rcu: fix locking cleanup fallout
Given that the rcp->lock is now acquired from call_rcu(), which can be
invoked from irq-disable regions, all acquisitions need to disable irqs.
The following patch fixes this.
Although I don't have any reason to believe that this is the cause of
Yinghai's oops, it does need to be fixed.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/rcuclassic.c b/kernel/rcuclassic.c
index fb1f1cc4..c6b6cf5 100644
--- a/kernel/rcuclassic.c
+++ b/kernel/rcuclassic.c
@@ -86,8 +86,10 @@
{
int cpu;
cpumask_t cpumask;
+ unsigned long flags;
+
set_need_resched();
- spin_lock(&rcp->lock);
+ spin_lock_irqsave(&rcp->lock, flags);
if (unlikely(!rcp->signaled)) {
rcp->signaled = 1;
/*
@@ -113,7 +115,7 @@
for_each_cpu_mask_nr(cpu, cpumask)
smp_send_reschedule(cpu);
}
- spin_unlock(&rcp->lock);
+ spin_unlock_irqrestore(&rcp->lock, flags);
}
#else
static inline void force_quiescent_state(struct rcu_data *rdp,
@@ -301,17 +303,18 @@
{
int cpu;
long delta;
+ unsigned long flags;
/* Only let one CPU complain about others per time interval. */
- spin_lock(&rcp->lock);
+ spin_lock_irqsave(&rcp->lock, flags);
delta = get_seconds() - rcp->gp_check;
if (delta < 2L || cpus_empty(rcp->cpumask)) {
spin_unlock(&rcp->lock);
return;
}
rcp->gp_check = get_seconds() + 30;
- spin_unlock(&rcp->lock);
+ spin_unlock_irqrestore(&rcp->lock, flags);
/* OK, time to rat on our buddy... */
@@ -324,13 +327,15 @@
static void print_cpu_stall(struct rcu_ctrlblk *rcp)
{
+ unsigned long flags;
+
printk(KERN_ERR "RCU detected CPU %d stall (t=%lu/%lu)\n",
smp_processor_id(), get_seconds(), rcp->gp_check);
dump_stack();
- spin_lock(&rcp->lock);
+ spin_lock_irqsave(&rcp->lock, flags);
if ((long)(get_seconds() - rcp->gp_check) >= 0L)
rcp->gp_check = get_seconds() + 30;
- spin_unlock(&rcp->lock);
+ spin_unlock_irqrestore(&rcp->lock, flags);
}
static void check_cpu_stall(struct rcu_ctrlblk *rcp, struct rcu_data *rdp)
@@ -413,6 +418,8 @@
static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp,
struct rcu_data *rdp)
{
+ unsigned long flags;
+
if (rdp->quiescbatch != rcp->cur) {
/* start new grace period: */
rdp->qs_pending = 1;
@@ -436,7 +443,7 @@
return;
rdp->qs_pending = 0;
- spin_lock(&rcp->lock);
+ spin_lock_irqsave(&rcp->lock, flags);
/*
* rdp->quiescbatch/rcp->cur and the cpu bitmap can come out of sync
* during cpu startup. Ignore the quiescent state.
@@ -444,7 +451,7 @@
if (likely(rdp->quiescbatch == rcp->cur))
cpu_quiet(rdp->cpu, rcp);
- spin_unlock(&rcp->lock);
+ spin_unlock_irqrestore(&rcp->lock, flags);
}
@@ -469,21 +476,22 @@
static void __rcu_offline_cpu(struct rcu_data *this_rdp,
struct rcu_ctrlblk *rcp, struct rcu_data *rdp)
{
+ unsigned long flags;
+
/*
* if the cpu going offline owns the grace period
* we can block indefinitely waiting for it, so flush
* it here
*/
- spin_lock_bh(&rcp->lock);
+ spin_lock_irqsave(&rcp->lock, flags);
if (rcp->cur != rcp->completed)
cpu_quiet(rdp->cpu, rcp);
rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail, rcp->cur + 1);
rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail[2], rcp->cur + 1);
- spin_unlock_bh(&rcp->lock);
+ spin_unlock(&rcp->lock);
- local_irq_disable();
this_rdp->qlen += rdp->qlen;
- local_irq_enable();
+ local_irq_restore(flags);
}
static void rcu_offline_cpu(int cpu)
@@ -550,12 +558,12 @@
if (rcu_batch_after(rdp->batch, rcp->pending)) {
/* and start it/schedule start if it's a new batch */
- spin_lock(&rcp->lock);
+ spin_lock_irqsave(&rcp->lock, flags);
if (rcu_batch_after(rdp->batch, rcp->pending)) {
rcp->pending = rdp->batch;
rcu_start_batch(rcp);
}
- spin_unlock(&rcp->lock);
+ spin_unlock_irqrestore(&rcp->lock, flags);
}
}
