else
+ load = source_load(i);
+
+ avg_load += load;
+ }
+
+ total_load += avg_load;
+ total_pwr += group->cpu_power;
+
+ /* Adjust by relative CPU power of the group */
+ avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
+
+ if (local_group) {
+ this_load = avg_load;
+ this = group;
+ goto nextgroup;
+ } else if (avg_load > max_load) {
+ max_load = avg_load;
+ busiest = group;
+ }
+nextgroup:
+ group = group->next;
+ } while (group != sd->groups);
+
+ if (!busiest || this_load >= max_load)
+ goto out_balanced;
+
+ avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
+
+ if (this_load >= avg_load ||
+ 100*max_load <= sd->imbalance_pct*this_load)
+ goto out_balanced;
+
+ /*
+ * We're trying to get all the cpus to the average_load, so we don't
+ * want to push ourselves above the average load, nor do we wish to
+ * reduce the max loaded cpu below the average load, as either of these
+ * actions would just result in more rebalancing later, and ping-pong
+ * tasks around. Thus we look for the minimum possible imbalance.
+ * Negative imbalances (*we* are more loaded than anyone else) will
+ * be counted as no imbalance for these purposes -- we can't fix that
+ * by pulling tasks to us. Be careful of negative numbers as they'll
+ * appear as very large values with unsigned longs.
+ */
+ /* How much load to actually move to equalise the imbalance */
+ *imbalance = min((max_load - avg_load) * busiest->cpu_power,
+ (avg_load - this_load) * this->cpu_power)
+ / SCHED_LOAD_SCALE;
+
+ if (*imbalance < SCHED_LOAD_SCALE) {
+ unsigned long pwr_now = 0, pwr_move = 0;
+ unsigned long tmp;
+
+ if (max_load - this_load >= SCHED_LOAD_SCALE*2) {
+ *imbalance = 1;
+ return busiest;
+ }
+
+ /*
+ * OK, we don't have enough imbalance to justify moving tasks,
+ * however we may be able to increase total CPU power used by
+ * moving them.
+ */
+
+ pwr_now += busiest->cpu_power*min(SCHED_LOAD_SCALE, max_load);
+ pwr_now += this->cpu_power*min(SCHED_LOAD_SCALE, this_load);
+ pwr_now /= SCHED_LOAD_SCALE;
+
+ /* Amount of load we'd subtract */
+ tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/busiest->cpu_power;
+ if (max_load > tmp)
+ pwr_move += busiest->cpu_power*min(SCHED_LOAD_SCALE,
+ max_load - tmp);
+
+ /* Amount of load we'd add */
+ if (max_load*busiest->cpu_power <
+ SCHED_LOAD_SCALE*SCHED_LOAD_SCALE)
+ tmp = max_load*busiest->cpu_power/this->cpu_power;
+ else
+ tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power;
+ pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp);
+ pwr_move /= SCHED_LOAD_SCALE;
+
+ /* Move if we gain throughput */
+ if (pwr_move <= pwr_now)
+ goto out_balanced;
+
+ *imbalance = 1;
+ return busiest;
+ }
+
+ /* Get rid of the scaling factor, rounding down as we divide */
+ *imbalance = *imbalance / SCHED_LOAD_SCALE;
+
+ return busiest;
+
+out_balanced:
+ if (busiest && (idle == NEWLY_IDLE ||
+ (idle == SCHED_IDLE && max_load > SCHED_LOAD_SCALE)) ) {
+ *imbalance = 1;
+ return busiest;
+ }
+
+ *imbalance = 0;
+ return NULL;
+}
+
+/*
+ * find_busiest_queue - find the busiest runqueue among the cpus in group.
+ */
+static runqueue_t *find_busiest_queue(struct sched_group *group)
+{
+ unsigned long load, max_load = 0;
+ runqueue_t *busiest = NULL;
+ int i;
+
+ for_each_cpu_mask(i, group->cpumask) {
+ load = source_load(i);
+
+ if (load > max_load) {
+ max_load = load;
+ busiest = cpu_rq(i);
+ }
+ }
+
+ return busiest;
+}
+
+/*
+ * Check this_cpu to ensure it is balanced within domain. Attempt to move
+ * tasks if there is an imbalance.
+ *
+ * Called with this_rq unlocked.
+ */
+static int load_balance(int this_cpu, runqueue_t *this_rq,
+ struct sched_domain *sd, enum idle_type idle)
+{
+ struct sched_group *group;
+ runqueue_t *busiest;
+ unsigned long imbalance;
+ int nr_moved;
+
+ spin_lock(&this_rq->lock);
+ schedstat_inc(sd, lb_cnt[idle]);
+
+ group = find_busiest_group(sd, this_cpu, &imbalance, idle);
+ if (!group) {
+ schedstat_inc(sd, lb_nobusyg[idle]);
+ goto out_balanced;
+ }
+
+ busiest = find_busiest_queue(group);
+ if (!busiest) {
+ schedstat_inc(sd, lb_nobusyq[idle]);
+ goto out_balanced;
+ }
+
+ /*
+ * This should be "impossible", but since load
+ * balancing is inherently racy and statistical,
+ * it could happen in theory.
+ */
+ if (unlikely(busiest == this_rq)) {
+ WARN_ON(1);
+ goto out_balanced;
+ }
+
+ schedstat_add(sd, lb_imbalance[idle], imbalance);
+
+ nr_moved = 0;
+ if (busiest->nr_running > 1) {
+ /*
+ * Attempt to move tasks. If find_busiest_group has found
+ * an imbalance but busiest->nr_running <= 1, the group is
+ * still unbalanced. nr_moved simply stays zero, so it is
+ * correctly treated as an imbalance.
+ */
+ double_lock_balance(this_rq, busiest);
+ nr_moved = move_tasks(this_rq, this_cpu, busiest,
+ imbalance, sd, idle);
+ spin_unlock(&busiest->lock);
+ }
+ spin_unlock(&this_rq->lock);
+
+ if (!nr_moved) {
+ schedstat_inc(sd, lb_failed[idle]);
+ sd->nr_balance_failed++;
+
+ if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
+ int wake = 0;
+
+ spin_lock(&busiest->lock);
+ if (!busiest->active_balance) {
+ busiest->active_balance = 1;
+ busiest->push_cpu = this_cpu;
+ wake = 1;
+ }
+ spin_unlock(&busiest->lock);
+ if (wake)
+ wake_up_process(busiest->migration_thread);
+
+ /*
+ * We've kicked active balancing, reset the failure
+ * counter.
+ */
+ sd->nr_balance_failed = sd->cache_nice_tries;
+ }
+
+ /*
+ * We were unbalanced, but unsuccessful in move_tasks(),
+ * so bump the balance_interval to lessen the lock contention.
+ */
+ if (sd->balance_interval < sd->max_interval)
+ sd->balance_interval++;
+ } else {
+ sd->nr_balance_failed = 0;
+
+ /* We were unbalanced, so reset the balancing interval */
+ sd->balance_interval = sd->min_interval;
+ }
+
+ return nr_moved;
+
+out_balanced:
+ spin_unlock(&this_rq->lock);
+
+ schedstat_inc(sd, lb_balanced[idle]);
+
+ /* tune up the balancing interval */
+ if (sd->balance_interval < sd->max_interval)
+ sd->balance_interval *= 2;
+
+ return 0;
+}
+
+/*
+ * Check this_cpu to ensure it is balanced within domain. Attempt to move
+ * tasks if there is an imbalance.
+ *
+ * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
+ * this_rq is locked.
+ */
+static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
+ struct sched_domain *sd)
+{
+ struct sched_group *group;
+ runqueue_t *busiest = NULL;
+ unsigned long imbalance;
+ int nr_moved = 0;
+
+ schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
+ group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE);
+ if (!group) {
+ schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
+ schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
+ goto out;
+ }
+
+ busiest = find_busiest_queue(group);
+ if (!busiest || busiest == this_rq) {
+ schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
+ schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
+ goto out;
+ }
+
+ /* Attempt to move tasks */
+ double_lock_balance(this_rq, busiest);
+
+ schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
+ nr_moved = move_tasks(this_rq, this_cpu, busiest,
+ imbalance, sd, NEWLY_IDLE);
+ if (!nr_moved)
+ schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
+
+ spin_unlock(&busiest->lock);
+
+out:
+ return nr_moved;
+}
+
+/*
+ * idle_balance is called by schedule() if this_cpu is about to become
+ * idle. Attempts to pull tasks from other CPUs.
+ */
+static inline void idle_balance(int this_cpu, runqueue_t *this_rq)
+{
+ struct sched_domain *sd;
+
+ for_each_domain(this_cpu, sd) {
+ if (sd->flags & SD_BALANCE_NEWIDLE) {
+ if (load_balance_newidle(this_cpu, this_rq, sd)) {
+ /* We've pulled tasks over so stop searching */
+ break;
+ }
+ }
+ }
+}
+
+/*
+ * active_load_balance is run by migration threads. It pushes running tasks
+ * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
+ * running on each physical CPU where possible, and avoids physical /
+ * logical imbalances.
+ *
+ * Called with busiest_rq locked.
+ */
+static void active_load_balance(runqueue_t *busiest_rq, int busiest_cpu)
+{
+ struct sched_domain *sd;
+ struct sched_group *cpu_group;
+ runqueue_t *target_rq;
+ cpumask_t visited_cpus;
+ int cpu;
+
+ /*
+ * Search for suitable CPUs to push tasks to in successively higher
+ * domains with SD_LOAD_BALANCE set.
+ */
+ visited_cpus = CPU_MASK_NONE;
+ for_each_domain(busiest_cpu, sd) {
+ if (!(sd->flags & SD_LOAD_BALANCE))
+ /* no more domains to search */
+ break;
+
+ schedstat_inc(sd, alb_cnt);
+
+ cpu_group = sd->groups;
+ do {
+ for_each_cpu_mask(cpu, cpu_group->cpumask) {
+ if (busiest_rq->nr_running <= 1)
+ /* no more tasks left to move */
+ return;
+ if (cpu_isset(cpu, visited_cpus))
+ continue;
+ cpu_set(cpu, visited_cpus);
+ if (!cpu_and_siblings_are_idle(cpu) || cpu == busiest_cpu)
+ continue;
+
+ target_rq = cpu_rq(cpu);
+ /*
+ * This condition is "impossible", if it occurs
+ * we need to fix it. Originally reported by
+ * Bjorn Helgaas on a 128-cpu setup.
+ */
+ BUG_ON(busiest_rq == target_rq);
+
+ /* move a task from busiest_rq to target_rq */
+ double_lock_balance(busiest_rq, target_rq);
+ if (move_tasks(target_rq, cpu, busiest_rq,
+ 1, sd, SCHED_IDLE)) {
+ schedstat_inc(sd, alb_pushed);
+ } else {
+ schedstat_inc(sd, alb_failed);
+ }
+ spin_unlock(&target_rq->lock);
+ }
+ cpu_group = cpu_group->next;
+ } while (cpu_group != sd->groups);
+ }
+}
+
+/*
+ * rebalance_tick will get called every timer tick, on every CPU.
+ *
+ * It checks each scheduling domain to see if it is due to be balanced,
+ * and initiates a balancing operation if so.
+ *
+ * Balancing parameters are set up in arch_init_sched_domains.
+ */
+
+/* Don't have all balancing operations going off at once */
+#define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
+
+static void rebalance_tick(int this_cpu, runqueue_t *this_rq,
+ enum idle_type idle)
+{
+ unsigned long old_load, this_load;
+ unsigned long j = jiffies + CPU_OFFSET(this_cpu);
+ struct sched_domain *sd;
+
+ /* Update our load */
+ old_load = this_rq->cpu_load;
+ this_load = this_rq->nr_running * SCHED_LOAD_SCALE;
+ /*
+ * Round up the averaging division if load is increasing. This
+ * prevents us from getting stuck on 9 if the load is 10, for
+ * example.
