kernel/smp.c - arm/linux-arm64-legacy - Git at Google

 /*
  * Generic helpers for smp ipi calls
  *
  * (C) Jens Axboe <jens.axboe@oracle.com> 2008
  *
  */
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/percpu.h>
 #include <linux/rcupdate.h>
 #include <linux/rculist.h>
 #include <linux/smp.h>

 static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
 static LIST_HEAD(call_function_queue);
 __cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock);

 enum {
 	CSD_FLAG_WAIT		= 0x01,
 	CSD_FLAG_ALLOC		= 0x02,
 };

 struct call_function_data {
 	struct call_single_data csd;
 	spinlock_t lock;
 	unsigned int refs;
 	cpumask_t cpumask;
 	struct rcu_head rcu_head;
 };

 struct call_single_queue {
 	struct list_head list;
 	spinlock_t lock;
 };

 static int __cpuinit init_call_single_data(void)
 {
 	int i;

 	for_each_possible_cpu(i) {
 		struct call_single_queue *q = &per_cpu(call_single_queue, i);

 		spin_lock_init(&q->lock);
 		INIT_LIST_HEAD(&q->list);
 	}
 	return 0;
 }
 early_initcall(init_call_single_data);

 static void csd_flag_wait(struct call_single_data *data)
 {
 	/* Wait for response */
 	do {
 		if (!(data->flags & CSD_FLAG_WAIT))
 			break;
 		cpu_relax();
 	} while (1);
 }

 /*
  * Insert a previously allocated call_single_data element for execution
  * on the given CPU. data must already have ->func, ->info, and ->flags set.
  */
 static void generic_exec_single(int cpu, struct call_single_data *data)
 {
 	struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
 	int wait = data->flags & CSD_FLAG_WAIT, ipi;
 	unsigned long flags;

 	spin_lock_irqsave(&dst->lock, flags);
 	ipi = list_empty(&dst->list);
 	list_add_tail(&data->list, &dst->list);
 	spin_unlock_irqrestore(&dst->lock, flags);

 	/*
 	 * Make the list addition visible before sending the ipi.
 	 */
 	smp_mb();

 	if (ipi)
 		arch_send_call_function_single_ipi(cpu);

 	if (wait)
 		csd_flag_wait(data);
 }

 static void rcu_free_call_data(struct rcu_head *head)
 {
 	struct call_function_data *data;

 	data = container_of(head, struct call_function_data, rcu_head);

 	kfree(data);
 }

 /*
  * Invoked by arch to handle an IPI for call function. Must be called with
  * interrupts disabled.
  */
 void generic_smp_call_function_interrupt(void)
 {
 	struct call_function_data *data;
 	int cpu = get_cpu();

 	/*
 	 * It's ok to use list_for_each_rcu() here even though we may delete
 	 * 'pos', since list_del_rcu() doesn't clear ->next
 	 */
 	rcu_read_lock();
 	list_for_each_entry_rcu(data, &call_function_queue, csd.list) {
 		int refs;

 		if (!cpu_isset(cpu, data->cpumask))
 			continue;

 		data->csd.func(data->csd.info);

 		spin_lock(&data->lock);
 		cpu_clear(cpu, data->cpumask);
 		WARN_ON(data->refs == 0);
 		data->refs--;
 		refs = data->refs;
 		spin_unlock(&data->lock);

 		if (refs)
 			continue;

 		spin_lock(&call_function_lock);
 		list_del_rcu(&data->csd.list);
 		spin_unlock(&call_function_lock);

 		if (data->csd.flags & CSD_FLAG_WAIT) {
 			/*
 			 * serialize stores to data with the flag clear
 			 * and wakeup
 			 */
 			smp_wmb();
 			data->csd.flags &= ~CSD_FLAG_WAIT;
 		}
 		if (data->csd.flags & CSD_FLAG_ALLOC)
 			call_rcu(&data->rcu_head, rcu_free_call_data);
 	}
 	rcu_read_unlock();

 	put_cpu();
 }

 /*
  * Invoked by arch to handle an IPI for call function single. Must be called
  * from the arch with interrupts disabled.
  */
 void generic_smp_call_function_single_interrupt(void)
 {
 	struct call_single_queue *q = &__get_cpu_var(call_single_queue);
 	LIST_HEAD(list);

