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authorThomas Gleixner <tglx@linutronix.de>2019-01-11 14:33:16 +0100
committerThomas Gleixner <tglx@linutronix.de>2019-01-15 16:34:37 +0100
commit93ad0fc088c5b4631f796c995bdd27a082ef33a6 (patch)
tree9589d3f1b8789c9772f38e48b8d303acb01cdf53 /kernel
parent1c7fc5cbc33980acd13d668f1c8f0313d6ae9fd8 (diff)
downloadlinux-93ad0fc088c5b4631f796c995bdd27a082ef33a6.tar.bz2
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.c1
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,