+ */
+ if (this_load > old_load)
+ old_load++;
+ this_rq->cpu_load = (old_load + this_load) / 2;
+
+ for_each_domain(this_cpu, sd) {
+ unsigned long interval;
+
+ if (!(sd->flags & SD_LOAD_BALANCE))
+ continue;
+
+ interval = sd->balance_interval;
+ if (idle != SCHED_IDLE)
+ interval *= sd->busy_factor;
+
+ /* scale ms to jiffies */
+ interval = msecs_to_jiffies(interval);
+ if (unlikely(!interval))
+ interval = 1;
+
+ if (j - sd->last_balance >= interval) {
+ if (load_balance(this_cpu, this_rq, sd, idle)) {
+ /* We've pulled tasks over so no longer idle */
+ idle = NOT_IDLE;
+ }
+ sd->last_balance += interval;
+ }
+ }
+}
+#else
+/*
+ * on UP we do not need to balance between CPUs:
+ */
+static inline void rebalance_tick(int cpu, runqueue_t *rq, enum idle_type idle)
+{
+}
+static inline void idle_balance(int cpu, runqueue_t *rq)
+{
+}
+#endif
+
+static inline int wake_priority_sleeper(runqueue_t *rq)
+{
+ int ret = 0;
+#ifdef CONFIG_SCHED_SMT
+ spin_lock(&rq->lock);
+ /*
+ * If an SMT sibling task has been put to sleep for priority
+ * reasons reschedule the idle task to see if it can now run.
+ */
+ if (rq->nr_running) {
+ resched_task(rq->idle);
+ ret = 1;
+ }
+ spin_unlock(&rq->lock);
+#endif
+ return ret;
+}
+
+DEFINE_PER_CPU(struct kernel_stat, kstat);
+
+EXPORT_PER_CPU_SYMBOL(kstat);
+
+/*
+ * This is called on clock ticks and on context switches.
+ * Bank in p->sched_time the ns elapsed since the last tick or switch.
+ */
+static inline void update_cpu_clock(task_t *p, runqueue_t *rq,
+ unsigned long long now)
+{
+ unsigned long long last = max(p->timestamp, rq->timestamp_last_tick);
+ p->sched_time += now - last;
+}
+
+/*
+ * Return current->sched_time plus any more ns on the sched_clock
+ * that have not yet been banked.
+ */
+unsigned long long current_sched_time(const task_t *tsk)
+{
+ unsigned long long ns;
+ unsigned long flags;
+ local_irq_save(flags);
+ ns = max(tsk->timestamp, task_rq(tsk)->timestamp_last_tick);
+ ns = tsk->sched_time + (sched_clock() - ns);
+ local_irq_restore(flags);
+ return ns;
+}
+
+/*
+ * We place interactive tasks back into the active array, if possible.
+ *
+ * To guarantee that this does not starve expired tasks we ignore the
+ * interactivity of a task if the first expired task had to wait more
+ * than a 'reasonable' amount of time. This deadline timeout is
+ * load-dependent, as the frequency of array switched decreases with
+ * increasing number of running tasks. We also ignore the interactivity
+ * if a better static_prio task has expired:
+ */
+#define EXPIRED_STARVING(rq) \
+ ((STARVATION_LIMIT && ((rq)->expired_timestamp && \
+ (jiffies - (rq)->expired_timestamp >= \
+ STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
+ ((rq)->curr->static_prio > (rq)->best_expired_prio))
+
+/*
+ * Account user cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @hardirq_offset: the offset to subtract from hardirq_count()
+ * @cputime: the cpu time spent in user space since the last update
+ */
+void account_user_time(struct task_struct *p, cputime_t cputime)
+{
+ struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+ cputime64_t tmp;
+
+ p->utime = cputime_add(p->utime, cputime);
+
+ /* Add user time to cpustat. */
+ tmp = cputime_to_cputime64(cputime);
+ if (TASK_NICE(p) > 0)
+ cpustat->nice = cputime64_add(cpustat->nice, tmp);
+ else
+ cpustat->user = cputime64_add(cpustat->user, tmp);
+}
+
+/*
+ * Account system cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @hardirq_offset: the offset to subtract from hardirq_count()
+ * @cputime: the cpu time spent in kernel space since the last update
+ */
+void account_system_time(struct task_struct *p, int hardirq_offset,
+ cputime_t cputime)
+{
+ struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+ runqueue_t *rq = this_rq();
+ cputime64_t tmp;
+
+ p->stime = cputime_add(p->stime, cputime);
+
+ /* Add system time to cpustat. */
+ tmp = cputime_to_cputime64(cputime);
+ if (hardirq_count() - hardirq_offset)
+ cpustat->irq = cputime64_add(cpustat->irq, tmp);
+ else if (softirq_count())
+ cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
+ else if (p != rq->idle)
+ cpustat->system = cputime64_add(cpustat->system, tmp);
+ else if (atomic_read(&rq->nr_iowait) > 0)
+ cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
+ else
+ cpustat->idle = cputime64_add(cpustat->idle, tmp);
+ /* Account for system time used */
+ acct_update_integrals(p);
+ /* Update rss highwater mark */
+ update_mem_hiwater(p);
+}
+
+/*
+ * Account for involuntary wait time.
+ * @p: the process from which the cpu time has been stolen
+ * @steal: the cpu time spent in involuntary wait
+ */
+void account_steal_time(struct task_struct *p, cputime_t steal)
+{
+ struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+ cputime64_t tmp = cputime_to_cputime64(steal);
+ runqueue_t *rq = this_rq();
+
+ if (p == rq->idle) {
+ p->stime = cputime_add(p->stime, steal);
+ if (atomic_read(&rq->nr_iowait) > 0)
+ cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
+ else
+ cpustat->idle = cputime64_add(cpustat->idle, tmp);
+ } else
+ cpustat->steal = cputime64_add(cpustat->steal, tmp);
+}
+
+/*
+ * This function gets called by the timer code, with HZ frequency.
+ * We call it with interrupts disabled.
+ *
+ * It also gets called by the fork code, when changing the parent's
+ * timeslices.
+ */
+void scheduler_tick(void)
+{
+ int cpu = smp_processor_id();
+ runqueue_t *rq = this_rq();
+ task_t *p = current;
+ unsigned long long now = sched_clock();
+
+ update_cpu_clock(p, rq, now);
+
+ rq->timestamp_last_tick = now;
+
+ if (p == rq->idle) {
+ if (wake_priority_sleeper(rq))
+ goto out;
+ rebalance_tick(cpu, rq, SCHED_IDLE);
+ return;
+ }
+
+ /* Task might have expired already, but not scheduled off yet */
+ if (p->array != rq->active) {
+ set_tsk_need_resched(p);
+ goto out;
+ }
+ spin_lock(&rq->lock);
+ /*
+ * The task was running during this tick - update the
+ * time slice counter. Note: we do not update a thread's
+ * priority until it either goes to sleep or uses up its
+ * timeslice. This makes it possible for interactive tasks
+ * to use up their timeslices at their highest priority levels.
+ */
+ if (rt_task(p)) {
+ /*
+ * RR tasks need a special form of timeslice management.
+ * FIFO tasks have no timeslices.
+ */
+ if ((p->policy == SCHED_RR) && !--p->time_slice) {
+ p->time_slice = task_timeslice(p);
+ p->first_time_slice = 0;
+ set_tsk_need_resched(p);
+
+ /* put it at the end of the queue: */
+ requeue_task(p, rq->active);
+ }
+ goto out_unlock;
+ }
+ if (!--p->time_slice) {
+ dequeue_task(p, rq->active);
+ set_tsk_need_resched(p);
+ p->prio = effective_prio(p);
+ p->time_slice = task_timeslice(p);
+ p->first_time_slice = 0;
+
+ if (!rq->expired_timestamp)
+ rq->expired_timestamp = jiffies;
+ if (!TASK_INTERACTIVE(p) || EXPIRED_STARVING(rq)) {
+ enqueue_task(p, rq->expired);
+ if (p->static_prio < rq->best_expired_prio)
+ rq->best_expired_prio = p->static_prio;
+ } else
+ enqueue_task(p, rq->active);
+ } else {
+ /*
+ * Prevent a too long timeslice allowing a task to monopolize
+ * the CPU. We do this by splitting up the timeslice into
+ * smaller pieces.
+ *
+ * Note: this does not mean the task's timeslices expire or
+ * get lost in any way, they just might be preempted by
+ * another task of equal priority. (one with higher
+ * priority would have preempted this task already.) We
+ * requeue this task to the end of the list on this priority
+ * level, which is in essence a round-robin of tasks with
+ * equal priority.
+ *
+ * This only applies to tasks in the interactive
+ * delta range with at least TIMESLICE_GRANULARITY to requeue.
+ */
+ if (TASK_INTERACTIVE(p) && !((task_timeslice(p) -
+ p->time_slice) % TIMESLICE_GRANULARITY(p)) &&
+ (p->time_slice >= TIMESLICE_GRANULARITY(p)) &&
+ (p->array == rq->active)) {
+
+ requeue_task(p, rq->active);
+ set_tsk_need_resched(p);
+ }
+ }
+out_unlock:
+ spin_unlock(&rq->lock);
+out:
+ rebalance_tick(cpu, rq, NOT_IDLE);
+}
+
+#ifdef CONFIG_SCHED_SMT
+static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
+{
+ struct sched_domain *sd = this_rq->sd;
+ cpumask_t sibling_map;
+ int i;
+
+ if (!(sd->flags & SD_SHARE_CPUPOWER))
+ return;
+
+ /*
+ * Unlock the current runqueue because we have to lock in
+ * CPU order to avoid deadlocks. Caller knows that we might
+ * unlock. We keep IRQs disabled.
+ */
+ spin_unlock(&this_rq->lock);
+
+ sibling_map = sd->span;
+
+ for_each_cpu_mask(i, sibling_map)
+ spin_lock(&cpu_rq(i)->lock);
+ /*
+ * We clear this CPU from the mask. This both simplifies the
+ * inner loop and keps this_rq locked when we exit:
+ */
+ cpu_clear(this_cpu, sibling_map);
+
+ for_each_cpu_mask(i, sibling_map) {
+ runqueue_t *smt_rq = cpu_rq(i);
+
+ /*
+ * If an SMT sibling task is sleeping due to priority
+ * reasons wake it up now.
+ */
+ if (smt_rq->curr == smt_rq->idle && smt_rq->nr_running)
+ resched_task(smt_rq->idle);
+ }
+
+ for_each_cpu_mask(i, sibling_map)
+ spin_unlock(&cpu_rq(i)->lock);
+ /*
+ * We exit with this_cpu's rq still held and IRQs
+ * still disabled:
+ */
+}
+
+static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
+{
+ struct sched_domain *sd = this_rq->sd;
+ cpumask_t sibling_map;
+ prio_array_t *array;
+ int ret = 0, i;
+ task_t *p;
+
+ if (!(sd->flags & SD_SHARE_CPUPOWER))
+ return 0;
+
+ /*
+ * The same locking rules and details apply as for
+ * wake_sleeping_dependent():
+ */
+ spin_unlock(&this_rq->lock);
+ sibling_map = sd->span;
+ for_each_cpu_mask(i, sibling_map)
+ spin_lock(&cpu_rq(i)->lock);
+ cpu_clear(this_cpu, sibling_map);
+
+ /*
+ * Establish next task to be run - it might have gone away because
+ * we released the runqueue lock above:
+ */
+ if (!this_rq->nr_running)
+ goto out_unlock;
+ array = this_rq->active;
+ if (!array->nr_active)
+ array = this_rq->expired;
+ BUG_ON(!array->nr_active);
+
+ p = list_entry(array->queue[sched_find_first_bit(array->bitmap)].next,
+ task_t, run_list);
+
+ for_each_cpu_mask(i, sibling_map) {
+ runqueue_t *smt_rq = cpu_rq(i);
+ task_t *smt_curr = smt_rq->curr;
+
+ /*
+ * If a user task with lower static priority than the
+ * running task on the SMT sibling is trying to schedule,
+ * delay it till there is proportionately less timeslice
+ * left of the sibling task to prevent a lower priority
+ * task from using an unfair proportion of the
+ * physical cpu's resources. -ck
+ */
+ if (((smt_curr->time_slice * (100 - sd->per_cpu_gain) / 100) >
+ task_timeslice(p) || rt_task(smt_curr)) &&
+ p->mm && smt_curr->mm && !rt_task(p))
+ ret = 1;
+
+ /*
+ * Reschedule a lower priority task on the SMT sibling,
+ * or wake it up if it has been put to sleep for priority
+ * reasons.
