53 lines
2.2 KiB
Diff
53 lines
2.2 KiB
Diff
From: Thomas Gleixner <tglx@linutronix.de>
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Date: Fri, 11 Jan 2019 14:33:16 +0100
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Subject: posix-cpu-timers: Unbreak timer rearming
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Origin: https://lore.kernel.org/lkml/20190111133500.840117406@linutronix.de/
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Bug-Debian: https://bugs.debian.org/919019
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Bug-Debian: https://bugs.debian.org/919049
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The recent commit which prevented a division by 0 issue in the alarm timer
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code broke posix CPU timers as an unwanted side effect.
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The reason is that the common rearm code checks for timer->it_interval
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being 0 now. What went unnoticed is that the posix cpu timer setup does not
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initialize timer->it_interval as it stores the interval in CPU timer
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specific storage. The reason for the separate storage is historical as the
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posix CPU timers always had a 64bit nanoseconds representation internally
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while timer->it_interval is type ktime_t which used to be a modified
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timespec representation on 32bit machines.
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Instead of reverting the offending commit and fixing the alarmtimer issue
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in the alarmtimer code, store the interval in timer->it_interval at CPU
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timer setup time so the common code check works. This also repairs the
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existing inconistency of the posix CPU timer code which kept a single shot
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timer armed despite of the interval being 0.
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The separate storage can be removed in mainline, but that needs to be a
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separate commit as the current one has to be backported to stable kernels.
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Fixes: 0e334db6bb4b ("posix-timers: Fix division by zero bug")
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Reported-by: H.J. Lu <hjl.tools@gmail.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: stable@vger.kernel.org
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: John Stultz <john.stultz@linaro.org>
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---
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kernel/time/posix-cpu-timers.c | 1 +
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1 file changed, 1 insertion(+)
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diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
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index 8f0644af40be..80f955210861 100644
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--- a/kernel/time/posix-cpu-timers.c
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+++ b/kernel/time/posix-cpu-timers.c
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@@ -685,6 +685,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
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* set up the signal and overrun bookkeeping.
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*/
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timer->it.cpu.incr = timespec64_to_ns(&new->it_interval);
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+ timer->it_interval = ns_to_ktime(timer->it.cpu.incr);
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/*
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* This acts as a modification timestamp for the timer,
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--
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2.20.1
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