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Commit e3920fb4 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Linus Torvalds
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[PATCH] Disable CPU hotplug during suspend 



The current suspend code has to be run on one CPU, so we use the CPU
hotplug to take the non-boot CPUs offline on SMP machines.  However, we
should also make sure that these CPUs will not be enabled by someone else
after we have disabled them.

The functions disable_nonboot_cpus() and enable_nonboot_cpus() are moved to
kernel/cpu.c, because they now refer to some stuff in there that should
better be static.  Also it's better if disable_nonboot_cpus() returns an
error instead of panicking if something goes wrong, and
enable_nonboot_cpus() has no reason to panic(), because the CPUs may have
been enabled by the userland before it tries to take them online.

Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Acked-by: default avatarPavel Machek <pavel@ucw.cz>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e8eff5ac

include/linux/cpu.h

+8 −0
Original line number Original line Diff line number Diff line
@@ -89,4 +89,12 @@ int cpu_down(unsigned int cpu); 
static inline int cpu_is_offline(int cpu) { return 0; }

static inline int cpu_is_offline(int cpu) { return 0; }

#endif

#endif





#ifdef CONFIG_SUSPEND_SMP

extern int disable_nonboot_cpus(void);

extern void enable_nonboot_cpus(void);

#else

static inline int disable_nonboot_cpus(void) { return 0; }

static inline void enable_nonboot_cpus(void) {}

#endif



#endif /* _LINUX_CPU_H_ */
 
#endif /* _LINUX_CPU_H_ */

include/linux/suspend.h

+0 −8
Original line number Original line Diff line number Diff line
@@ -57,14 +57,6 @@ static inline int software_suspend(void) 
}

}

#endif /* CONFIG_PM */

#endif /* CONFIG_PM */





#ifdef CONFIG_SUSPEND_SMP

extern void disable_nonboot_cpus(void);

extern void enable_nonboot_cpus(void);

#else

static inline void disable_nonboot_cpus(void) {}

static inline void enable_nonboot_cpus(void) {}

#endif



void save_processor_state(void);

void save_processor_state(void);

void restore_processor_state(void);

void restore_processor_state(void);

struct saved_context;

struct saved_context;

kernel/cpu.c

+118 −20
Original line number Original line Diff line number Diff line
@@ -21,6 +21,11 @@ static DEFINE_MUTEX(cpu_bitmask_lock); 




static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain);

static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain);





/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.

 * Should always be manipulated under cpu_add_remove_lock

 */

static int cpu_hotplug_disabled;



#ifdef CONFIG_HOTPLUG_CPU

#ifdef CONFIG_HOTPLUG_CPU





/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */

/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
@@ -108,30 +113,25 @@ static int take_cpu_down(void *unused) 
	return 0;

	return 0;

}

}





int cpu_down(unsigned int cpu)

/* Requires cpu_add_remove_lock to be held */

static int _cpu_down(unsigned int cpu)

{

{

	int err;

	int err;

	struct task_struct *p;

	struct task_struct *p;

	cpumask_t old_allowed, tmp;

	cpumask_t old_allowed, tmp;





	mutex_lock(&cpu_add_remove_lock);

	if (num_online_cpus() == 1)

	if (num_online_cpus() == 1) {

		return -EBUSY;

		err = -EBUSY;

		goto out;

	}





	if (!cpu_online(cpu)) {

	if (!cpu_online(cpu))

		err = -EINVAL;

		return -EINVAL;

		goto out;

	}





	err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,

	err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,

						(void *)(long)cpu);

						(void *)(long)cpu);

	if (err == NOTIFY_BAD) {

	if (err == NOTIFY_BAD) {

		printk("%s: attempt to take down CPU %u failed\n",

		printk("%s: attempt to take down CPU %u failed\n",

				__FUNCTION__, cpu);

				__FUNCTION__, cpu);

		err = -EINVAL;

		return -EINVAL;

		goto out;

	}

	}





	/* Ensure that we are not runnable on dying cpu */

	/* Ensure that we are not runnable on dying cpu */
@@ -179,22 +179,32 @@ int cpu_down(unsigned int cpu) 
	err = kthread_stop(p);

	err = kthread_stop(p);

out_allowed:

out_allowed:

	set_cpus_allowed(current, old_allowed);

	set_cpus_allowed(current, old_allowed);

out:

	return err;

}



int cpu_down(unsigned int cpu)

{

	int err = 0;



	mutex_lock(&cpu_add_remove_lock);

	if (cpu_hotplug_disabled)

		err = -EBUSY;

	else

		err = _cpu_down(cpu);



	mutex_unlock(&cpu_add_remove_lock);

	mutex_unlock(&cpu_add_remove_lock);

	return err;

	return err;

}

}

#endif /*CONFIG_HOTPLUG_CPU*/

#endif /*CONFIG_HOTPLUG_CPU*/





int __devinit cpu_up(unsigned int cpu)

/* Requires cpu_add_remove_lock to be held */

static int __devinit _cpu_up(unsigned int cpu)

