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notifier: Fix broken error handling pattern

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The current notifiers have the following error handling pattern all
over the place:

	int err, nr;

	err = __foo_notifier_call_chain(&chain, val_up, v, -1, &nr);
	if (err & NOTIFIER_STOP_MASK)
		__foo_notifier_call_chain(&chain, val_down, v, nr-1, NULL)

And aside from the endless repetition thereof, it is broken. Consider
blocking notifiers; both calls take and drop the rwsem, this means
that the notifier list can change in between the two calls, making @nr
meaningless.

Fix this by replacing all the __foo_notifier_call_chain() functions
with foo_notifier_call_chain_robust() that embeds the above pattern,
but ensures it is inside a single lock region.

Note: I switched atomic_notifier_call_chain_robust() to use
      the spinlock, since RCU cannot provide the guarantee
      required for the recovery.

Note: software_resume() error handling was broken afaict.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20200818135804.325626653@infradead.org
This commit is contained in:
Peter Zijlstra 2020-08-18 15:57:36 +02:00 • committed by Ingo Molnar
parent f75aef392f
commit 70d9329857
9 changed files with 147 additions and 140 deletions
Download patch file Download diff file Expand all files Collapse all files

39
kernel/power/hibernate.c
View file

@ -706,8 +706,8 @@ static int load_image_and_restore(void)
*/
int hibernate(void)
{
int error, nr_calls = 0;
bool snapshot_test = false;
int error;
if (!hibernation_available()) {
pm_pr_dbg("Hibernation not available.\n");
@ -723,11 +723,9 @@ int hibernate(void)
pr_info("hibernation entry\n");
pm_prepare_console();
error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
if (error) {
nr_calls--;
goto Exit;
}
error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
if (error)
goto Restore;
ksys_sync_helper();
@ -785,7 +783,8 @@ int hibernate(void)
/* Don't bother checking whether freezer_test_done is true */
freezer_test_done = false;
Exit:
__pm_notifier_call_chain(PM_POST_HIBERNATION, nr_calls, NULL);
pm_notifier_call_chain(PM_POST_HIBERNATION);
Restore:
pm_restore_console();
hibernate_release();
Unlock:
@ -804,7 +803,7 @@ int hibernate(void)
*/
int hibernate_quiet_exec(int (*func)(void *data), void *data)
{
int error, nr_calls = 0;
int error;
lock_system_sleep();
@ -815,11 +814,9 @@ int hibernate_quiet_exec(int (*func)(void *data), void *data)
pm_prepare_console();
error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
if (error) {
nr_calls--;
goto exit;
}
error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
if (error)
goto restore;
error = freeze_processes();
if (error)
@ -880,8 +877,9 @@ thaw:
thaw_processes();
exit:
__pm_notifier_call_chain(PM_POST_HIBERNATION, nr_calls, NULL);
pm_notifier_call_chain(PM_POST_HIBERNATION);
restore:
pm_restore_console();
hibernate_release();
@ -910,7 +908,7 @@ EXPORT_SYMBOL_GPL(hibernate_quiet_exec);
*/
static int software_resume(void)
{
int error, nr_calls = 0;
int error;
/*
* If the user said "noresume".. bail out early.
@ -997,11 +995,9 @@ static int software_resume(void)
pr_info("resume from hibernation\n");
pm_prepare_console();
error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
if (error) {
nr_calls--;
goto Close_Finish;
}
error = pm_notifier_call_chain_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE);
if (error)
goto Restore;
pm_pr_dbg("Preparing processes for hibernation restore.\n");
error = freeze_processes();
@ -1017,7 +1013,8 @@ static int software_resume(void)
error = load_image_and_restore();
thaw_processes();
Finish:
__pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
pm_notifier_call_chain(PM_POST_RESTORE);
Restore:
pm_restore_console();
pr_info("resume failed (%d)\n", error);
hibernate_release();