+ */
+ if ((((p->time_slice * (100 - sd->per_cpu_gain) / 100) >
+ task_timeslice(smt_curr) || rt_task(p)) &&
+ smt_curr->mm && p->mm && !rt_task(smt_curr)) ||
+ (smt_curr == smt_rq->idle && smt_rq->nr_running))
+ resched_task(smt_curr);
+ }
+out_unlock:
+ for_each_cpu_mask(i, sibling_map)
+ spin_unlock(&cpu_rq(i)->lock);
+ return ret;
+}
+#else
+static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
+{
+}
+
+static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
+{
+ return 0;
+}
+#endif
+
+#if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
+
+void fastcall add_preempt_count(int val)
+{
+ /*
+ * Underflow?
+ */
+ BUG_ON(((int)preempt_count() < 0));
+ preempt_count() += val;
+ /*
+ * Spinlock count overflowing soon?
+ */
+ BUG_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK-10);
+}
+EXPORT_SYMBOL(add_preempt_count);
+
+void fastcall sub_preempt_count(int val)
+{
+ /*
+ * Underflow?
+ */
+ BUG_ON(val > preempt_count());
+ /*
+ * Is the spinlock portion underflowing?
+ */
+ BUG_ON((val < PREEMPT_MASK) && !(preempt_count() & PREEMPT_MASK));
+ preempt_count() -= val;
+}
+EXPORT_SYMBOL(sub_preempt_count);
+
+#endif
+
+/*
+ * schedule() is the main scheduler function.
+ */
+asmlinkage void __sched schedule(void)
+{
+ long *switch_count;
+ task_t *prev, *next;
+ runqueue_t *rq;
+ prio_array_t *array;
+ struct list_head *queue;
+ unsigned long long now;
+ unsigned long run_time;
+ int cpu, idx;
+
+ /*
+ * Test if we are atomic. Since do_exit() needs to call into
+ * schedule() atomically, we ignore that path for now.
+ * Otherwise, whine if we are scheduling when we should not be.
+ */
+ if (likely(!current->exit_state)) {
+ if (unlikely(in_atomic())) {
+ printk(KERN_ERR "scheduling while atomic: "
+ "%s/0x%08x/%d\n",
+ current->comm, preempt_count(), current->pid);
+ dump_stack();
+ }
+ }
+ profile_hit(SCHED_PROFILING, __builtin_return_address(0));
+
+need_resched:
+ preempt_disable();
+ prev = current;
+ release_kernel_lock(prev);
+need_resched_nonpreemptible:
+ rq = this_rq();
+
+ /*
+ * The idle thread is not allowed to schedule!
+ * Remove this check after it has been exercised a bit.
+ */
+ if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) {
+ printk(KERN_ERR "bad: scheduling from the idle thread!\n");
+ dump_stack();
+ }
+
+ schedstat_inc(rq, sched_cnt);
+ now = sched_clock();
+ if (likely((long long)now - prev->timestamp < NS_MAX_SLEEP_AVG)) {
+ run_time = now - prev->timestamp;
+ if (unlikely((long long)now - prev->timestamp < 0))
+ run_time = 0;
+ } else
+ run_time = NS_MAX_SLEEP_AVG;
+
+ /*
+ * Tasks charged proportionately less run_time at high sleep_avg to
+ * delay them losing their interactive status
+ */
+ run_time /= (CURRENT_BONUS(prev) ? : 1);
+
+ spin_lock_irq(&rq->lock);
+
+ if (unlikely(prev->flags & PF_DEAD))
+ prev->state = EXIT_DEAD;
+
+ switch_count = &prev->nivcsw;
+ if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
+ switch_count = &prev->nvcsw;
+ if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
+ unlikely(signal_pending(prev))))
+ prev->state = TASK_RUNNING;
+ else {
+ if (prev->state == TASK_UNINTERRUPTIBLE)
+ rq->nr_uninterruptible++;
+ deactivate_task(prev, rq);
+ }
+ }
+
+ cpu = smp_processor_id();
+ if (unlikely(!rq->nr_running)) {
+go_idle:
+ idle_balance(cpu, rq);
+ if (!rq->nr_running) {
+ next = rq->idle;
+ rq->expired_timestamp = 0;
+ wake_sleeping_dependent(cpu, rq);
+ /*
+ * wake_sleeping_dependent() might have released
+ * the runqueue, so break out if we got new
+ * tasks meanwhile:
+ */
+ if (!rq->nr_running)
+ goto switch_tasks;
+ }
+ } else {
+ if (dependent_sleeper(cpu, rq)) {
+ next = rq->idle;
+ goto switch_tasks;
+ }
+ /*
+ * dependent_sleeper() releases and reacquires the runqueue
+ * lock, hence go into the idle loop if the rq went
+ * empty meanwhile:
+ */
+ if (unlikely(!rq->nr_running))
+ goto go_idle;
+ }
+
+ array = rq->active;
+ if (unlikely(!array->nr_active)) {
+ /*
+ * Switch the active and expired arrays.
+ */
+ schedstat_inc(rq, sched_switch);
+ rq->active = rq->expired;
+ rq->expired = array;
+ array = rq->active;
+ rq->expired_timestamp = 0;
+ rq->best_expired_prio = MAX_PRIO;
+ }
+
+ idx = sched_find_first_bit(array->bitmap);
+ queue = array->queue + idx;
+ next = list_entry(queue->next, task_t, run_list);
+
+ if (!rt_task(next) && next->activated > 0) {
+ unsigned long long delta = now - next->timestamp;
+ if (unlikely((long long)now - next->timestamp < 0))
+ delta = 0;
+
+ if (next->activated == 1)
+ delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
+
+ array = next->array;
+ dequeue_task(next, array);
+ recalc_task_prio(next, next->timestamp + delta);
+ enqueue_task(next, array);
+ }
+ next->activated = 0;
+switch_tasks:
+ if (next == rq->idle)
+ schedstat_inc(rq, sched_goidle);
+ prefetch(next);
+ clear_tsk_need_resched(prev);
+ rcu_qsctr_inc(task_cpu(prev));
+
+ update_cpu_clock(prev, rq, now);
+
+ prev->sleep_avg -= run_time;
+ if ((long)prev->sleep_avg <= 0)
+ prev->sleep_avg = 0;
+ prev->timestamp = prev->last_ran = now;
+
+ sched_info_switch(prev, next);
+ if (likely(prev != next)) {
+ next->timestamp = now;
+ rq->nr_switches++;
+ rq->curr = next;
+ ++*switch_count;
+
+ prepare_arch_switch(rq, next);
+ prev = context_switch(rq, prev, next);
+ barrier();
+
+ finish_task_switch(prev);
+ } else
+ spin_unlock_irq(&rq->lock);
+
+ prev = current;
+ if (unlikely(reacquire_kernel_lock(prev) < 0))
+ goto need_resched_nonpreemptible;
+ preempt_enable_no_resched();
+ if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
+ goto need_resched;
+}
+
+EXPORT_SYMBOL(schedule);
+
+#ifdef CONFIG_PREEMPT
+/*
+ * this is is the entry point to schedule() from in-kernel preemption
+ * off of preempt_enable. Kernel preemptions off return from interrupt
+ * occur there and call schedule directly.
+ */
+asmlinkage void __sched preempt_schedule(void)
+{
+ struct thread_info *ti = current_thread_info();
+#ifdef CONFIG_PREEMPT_BKL
+ struct task_struct *task = current;
+ int saved_lock_depth;
+#endif
+ /*
+ * If there is a non-zero preempt_count or interrupts are disabled,
+ * we do not want to preempt the current task. Just return..
+ */
+ if (unlikely(ti->preempt_count || irqs_disabled()))
+ return;
+
+need_resched:
+ add_preempt_count(PREEMPT_ACTIVE);
+ /*
+ * We keep the big kernel semaphore locked, but we
+ * clear ->lock_depth so that schedule() doesnt
+ * auto-release the semaphore:
+ */
+#ifdef CONFIG_PREEMPT_BKL
+ saved_lock_depth = task->lock_depth;
+ task->lock_depth = -1;
+#endif
+ schedule();
+#ifdef CONFIG_PREEMPT_BKL
+ task->lock_depth = saved_lock_depth;
+#endif
+ sub_preempt_count(PREEMPT_ACTIVE);
+
+ /* we could miss a preemption opportunity between schedule and now */
+ barrier();
+ if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
+ goto need_resched;
+}
+
+EXPORT_SYMBOL(preempt_schedule);
+
+/*
+ * this is is the entry point to schedule() from kernel preemption
+ * off of irq context.
+ * Note, that this is called and return with irqs disabled. This will
+ * protect us against recursive calling from irq.
+ */
+asmlinkage void __sched preempt_schedule_irq(void)
+{
+ struct thread_info *ti = current_thread_info();
+#ifdef CONFIG_PREEMPT_BKL
+ struct task_struct *task = current;
+ int saved_lock_depth;
+#endif
+ /* Catch callers which need to be fixed*/
+ BUG_ON(ti->preempt_count || !irqs_disabled());
+
+need_resched:
+ add_preempt_count(PREEMPT_ACTIVE);
+ /*
+ * We keep the big kernel semaphore locked, but we
+ * clear ->lock_depth so that schedule() doesnt
+ * auto-release the semaphore:
+ */
+#ifdef CONFIG_PREEMPT_BKL
+ saved_lock_depth = task->lock_depth;
+ task->lock_depth = -1;
+#endif
+ local_irq_enable();
+ schedule();
+ local_irq_disable();
+#ifdef CONFIG_PREEMPT_BKL
+ task->lock_depth = saved_lock_depth;
+#endif
+ sub_preempt_count(PREEMPT_ACTIVE);
+
+ /* we could miss a preemption opportunity between schedule and now */
+ barrier();
+ if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
+ goto need_resched;
+}
+
+#endif /* CONFIG_PREEMPT */
+
+int default_wake_function(wait_queue_t *curr, unsigned mode, int sync, void *key)
+{
+ task_t *p = curr->task;
+ return try_to_wake_up(p, mode, sync);
+}
+
+EXPORT_SYMBOL(default_wake_function);
+
+/*
+ * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
+ * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
+ * number) then we wake all the non-exclusive tasks and one exclusive task.
+ *
+ * There are circumstances in which we can try to wake a task which has already
+ * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
+ * zero in this (rare) case, and we handle it by continuing to scan the queue.
+ */
+static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
+ int nr_exclusive, int sync, void *key)
+{
+ struct list_head *tmp, *next;
+
+ list_for_each_safe(tmp, next, &q->task_list) {
+ wait_queue_t *curr;
+ unsigned flags;
+ curr = list_entry(tmp, wait_queue_t, task_list);
+ flags = curr->flags;
+ if (curr->func(curr, mode, sync, key) &&
+ (flags & WQ_FLAG_EXCLUSIVE) &&
+ !--nr_exclusive)
+ break;
+ }
+}
+
+/**
+ * __wake_up - wake up threads blocked on a waitqueue.
+ * @q: the waitqueue
+ * @mode: which threads
+ * @nr_exclusive: how many wake-one or wake-many threads to wake up
+ */
+void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
+ int nr_exclusive, void *key)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&q->lock, flags);
+ __wake_up_common(q, mode, nr_exclusive, 0, key);
+ spin_unlock_irqrestore(&q->lock, flags);
+}
+
+EXPORT_SYMBOL(__wake_up);
+
+/*
+ * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
+ */
+void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
+{
+ __wake_up_common(q, mode, 1, 0, NULL);
+}
+
+/**
+ * __wake_up - sync- wake up threads blocked on a waitqueue.
+ * @q: the waitqueue
+ * @mode: which threads
+ * @nr_exclusive: how many wake-one or wake-many threads to wake up
+ *
+ * The sync wakeup differs that the waker knows that it will schedule
+ * away soon, so while the target thread will be woken up, it will not
+ * be migrated to another CPU - ie. the two threads are 'synchronized'
+ * with each other. This can prevent needless bouncing between CPUs.
+ *
+ * On UP it can prevent extra preemption.
