arch/ia64/kernel/smp.c - linux - Git at Google

 /*
  * SMP Support
  *
  * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
  * Copyright (C) 1999, 2001, 2003 David Mosberger-Tang <davidm@hpl.hp.com>
  *
  * Lots of stuff stolen from arch/alpha/kernel/smp.c
  *
  * 01/05/16 Rohit Seth <rohit.seth@intel.com>  IA64-SMP functions. Reorganized
  * the existing code (on the lines of x86 port).
  * 00/09/11 David Mosberger <davidm@hpl.hp.com> Do loops_per_jiffy
  * calibration on each CPU.
  * 00/08/23 Asit Mallick <asit.k.mallick@intel.com> fixed logical processor id
  * 00/03/31 Rohit Seth <rohit.seth@intel.com>	Fixes for Bootstrap Processor
  * & cpu_online_map now gets done here (instead of setup.c)
  * 99/10/05 davidm	Update to bring it in sync with new command-line processing
  *  scheme.
  * 10/13/00 Goutham Rao <goutham.rao@intel.com> Updated smp_call_function and
  *		smp_call_function_single to resend IPI on timeouts
  */
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/smp.h>
 #include <linux/kernel_stat.h>
 #include <linux/mm.h>
 #include <linux/cache.h>
 #include <linux/delay.h>
 #include <linux/efi.h>
 #include <linux/bitops.h>
 #include <linux/kexec.h>

 #include <asm/atomic.h>
 #include <asm/current.h>
 #include <asm/delay.h>
 #include <asm/machvec.h>
 #include <asm/io.h>
 #include <asm/irq.h>
 #include <asm/page.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/ptrace.h>
 #include <asm/sal.h>
 #include <asm/system.h>
 #include <asm/tlbflush.h>
 #include <asm/unistd.h>
 #include <asm/mca.h>

 /*
  * Note: alignment of 4 entries/cacheline was empirically determined
  * to be a good tradeoff between hot cachelines & spreading the array
  * across too many cacheline.
  */
 static struct local_tlb_flush_counts {
 	unsigned int count;
 } __attribute__((__aligned__(32))) local_tlb_flush_counts[NR_CPUS];

 static DEFINE_PER_CPU(unsigned int, shadow_flush_counts[NR_CPUS]) ____cacheline_aligned;


 /*
  * Structure and data for smp_call_function(). This is designed to minimise static memory
  * requirements. It also looks cleaner.
  */
 static  __cacheline_aligned DEFINE_SPINLOCK(call_lock);

 struct call_data_struct {
 	void (*func) (void *info);
 	void *info;
 	long wait;
 	atomic_t started;
 	atomic_t finished;
 };

 static volatile struct call_data_struct *call_data;

 #define IPI_CALL_FUNC		0
 #define IPI_CPU_STOP		1
 #define IPI_KDUMP_CPU_STOP	3

 /* This needs to be cacheline aligned because it is written to by *other* CPUs.  */
 static DEFINE_PER_CPU_SHARED_ALIGNED(u64, ipi_operation);

 extern void cpu_halt (void);

 void
 lock_ipi_calllock(void)
 {
 	spin_lock_irq(&call_lock);
 }

 void
 unlock_ipi_calllock(void)
 {
 	spin_unlock_irq(&call_lock);
 }

 static void
 stop_this_cpu (void)
 {
 	/*
 	 * Remove this CPU:
 	 */
 	cpu_clear(smp_processor_id(), cpu_online_map);
 	max_xtp();
 	local_irq_disable();
 	cpu_halt();
 }

 void
 cpu_die(void)
 {
 	max_xtp();
 	local_irq_disable();
 	cpu_halt();
 	/* Should never be here */
 	BUG();
 	for (;;);
 }

 irqreturn_t
 handle_IPI (int irq, void *dev_id)
 {
 	int this_cpu = get_cpu();
 	unsigned long *pending_ipis = &__ia64_per_cpu_var(ipi_operation);
 	unsigned long ops;

 	mb();	/* Order interrupt and bit testing. */
 	while ((ops = xchg(pending_ipis, 0)) != 0) {
 		mb();	/* Order bit clearing and data access. */
 		do {
 			unsigned long which;

 			which = ffz(~ops);
 			ops &= ~(1 << which);

 			switch (which) {
 			      case IPI_CALL_FUNC:
 			      {
 				      struct call_data_struct *data;
 				      void (*func)(void *info);
 				      void *info;
 				      int wait;