 	/*
 	 * Need to see other stores to list head for checking whether
 	 * list is empty without holding q->lock
 	 */
 	smp_read_barrier_depends();
 	while (!list_empty(&q->list)) {
 		unsigned int data_flags;

 		spin_lock(&q->lock);
 		list_replace_init(&q->list, &list);
 		spin_unlock(&q->lock);

 		while (!list_empty(&list)) {
 			struct call_single_data *data;

 			data = list_entry(list.next, struct call_single_data,
 						list);
 			list_del(&data->list);

 			/*
 			 * 'data' can be invalid after this call if
 			 * flags == 0 (when called through
 			 * generic_exec_single(), so save them away before
 			 * making the call.
 			 */
 			data_flags = data->flags;

 			data->func(data->info);

 			if (data_flags & CSD_FLAG_WAIT) {
 				smp_wmb();
 				data->flags &= ~CSD_FLAG_WAIT;
 			} else if (data_flags & CSD_FLAG_ALLOC)
 				kfree(data);
 		}
 		/*
 		 * See comment on outer loop
 		 */
 		smp_read_barrier_depends();
 	}
 }

 /*
  * smp_call_function_single - Run a function on a specific CPU
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
  * @wait: If true, wait until function has completed on other CPUs.
  *
  * Returns 0 on success, else a negative status code. Note that @wait
  * will be implicitly turned on in case of allocation failures, since
  * we fall back to on-stack allocation.
  */
 int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
 			     int wait)
 {
 	struct call_single_data d;
 	unsigned long flags;
 	/* prevent preemption and reschedule on another processor,
 	   as well as CPU removal */
 	int me = get_cpu();
 	int err = 0;

 	/* Can deadlock when called with interrupts disabled */
 	WARN_ON(irqs_disabled());

 	if (cpu == me) {
 		local_irq_save(flags);
 		func(info);
 		local_irq_restore(flags);
 	} else if ((unsigned)cpu < NR_CPUS && cpu_online(cpu)) {
 		struct call_single_data *data = NULL;

 		if (!wait) {
 			data = kmalloc(sizeof(*data), GFP_ATOMIC);
 			if (data)
 				data->flags = CSD_FLAG_ALLOC;
 		}
 		if (!data) {
 			data = &d;
 			data->flags = CSD_FLAG_WAIT;
 		}

 		data->func = func;
 		data->info = info;
 		generic_exec_single(cpu, data);
 	} else {
 		err = -ENXIO;	/* CPU not online */
 	}

 	put_cpu();
 	return err;
 }
 EXPORT_SYMBOL(smp_call_function_single);

 /**
  * __smp_call_function_single(): Run a function on another CPU
  * @cpu: The CPU to run on.
  * @data: Pre-allocated and setup data structure
  *
  * Like smp_call_function_single(), but allow caller to pass in a pre-allocated
  * data structure. Useful for embedding @data inside other structures, for
  * instance.
  *
  */
 void __smp_call_function_single(int cpu, struct call_single_data *data)
 {
 	/* Can deadlock when called with interrupts disabled */
 	WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());

 	generic_exec_single(cpu, data);
 }

 /* Dummy function */
 static void quiesce_dummy(void *unused)
 {
 }

 /*
  * Ensure stack based data used in call function mask is safe to free.
  *
  * This is needed by smp_call_function_mask when using on-stack data, because
  * a single call function queue is shared by all CPUs, and any CPU may pick up
  * the data item on the queue at any time before it is deleted. So we need to
  * ensure that all CPUs have transitioned through a quiescent state after
  * this call.
  *
  * This is a very slow function, implemented by sending synchronous IPIs to
  * all possible CPUs. For this reason, we have to alloc data rather than use
  * stack based data even in the case of synchronous calls. The stack based
  * data is then just used for deadlock/oom fallback which will be very rare.
  *
  * If a faster scheme can be made, we could go back to preferring stack based
  * data -- the data allocation/free is non-zero cost.
  */
 static void smp_call_function_mask_quiesce_stack(cpumask_t mask)
 {
 	struct call_single_data data;
 	int cpu;

 	data.func = quiesce_dummy;
 	data.info = NULL;

 	for_each_cpu_mask(cpu, mask) {
 		data.flags = CSD_FLAG_WAIT;
 		generic_exec_single(cpu, &data);
 	}
 }