+ */
+void fastcall __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
+{
+ unsigned long flags;
+ int sync = 1;
+
+ if (unlikely(!q))
+ return;
+
+ if (unlikely(!nr_exclusive))
+ sync = 0;
+
+ spin_lock_irqsave(&q->lock, flags);
+ __wake_up_common(q, mode, nr_exclusive, sync, NULL);
+ spin_unlock_irqrestore(&q->lock, flags);
+}
+EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
+
+void fastcall complete(struct completion *x)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&x->wait.lock, flags);
+ x->done++;
+ __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
+ 1, 0, NULL);
+ spin_unlock_irqrestore(&x->wait.lock, flags);
+}
+EXPORT_SYMBOL(complete);
+
+void fastcall complete_all(struct completion *x)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&x->wait.lock, flags);
+ x->done += UINT_MAX/2;
+ __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
+ 0, 0, NULL);
+ spin_unlock_irqrestore(&x->wait.lock, flags);
+}
+EXPORT_SYMBOL(complete_all);
+
+void fastcall __sched wait_for_completion(struct completion *x)
+{
+ might_sleep();
+ spin_lock_irq(&x->wait.lock);
+ if (!x->done) {
+ DECLARE_WAITQUEUE(wait, current);
+
+ wait.flags |= WQ_FLAG_EXCLUSIVE;
+ __add_wait_queue_tail(&x->wait, &wait);
+ do {
+ __set_current_state(TASK_UNINTERRUPTIBLE);
+ spin_unlock_irq(&x->wait.lock);
+ schedule();
+ spin_lock_irq(&x->wait.lock);
+ } while (!x->done);
+ __remove_wait_queue(&x->wait, &wait);
+ }
+ x->done--;
+ spin_unlock_irq(&x->wait.lock);
+}
+EXPORT_SYMBOL(wait_for_completion);
+
+unsigned long fastcall __sched
+wait_for_completion_timeout(struct completion *x, unsigned long timeout)
+{
+ might_sleep();
+
+ spin_lock_irq(&x->wait.lock);
+ if (!x->done) {
+ DECLARE_WAITQUEUE(wait, current);
+
+ wait.flags |= WQ_FLAG_EXCLUSIVE;
+ __add_wait_queue_tail(&x->wait, &wait);
+ do {
+ __set_current_state(TASK_UNINTERRUPTIBLE);
+ spin_unlock_irq(&x->wait.lock);
+ timeout = schedule_timeout(timeout);
+ spin_lock_irq(&x->wait.lock);
+ if (!timeout) {
+ __remove_wait_queue(&x->wait, &wait);
+ goto out;
+ }
+ } while (!x->done);
+ __remove_wait_queue(&x->wait, &wait);
+ }
+ x->done--;
+out:
+ spin_unlock_irq(&x->wait.lock);
+ return timeout;
+}
+EXPORT_SYMBOL(wait_for_completion_timeout);
+
+int fastcall __sched wait_for_completion_interruptible(struct completion *x)
+{
+ int ret = 0;
+
+ might_sleep();
+
+ spin_lock_irq(&x->wait.lock);
+ if (!x->done) {
+ DECLARE_WAITQUEUE(wait, current);
+
+ wait.flags |= WQ_FLAG_EXCLUSIVE;
+ __add_wait_queue_tail(&x->wait, &wait);
+ do {
+ if (signal_pending(current)) {
+ ret = -ERESTARTSYS;
+ __remove_wait_queue(&x->wait, &wait);
+ goto out;
+ }
+ __set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irq(&x->wait.lock);
+ schedule();
+ spin_lock_irq(&x->wait.lock);
+ } while (!x->done);
+ __remove_wait_queue(&x->wait, &wait);
+ }
+ x->done--;
+out:
+ spin_unlock_irq(&x->wait.lock);
+
+ return ret;
+}
+EXPORT_SYMBOL(wait_for_completion_interruptible);
+
+unsigned long fastcall __sched
+wait_for_completion_interruptible_timeout(struct completion *x,
+ unsigned long timeout)
+{
+ might_sleep();
+
+ spin_lock_irq(&x->wait.lock);
+ if (!x->done) {
+ DECLARE_WAITQUEUE(wait, current);
+
+ wait.flags |= WQ_FLAG_EXCLUSIVE;
+ __add_wait_queue_tail(&x->wait, &wait);
+ do {
+ if (signal_pending(current)) {
+ timeout = -ERESTARTSYS;
+ __remove_wait_queue(&x->wait, &wait);
+ goto out;
+ }
+ __set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irq(&x->wait.lock);
+ timeout = schedule_timeout(timeout);
+ spin_lock_irq(&x->wait.lock);
+ if (!timeout) {
+ __remove_wait_queue(&x->wait, &wait);
+ goto out;
+ }
+ } while (!x->done);
+ __remove_wait_queue(&x->wait, &wait);
+ }
+ x->done--;
+out:
+ spin_unlock_irq(&x->wait.lock);
+ return timeout;
+}
+EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
+
+
+#define SLEEP_ON_VAR \
+ unsigned long flags; \
+ wait_queue_t wait; \
+ init_waitqueue_entry(&wait, current);
+
+#define SLEEP_ON_HEAD \
+ spin_lock_irqsave(&q->lock,flags); \
+ __add_wait_queue(q, &wait); \
+ spin_unlock(&q->lock);
+
+#define SLEEP_ON_TAIL \
+ spin_lock_irq(&q->lock); \
+ __remove_wait_queue(q, &wait); \
+ spin_unlock_irqrestore(&q->lock, flags);
+
+void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q)
+{
+ SLEEP_ON_VAR
+
+ current->state = TASK_INTERRUPTIBLE;
+
+ SLEEP_ON_HEAD
+ schedule();
+ SLEEP_ON_TAIL
+}
+
+EXPORT_SYMBOL(interruptible_sleep_on);
+
+long fastcall __sched interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
+{
+ SLEEP_ON_VAR
+
+ current->state = TASK_INTERRUPTIBLE;
+
+ SLEEP_ON_HEAD
+ timeout = schedule_timeout(timeout);
+ SLEEP_ON_TAIL
+
+ return timeout;
+}
+
+EXPORT_SYMBOL(interruptible_sleep_on_timeout);
+
+void fastcall __sched sleep_on(wait_queue_head_t *q)
+{
+ SLEEP_ON_VAR
+
+ current->state = TASK_UNINTERRUPTIBLE;
+
+ SLEEP_ON_HEAD
+ schedule();
+ SLEEP_ON_TAIL
+}
+
+EXPORT_SYMBOL(sleep_on);
+
+long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
+{
+ SLEEP_ON_VAR
+
+ current->state = TASK_UNINTERRUPTIBLE;
+
+ SLEEP_ON_HEAD
+ timeout = schedule_timeout(timeout);
+ SLEEP_ON_TAIL
+
+ return timeout;
+}
+
+EXPORT_SYMBOL(sleep_on_timeout);
+
+void set_user_nice(task_t *p, long nice)
+{
+ unsigned long flags;
+ prio_array_t *array;
+ runqueue_t *rq;
+ int old_prio, new_prio, delta;
+
+ if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
+ return;
+ /*
+ * We have to be careful, if called from sys_setpriority(),
+ * the task might be in the middle of scheduling on another CPU.
+ */
+ rq = task_rq_lock(p, &flags);
+ /*
+ * The RT priorities are set via sched_setscheduler(), but we still
+ * allow the 'normal' nice value to be set - but as expected
+ * it wont have any effect on scheduling until the task is
+ * not SCHED_NORMAL:
+ */
+ if (rt_task(p)) {
+ p->static_prio = NICE_TO_PRIO(nice);
+ goto out_unlock;
+ }
+ array = p->array;
+ if (array)
+ dequeue_task(p, array);
+
+ old_prio = p->prio;
+ new_prio = NICE_TO_PRIO(nice);
+ delta = new_prio - old_prio;
+ p->static_prio = NICE_TO_PRIO(nice);
+ p->prio += delta;
+
+ if (array) {
+ enqueue_task(p, array);
+ /*
+ * If the task increased its priority or is running and
+ * lowered its priority, then reschedule its CPU:
+ */
+ if (delta < 0 || (delta > 0 && task_running(rq, p)))
+ resched_task(rq->curr);
+ }
+out_unlock:
+ task_rq_unlock(rq, &flags);
+}
+
+EXPORT_SYMBOL(set_user_nice);
+
+#ifdef __ARCH_WANT_SYS_NICE
+
+/*
+ * sys_nice - change the priority of the current process.
+ * @increment: priority increment
+ *
+ * sys_setpriority is a more generic, but much slower function that
+ * does similar things.
+ */
+asmlinkage long sys_nice(int increment)
+{
+ int retval;
+ long nice;
+
+ /*
+ * Setpriority might change our priority at the same moment.
+ * We don't have to worry. Conceptually one call occurs first
+ * and we have a single winner.
+ */
+ if (increment < 0) {
+ if (!capable(CAP_SYS_NICE))
+ return -EPERM;
+ if (increment < -40)
+ increment = -40;
+ }
+ if (increment > 40)
+ increment = 40;
+
+ nice = PRIO_TO_NICE(current->static_prio) + increment;
+ if (nice < -20)
+ nice = -20;
+ if (nice > 19)
+ nice = 19;
+
+ retval = security_task_setnice(current, nice);
+ if (retval)
+ return retval;
+
+ set_user_nice(current, nice);
+ return 0;
+}
+
+#endif
+
+/**
+ * task_prio - return the priority value of a given task.
+ * @p: the task in question.
+ *
+ * This is the priority value as seen by users in /proc.
+ * RT tasks are offset by -200. Normal tasks are centered
+ * around 0, value goes from -16 to +15.
+ */
+int task_prio(const task_t *p)
+{
+ return p->prio - MAX_RT_PRIO;
+}
+
+/**
+ * task_nice - return the nice value of a given task.
+ * @p: the task in question.
+ */
+int task_nice(const task_t *p)
+{
+ return TASK_NICE(p);
+}
+
+/*
+ * The only users of task_nice are binfmt_elf and binfmt_elf32.
+ * binfmt_elf is no longer modular, but binfmt_elf32 still is.
+ * Therefore, task_nice is needed if there is a compat_mode.
+ */
+#ifdef CONFIG_COMPAT
+EXPORT_SYMBOL_GPL(task_nice);
+#endif
+
+/**
+ * idle_cpu - is a given cpu idle currently?
+ * @cpu: the processor in question.
+ */
+int idle_cpu(int cpu)
+{
+ return cpu_curr(cpu) == cpu_rq(cpu)->idle;
+}
+
+EXPORT_SYMBOL_GPL(idle_cpu);
+
+/**
+ * idle_task - return the idle task for a given cpu.
+ * @cpu: the processor in question.
+ */
+task_t *idle_task(int cpu)
+{
+ return cpu_rq(cpu)->idle;
+}
+
+/**
+ * find_process_by_pid - find a process with a matching PID value.
+ * @pid: the pid in question.
+ */
+static inline task_t *find_process_by_pid(pid_t pid)
+{
+ return pid ? find_task_by_pid(pid) : current;
+}
+
+/* Actually do priority change: must hold rq lock. */
+static void __setscheduler(struct task_struct *p, int policy, int prio)
+{
+ BUG_ON(p->array);
+ p->policy = policy;
+ p->rt_priority = prio;
+ if (policy != SCHED_NORMAL)
+ p->prio = MAX_USER_RT_PRIO-1 - p->rt_priority;
+ else
+ p->prio = p->static_prio;
+}
+
+/**
+ * sched_setscheduler - change the scheduling policy and/or RT priority of
+ * a thread.
+ * @p: the task in question.
+ * @policy: new policy.
+ * @param: structure containing the new RT priority.
+ */
+int sched_setscheduler(struct task_struct *p, int policy, struct sched_param *param)
+{
+ int retval;
+ int oldprio, oldpolicy = -1;
+ prio_array_t *array;
+ unsigned long flags;
+ runqueue_t *rq;
+
+recheck:
+ /* double check policy once rq lock held */
+ if (policy < 0)
+ policy = oldpolicy = p->policy;
+ else if (policy != SCHED_FIFO && policy != SCHED_RR &&
+ policy != SCHED_NORMAL)
+ return -EINVAL;
+ /*
+ * Valid priorities for SCHED_FIFO and SCHED_RR are
+ * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
+ */
+ if (param->sched_priority < 0 ||
+ param->sched_priority > MAX_USER_RT_PRIO-1)
+ return -EINVAL;
+ if ((policy == SCHED_NORMAL) != (param->sched_priority == 0))
+ return -EINVAL;
+
+ if ((policy == SCHED_FIFO || policy == SCHED_RR) &&
+ !capable(CAP_SYS_NICE))
+ return -EPERM;
+ if ((current->euid != p->euid) && (current->euid != p->uid) &&
+ !capable(CAP_SYS_NICE))
+ return -EPERM;
+
+ retval = security_task_setscheduler(p, policy, param);
+ if (retval)
+ return retval;
+ /*
+ * To be able to change p->policy safely, the apropriate
+ * runqueue lock must be held.
