Messages in this thread | | | Date | Wed, 4 Apr 2018 09:37:15 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH RT 1/3] alarmtimer: Prevent live lock in alarm_cancel() |
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On 2018-04-03 20:32:36 [+0200], Daniel Wagner wrote: > Hi Sebastian, > > On 03/28/2018 12:07 PM, Sebastian Andrzej Siewior wrote: > > If alarm_try_to_cancel() requires a retry, then depending on the > > priority setting the retry loop might prevent timer callback completion > > on RT. Prevent that by waiting for completion on RT, no change for a > > non RT kernel. > > > > Cc: stable-rt@vger.kernel.org > > How relevant is this serie for trees before eae1c4ae275f ("posix-timers: > Make use of cancel/arm callbacks")? Patch #2 seems to depend on that change > which was added in v4.12.
so #1 looks relevant since that alarmtimer was introduced. #2 since the change you mentioned because after that patch alarmtimer would be handled wrongly - before you should do the schedule_timout() which should be fine. And #3 since 3.0+ (since the RCU-readsection was added) but it is not easy to trigger (you would have to delete the timer while a callback is waiting for it).
> Thanks, > Daniel
Sebastian
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