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 <[email protected]> Reported-by: Chen Gang <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> Cc: Stanislaw Gruszka <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Chen Gang <[email protected]> --- kernel/posix-cpu-timers.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index edf94b6..afd79a9 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -1062,6 +1062,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer) * not yet reaped. Take this opportunity to * drop our task ref. */ + cpu_timer_sample_group(timer->it_clock, p, &now); clear_dead_task(timer, now); goto out_unlock; } -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