 				      /* release the 'pointer lock' */
 				      data = (struct call_data_struct *) call_data;
 				      func = data->func;
 				      info = data->info;
 				      wait = data->wait;

 				      mb();
 				      atomic_inc(&data->started);
 				      /*
 				       * At this point the structure may be gone unless
 				       * wait is true.
 				       */
 				      (*func)(info);

 				      /* Notify the sending CPU that the task is done.  */
 				      mb();
 				      if (wait)
 					      atomic_inc(&data->finished);
 			      }
 			      break;

 			      case IPI_CPU_STOP:
 				stop_this_cpu();
 				break;
 #ifdef CONFIG_KEXEC
 			      case IPI_KDUMP_CPU_STOP:
 				unw_init_running(kdump_cpu_freeze, NULL);
 				break;
 #endif
 			      default:
 				printk(KERN_CRIT "Unknown IPI on CPU %d: %lu\n", this_cpu, which);
 				break;
 			}
 		} while (ops);
 		mb();	/* Order data access and bit testing. */
 	}
 	put_cpu();
 	return IRQ_HANDLED;
 }

 /*
  * Called with preemption disabled.
  */
 static inline void
 send_IPI_single (int dest_cpu, int op)
 {
 	set_bit(op, &per_cpu(ipi_operation, dest_cpu));
 	platform_send_ipi(dest_cpu, IA64_IPI_VECTOR, IA64_IPI_DM_INT, 0);
 }

 /*
  * Called with preemption disabled.
  */
 static inline void
 send_IPI_allbutself (int op)
 {
 	unsigned int i;

 	for_each_online_cpu(i) {
 		if (i != smp_processor_id())
 			send_IPI_single(i, op);
 	}
 }

 /*
  * Called with preemption disabled.
  */
 static inline void
 send_IPI_all (int op)
 {
 	int i;

 	for_each_online_cpu(i) {
 		send_IPI_single(i, op);
 	}
 }

 /*
  * Called with preemption disabled.
  */
 static inline void
 send_IPI_self (int op)
 {
 	send_IPI_single(smp_processor_id(), op);
 }

 #ifdef CONFIG_KEXEC
 void
 kdump_smp_send_stop(void)
 {
  	send_IPI_allbutself(IPI_KDUMP_CPU_STOP);
 }

 void
 kdump_smp_send_init(void)
 {
 	unsigned int cpu, self_cpu;
 	self_cpu = smp_processor_id();
 	for_each_online_cpu(cpu) {
 		if (cpu != self_cpu) {
 			if(kdump_status[cpu] == 0)
 				platform_send_ipi(cpu, 0, IA64_IPI_DM_INIT, 0);
 		}
 	}
 }
 #endif
 /*
  * Called with preemption disabled.
  */
 void
 smp_send_reschedule (int cpu)
 {
 	platform_send_ipi(cpu, IA64_IPI_RESCHEDULE, IA64_IPI_DM_INT, 0);
 }

 /*
  * Called with preemption disabled.
  */
 static void
 smp_send_local_flush_tlb (int cpu)
 {
 	platform_send_ipi(cpu, IA64_IPI_LOCAL_TLB_FLUSH, IA64_IPI_DM_INT, 0);
 }

 void
 smp_local_flush_tlb(void)
 {
 	/*
 	 * Use atomic ops. Otherwise, the load/increment/store sequence from
 	 * a "++" operation can have the line stolen between the load & store.
 	 * The overhead of the atomic op in negligible in this case & offers
 	 * significant benefit for the brief periods where lots of cpus
 	 * are simultaneously flushing TLBs.
 	 */
 	ia64_fetchadd(1, &local_tlb_flush_counts[smp_processor_id()].count, acq);
 	local_flush_tlb_all();
 }

 #define FLUSH_DELAY	5 /* Usec backoff to eliminate excessive cacheline bouncing */

 void
 smp_flush_tlb_cpumask(cpumask_t xcpumask)
 {
 	unsigned int *counts = __ia64_per_cpu_var(shadow_flush_counts);
 	cpumask_t cpumask = xcpumask;
 	int mycpu, cpu, flush_mycpu = 0;

 	preempt_disable();
 	mycpu = smp_processor_id();

 	for_each_cpu_mask(cpu, cpumask)
 		counts[cpu] = local_tlb_flush_counts[cpu].count;

 	mb();
 	for_each_cpu_mask(cpu, cpumask) {
 		if (cpu == mycpu)
 			flush_mycpu = 1;
 		else
 			smp_send_local_flush_tlb(cpu);
 	}