{

{

	int ret;

	int ret;

	void *hcpu = (void *)(long)cpu;

	void *hcpu = (void *)(long)cpu;





	mutex_lock(&cpu_add_remove_lock);

	if (cpu_online(cpu) || !cpu_present(cpu))

	if (cpu_online(cpu) || !cpu_present(cpu)) {

		return -EINVAL;

		ret = -EINVAL;

		goto out;

	}





	ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);

	ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);

	if (ret == NOTIFY_BAD) {

	if (ret == NOTIFY_BAD) {
@@ -219,7 +229,95 @@ int __devinit cpu_up(unsigned int cpu) 
	if (ret != 0)

	if (ret != 0)

		blocking_notifier_call_chain(&cpu_chain,

		blocking_notifier_call_chain(&cpu_chain,

				CPU_UP_CANCELED, hcpu);

				CPU_UP_CANCELED, hcpu);



	return ret;

}



int __devinit cpu_up(unsigned int cpu)

{

	int err = 0;



	mutex_lock(&cpu_add_remove_lock);

	if (cpu_hotplug_disabled)

		err = -EBUSY;

	else

		err = _cpu_up(cpu);



	mutex_unlock(&cpu_add_remove_lock);

	return err;

}



#ifdef CONFIG_SUSPEND_SMP

static cpumask_t frozen_cpus;



int disable_nonboot_cpus(void)

{

	int cpu, first_cpu, error;



	mutex_lock(&cpu_add_remove_lock);

	first_cpu = first_cpu(cpu_present_map);

	if (!cpu_online(first_cpu)) {

		error = _cpu_up(first_cpu);

		if (error) {

			printk(KERN_ERR "Could not bring CPU%d up.\n",

				first_cpu);

			goto out;

		}

	}

	error = set_cpus_allowed(current, cpumask_of_cpu(first_cpu));

	if (error) {

		printk(KERN_ERR "Could not run on CPU%d\n", first_cpu);

		goto out;

	}

	/* We take down all of the non-boot CPUs in one shot to avoid races

	 * with the userspace trying to use the CPU hotplug at the same time

	 */

	cpus_clear(frozen_cpus);

	printk("Disabling non-boot CPUs ...\n");

	for_each_online_cpu(cpu) {

		if (cpu == first_cpu)

			continue;

		error = _cpu_down(cpu);

		if (!error) {

			cpu_set(cpu, frozen_cpus);

			printk("CPU%d is down\n", cpu);

		} else {

			printk(KERN_ERR "Error taking CPU%d down: %d\n",

				cpu, error);

			break;

		}

	}

	if (!error) {

		BUG_ON(num_online_cpus() > 1);

		/* Make sure the CPUs won't be enabled by someone else */

		cpu_hotplug_disabled = 1;

	} else {

		printk(KERN_ERR "Non-boot CPUs are not disabled");

	}

out:

out:

	mutex_unlock(&cpu_add_remove_lock);

	mutex_unlock(&cpu_add_remove_lock);

	return ret;

	return error;

}



void enable_nonboot_cpus(void)

{

	int cpu, error;



	/* Allow everyone to use the CPU hotplug again */

	mutex_lock(&cpu_add_remove_lock);

	cpu_hotplug_disabled = 0;

	mutex_unlock(&cpu_add_remove_lock);



	printk("Enabling non-boot CPUs ...\n");

	for_each_cpu_mask(cpu, frozen_cpus) {

		error = cpu_up(cpu);

		if (!error) {

			printk("CPU%d is up\n", cpu);

			continue;

		}

		printk(KERN_WARNING "Error taking CPU%d up: %d\n",

			cpu, error);

	}

	cpus_clear(frozen_cpus);

}

}

#endif

kernel/power/Makefile

+0 −2
Original line number Original line Diff line number Diff line
@@ -7,6 +7,4 @@ obj-y := main.o process.o console.o 
obj-$(CONFIG_PM_LEGACY)		+= pm.o

obj-$(CONFIG_PM_LEGACY)		+= pm.o

obj-$(CONFIG_SOFTWARE_SUSPEND)	+= swsusp.o disk.o snapshot.o swap.o user.o

obj-$(CONFIG_SOFTWARE_SUSPEND)	+= swsusp.o disk.o snapshot.o swap.o user.o





obj-$(CONFIG_SUSPEND_SMP)	+= smp.o



obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o
 
obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o

kernel/power/disk.c

+6 −1
Original line number Original line Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/fs.h>

#include <linux/fs.h>

#include <linux/mount.h>

#include <linux/mount.h>

#include <linux/pm.h>

#include <linux/pm.h>

#include <linux/cpu.h>





#include "power.h"

#include "power.h"
@@ -72,7 +73,10 @@ static int prepare_processes(void) 
	int error;

	int error;





	pm_prepare_console();

	pm_prepare_console();

	disable_nonboot_cpus();



	error = disable_nonboot_cpus();

	if (error)

		goto enable_cpus;





	if (freeze_processes()) {

	if (freeze_processes()) {

		error = -EBUSY;

		error = -EBUSY;
@@ -84,6 +88,7 @@ static int prepare_processes(void) 
		return 0;

		return 0;

thaw:

thaw:

	thaw_processes();

	thaw_processes();

enable_cpus:

	enable_nonboot_cpus();

	enable_nonboot_cpus();

	pm_restore_console();

	pm_restore_console();

	return error;

	return error;