+ */
+ rq = task_rq_lock(p, &flags);
+ /* recheck policy now with rq lock held */
+ if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
+ policy = oldpolicy = -1;
+ task_rq_unlock(rq, &flags);
+ goto recheck;
+ }
+ array = p->array;
+ if (array)
+ deactivate_task(p, rq);
+ oldprio = p->prio;
+ __setscheduler(p, policy, param->sched_priority);
+ if (array) {
+ __activate_task(p, rq);
+ /*
+ * Reschedule if we are currently running on this runqueue and
+ * our priority decreased, or if we are not currently running on
+ * this runqueue and our priority is higher than the current's
+ */
+ if (task_running(rq, p)) {
+ if (p->prio > oldprio)
+ resched_task(rq->curr);
+ } else if (TASK_PREEMPTS_CURR(p, rq))
+ resched_task(rq->curr);
+ }
+ task_rq_unlock(rq, &flags);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(sched_setscheduler);
+
+static int do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
+{
+ int retval;
+ struct sched_param lparam;
+ struct task_struct *p;
+
+ if (!param || pid < 0)
+ return -EINVAL;
+ if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
+ return -EFAULT;
+ read_lock_irq(&tasklist_lock);
+ p = find_process_by_pid(pid);
+ if (!p) {
+ read_unlock_irq(&tasklist_lock);
+ return -ESRCH;
+ }
+ retval = sched_setscheduler(p, policy, &lparam);
+ read_unlock_irq(&tasklist_lock);
+ return retval;
+}
+
+/**
+ * sys_sched_setscheduler - set/change the scheduler policy and RT priority
+ * @pid: the pid in question.
+ * @policy: new policy.
+ * @param: structure containing the new RT priority.
+ */
+asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
+ struct sched_param __user *param)
+{
+ return do_sched_setscheduler(pid, policy, param);
+}
+
+/**
+ * sys_sched_setparam - set/change the RT priority of a thread
+ * @pid: the pid in question.
+ * @param: structure containing the new RT priority.
+ */
+asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
+{
+ return do_sched_setscheduler(pid, -1, param);
+}
+
+/**
+ * sys_sched_getscheduler - get the policy (scheduling class) of a thread
+ * @pid: the pid in question.
+ */
+asmlinkage long sys_sched_getscheduler(pid_t pid)
+{
+ int retval = -EINVAL;
+ task_t *p;
+
+ if (pid < 0)
+ goto out_nounlock;
+
+ retval = -ESRCH;
+ read_lock(&tasklist_lock);
+ p = find_process_by_pid(pid);
+ if (p) {
+ retval = security_task_getscheduler(p);
+ if (!retval)
+ retval = p->policy;
+ }
+ read_unlock(&tasklist_lock);
+
+out_nounlock:
+ return retval;
+}
+
+/**
+ * sys_sched_getscheduler - get the RT priority of a thread
+ * @pid: the pid in question.
+ * @param: structure containing the RT priority.
+ */
+asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
+{
+ struct sched_param lp;
+ int retval = -EINVAL;
+ task_t *p;
+
+ if (!param || pid < 0)
+ goto out_nounlock;
+
+ read_lock(&tasklist_lock);
+ p = find_process_by_pid(pid);
+ retval = -ESRCH;
+ if (!p)
+ goto out_unlock;
+
+ retval = security_task_getscheduler(p);
+ if (retval)
+ goto out_unlock;
+
+ lp.sched_priority = p->rt_priority;
+ read_unlock(&tasklist_lock);
+
+ /*
+ * This one might sleep, we cannot do it with a spinlock held ...
+ */
+ retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
+
+out_nounlock:
+ return retval;
+
+out_unlock:
+ read_unlock(&tasklist_lock);
+ return retval;
+}
+
+long sched_setaffinity(pid_t pid, cpumask_t new_mask)
+{
+ task_t *p;
+ int retval;
+ cpumask_t cpus_allowed;
+
+ lock_cpu_hotplug();
+ read_lock(&tasklist_lock);
+
+ p = find_process_by_pid(pid);
+ if (!p) {
+ read_unlock(&tasklist_lock);
+ unlock_cpu_hotplug();
+ return -ESRCH;
+ }
+
+ /*
+ * It is not safe to call set_cpus_allowed with the
+ * tasklist_lock held. We will bump the task_struct's
+ * usage count and then drop tasklist_lock.
+ */
+ get_task_struct(p);
+ read_unlock(&tasklist_lock);
+
+ retval = -EPERM;
+ if ((current->euid != p->euid) && (current->euid != p->uid) &&
+ !capable(CAP_SYS_NICE))
+ goto out_unlock;
+
+ cpus_allowed = cpuset_cpus_allowed(p);
+ cpus_and(new_mask, new_mask, cpus_allowed);
+ retval = set_cpus_allowed(p, new_mask);
+
+out_unlock:
+ put_task_struct(p);
+ unlock_cpu_hotplug();
+ return retval;
+}
+
+static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
+ cpumask_t *new_mask)
+{
+ if (len < sizeof(cpumask_t)) {
+ memset(new_mask, 0, sizeof(cpumask_t));
+ } else if (len > sizeof(cpumask_t)) {
+ len = sizeof(cpumask_t);
+ }
+ return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
+}
+
+/**
+ * sys_sched_setaffinity - set the cpu affinity of a process
+ * @pid: pid of the process
+ * @len: length in bytes of the bitmask pointed to by user_mask_ptr
+ * @user_mask_ptr: user-space pointer to the new cpu mask
+ */
+asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
+ unsigned long __user *user_mask_ptr)
+{
+ cpumask_t new_mask;
+ int retval;
+
+ retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
+ if (retval)
+ return retval;
+
+ return sched_setaffinity(pid, new_mask);
+}
+
+/*
+ * Represents all cpu's present in the system
+ * In systems capable of hotplug, this map could dynamically grow
+ * as new cpu's are detected in the system via any platform specific
+ * method, such as ACPI for e.g.
+ */
+
+cpumask_t cpu_present_map;
+EXPORT_SYMBOL(cpu_present_map);
+
+#ifndef CONFIG_SMP
+cpumask_t cpu_online_map = CPU_MASK_ALL;
+cpumask_t cpu_possible_map = CPU_MASK_ALL;
+#endif
+
+long sched_getaffinity(pid_t pid, cpumask_t *mask)
+{
+ int retval;
+ task_t *p;
+
+ lock_cpu_hotplug();
+ read_lock(&tasklist_lock);
+
+ retval = -ESRCH;
+ p = find_process_by_pid(pid);
+ if (!p)
+ goto out_unlock;
+
+ retval = 0;
+ cpus_and(*mask, p->cpus_allowed, cpu_possible_map);
+
+out_unlock:
+ read_unlock(&tasklist_lock);
+ unlock_cpu_hotplug();
+ if (retval)
+ return retval;
+
+ return 0;
+}
+
+/**
+ * sys_sched_getaffinity - get the cpu affinity of a process
+ * @pid: pid of the process
+ * @len: length in bytes of the bitmask pointed to by user_mask_ptr
+ * @user_mask_ptr: user-space pointer to hold the current cpu mask
+ */
+asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
+ unsigned long __user *user_mask_ptr)
+{
+ int ret;
+ cpumask_t mask;
+
+ if (len < sizeof(cpumask_t))
+ return -EINVAL;
+
+ ret = sched_getaffinity(pid, &mask);
+ if (ret < 0)
+ return ret;
+
+ if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
+ return -EFAULT;
+
+ return sizeof(cpumask_t);
+}
+
+/**
+ * sys_sched_yield - yield the current processor to other threads.
+ *
+ * this function yields the current CPU by moving the calling thread
+ * to the expired array. If there are no other threads running on this
+ * CPU then this function will return.
+ */
+asmlinkage long sys_sched_yield(void)
+{
+ runqueue_t *rq = this_rq_lock();
+ prio_array_t *array = current->array;
+ prio_array_t *target = rq->expired;
+
+ schedstat_inc(rq, yld_cnt);
+ /*
+ * We implement yielding by moving the task into the expired
+ * queue.
+ *
+ * (special rule: RT tasks will just roundrobin in the active
+ * array.)
+ */
+ if (rt_task(current))
+ target = rq->active;
+
+ if (current->array->nr_active == 1) {
+ schedstat_inc(rq, yld_act_empty);
+ if (!rq->expired->nr_active)
+ schedstat_inc(rq, yld_both_empty);
+ } else if (!rq->expired->nr_active)
+ schedstat_inc(rq, yld_exp_empty);
+
+ if (array != target) {
+ dequeue_task(current, array);
+ enqueue_task(current, target);
+ } else
+ /*
+ * requeue_task is cheaper so perform that if possible.
+ */
+ requeue_task(current, array);
+
+ /*
+ * Since we are going to call schedule() anyway, there's
+ * no need to preempt or enable interrupts:
+ */
+ __release(rq->lock);
+ _raw_spin_unlock(&rq->lock);
+ preempt_enable_no_resched();
+
+ schedule();
+
+ return 0;
+}
+
+static inline void __cond_resched(void)
+{
+ do {
+ add_preempt_count(PREEMPT_ACTIVE);
+ schedule();
+ sub_preempt_count(PREEMPT_ACTIVE);
+ } while (need_resched());
+}
+
+int __sched cond_resched(void)
+{
+ if (need_resched()) {
+ __cond_resched();
+ return 1;
+ }
+ return 0;
+}
+
+EXPORT_SYMBOL(cond_resched);
+
+/*
+ * cond_resched_lock() - if a reschedule is pending, drop the given lock,
+ * call schedule, and on return reacquire the lock.
+ *
+ * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
+ * operations here to prevent schedule() from being called twice (once via
+ * spin_unlock(), once by hand).
+ */
+int cond_resched_lock(spinlock_t * lock)
+{
+ if (need_lockbreak(lock)) {
+ spin_unlock(lock);
+ cpu_relax();
+ spin_lock(lock);
+ }
+ if (need_resched()) {
+ _raw_spin_unlock(lock);
+ preempt_enable_no_resched();
+ __cond_resched();
+ spin_lock(lock);
+ return 1;
+ }
+ return 0;
+}
+
+EXPORT_SYMBOL(cond_resched_lock);
+
+int __sched cond_resched_softirq(void)
+{
+ BUG_ON(!in_softirq());
+
+ if (need_resched()) {
+ __local_bh_enable();
+ __cond_resched();
+ local_bh_disable();
+ return 1;
+ }
+ return 0;
+}
+
+EXPORT_SYMBOL(cond_resched_softirq);
+
+
+/**
+ * yield - yield the current processor to other threads.
+ *
+ * this is a shortcut for kernel-space yielding - it marks the
+ * thread runnable and calls sys_sched_yield().
+ */
+void __sched yield(void)
+{
+ set_current_state(TASK_RUNNING);
+ sys_sched_yield();
+}
+
+EXPORT_SYMBOL(yield);
+
+/*
+ * This task is about to go to sleep on IO. Increment rq->nr_iowait so
+ * that process accounting knows that this is a task in IO wait state.
+ *
+ * But don't do that if it is a deliberate, throttling IO wait (this task
+ * has set its backing_dev_info: the queue against which it should throttle)
+ */
+void __sched io_schedule(void)
+{
+ struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id());
+
+ atomic_inc(&rq->nr_iowait);
+ schedule();
+ atomic_dec(&rq->nr_iowait);
+}
+
+EXPORT_SYMBOL(io_schedule);
+
+long __sched io_schedule_timeout(long timeout)
+{
+ struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id());
+ long ret;
+
+ atomic_inc(&rq->nr_iowait);
+ ret = schedule_timeout(timeout);
+ atomic_dec(&rq->nr_iowait);
+ return ret;
+}
+
+/**
+ * sys_sched_get_priority_max - return maximum RT priority.
+ * @policy: scheduling class.
+ *
+ * this syscall returns the maximum rt_priority that can be used
+ * by a given scheduling class.