 	if (flush_mycpu)
 		smp_local_flush_tlb();

 	for_each_cpu_mask(cpu, cpumask)
 		while(counts[cpu] == local_tlb_flush_counts[cpu].count)
 			udelay(FLUSH_DELAY);

 	preempt_enable();
 }

 void
 smp_flush_tlb_all (void)
 {
 	on_each_cpu((void (*)(void *))local_flush_tlb_all, NULL, 1, 1);
 }

 void
 smp_flush_tlb_mm (struct mm_struct *mm)
 {
 	preempt_disable();
 	/* this happens for the common case of a single-threaded fork():  */
 	if (likely(mm == current->active_mm && atomic_read(&mm->mm_users) == 1))
 	{
 		local_finish_flush_tlb_mm(mm);
 		preempt_enable();
 		return;
 	}

 	preempt_enable();
 	/*
 	 * We could optimize this further by using mm->cpu_vm_mask to track which CPUs
 	 * have been running in the address space.  It's not clear that this is worth the
 	 * trouble though: to avoid races, we have to raise the IPI on the target CPU
 	 * anyhow, and once a CPU is interrupted, the cost of local_flush_tlb_all() is
 	 * rather trivial.
 	 */
 	on_each_cpu((void (*)(void *))local_finish_flush_tlb_mm, mm, 1, 1);
 }

 /*
  * 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.
  *  <nonatomic>	Currently unused.
  *  <wait>	If true, wait until function has completed on other CPUs.
  *  [RETURNS]   0 on success, else a negative status code.
  *
  * Does not return until the remote CPU is nearly ready to execute <func>
  * or is or has executed.
  */

 int
 smp_call_function_single (int cpuid, void (*func) (void *info), void *info, int nonatomic,
 			  int wait)
 {
 	struct call_data_struct data;
 	int cpus = 1;
 	int me = get_cpu(); /* prevent preemption and reschedule on another processor */

 	if (cpuid == me) {
 		local_irq_disable();
 		func(info);
 		local_irq_enable();
 		put_cpu();
 		return 0;
 	}

 	data.func = func;
 	data.info = info;
 	atomic_set(&data.started, 0);
 	data.wait = wait;
 	if (wait)
 		atomic_set(&data.finished, 0);

 	spin_lock_bh(&call_lock);

 	call_data = &data;
 	mb();	/* ensure store to call_data precedes setting of IPI_CALL_FUNC */
   	send_IPI_single(cpuid, IPI_CALL_FUNC);

 	/* Wait for response */
 	while (atomic_read(&data.started) != cpus)
 		cpu_relax();

 	if (wait)
 		while (atomic_read(&data.finished) != cpus)
 			cpu_relax();
 	call_data = NULL;

 	spin_unlock_bh(&call_lock);
 	put_cpu();
 	return 0;
 }
 EXPORT_SYMBOL(smp_call_function_single);

 /*
  * this function sends a 'generic call function' IPI to all other CPUs
  * in the system.
  */

 /*
  *  [SUMMARY]	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.
  *  <nonatomic>	currently unused.
  *  <wait>	If true, wait (atomically) until function has completed on other CPUs.
  *  [RETURNS]   0 on success, else a negative status code.
  *
  * Does not return until remote CPUs are nearly ready to execute <func> or are or have
  * executed.
  *
  * 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 *info), void *info, int nonatomic, int wait)
 {
 	struct call_data_struct data;
 	int cpus;

 	spin_lock(&call_lock);
 	cpus = num_online_cpus() - 1;
 	if (!cpus) {
 		spin_unlock(&call_lock);
 		return 0;
 	}

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

 	data.func = func;
 	data.info = info;
 	atomic_set(&data.started, 0);
 	data.wait = wait;
 	if (wait)
 		atomic_set(&data.finished, 0);

 	call_data = &data;
 	mb();	/* ensure store to call_data precedes setting of IPI_CALL_FUNC */
 	send_IPI_allbutself(IPI_CALL_FUNC);

 	/* Wait for response */
 	while (atomic_read(&data.started) != cpus)
 		cpu_relax();

 	if (wait)
 		while (atomic_read(&data.finished) != cpus)
 			cpu_relax();
 	call_data = NULL;

 	spin_unlock(&call_lock);
 	return 0;
 }
 EXPORT_SYMBOL(smp_call_function);

