Messages in this thread | | | Date | Mon, 6 Nov 2017 12:13:26 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH] PM / s2idle: Clear the events_check_enabled flag |
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On Tue 2017-10-31 14:44:24, Rajat Jain wrote: > 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. > > What this patch does: > > It moves the clearing of the flag to 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> -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html [unhandled content-type:application/pgp-signature] | |