This is a note to let you know that I've just added the patch titled
PM / s2idle: Clear the events_check_enabled flag
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: pm-s2idle-clear-the-events_check_enabled-flag.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Mon Dec 18 13:28:59 CET 2017
From: Rajat Jain rajatja@google.com Date: Tue, 31 Oct 2017 14:44:24 -0700 Subject: PM / s2idle: Clear the events_check_enabled flag
From: Rajat Jain rajatja@google.com
[ Upstream commit 95b982b45122c57da2ee0b46cce70775e1d987af ]
Problem: This flag does not get cleared currently in the suspend or resume path in the following cases:
* In case some driver's suspend routine returns an error. * Successful s2idle case * etc?
Why is this a problem: What happens is that the next suspend attempt could fail even though the user did not enable the flag by writing to /sys/power/wakeup_count. This is 1 use case how the issue can be seen (but similar use case with driver suspend failure can be thought of):
1. Read /sys/power/wakeup_count 2. echo count > /sys/power/wakeup_count 3. echo freeze > /sys/power/wakeup_count 4. Let the system suspend, and wakeup the system using some wake source that calls pm_wakeup_event() e.g. power button or something. 5. Note that the combined wakeup count would be incremented due to the pm_wakeup_event() in the resume path. 6. After resuming the events_check_enabled flag is still set.
At this point if the user attempts to freeze again (without writing to /sys/power/wakeup_count), the suspend would fail even though there has been no wake event since the past resume.
Address that by clearing the flag just before a resume is completed, so that it is always cleared for the corner cases mentioned above.
Signed-off-by: Rajat Jain rajatja@google.com Acked-by: Pavel Machek pavel@ucw.cz Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/power/suspend.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -437,7 +437,6 @@ static int suspend_enter(suspend_state_t error = suspend_ops->enter(state); trace_suspend_resume(TPS("machine_suspend"), state, false); - events_check_enabled = false; } else if (*wakeup) { error = -EBUSY; } @@ -582,6 +581,7 @@ static int enter_state(suspend_state_t s pm_restore_gfp_mask();
Finish: + events_check_enabled = false; pm_pr_dbg("Finishing wakeup.\n"); suspend_finish(); Unlock:
Patches currently in stable-queue which might be from rajatja@google.com are
queue-4.14/pm-s2idle-clear-the-events_check_enabled-flag.patch