Re: [PATCH 1/3] posix-timers: Correctly get dying task time samplein posix_cpu_timer_schedule()
From: Frederic Weisbecker
Date: Thu Apr 11 2013 - 11:28:39 EST
On Mon, Apr 01, 2013 at 08:07:59AM +0800, Chen Gang wrote:
> On 2013å03æ30æ 21:15, Frederic Weisbecker wrote:
> > In order to arm the next timer to schedule, we take a sample of the
> > current process or thread cputime.
> > If the task is dying though, we don't arm anything but we
> > cache the remaining timer expiration delta for further reads.
> > Something similar is performed in posix_cpu_timer_get() but
> > here we forget to take the process wide cputime sample
> > before caching it.
> > As a result we are storing random stack content, leading
> > every further reads of that timer to return junk values.
> > Fix this by taking the appropriate sample in the case of
> > process wide timers.
> > Reported-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Reported-by: Chen Gang <gang.chen@xxxxxxxxxxx>
> > Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> > Cc: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxx>
> > Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> > Cc: Chen Gang <gang.chen@xxxxxxxxxxx>
> > ---
> thank you for mark me as reported by, although I reported too late
> (Andrew Morton is the first reporter).
Bug reporters simply deserve to be credited, no sorting is required ;)
> next, I should continue to try to find another issues about kernel.
I encourage you to do so :)
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