 /**
  * smp_call_function_mask(): Run a function on a set of other CPUs.
  * @mask: The set of cpus to run on.
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
  * @wait: If true, wait (atomically) until function has completed on other CPUs.
  *
  * Returns 0 on success, else a negative status code.
  *
  * If @wait is true, then returns once @func has returned. Note that @wait
  * will be implicitly turned on in case of allocation failures, since
  * we fall back to on-stack allocation.
  *
  * You must not call this function with disabled interrupts or from a
  * hardware interrupt handler or from a bottom half handler. Preemption
  * must be disabled when calling this function.
  */
 int smp_call_function_mask(cpumask_t mask, void (*func)(void *), void *info,
 			   int wait)
 {
 	struct call_function_data d;
 	struct call_function_data *data = NULL;
 	cpumask_t allbutself;
 	unsigned long flags;
 	int cpu, num_cpus;
 	int slowpath = 0;

 	/* Can deadlock when called with interrupts disabled */
 	WARN_ON(irqs_disabled());

 	cpu = smp_processor_id();
 	allbutself = cpu_online_map;
 	cpu_clear(cpu, allbutself);
 	cpus_and(mask, mask, allbutself);
 	num_cpus = cpus_weight(mask);

 	/*
 	 * If zero CPUs, return. If just a single CPU, turn this request
 	 * into a targetted single call instead since it's faster.
 	 */
 	if (!num_cpus)
 		return 0;
 	else if (num_cpus == 1) {
 		cpu = first_cpu(mask);
 		return smp_call_function_single(cpu, func, info, wait);
 	}

 	data = kmalloc(sizeof(*data), GFP_ATOMIC);
 	if (data) {
 		data->csd.flags = CSD_FLAG_ALLOC;
 		if (wait)
 			data->csd.flags |= CSD_FLAG_WAIT;
 	} else {
 		data = &d;
 		data->csd.flags = CSD_FLAG_WAIT;
 		wait = 1;
 		slowpath = 1;
 	}

 	spin_lock_init(&data->lock);
 	data->csd.func = func;
 	data->csd.info = info;
 	data->refs = num_cpus;
 	data->cpumask = mask;

 	spin_lock_irqsave(&call_function_lock, flags);
 	list_add_tail_rcu(&data->csd.list, &call_function_queue);
 	spin_unlock_irqrestore(&call_function_lock, flags);

 	/*
 	 * Make the list addition visible before sending the ipi.
 	 */
 	smp_mb();

 	/* Send a message to all CPUs in the map */
 	arch_send_call_function_ipi(mask);

 	/* optionally wait for the CPUs to complete */
 	if (wait) {
 		csd_flag_wait(&data->csd);
 		if (unlikely(slowpath))
 			smp_call_function_mask_quiesce_stack(mask);
 	}

 	return 0;
 }
 EXPORT_SYMBOL(smp_call_function_mask);

 /**
  * smp_call_function(): Run a function on all other CPUs.
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
  * @wait: If true, wait (atomically) until function has completed on other CPUs.
  *
  * Returns 0 on success, else a negative status code.
  *
  * If @wait is true, then returns once @func has returned; otherwise
  * it returns just before the target cpu calls @func. In case of allocation
  * failure, @wait will be implicitly turned on.
  *
  * You must not call this function with disabled interrupts or from a
  * hardware interrupt handler or from a bottom half handler.
  */
 int smp_call_function(void (*func)(void *), void *info, int wait)
 {
 	int ret;

 	preempt_disable();
 	ret = smp_call_function_mask(cpu_online_map, func, info, wait);
 	preempt_enable();
 	return ret;
 }
 EXPORT_SYMBOL(smp_call_function);