+ */
+asmlinkage long sys_sched_get_priority_max(int policy)
+{
+ int ret = -EINVAL;
+
+ switch (policy) {
+ case SCHED_FIFO:
+ case SCHED_RR:
+ ret = MAX_USER_RT_PRIO-1;
+ break;
+ case SCHED_NORMAL:
+ ret = 0;
+ break;
+ }
+ return ret;
+}
+
+/**
+ * sys_sched_get_priority_min - return minimum RT priority.
+ * @policy: scheduling class.
+ *
+ * this syscall returns the minimum rt_priority that can be used
+ * by a given scheduling class.
+ */
+asmlinkage long sys_sched_get_priority_min(int policy)
+{
+ int ret = -EINVAL;
+
+ switch (policy) {
+ case SCHED_FIFO:
+ case SCHED_RR:
+ ret = 1;
+ break;
+ case SCHED_NORMAL:
+ ret = 0;
+ }
+ return ret;
+}
+
+/**
+ * sys_sched_rr_get_interval - return the default timeslice of a process.
+ * @pid: pid of the process.
+ * @interval: userspace pointer to the timeslice value.
+ *
+ * this syscall writes the default timeslice value of a given process
+ * into the user-space timespec buffer. A value of '0' means infinity.
+ */
+asmlinkage
+long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
+{
+ int retval = -EINVAL;
+ struct timespec t;
+ task_t *p;
+
+ if (pid < 0)
+ goto out_nounlock;
+
+ retval = -ESRCH;
+ read_lock(&tasklist_lock);
+ p = find_process_by_pid(pid);
+ if (!p)
+ goto out_unlock;
+
+ retval = security_task_getscheduler(p);
+ if (retval)
+ goto out_unlock;
+
+ jiffies_to_timespec(p->policy & SCHED_FIFO ?
+ 0 : task_timeslice(p), &t);
+ read_unlock(&tasklist_lock);
+ retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
+out_nounlock:
+ return retval;
+out_unlock:
+ read_unlock(&tasklist_lock);
+ return retval;
+}
+
+static inline struct task_struct *eldest_child(struct task_struct *p)
+{
+ if (list_empty(&p->children)) return NULL;
+ return list_entry(p->children.next,struct task_struct,sibling);
+}
+
+static inline struct task_struct *older_sibling(struct task_struct *p)
+{
+ if (p->sibling.prev==&p->parent->children) return NULL;
+ return list_entry(p->sibling.prev,struct task_struct,sibling);
+}
+
+static inline struct task_struct *younger_sibling(struct task_struct *p)
+{
+ if (p->sibling.next==&p->parent->children) return NULL;
+ return list_entry(p->sibling.next,struct task_struct,sibling);
+}
+
+static void show_task(task_t * p)
+{
+ task_t *relative;
+ unsigned state;
+ unsigned long free = 0;
+ static const char *stat_nam[] = { "R", "S", "D", "T", "t", "Z", "X" };
+
+ printk("%-13.13s ", p->comm);
+ state = p->state ? __ffs(p->state) + 1 : 0;
+ if (state < ARRAY_SIZE(stat_nam))
+ printk(stat_nam[state]);
+ else
+ printk("?");
+#if (BITS_PER_LONG == 32)
+ if (state == TASK_RUNNING)
+ printk(" running ");
+ else
+ printk(" %08lX ", thread_saved_pc(p));
+#else
+ if (state == TASK_RUNNING)
+ printk(" running task ");
+ else
+ printk(" %016lx ", thread_saved_pc(p));
+#endif
+#ifdef CONFIG_DEBUG_STACK_USAGE
+ {
+ unsigned long * n = (unsigned long *) (p->thread_info+1);
+ while (!*n)
+ n++;
+ free = (unsigned long) n - (unsigned long)(p->thread_info+1);
+ }
+#endif
+ printk("%5lu %5d %6d ", free, p->pid, p->parent->pid);
+ if ((relative = eldest_child(p)))
+ printk("%5d ", relative->pid);
+ else
+ printk(" ");
+ if ((relative = younger_sibling(p)))
+ printk("%7d", relative->pid);
+ else
+ printk(" ");
+ if ((relative = older_sibling(p)))
+ printk(" %5d", relative->pid);
+ else
+ printk(" ");
+ if (!p->mm)
+ printk(" (L-TLB)\n");
+ else
+ printk(" (NOTLB)\n");
+
+ if (state != TASK_RUNNING)
+ show_stack(p, NULL);
+}
+
+void show_state(void)
+{
+ task_t *g, *p;
+
+#if (BITS_PER_LONG == 32)
+ printk("\n"
+ " sibling\n");
+ printk(" task PC pid father child younger older\n");
+#else
+ printk("\n"
+ " sibling\n");
+ printk(" task PC pid father child younger older\n");
+#endif
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
+ /*
+ * reset the NMI-timeout, listing all files on a slow
+ * console might take alot of time:
+ */
+ touch_nmi_watchdog();
+ show_task(p);
+ } while_each_thread(g, p);
+
+ read_unlock(&tasklist_lock);
+}
+
+void __devinit init_idle(task_t *idle, int cpu)
+{
+ runqueue_t *rq = cpu_rq(cpu);
+ unsigned long flags;
+
+ idle->sleep_avg = 0;
+ idle->array = NULL;
+ idle->prio = MAX_PRIO;
+ idle->state = TASK_RUNNING;
+ idle->cpus_allowed = cpumask_of_cpu(cpu);
+ set_task_cpu(idle, cpu);
+
+ spin_lock_irqsave(&rq->lock, flags);
+ rq->curr = rq->idle = idle;
+ set_tsk_need_resched(idle);
+ spin_unlock_irqrestore(&rq->lock, flags);
+
+ /* Set the preempt count _outside_ the spinlocks! */
+#if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
+ idle->thread_info->preempt_count = (idle->lock_depth >= 0);
+#else
+ idle->thread_info->preempt_count = 0;
+#endif
+}
+
+/*
+ * In a system that switches off the HZ timer nohz_cpu_mask
+ * indicates which cpus entered this state. This is used
+ * in the rcu update to wait only for active cpus. For system
+ * which do not switch off the HZ timer nohz_cpu_mask should
+ * always be CPU_MASK_NONE.
+ */
+cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
+
+#ifdef CONFIG_SMP
+/*
+ * This is how migration works:
+ *
+ * 1) we queue a migration_req_t structure in the source CPU's
+ * runqueue and wake up that CPU's migration thread.
+ * 2) we down() the locked semaphore => thread blocks.
+ * 3) migration thread wakes up (implicitly it forces the migrated
+ * thread off the CPU)
+ * 4) it gets the migration request and checks whether the migrated
+ * task is still in the wrong runqueue.
+ * 5) if it's in the wrong runqueue then the migration thread removes
+ * it and puts it into the right queue.
+ * 6) migration thread up()s the semaphore.
+ * 7) we wake up and the migration is done.
+ */
+
+/*
+ * Change a given task's CPU affinity. Migrate the thread to a
+ * proper CPU and schedule it away if the CPU it's executing on
+ * is removed from the allowed bitmask.
+ *
+ * NOTE: the caller must have a valid reference to the task, the
+ * task must not exit() & deallocate itself prematurely. The
+ * call is not atomic; no spinlocks may be held.
+ */
+int set_cpus_allowed(task_t *p, cpumask_t new_mask)
+{
+ unsigned long flags;
+ int ret = 0;
+ migration_req_t req;
+ runqueue_t *rq;
+
+ rq = task_rq_lock(p, &flags);
+ if (!cpus_intersects(new_mask, cpu_online_map)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ p->cpus_allowed = new_mask;
+ /* Can the task run on the task's current CPU? If so, we're done */
+ if (cpu_isset(task_cpu(p), new_mask))
+ goto out;
+
+ if (migrate_task(p, any_online_cpu(new_mask), &req)) {
+ /* Need help from migration thread: drop lock and wait. */
+ task_rq_unlock(rq, &flags);
+ wake_up_process(rq->migration_thread);
+ wait_for_completion(&req.done);
+ tlb_migrate_finish(p->mm);
+ return 0;
+ }
+out:
+ task_rq_unlock(rq, &flags);
+ return ret;
+}
+
+EXPORT_SYMBOL_GPL(set_cpus_allowed);
+
+/*
+ * Move (not current) task off this cpu, onto dest cpu. We're doing
+ * this because either it can't run here any more (set_cpus_allowed()
+ * away from this CPU, or CPU going down), or because we're
+ * attempting to rebalance this task on exec (sched_exec).
+ *
+ * So we race with normal scheduler movements, but that's OK, as long
+ * as the task is no longer on this CPU.
+ */
+static void __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
+{
+ runqueue_t *rq_dest, *rq_src;
+
+ if (unlikely(cpu_is_offline(dest_cpu)))
+ return;
+
+ rq_src = cpu_rq(src_cpu);
+ rq_dest = cpu_rq(dest_cpu);
+
+ double_rq_lock(rq_src, rq_dest);
+ /* Already moved. */
+ if (task_cpu(p) != src_cpu)
+ goto out;
+ /* Affinity changed (again). */
+ if (!cpu_isset(dest_cpu, p->cpus_allowed))
+ goto out;
+
+ set_task_cpu(p, dest_cpu);
+ if (p->array) {
+ /*
+ * Sync timestamp with rq_dest's before activating.
+ * The same thing could be achieved by doing this step
+ * afterwards, and pretending it was a local activate.
+ * This way is cleaner and logically correct.
+ */
+ p->timestamp = p->timestamp - rq_src->timestamp_last_tick
+ + rq_dest->timestamp_last_tick;
+ deactivate_task(p, rq_src);
+ activate_task(p, rq_dest, 0);
+ if (TASK_PREEMPTS_CURR(p, rq_dest))
+ resched_task(rq_dest->curr);
+ }
+
+out:
+ double_rq_unlock(rq_src, rq_dest);
+}
+
+/*
+ * migration_thread - this is a highprio system thread that performs
+ * thread migration by bumping thread off CPU then 'pushing' onto
+ * another runqueue.
+ */
+static int migration_thread(void * data)
+{
+ runqueue_t *rq;
+ int cpu = (long)data;
+
+ rq = cpu_rq(cpu);
+ BUG_ON(rq->migration_thread != current);
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ while (!kthread_should_stop()) {
+ struct list_head *head;
+ migration_req_t *req;
+
+ if (current->flags & PF_FREEZE)
+ refrigerator(PF_FREEZE);
+
+ spin_lock_irq(&rq->lock);
+
+ if (cpu_is_offline(cpu)) {
+ spin_unlock_irq(&rq->lock);
+ goto wait_to_die;
+ }
+
+ if (rq->active_balance) {
+ active_load_balance(rq, cpu);
+ rq->active_balance = 0;
+ }
+
+ head = &rq->migration_queue;
+
+ if (list_empty(head)) {
+ spin_unlock_irq(&rq->lock);
+ schedule();
+ set_current_state(TASK_INTERRUPTIBLE);
+ continue;
+ }
+ req = list_entry(head->next, migration_req_t, list);
+ list_del_init(head->next);
+
+ if (req->type == REQ_MOVE_TASK) {
+ spin_unlock(&rq->lock);
+ __migrate_task(req->task, cpu, req->dest_cpu);
+ local_irq_enable();
+ } else if (req->type == REQ_SET_DOMAIN) {
+ rq->sd = req->sd;
+ spin_unlock_irq(&rq->lock);
+ } else {
+ spin_unlock_irq(&rq->lock);
+ WARN_ON(1);
+ }
+
+ complete(&req->done);
+ }
+ __set_current_state(TASK_RUNNING);
+ return 0;
+
+wait_to_die:
+ /* Wait for kthread_stop */
+ set_current_state(TASK_INTERRUPTIBLE);
+ while (!kthread_should_stop()) {
+ schedule();
+ set_current_state(TASK_INTERRUPTIBLE);
+ }
+ __set_current_state(TASK_RUNNING);
+ return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+/* Figure out where task on dead CPU should go, use force if neccessary. */
+static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *tsk)
+{
+ int dest_cpu;
+ cpumask_t mask;
+
+ /* On same node? */
+ mask = node_to_cpumask(cpu_to_node(dead_cpu));
+ cpus_and(mask, mask, tsk->cpus_allowed);
+ dest_cpu = any_online_cpu(mask);
+
+ /* On any allowed CPU? */
+ if (dest_cpu == NR_CPUS)
+ dest_cpu = any_online_cpu(tsk->cpus_allowed);
+
+ /* No more Mr. Nice Guy. */
+ if (dest_cpu == NR_CPUS) {
+ tsk->cpus_allowed = cpuset_cpus_allowed(tsk);
+ dest_cpu = any_online_cpu(tsk->cpus_allowed);
+
+ /*
+ * Don't tell them about moving exiting tasks or
+ * kernel threads (both mm NULL), since they never
+ * leave kernel.
