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| author | Thomas Gleixner <tglx@linutronix.de> | 2019-01-11 14:33:16 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-01-31 08:14:39 +0100 |
| commit | 21c0d1621b8d4b20f19f383de03d14095657016f (patch) | |
| tree | 11454f342d15ab66fb21df73f2e19567d3a76e5e /kernel/time | |
| parent | dd085f9b1dc15dfbd3e5ced275a92324f5e16a44 (diff) | |
| download | linux-stable-21c0d1621b8d4b20f19f383de03d14095657016f.tar.gz linux-stable-21c0d1621b8d4b20f19f383de03d14095657016f.tar.bz2 linux-stable-21c0d1621b8d4b20f19f383de03d14095657016f.zip | |
posix-cpu-timers: Unbreak timer rearming
commit 93ad0fc088c5b4631f796c995bdd27a082ef33a6 upstream.
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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/time')
| -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 ce32cf741b25..76801b9b481e 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, |