 void ipi_call_lock(void)
 {
 	spin_lock(&call_function_lock);
 }

 void ipi_call_unlock(void)
 {
 	spin_unlock(&call_function_lock);
 }

 void ipi_call_lock_irq(void)
 {
 	spin_lock_irq(&call_function_lock);
 }

 void ipi_call_unlock_irq(void)
 {
 	spin_unlock_irq(&call_function_lock);
 }
	/*
	* Generic helpers for smp ipi calls
	*
	* (C) Jens Axboe <jens.axboe@oracle.com> 2008
	*
	*/
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/percpu.h>
	#include <linux/rcupdate.h>
	#include <linux/rculist.h>
	#include <linux/smp.h>

	static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
	static LIST_HEAD(call_function_queue);
	__cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock);

	enum {
	CSD_FLAG_WAIT = 0x01,
	CSD_FLAG_ALLOC = 0x02,
	};

	struct call_function_data {
	struct call_single_data csd;
	spinlock_t lock;
	unsigned int refs;
	cpumask_t cpumask;
	struct rcu_head rcu_head;
	};

	struct call_single_queue {
	struct list_head list;
	spinlock_t lock;
	};

	static int __cpuinit init_call_single_data(void)
	{
	int i;

	for_each_possible_cpu(i) {
	struct call_single_queue *q = &per_cpu(call_single_queue, i);

	spin_lock_init(&q->lock);
	INIT_LIST_HEAD(&q->list);
	}
	return 0;
	}
	early_initcall(init_call_single_data);

	static void csd_flag_wait(struct call_single_data *data)
	{
	/* Wait for response */
	do {
	if (!(data->flags & CSD_FLAG_WAIT))
	break;
	cpu_relax();
	} while (1);
	}

	/*
	* Insert a previously allocated call_single_data element for execution
	* on the given CPU. data must already have ->func, ->info, and ->flags set.
	*/
	static void generic_exec_single(int cpu, struct call_single_data *data)
	{
	struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
	int wait = data->flags & CSD_FLAG_WAIT, ipi;
	unsigned long flags;

	spin_lock_irqsave(&dst->lock, flags);
	ipi = list_empty(&dst->list);
	list_add_tail(&data->list, &dst->list);
	spin_unlock_irqrestore(&dst->lock, flags);

	/*
	* Make the list addition visible before sending the ipi.
	*/
	smp_mb();

	if (ipi)
	arch_send_call_function_single_ipi(cpu);

	if (wait)
	csd_flag_wait(data);
	}

	static void rcu_free_call_data(struct rcu_head *head)
	{
	struct call_function_data *data;

	data = container_of(head, struct call_function_data, rcu_head);

	kfree(data);
	}

	/*
	* Invoked by arch to handle an IPI for call function. Must be called with
	* interrupts disabled.
	*/
	void generic_smp_call_function_interrupt(void)
	{
	struct call_function_data *data;
	int cpu = get_cpu();

	/*
	* It's ok to use list_for_each_rcu() here even though we may delete
	* 'pos', since list_del_rcu() doesn't clear ->next
	*/
	rcu_read_lock();
	list_for_each_entry_rcu(data, &call_function_queue, csd.list) {
	int refs;

	if (!cpu_isset(cpu, data->cpumask))
	continue;

	data->csd.func(data->csd.info);

	spin_lock(&data->lock);
	cpu_clear(cpu, data->cpumask);
	WARN_ON(data->refs == 0);
	data->refs--;
	refs = data->refs;
	spin_unlock(&data->lock);

	if (refs)
	continue;

	spin_lock(&call_function_lock);
	list_del_rcu(&data->csd.list);
	spin_unlock(&call_function_lock);

	if (data->csd.flags & CSD_FLAG_WAIT) {
	/*
	* serialize stores to data with the flag clear
	* and wakeup
	*/
	smp_wmb();
	data->csd.flags &= ~CSD_FLAG_WAIT;
	}
	if (data->csd.flags & CSD_FLAG_ALLOC)
	call_rcu(&data->rcu_head, rcu_free_call_data);
	}
	rcu_read_unlock();

	put_cpu();
	}

	/*
	* Invoked by arch to handle an IPI for call function single. Must be called
	* from the arch with interrupts disabled.
	*/
	void generic_smp_call_function_single_interrupt(void)
	{
	struct call_single_queue *q = &__get_cpu_var(call_single_queue);
	LIST_HEAD(list);

