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| author | Thomas Gleixner <tglx@linutronix.de> | 2019-01-11 14:33:16 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-01-15 16:34:37 +0100 |
| commit | 93ad0fc088c5b4631f796c995bdd27a082ef33a6 (patch) | |
| tree | 9589d3f1b8789c9772f38e48b8d303acb01cdf53 /kernel | |
| parent | Linux 5.0-rc2 (diff) | |
| download | linux-93ad0fc088c5b4631f796c995bdd27a082ef33a6.tar.xz linux-93ad0fc088c5b4631f796c995bdd27a082ef33a6.zip | |
posix-cpu-timers: Unbreak timer rearming
The recent commit which prevented a division by 0 issue in the alarm timer
code broke posix CPU timers as an unwanted side effect.
The reason is that the common rearm code checks for timer->it_interval
being 0 now. What went unnoticed is that the posix cpu timer setup does not
initialize timer->it_interval as it stores the interval in CPU timer
specific storage. The reason for the separate storage is historical as the
posix CPU timers always had a 64bit nanoseconds representation internally
while timer->it_interval is type ktime_t which used to be a modified
timespec representation on 32bit machines.
Instead of reverting the offending commit and fixing the alarmtimer issue
in the alarmtimer code, store the interval in timer->it_interval at CPU
timer setup time so the common code check works. This also repairs the
existing inconistency of the posix CPU timer code which kept a single shot
timer armed despite of the interval being 0.
The separate storage can be removed in mainline, but that needs to be a
separate commit as the current one has to be backported to stable kernels.
Fixes: 0e334db6bb4b ("posix-timers: Fix division by zero bug")
Reported-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190111133500.840117406@linutronix.de
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/posix-cpu-timers.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 8f0644af40be..80f955210861 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -685,6 +685,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, * set up the signal and overrun bookkeeping. */ timer->it.cpu.incr = timespec64_to_ns(&new->it_interval); + timer->it_interval = ns_to_ktime(timer->it.cpu.incr); /* * This acts as a modification timestamp for the timer, |