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PM: hibernate: Incorporate concurrency handling

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Hibernation concurrency handling is currently delegated to user.c,
where it's also used for regulating the access to the snapshot device.

In the prospective of making user.c a separate configuration option,
such mutual exclusion is brought into hibernate.c and made available
through accessor helpers hereby introduced.

Signed-off-by: Domenico Andreoli <domenico.andreoli@linux.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Domenico Andreoli 2020-05-07 09:19:52 +02:00 committed by Rafael J. Wysocki
parent 3a4ccdb92e
commit ab7e9b067f
3 changed files with 22 additions and 12 deletions
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20
kernel/power/hibernate.c
View file

@ -67,6 +67,18 @@ bool freezer_test_done;
static const struct platform_hibernation_ops *hibernation_ops;
static atomic_t hibernate_atomic = ATOMIC_INIT(1);
bool hibernate_acquire(void)
{
return atomic_add_unless(&hibernate_atomic, -1, 0);
}
void hibernate_release(void)
{
atomic_inc(&hibernate_atomic);
}
bool hibernation_available(void)
{
return nohibernate == 0 && !security_locked_down(LOCKDOWN_HIBERNATION);
@ -704,7 +716,7 @@ int hibernate(void)
lock_system_sleep();
/* The snapshot device should not be opened while we're running */
if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
if (!hibernate_acquire()) {
error = -EBUSY;
goto Unlock;
}
@ -775,7 +787,7 @@ int hibernate(void)
Exit:
__pm_notifier_call_chain(PM_POST_HIBERNATION, nr_calls, NULL);
pm_restore_console();
atomic_inc(&snapshot_device_available);
hibernate_release();
Unlock:
unlock_system_sleep();
pr_info("hibernation exit\n");
@ -880,7 +892,7 @@ static int software_resume(void)
goto Unlock;
/* The snapshot device should not be opened while we're running */
if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
if (!hibernate_acquire()) {
error = -EBUSY;
swsusp_close(FMODE_READ);
goto Unlock;
@ -911,7 +923,7 @@ static int software_resume(void)
__pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
pm_restore_console();
pr_info("resume failed (%d)\n", error);
atomic_inc(&snapshot_device_available);
hibernate_release();
/* For success case, the suspend path will release the lock */
Unlock:
mutex_unlock(&system_transition_mutex);

4
kernel/power/power.h
View file

@ -154,8 +154,8 @@ extern int snapshot_write_next(struct snapshot_handle *handle);
extern void snapshot_write_finalize(struct snapshot_handle *handle);
extern int snapshot_image_loaded(struct snapshot_handle *handle);
/* If unset, the snapshot device cannot be open. */
extern atomic_t snapshot_device_available;
extern bool hibernate_acquire(void);
extern void hibernate_release(void);
extern sector_t alloc_swapdev_block(int swap);
extern void free_all_swap_pages(int swap);

10
kernel/power/user.c
View file

@ -37,8 +37,6 @@ static struct snapshot_data {
bool free_bitmaps;
} snapshot_state;
atomic_t snapshot_device_available = ATOMIC_INIT(1);
static int snapshot_open(struct inode *inode, struct file *filp)
{
struct snapshot_data *data;
@ -49,13 +47,13 @@ static int snapshot_open(struct inode *inode, struct file *filp)
lock_system_sleep();
if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
if (!hibernate_acquire()) {
error = -EBUSY;
goto Unlock;
}
if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
atomic_inc(&snapshot_device_available);
hibernate_release();
error = -ENOSYS;
goto Unlock;
}
@ -92,7 +90,7 @@ static int snapshot_open(struct inode *inode, struct file *filp)
__pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
}
if (error)
atomic_inc(&snapshot_device_available);
hibernate_release();
data->frozen = false;
data->ready = false;
@ -122,7 +120,7 @@ static int snapshot_release(struct inode *inode, struct file *filp)
}
pm_notifier_call_chain(data->mode == O_RDONLY ?
PM_POST_HIBERNATION : PM_POST_RESTORE);
atomic_inc(&snapshot_device_available);
hibernate_release();
unlock_system_sleep();