+ */
+ if (tsk->mm && printk_ratelimit())
+ printk(KERN_INFO "process %d (%s) no "
+ "longer affine to cpu%d\n",
+ tsk->pid, tsk->comm, dead_cpu);
+ }
+ __migrate_task(tsk, dead_cpu, dest_cpu);
+}
+
+/*
+ * While a dead CPU has no uninterruptible tasks queued at this point,
+ * it might still have a nonzero ->nr_uninterruptible counter, because
+ * for performance reasons the counter is not stricly tracking tasks to
+ * their home CPUs. So we just add the counter to another CPU's counter,
+ * to keep the global sum constant after CPU-down:
+ */
+static void migrate_nr_uninterruptible(runqueue_t *rq_src)
+{
+ runqueue_t *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL));
+ unsigned long flags;
+
+ local_irq_save(flags);
+ double_rq_lock(rq_src, rq_dest);
+ rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
+ rq_src->nr_uninterruptible = 0;
+ double_rq_unlock(rq_src, rq_dest);
+ local_irq_restore(flags);
+}
+
+/* Run through task list and migrate tasks from the dead cpu. */
+static void migrate_live_tasks(int src_cpu)
+{
+ struct task_struct *tsk, *t;
+
+ write_lock_irq(&tasklist_lock);
+
+ do_each_thread(t, tsk) {
+ if (tsk == current)
+ continue;
+
+ if (task_cpu(tsk) == src_cpu)
+ move_task_off_dead_cpu(src_cpu, tsk);
+ } while_each_thread(t, tsk);
+
+ write_unlock_irq(&tasklist_lock);
+}
+
+/* Schedules idle task to be the next runnable task on current CPU.
+ * It does so by boosting its priority to highest possible and adding it to
+ * the _front_ of runqueue. Used by CPU offline code.
+ */
+void sched_idle_next(void)
+{
+ int cpu = smp_processor_id();
+ runqueue_t *rq = this_rq();
+ struct task_struct *p = rq->idle;
+ unsigned long flags;
+
+ /* cpu has to be offline */
+ BUG_ON(cpu_online(cpu));
+
+ /* Strictly not necessary since rest of the CPUs are stopped by now
+ * and interrupts disabled on current cpu.
+ */
+ spin_lock_irqsave(&rq->lock, flags);
+
+ __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
+ /* Add idle task to _front_ of it's priority queue */
+ __activate_idle_task(p, rq);
+
+ spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+/* Ensures that the idle task is using init_mm right before its cpu goes
+ * offline.
+ */
+void idle_task_exit(void)
+{
+ struct mm_struct *mm = current->active_mm;
+
+ BUG_ON(cpu_online(smp_processor_id()));
+
+ if (mm != &init_mm)
+ switch_mm(mm, &init_mm, current);
+ mmdrop(mm);
+}
+
+static void migrate_dead(unsigned int dead_cpu, task_t *tsk)
+{
+ struct runqueue *rq = cpu_rq(dead_cpu);
+
+ /* Must be exiting, otherwise would be on tasklist. */
+ BUG_ON(tsk->exit_state != EXIT_ZOMBIE && tsk->exit_state != EXIT_DEAD);
+
+ /* Cannot have done final schedule yet: would have vanished. */
+ BUG_ON(tsk->flags & PF_DEAD);
+
+ get_task_struct(tsk);
+
+ /*
+ * Drop lock around migration; if someone else moves it,
+ * that's OK. No task can be added to this CPU, so iteration is
+ * fine.
+ */
+ spin_unlock_irq(&rq->lock);
+ move_task_off_dead_cpu(dead_cpu, tsk);
+ spin_lock_irq(&rq->lock);
+
+ put_task_struct(tsk);
+}
+
+/* release_task() removes task from tasklist, so we won't find dead tasks. */
+static void migrate_dead_tasks(unsigned int dead_cpu)
+{
+ unsigned arr, i;
+ struct runqueue *rq = cpu_rq(dead_cpu);
+
+ for (arr = 0; arr < 2; arr++) {
+ for (i = 0; i < MAX_PRIO; i++) {
+ struct list_head *list = &rq->arrays[arr].queue[i];
+ while (!list_empty(list))
+ migrate_dead(dead_cpu,
+ list_entry(list->next, task_t,
+ run_list));
+ }
+ }
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+/*
+ * migration_call - callback that gets triggered when a CPU is added.
+ * Here we can start up the necessary migration thread for the new CPU.
+ */
+static int migration_call(struct notifier_block *nfb, unsigned long action,
+ void *hcpu)
+{
+ int cpu = (long)hcpu;
+ struct task_struct *p;
+ struct runqueue *rq;
+ unsigned long flags;
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
+ if (IS_ERR(p))
+ return NOTIFY_BAD;
+ p->flags |= PF_NOFREEZE;
+ kthread_bind(p, cpu);
+ /* Must be high prio: stop_machine expects to yield to it. */
+ rq = task_rq_lock(p, &flags);
+ __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
+ task_rq_unlock(rq, &flags);
+ cpu_rq(cpu)->migration_thread = p;
+ break;
+ case CPU_ONLINE:
+ /* Strictly unneccessary, as first user will wake it. */
+ wake_up_process(cpu_rq(cpu)->migration_thread);
+ break;
+#ifdef CONFIG_HOTPLUG_CPU
+ case CPU_UP_CANCELED:
+ /* Unbind it from offline cpu so it can run. Fall thru. */
+ kthread_bind(cpu_rq(cpu)->migration_thread,smp_processor_id());
+ kthread_stop(cpu_rq(cpu)->migration_thread);
+ cpu_rq(cpu)->migration_thread = NULL;
+ break;
+ case CPU_DEAD:
+ migrate_live_tasks(cpu);
+ rq = cpu_rq(cpu);
+ kthread_stop(rq->migration_thread);
+ rq->migration_thread = NULL;
+ /* Idle task back to normal (off runqueue, low prio) */
+ rq = task_rq_lock(rq->idle, &flags);
+ deactivate_task(rq->idle, rq);
+ rq->idle->static_prio = MAX_PRIO;
+ __setscheduler(rq->idle, SCHED_NORMAL, 0);
+ migrate_dead_tasks(cpu);
+ task_rq_unlock(rq, &flags);
+ migrate_nr_uninterruptible(rq);
+ BUG_ON(rq->nr_running != 0);
+
+ /* No need to migrate the tasks: it was best-effort if
+ * they didn't do lock_cpu_hotplug(). Just wake up
+ * the requestors. */
+ spin_lock_irq(&rq->lock);
+ while (!list_empty(&rq->migration_queue)) {
+ migration_req_t *req;
+ req = list_entry(rq->migration_queue.next,
+ migration_req_t, list);
+ BUG_ON(req->type != REQ_MOVE_TASK);
+ list_del_init(&req->list);
+ complete(&req->done);
+ }
+ spin_unlock_irq(&rq->lock);
+ break;
+#endif
+ }
+ return NOTIFY_OK;
+}
+
+/* Register at highest priority so that task migration (migrate_all_tasks)
+ * happens before everything else.
+ */
+static struct notifier_block __devinitdata migration_notifier = {
+ .notifier_call = migration_call,
+ .priority = 10
+};
+
+int __init migration_init(void)
+{
+ void *cpu = (void *)(long)smp_processor_id();
+ /* Start one for boot CPU. */
+ migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
+ migration_call(&migration_notifier, CPU_ONLINE, cpu);
+ register_cpu_notifier(&migration_notifier);
+ return 0;
+}
+#endif
+
+#ifdef CONFIG_SMP
+#define SCHED_DOMAIN_DEBUG
+#ifdef SCHED_DOMAIN_DEBUG
+static void sched_domain_debug(struct sched_domain *sd, int cpu)
+{
+ int level = 0;
+
+ printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
+
+ do {
+ int i;
+ char str[NR_CPUS];
+ struct sched_group *group = sd->groups;
+ cpumask_t groupmask;
+
+ cpumask_scnprintf(str, NR_CPUS, sd->span);
+ cpus_clear(groupmask);
+
+ printk(KERN_DEBUG);
+ for (i = 0; i < level + 1; i++)
+ printk(" ");
+ printk("domain %d: ", level);
+
+ if (!(sd->flags & SD_LOAD_BALANCE)) {
+ printk("does not load-balance\n");
+ if (sd->parent)
+ printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain has parent");
+ break;
+ }
+
+ printk("span %s\n", str);
+
+ if (!cpu_isset(cpu, sd->span))
+ printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
+ if (!cpu_isset(cpu, group->cpumask))
+ printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
+
+ printk(KERN_DEBUG);
+ for (i = 0; i < level + 2; i++)
+ printk(" ");
+ printk("groups:");
+ do {
+ if (!group) {
+ printk("\n");
+ printk(KERN_ERR "ERROR: group is NULL\n");
+ break;
+ }
+
+ if (!group->cpu_power) {
+ printk("\n");
+ printk(KERN_ERR "ERROR: domain->cpu_power not set\n");
+ }
+
+ if (!cpus_weight(group->cpumask)) {
+ printk("\n");
+ printk(KERN_ERR "ERROR: empty group\n");
+ }
+
+ if (cpus_intersects(groupmask, group->cpumask)) {
+ printk("\n");
+ printk(KERN_ERR "ERROR: repeated CPUs\n");
+ }
+
+ cpus_or(groupmask, groupmask, group->cpumask);
+
+ cpumask_scnprintf(str, NR_CPUS, group->cpumask);
+ printk(" %s", str);
+
+ group = group->next;
+ } while (group != sd->groups);
+ printk("\n");
+
+ if (!cpus_equal(sd->span, groupmask))
+ printk(KERN_ERR "ERROR: groups don't span domain->span\n");
+
+ level++;
+ sd = sd->parent;
+
+ if (sd) {
+ if (!cpus_subset(groupmask, sd->span))
+ printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
+ }
+
+ } while (sd);
+}
+#else
+#define sched_domain_debug(sd, cpu) {}
+#endif
+
+/*
+ * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
+ * hold the hotplug lock.
+ */
+void __devinit cpu_attach_domain(struct sched_domain *sd, int cpu)
+{
+ migration_req_t req;
+ unsigned long flags;
+ runqueue_t *rq = cpu_rq(cpu);
+ int local = 1;
+
+ sched_domain_debug(sd, cpu);
+
+ spin_lock_irqsave(&rq->lock, flags);
+
+ if (cpu == smp_processor_id() || !cpu_online(cpu)) {
+ rq->sd = sd;
+ } else {
+ init_completion(&req.done);
+ req.type = REQ_SET_DOMAIN;
+ req.sd = sd;
+ list_add(&req.list, &rq->migration_queue);
+ local = 0;
+ }
+
+ spin_unlock_irqrestore(&rq->lock, flags);
+
+ if (!local) {
+ wake_up_process(rq->migration_thread);
+ wait_for_completion(&req.done);
+ }
+}
+
+/* cpus with isolated domains */
+cpumask_t __devinitdata cpu_isolated_map = CPU_MASK_NONE;
+
+/* Setup the mask of cpus configured for isolated domains */
+static int __init isolated_cpu_setup(char *str)
+{
+ int ints[NR_CPUS], i;
+
+ str = get_options(str, ARRAY_SIZE(ints), ints);
+ cpus_clear(cpu_isolated_map);
+ for (i = 1; i <= ints[0]; i++)
+ if (ints[i] < NR_CPUS)
+ cpu_set(ints[i], cpu_isolated_map);
+ return 1;
+}
+
+__setup ("isolcpus=", isolated_cpu_setup);
+
+/*
+ * init_sched_build_groups takes an array of groups, the cpumask we wish
+ * to span, and a pointer to a function which identifies what group a CPU
+ * belongs to. The return value of group_fn must be a valid index into the
+ * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
+ * keep track of groups covered with a cpumask_t).
+ *
+ * init_sched_build_groups will build a circular linked list of the groups
+ * covered by the given span, and will set each group's ->cpumask correctly,
+ * and ->cpu_power to 0.
