| From | lizf@kernel ... | Subject | [PATCH 3.4 39/91] alarmtimer: Lock k_itimer during timer callback | Date | Thu, 27 Nov 2014 16:42:22 +0800 |
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From: Richard Larocque <rlarocque@google.com>
3.4.105-rc1 review patch. If anyone has any objections, please let me know.
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commit 474e941bed9262f5fa2394f9a4a67e24499e5926 upstream.
Locks the k_itimer's it_lock member when handling the alarm timer's expiry callback.
The regular posix timers defined in posix-timers.c have this lock held during timout processing because their callbacks are routed through posix_timer_fn(). The alarm timers follow a different path, so they ought to grab the lock somewhere else.
Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Sharvil Nanavati <sharvil@google.com> Signed-off-by: Richard Larocque <rlarocque@google.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Zefan Li <lizefan@huawei.com> --- kernel/time/alarmtimer.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index c870118..3ce9262 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -454,8 +454,12 @@ static enum alarmtimer_type clock2alarm(clockid_t clockid) static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm, ktime_t now) { + unsigned long flags; struct k_itimer *ptr = container_of(alarm, struct k_itimer, it.alarm.alarmtimer); + enum alarmtimer_restart result = ALARMTIMER_NORESTART; + + spin_lock_irqsave(&ptr->it_lock, flags); if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) { if (posix_timer_event(ptr, 0) != 0) ptr->it_overrun++; @@ -465,9 +469,11 @@ static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm, if (ptr->it.alarm.interval.tv64) { ptr->it_overrun += alarm_forward(alarm, now, ptr->it.alarm.interval); - return ALARMTIMER_RESTART; + result = ALARMTIMER_RESTART; } - return ALARMTIMER_NORESTART; + spin_unlock_irqrestore(&ptr->it_lock, flags); + + return result; } /** -- 1.9.1
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