	/*
	* Need to see other stores to list head for checking whether
	* list is empty without holding q->lock
	*/
	smp_read_barrier_depends();
	while (!list_empty(&q->list)) {
	unsigned int data_flags;

	spin_lock(&q->lock);
	list_replace_init(&q->list, &list);
	spin_unlock(&q->lock);

	while (!list_empty(&list)) {
	struct call_single_data *data;

	data = list_entry(list.next, struct call_single_data,
	list);
	list_del(&data->list);

	/*
	* 'data' can be invalid after this call if
	* flags == 0 (when called through
	* generic_exec_single(), so save them away before
	* making the call.
	*/
	data_flags = data->flags;

	data->func(data->info);

	if (data_flags & CSD_FLAG_WAIT) {
	smp_wmb();
	data->flags &= ~CSD_FLAG_WAIT;
	} else if (data_flags & CSD_FLAG_ALLOC)
	kfree(data);
	}
	/*
	* See comment on outer loop
	*/
	smp_read_barrier_depends();
	}
	}

	/*
	* smp_call_function_single - Run a function on a specific CPU
	* @func: The function to run. This must be fast and non-blocking.
	* @info: An arbitrary pointer to pass to the function.
	* @wait: If true, wait until function has completed on other CPUs.
	*
	* Returns 0 on success, else a negative status code. Note that @wait
	* will be implicitly turned on in case of allocation failures, since
	* we fall back to on-stack allocation.
	*/
	int smp_call_function_single(int cpu, void (func) (void info), void *info,
	int wait)
	{
	struct call_single_data d;
	unsigned long flags;
	/* prevent preemption and reschedule on another processor,
	as well as CPU removal */
	int me = get_cpu();
	int err = 0;

	/* Can deadlock when called with interrupts disabled */
	WARN_ON(irqs_disabled());

	if (cpu == me) {
	local_irq_save(flags);
	func(info);
	local_irq_restore(flags);
	} else if ((unsigned)cpu < NR_CPUS && cpu_online(cpu)) {
	struct call_single_data *data = NULL;

	if (!wait) {
	data = kmalloc(sizeof(*data), GFP_ATOMIC);
	if (data)
	data->flags = CSD_FLAG_ALLOC;
	}
	if (!data) {
	data = &d;
	data->flags = CSD_FLAG_WAIT;
	}

	data->func = func;
	data->info = info;
	generic_exec_single(cpu, data);
	} else {
	err = -ENXIO; /* CPU not online */
	}

	put_cpu();
	return err;
	}
	EXPORT_SYMBOL(smp_call_function_single);

	/**
	* __smp_call_function_single(): Run a function on another CPU
	* @cpu: The CPU to run on.
	* @data: Pre-allocated and setup data structure
	*
	* Like smp_call_function_single(), but allow caller to pass in a pre-allocated
	* data structure. Useful for embedding @data inside other structures, for
	* instance.
	*
	*/
	void __smp_call_function_single(int cpu, struct call_single_data *data)
	{
	/* Can deadlock when called with interrupts disabled */
	WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled());

	generic_exec_single(cpu, data);
	}

	/* Dummy function */
	static void quiesce_dummy(void *unused)
	{
	}

	/*
	* Ensure stack based data used in call function mask is safe to free.
	*
	* This is needed by smp_call_function_mask when using on-stack data, because
	* a single call function queue is shared by all CPUs, and any CPU may pick up
	* the data item on the queue at any time before it is deleted. So we need to
	* ensure that all CPUs have transitioned through a quiescent state after
	* this call.
	*
	* This is a very slow function, implemented by sending synchronous IPIs to
	* all possible CPUs. For this reason, we have to alloc data rather than use
	* stack based data even in the case of synchronous calls. The stack based
	* data is then just used for deadlock/oom fallback which will be very rare.
	*
	* If a faster scheme can be made, we could go back to preferring stack based
	* data -- the data allocation/free is non-zero cost.
	*/
	static void smp_call_function_mask_quiesce_stack(cpumask_t mask)
	{
	struct call_single_data data;
	int cpu;

	data.func = quiesce_dummy;
	data.info = NULL;

	for_each_cpu_mask(cpu, mask) {
	data.flags = CSD_FLAG_WAIT;
	generic_exec_single(cpu, &data);
	}
	}