+ */
+void __devinit init_sched_build_groups(struct sched_group groups[],
+ cpumask_t span, int (*group_fn)(int cpu))
+{
+ struct sched_group *first = NULL, *last = NULL;
+ cpumask_t covered = CPU_MASK_NONE;
+ int i;
+
+ for_each_cpu_mask(i, span) {
+ int group = group_fn(i);
+ struct sched_group *sg = &groups[group];
+ int j;
+
+ if (cpu_isset(i, covered))
+ continue;
+
+ sg->cpumask = CPU_MASK_NONE;
+ sg->cpu_power = 0;
+
+ for_each_cpu_mask(j, span) {
+ if (group_fn(j) != group)
+ continue;
+
+ cpu_set(j, covered);
+ cpu_set(j, sg->cpumask);
+ }
+ if (!first)
+ first = sg;
+ if (last)
+ last->next = sg;
+ last = sg;
+ }
+ last->next = first;
+}
+
+
+#ifdef ARCH_HAS_SCHED_DOMAIN
+extern void __devinit arch_init_sched_domains(void);
+extern void __devinit arch_destroy_sched_domains(void);
+#else
+#ifdef CONFIG_SCHED_SMT
+static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
+static struct sched_group sched_group_cpus[NR_CPUS];
+static int __devinit cpu_to_cpu_group(int cpu)
+{
+ return cpu;
+}
+#endif
+
+static DEFINE_PER_CPU(struct sched_domain, phys_domains);
+static struct sched_group sched_group_phys[NR_CPUS];
+static int __devinit cpu_to_phys_group(int cpu)
+{
+#ifdef CONFIG_SCHED_SMT
+ return first_cpu(cpu_sibling_map[cpu]);
+#else
+ return cpu;
+#endif
+}
+
+#ifdef CONFIG_NUMA
+
+static DEFINE_PER_CPU(struct sched_domain, node_domains);
+static struct sched_group sched_group_nodes[MAX_NUMNODES];
+static int __devinit cpu_to_node_group(int cpu)
+{
+ return cpu_to_node(cpu);
+}
+#endif
+
+#if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
+/*
+ * The domains setup code relies on siblings not spanning
+ * multiple nodes. Make sure the architecture has a proper
+ * siblings map:
+ */
+static void check_sibling_maps(void)
+{
+ int i, j;
+
+ for_each_online_cpu(i) {
+ for_each_cpu_mask(j, cpu_sibling_map[i]) {
+ if (cpu_to_node(i) != cpu_to_node(j)) {
+ printk(KERN_INFO "warning: CPU %d siblings map "
+ "to different node - isolating "
+ "them.\n", i);
+ cpu_sibling_map[i] = cpumask_of_cpu(i);
+ break;
+ }
+ }
+ }
+}
+#endif
+
+/*
+ * Set up scheduler domains and groups. Callers must hold the hotplug lock.
+ */
+static void __devinit arch_init_sched_domains(void)
+{
+ int i;
+ cpumask_t cpu_default_map;
+
+#if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
+ check_sibling_maps();
+#endif
+ /*
+ * Setup mask for cpus without special case scheduling requirements.
+ * For now this just excludes isolated cpus, but could be used to
+ * exclude other special cases in the future.
+ */
+ cpus_complement(cpu_default_map, cpu_isolated_map);
+ cpus_and(cpu_default_map, cpu_default_map, cpu_online_map);
+
+ /*
+ * Set up domains. Isolated domains just stay on the dummy domain.
+ */
+ for_each_cpu_mask(i, cpu_default_map) {
+ int group;
+ struct sched_domain *sd = NULL, *p;
+ cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
+
+ cpus_and(nodemask, nodemask, cpu_default_map);
+
+#ifdef CONFIG_NUMA
+ sd = &per_cpu(node_domains, i);
+ group = cpu_to_node_group(i);
+ *sd = SD_NODE_INIT;
+ sd->span = cpu_default_map;
+ sd->groups = &sched_group_nodes[group];
+#endif
+
+ p = sd;
+ sd = &per_cpu(phys_domains, i);
+ group = cpu_to_phys_group(i);
+ *sd = SD_CPU_INIT;
+ sd->span = nodemask;
+ sd->parent = p;
+ sd->groups = &sched_group_phys[group];
+
+#ifdef CONFIG_SCHED_SMT
+ p = sd;
+ sd = &per_cpu(cpu_domains, i);
+ group = cpu_to_cpu_group(i);
+ *sd = SD_SIBLING_INIT;
+ sd->span = cpu_sibling_map[i];
+ cpus_and(sd->span, sd->span, cpu_default_map);
+ sd->parent = p;
+ sd->groups = &sched_group_cpus[group];
+#endif
+ }
+
+#ifdef CONFIG_SCHED_SMT
+ /* Set up CPU (sibling) groups */
+ for_each_online_cpu(i) {
+ cpumask_t this_sibling_map = cpu_sibling_map[i];
+ cpus_and(this_sibling_map, this_sibling_map, cpu_default_map);
+ if (i != first_cpu(this_sibling_map))
+ continue;
+
+ init_sched_build_groups(sched_group_cpus, this_sibling_map,
+ &cpu_to_cpu_group);
+ }
+#endif
+
+ /* Set up physical groups */
+ for (i = 0; i < MAX_NUMNODES; i++) {
+ cpumask_t nodemask = node_to_cpumask(i);
+
+ cpus_and(nodemask, nodemask, cpu_default_map);
+ if (cpus_empty(nodemask))
+ continue;
+
+ init_sched_build_groups(sched_group_phys, nodemask,
+ &cpu_to_phys_group);
+ }
+
+#ifdef CONFIG_NUMA
+ /* Set up node groups */
+ init_sched_build_groups(sched_group_nodes, cpu_default_map,
+ &cpu_to_node_group);
+#endif
+
+ /* Calculate CPU power for physical packages and nodes */
+ for_each_cpu_mask(i, cpu_default_map) {
+ int power;
+ struct sched_domain *sd;
+#ifdef CONFIG_SCHED_SMT
+ sd = &per_cpu(cpu_domains, i);
+ power = SCHED_LOAD_SCALE;
+ sd->groups->cpu_power = power;
+#endif
+
+ sd = &per_cpu(phys_domains, i);
+ power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
+ (cpus_weight(sd->groups->cpumask)-1) / 10;
+ sd->groups->cpu_power = power;
+
+#ifdef CONFIG_NUMA
+ if (i == first_cpu(sd->groups->cpumask)) {
+ /* Only add "power" once for each physical package. */
+ sd = &per_cpu(node_domains, i);
+ sd->groups->cpu_power += power;
+ }
+#endif
+ }
+
+ /* Attach the domains */
+ for_each_online_cpu(i) {
+ struct sched_domain *sd;
+#ifdef CONFIG_SCHED_SMT
+ sd = &per_cpu(cpu_domains, i);
+#else
+ sd = &per_cpu(phys_domains, i);
+#endif
+ cpu_attach_domain(sd, i);
+ }
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void __devinit arch_destroy_sched_domains(void)
+{
+ /* Do nothing: everything is statically allocated. */
+}
+#endif
+
+#endif /* ARCH_HAS_SCHED_DOMAIN */
+
+/*
+ * Initial dummy domain for early boot and for hotplug cpu. Being static,
+ * it is initialized to zero, so all balancing flags are cleared which is
+ * what we want.
+ */
+static struct sched_domain sched_domain_dummy;
+
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * Force a reinitialization of the sched domains hierarchy. The domains
+ * and groups cannot be updated in place without racing with the balancing
+ * code, so we temporarily attach all running cpus to a "dummy" domain
+ * which will prevent rebalancing while the sched domains are recalculated.
+ */
+static int update_sched_domains(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ int i;
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ case CPU_DOWN_PREPARE:
+ for_each_online_cpu(i)
+ cpu_attach_domain(&sched_domain_dummy, i);
+ arch_destroy_sched_domains();
+ return NOTIFY_OK;
+
+ case CPU_UP_CANCELED:
+ case CPU_DOWN_FAILED:
+ case CPU_ONLINE:
+ case CPU_DEAD:
+ /*
+ * Fall through and re-initialise the domains.
+ */
+ break;
+ default:
+ return NOTIFY_DONE;
+ }
+
+ /* The hotplug lock is already held by cpu_up/cpu_down */
+ arch_init_sched_domains();
+
+ return NOTIFY_OK;
+}
+#endif
+
+void __init sched_init_smp(void)
+{
+ lock_cpu_hotplug();
+ arch_init_sched_domains();
+ unlock_cpu_hotplug();
+ /* XXX: Theoretical race here - CPU may be hotplugged now */
+ hotcpu_notifier(update_sched_domains, 0);
+}
+#else
+void __init sched_init_smp(void)
+{
+}
+#endif /* CONFIG_SMP */
+
+int in_sched_functions(unsigned long addr)
+{
+ /* Linker adds these: start and end of __sched functions */
+ extern char __sched_text_start[], __sched_text_end[];
+ return in_lock_functions(addr) ||
+ (addr >= (unsigned long)__sched_text_start
+ && addr < (unsigned long)__sched_text_end);
+}
+
+void __init sched_init(void)
+{
+ runqueue_t *rq;
+ int i, j, k;
+
+ for (i = 0; i < NR_CPUS; i++) {
+ prio_array_t *array;
+
+ rq = cpu_rq(i);
+ spin_lock_init(&rq->lock);
+ rq->active = rq->arrays;
+ rq->expired = rq->arrays + 1;
+ rq->best_expired_prio = MAX_PRIO;
+
+#ifdef CONFIG_SMP
+ rq->sd = &sched_domain_dummy;
+ rq->cpu_load = 0;
+ rq->active_balance = 0;
+ rq->push_cpu = 0;
+ rq->migration_thread = NULL;
+ INIT_LIST_HEAD(&rq->migration_queue);
+#endif
+ atomic_set(&rq->nr_iowait, 0);
+
+ for (j = 0; j < 2; j++) {
+ array = rq->arrays + j;
+ for (k = 0; k < MAX_PRIO; k++) {
+ INIT_LIST_HEAD(array->queue + k);
+ __clear_bit(k, array->bitmap);
+ }
+ // delimiter for bitsearch
+ __set_bit(MAX_PRIO, array->bitmap);
+ }
+ }
+
+ /*
+ * The boot idle thread does lazy MMU switching as well:
+ */
+ atomic_inc(&init_mm.mm_count);
+ enter_lazy_tlb(&init_mm, current);
+
+ /*
+ * Make us the idle thread. Technically, schedule() should not be
+ * called from this thread, however somewhere below it might be,
+ * but because we are the idle thread, we just pick up running again
+ * when this runqueue becomes "idle".
+ */
+ init_idle(current, smp_processor_id());
+}
+
+#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
+void __might_sleep(char *file, int line)
+{
+#if defined(in_atomic)
+ static unsigned long prev_jiffy; /* ratelimiting */
+
+ if ((in_atomic() || irqs_disabled()) &&
+ system_state == SYSTEM_RUNNING && !oops_in_progress) {
+ if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
+ return;
+ prev_jiffy = jiffies;
+ printk(KERN_ERR "Debug: sleeping function called from invalid"
+ " context at %s:%d\n", file, line);
+ printk("in_atomic():%d, irqs_disabled():%d\n",
+ in_atomic(), irqs_disabled());
+ dump_stack();
+ }
+#endif
+}
+EXPORT_SYMBOL(__might_sleep);
+#endif
+
+#ifdef CONFIG_MAGIC_SYSRQ
+void normalize_rt_tasks(void)
+{
+ struct task_struct *p;
+ prio_array_t *array;
+ unsigned long flags;
+ runqueue_t *rq;
+
+ read_lock_irq(&tasklist_lock);
+ for_each_process (p) {
+ if (!rt_task(p))
+ continue;
+
+ rq = task_rq_lock(p, &flags);
+
+ array = p->array;
+ if (array)
+ deactivate_task(p, task_rq(p));
+ __setscheduler(p, SCHED_NORMAL, 0);
+ if (array) {
+ __activate_task(p, task_rq(p));
+ resched_task(rq->curr);
+ }
+
+ task_rq_unlock(rq, &flags);
+ }
+ read_unlock_irq(&tasklist_lock);
+}
+
+#endif /* CONFIG_MAGIC_SYSRQ */
