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PM / hibernate / memory hotplug: Rework mutual exclusion 

Since all of the memory hotplug operations have to be carried out
under device_hotplug_lock, they won't need to acquire pm_mutex if
device_hotplug_lock is held around hibernation.

For this reason, make the hibernation code acquire
device_hotplug_lock after freezing user space processes and
release it before thawing them.  At the same tim drop the
lock_system_sleep() and unlock_system_sleep() calls from
lock_memory_hotplug() and unlock_memory_hotplug(), respectively.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
This commit is contained in:
Rafael J. Wysocki 2013-08-30 14:19:46 +02:00
parent 8fd37a4c98
commit 942f40155a
3 changed files with 6 additions and 4 deletions
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4
kernel/power/hibernate.c
View File

@ -652,6 +652,7 @@ int hibernate(void)
if (error)
goto Exit;
lock_device_hotplug();
/* Allocate memory management structures */
error = create_basic_memory_bitmaps();
if (error)
@ -685,6 +686,7 @@ int hibernate(void)
Free_bitmaps:
free_basic_memory_bitmaps();
Thaw:
unlock_device_hotplug();
thaw_processes();
/* Don't bother checking whether freezer_test_done is true */
@ -814,6 +816,7 @@ static int software_resume(void)
pr_debug("PM: Loading hibernation image.\n");
lock_device_hotplug();
error = create_basic_memory_bitmaps();
if (error)
goto Thaw;
@ -827,6 +830,7 @@ static int software_resume(void)
swsusp_free();
free_basic_memory_bitmaps();
Thaw:
unlock_device_hotplug();
thaw_processes();
Finish:
pm_notifier_call_chain(PM_POST_RESTORE);

2
kernel/power/user.c
View File

@ -201,6 +201,7 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
if (!mutex_trylock(&pm_mutex))
return -EBUSY;
lock_device_hotplug();
data = filp->private_data;
switch (cmd) {
@ -373,6 +374,7 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
}
unlock_device_hotplug();
mutex_unlock(&pm_mutex);
return error;

4
mm/memory_hotplug.c
View File

@ -51,14 +51,10 @@ DEFINE_MUTEX(mem_hotplug_mutex);
void lock_memory_hotplug(void)
{
mutex_lock(&mem_hotplug_mutex);
/* for exclusive hibernation if CONFIG_HIBERNATION=y */
lock_system_sleep();
}
void unlock_memory_hotplug(void)
{
unlock_system_sleep();
mutex_unlock(&mem_hotplug_mutex);
}