	/**
	* smp_call_function_mask(): Run a function on a set of other CPUs.
	* @mask: The set of cpus to run on.
	* @func: The function to run. This must be fast and non-blocking.
	* @info: An arbitrary pointer to pass to the function.
	* @wait: If true, wait (atomically) until function has completed on other CPUs.
	*
	* Returns 0 on success, else a negative status code.
	*
	* If @wait is true, then returns once @func has returned. Note that @wait
	* will be implicitly turned on in case of allocation failures, since
	* we fall back to on-stack allocation.
	*
	* You must not call this function with disabled interrupts or from a
	* hardware interrupt handler or from a bottom half handler. Preemption
	* must be disabled when calling this function.
	*/
	int smp_call_function_mask(cpumask_t mask, void (func)(void ), void *info,
	int wait)
	{
	struct call_function_data d;
	struct call_function_data *data = NULL;
	cpumask_t allbutself;
	unsigned long flags;
	int cpu, num_cpus;
	int slowpath = 0;

	/* Can deadlock when called with interrupts disabled */
	WARN_ON(irqs_disabled());

	cpu = smp_processor_id();
	allbutself = cpu_online_map;
	cpu_clear(cpu, allbutself);
	cpus_and(mask, mask, allbutself);
	num_cpus = cpus_weight(mask);

	/*
	* If zero CPUs, return. If just a single CPU, turn this request
	* into a targetted single call instead since it's faster.
	*/
	if (!num_cpus)
	return 0;
	else if (num_cpus == 1) {
	cpu = first_cpu(mask);
	return smp_call_function_single(cpu, func, info, wait);
	}

	data = kmalloc(sizeof(*data), GFP_ATOMIC);
	if (data) {
	data->csd.flags = CSD_FLAG_ALLOC;
	if (wait)
	data->csd.flags \|= CSD_FLAG_WAIT;
	} else {
	data = &d;
	data->csd.flags = CSD_FLAG_WAIT;
	wait = 1;
	slowpath = 1;
	}

	spin_lock_init(&data->lock);
	data->csd.func = func;
	data->csd.info = info;
	data->refs = num_cpus;
	data->cpumask = mask;

	spin_lock_irqsave(&call_function_lock, flags);
	list_add_tail_rcu(&data->csd.list, &call_function_queue);
	spin_unlock_irqrestore(&call_function_lock, flags);

	/*
	* Make the list addition visible before sending the ipi.
	*/
	smp_mb();

	/* Send a message to all CPUs in the map */
	arch_send_call_function_ipi(mask);

	/* optionally wait for the CPUs to complete */
	if (wait) {
	csd_flag_wait(&data->csd);
	if (unlikely(slowpath))
	smp_call_function_mask_quiesce_stack(mask);
	}

	return 0;
	}
	EXPORT_SYMBOL(smp_call_function_mask);

	/**
	* smp_call_function(): Run a function on all other CPUs.
	* @func: The function to run. This must be fast and non-blocking.
	* @info: An arbitrary pointer to pass to the function.
	* @wait: If true, wait (atomically) until function has completed on other CPUs.
	*
	* Returns 0 on success, else a negative status code.
	*
	* If @wait is true, then returns once @func has returned; otherwise
	* it returns just before the target cpu calls @func. In case of allocation
	* failure, @wait will be implicitly turned on.
	*
	* You must not call this function with disabled interrupts or from a
	* hardware interrupt handler or from a bottom half handler.
	*/
	int smp_call_function(void (func)(void ), void *info, int wait)
	{
	int ret;

	preempt_disable();
	ret = smp_call_function_mask(cpu_online_map, func, info, wait);
	preempt_enable();
	return ret;
	}
	EXPORT_SYMBOL(smp_call_function);

	void ipi_call_lock(void)
	{
	spin_lock(&call_function_lock);
	}

	void ipi_call_unlock(void)
	{
	spin_unlock(&call_function_lock);
	}

	void ipi_call_lock_irq(void)
	{
	spin_lock_irq(&call_function_lock);
	}

	void ipi_call_unlock_irq(void)
	{
	spin_unlock_irq(&call_function_lock);
	}