 /*
  * this function calls the 'stop' function on all other CPUs in the system.
  */
 void
 smp_send_stop (void)
 {
 	send_IPI_allbutself(IPI_CPU_STOP);
 }

 int
 setup_profiling_timer (unsigned int multiplier)
 {
 	return -EINVAL;
 }
	/*
	* SMP Support
	*
	* Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
	* Copyright (C) 1999, 2001, 2003 David Mosberger-Tang <davidm@hpl.hp.com>
	*
	* Lots of stuff stolen from arch/alpha/kernel/smp.c
	*
	* 01/05/16 Rohit Seth <rohit.seth@intel.com> IA64-SMP functions. Reorganized
	* the existing code (on the lines of x86 port).
	* 00/09/11 David Mosberger <davidm@hpl.hp.com> Do loops_per_jiffy
	* calibration on each CPU.
	* 00/08/23 Asit Mallick <asit.k.mallick@intel.com> fixed logical processor id
	* 00/03/31 Rohit Seth <rohit.seth@intel.com> Fixes for Bootstrap Processor
	* & cpu_online_map now gets done here (instead of setup.c)
	* 99/10/05 davidm Update to bring it in sync with new command-line processing
	* scheme.
	* 10/13/00 Goutham Rao <goutham.rao@intel.com> Updated smp_call_function and
	* smp_call_function_single to resend IPI on timeouts
	*/
	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/sched.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/smp.h>
	#include <linux/kernel_stat.h>
	#include <linux/mm.h>
	#include <linux/cache.h>
	#include <linux/delay.h>
	#include <linux/efi.h>
	#include <linux/bitops.h>
	#include <linux/kexec.h>

	#include <asm/atomic.h>
	#include <asm/current.h>
	#include <asm/delay.h>
	#include <asm/machvec.h>
	#include <asm/io.h>
	#include <asm/irq.h>
	#include <asm/page.h>
	#include <asm/pgalloc.h>
	#include <asm/pgtable.h>
	#include <asm/processor.h>
	#include <asm/ptrace.h>
	#include <asm/sal.h>
	#include <asm/system.h>
	#include <asm/tlbflush.h>
	#include <asm/unistd.h>
	#include <asm/mca.h>

	/*
	* Note: alignment of 4 entries/cacheline was empirically determined
	* to be a good tradeoff between hot cachelines & spreading the array
	* across too many cacheline.
	*/
	static struct local_tlb_flush_counts {
	unsigned int count;
	} __attribute__((__aligned__(32))) local_tlb_flush_counts[NR_CPUS];

	static DEFINE_PER_CPU(unsigned int, shadow_flush_counts[NR_CPUS]) ____cacheline_aligned;


	/*
	* Structure and data for smp_call_function(). This is designed to minimise static memory
	* requirements. It also looks cleaner.
	*/
	static __cacheline_aligned DEFINE_SPINLOCK(call_lock);

	struct call_data_struct {
	void (func) (void info);
	void *info;
	long wait;
	atomic_t started;
	atomic_t finished;
	};

	static volatile struct call_data_struct *call_data;

	#define IPI_CALL_FUNC 0
	#define IPI_CPU_STOP 1
	#define IPI_KDUMP_CPU_STOP 3

	/* This needs to be cacheline aligned because it is written to by other CPUs. */
	static DEFINE_PER_CPU_SHARED_ALIGNED(u64, ipi_operation);

	extern void cpu_halt (void);

	void
	lock_ipi_calllock(void)
	{
	spin_lock_irq(&call_lock);
	}

	void
	unlock_ipi_calllock(void)
	{
	spin_unlock_irq(&call_lock);
	}

	static void
	stop_this_cpu (void)
	{
	/*
	* Remove this CPU:
	*/
	cpu_clear(smp_processor_id(), cpu_online_map);
	max_xtp();
	local_irq_disable();
	cpu_halt();
	}

	void
	cpu_die(void)
	{
	max_xtp();
	local_irq_disable();
	cpu_halt();
	/* Should never be here */
	BUG();
	for (;;);
	}

	irqreturn_t
	handle_IPI (int irq, void *dev_id)
	{
	int this_cpu = get_cpu();
	unsigned long *pending_ipis = &__ia64_per_cpu_var(ipi_operation);
	unsigned long ops;

	mb(); /* Order interrupt and bit testing. */
	while ((ops = xchg(pending_ipis, 0)) != 0) {
	mb(); /* Order bit clearing and data access. */
	do {
	unsigned long which;

	which = ffz(~ops);
	ops &= ~(1 << which);

	switch (which) {
	case IPI_CALL_FUNC:
	{
	struct call_data_struct *data;
	void (func)(void info);
	void *info;
	int wait;

	/* release the 'pointer lock' */
	data = (struct call_data_struct *) call_data;
	func = data->func;
	info = data->info;
	wait = data->wait;

	mb();
	atomic_inc(&data->started);
	/*
	* At this point the structure may be gone unless
	* wait is true.
	*/
	(*func)(info);

	/* Notify the sending CPU that the task is done. */
	mb();
	if (wait)
	atomic_inc(&data->finished);
	}
	break;

	case IPI_CPU_STOP:
	stop_this_cpu();
	break;
	#ifdef CONFIG_KEXEC
	case IPI_KDUMP_CPU_STOP:
	unw_init_running(kdump_cpu_freeze, NULL);
	break;
	#endif
	default:
	printk(KERN_CRIT "Unknown IPI on CPU %d: %lu\n", this_cpu, which);
	break;
	}
	} while (ops);
	mb(); /* Order data access and bit testing. */
	}
	put_cpu();
	return IRQ_HANDLED;
	}

	/*
	* Called with preemption disabled.
	*/
	static inline void
	send_IPI_single (int dest_cpu, int op)
	{
	set_bit(op, &per_cpu(ipi_operation, dest_cpu));
	platform_send_ipi(dest_cpu, IA64_IPI_VECTOR, IA64_IPI_DM_INT, 0);
	}

	/*
	* Called with preemption disabled.
	*/
	static inline void
	send_IPI_allbutself (int op)
	{
	unsigned int i;

	for_each_online_cpu(i) {
	if (i != smp_processor_id())
	send_IPI_single(i, op);
	}
	}

	/*
	* Called with preemption disabled.
	*/
	static inline void
	send_IPI_all (int op)
	{
	int i;

	for_each_online_cpu(i) {
	send_IPI_single(i, op);
	}
	}

	/*
	* Called with preemption disabled.
	*/
	static inline void
	send_IPI_self (int op)
	{
	send_IPI_single(smp_processor_id(), op);
	}

	#ifdef CONFIG_KEXEC
	void
	kdump_smp_send_stop(void)
	{
	send_IPI_allbutself(IPI_KDUMP_CPU_STOP);
	}

	void
	kdump_smp_send_init(void)
	{
	unsigned int cpu, self_cpu;
	self_cpu = smp_processor_id();
	for_each_online_cpu(cpu) {
	if (cpu != self_cpu) {
	if(kdump_status[cpu] == 0)
	platform_send_ipi(cpu, 0, IA64_IPI_DM_INIT, 0);
	}
	}
	}
	#endif
	/*
	* Called with preemption disabled.
	*/
	void
	smp_send_reschedule (int cpu)
	{
	platform_send_ipi(cpu, IA64_IPI_RESCHEDULE, IA64_IPI_DM_INT, 0);
	}

	/*
	* Called with preemption disabled.
	*/
	static void
	smp_send_local_flush_tlb (int cpu)
	{
	platform_send_ipi(cpu, IA64_IPI_LOCAL_TLB_FLUSH, IA64_IPI_DM_INT, 0);
	}

	void
	smp_local_flush_tlb(void)
	{
	/*
	* Use atomic ops. Otherwise, the load/increment/store sequence from
	* a "++" operation can have the line stolen between the load & store.
	* The overhead of the atomic op in negligible in this case & offers
	* significant benefit for the brief periods where lots of cpus
	* are simultaneously flushing TLBs.
	*/
	ia64_fetchadd(1, &local_tlb_flush_counts[smp_processor_id()].count, acq);
	local_flush_tlb_all();
	}

	#define FLUSH_DELAY 5 /* Usec backoff to eliminate excessive cacheline bouncing */

	void
	smp_flush_tlb_cpumask(cpumask_t xcpumask)
	{
	unsigned int *counts = __ia64_per_cpu_var(shadow_flush_counts);
	cpumask_t cpumask = xcpumask;
	int mycpu, cpu, flush_mycpu = 0;

	preempt_disable();
	mycpu = smp_processor_id();

	for_each_cpu_mask(cpu, cpumask)
	counts[cpu] = local_tlb_flush_counts[cpu].count;

	mb();
	for_each_cpu_mask(cpu, cpumask) {
	if (cpu == mycpu)
	flush_mycpu = 1;
	else
	smp_send_local_flush_tlb(cpu);
	}

	if (flush_mycpu)
	smp_local_flush_tlb();

	for_each_cpu_mask(cpu, cpumask)
	while(counts[cpu] == local_tlb_flush_counts[cpu].count)
	udelay(FLUSH_DELAY);

	preempt_enable();
	}

	void
	smp_flush_tlb_all (void)
	{
	on_each_cpu((void ()(void ))local_flush_tlb_all, NULL, 1, 1);
	}

	void
	smp_flush_tlb_mm (struct mm_struct *mm)
	{
	preempt_disable();
	/* this happens for the common case of a single-threaded fork(): */
	if (likely(mm == current->active_mm && atomic_read(&mm->mm_users) == 1))
	{
	local_finish_flush_tlb_mm(mm);
	preempt_enable();
	return;
	}

	preempt_enable();
	/*
	* We could optimize this further by using mm->cpu_vm_mask to track which CPUs
	* have been running in the address space. It's not clear that this is worth the
	* trouble though: to avoid races, we have to raise the IPI on the target CPU
	* anyhow, and once a CPU is interrupted, the cost of local_flush_tlb_all() is
	* rather trivial.
	*/
	on_each_cpu((void ()(void ))local_finish_flush_tlb_mm, mm, 1, 1);
	}

	/*
	* 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.
	* <nonatomic> Currently unused.
	* <wait> If true, wait until function has completed on other CPUs.
	* [RETURNS] 0 on success, else a negative status code.
	*
	* Does not return until the remote CPU is nearly ready to execute <func>
	* or is or has executed.
	*/

	int
	smp_call_function_single (int cpuid, void (func) (void info), void *info, int nonatomic,
	int wait)
	{
	struct call_data_struct data;
	int cpus = 1;
	int me = get_cpu(); /* prevent preemption and reschedule on another processor */

	if (cpuid == me) {
	local_irq_disable();
	func(info);
	local_irq_enable();
	put_cpu();
	return 0;
	}

	data.func = func;
	data.info = info;
	atomic_set(&data.started, 0);
	data.wait = wait;
	if (wait)
	atomic_set(&data.finished, 0);

	spin_lock_bh(&call_lock);

	call_data = &data;
	mb(); /* ensure store to call_data precedes setting of IPI_CALL_FUNC */
	send_IPI_single(cpuid, IPI_CALL_FUNC);

	/* Wait for response */
	while (atomic_read(&data.started) != cpus)
	cpu_relax();

	if (wait)
	while (atomic_read(&data.finished) != cpus)
	cpu_relax();
	call_data = NULL;

	spin_unlock_bh(&call_lock);
	put_cpu();
	return 0;
	}
	EXPORT_SYMBOL(smp_call_function_single);

	/*
	* this function sends a 'generic call function' IPI to all other CPUs
	* in the system.
	*/

	/*
	* [SUMMARY] 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.
	* <nonatomic> currently unused.
	* <wait> If true, wait (atomically) until function has completed on other CPUs.
	* [RETURNS] 0 on success, else a negative status code.
	*
	* Does not return until remote CPUs are nearly ready to execute <func> or are or have
	* executed.
	*
	* 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 info), void *info, int nonatomic, int wait)
	{
	struct call_data_struct data;
	int cpus;

	spin_lock(&call_lock);
	cpus = num_online_cpus() - 1;
	if (!cpus) {
	spin_unlock(&call_lock);
	return 0;
	}

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

	data.func = func;
	data.info = info;
	atomic_set(&data.started, 0);
	data.wait = wait;
	if (wait)
	atomic_set(&data.finished, 0);

	call_data = &data;
	mb(); /* ensure store to call_data precedes setting of IPI_CALL_FUNC */
	send_IPI_allbutself(IPI_CALL_FUNC);

	/* Wait for response */
	while (atomic_read(&data.started) != cpus)
	cpu_relax();

	if (wait)
	while (atomic_read(&data.finished) != cpus)
	cpu_relax();
	call_data = NULL;

	spin_unlock(&call_lock);
	return 0;
	}
	EXPORT_SYMBOL(smp_call_function);

	/*
	* this function calls the 'stop' function on all other CPUs in the system.
	*/
	void
	smp_send_stop (void)
	{
	send_IPI_allbutself(IPI_CPU_STOP);
	}

	int
	setup_profiling_timer (unsigned int multiplier)
	{
	return -EINVAL;
	}