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authorMax Asbock <masbock@linux.vnet.ibm.com>2011-06-13 10:18:32 -0700
committerThomas Gleixner <tglx@linutronix.de>2011-06-14 11:46:14 +0200
commit1123d93963cbd2546449d4d9f0c568e323cb0ac6 (patch)
treef8d9a07c85bab7e82c8e0b55c98dff9d8dff94db
parent2c53b436a30867eb6b47dd7bab23ba638d1fb0d2 (diff)
timerfd: Fix wakeup of processes when timer is cancelled on clock change
Currently processes waiting with poll on cancelable timerfd timers are not woken up when the timers are canceled. When the system time is set the clock_was_set() function calls timerfd_clock_was_set() to cancel and wake up processes waiting on potential cancelable timerfd timers. However the wake up currently has no effect because in the case of timerfd_read it is dependent on ctx->ticks not being 0. timerfd_poll also requires ctx->ticks being non zero. As a consequence processes waiting on cancelable timers only get woken up when the timers expire. This patch fixes this by incrementing ctx->ticks before calling wake_up. Signed-off-by: Max Asbock <masbock@linux.vnet.ibm.com> Cc: kay.sievers@vrfy.org Cc: virtuoso@slind.org Cc: johnstul <johnstul@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1307985512.4710.41.camel@w-amax.beaverton.ibm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--fs/timerfd.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/timerfd.c b/fs/timerfd.c
index f67acbdda5e..dffeb3795af 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -61,7 +61,9 @@ static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
/*
* Called when the clock was set to cancel the timers in the cancel
- * list.
+ * list. This will wake up processes waiting on these timers. The
+ * wake-up requires ctx->ticks to be non zero, therefore we increment
+ * it before calling wake_up_locked().
*/
void timerfd_clock_was_set(void)
{
@@ -76,6 +78,7 @@ void timerfd_clock_was_set(void)
spin_lock_irqsave(&ctx->wqh.lock, flags);
if (ctx->moffs.tv64 != moffs.tv64) {
ctx->moffs.tv64 = KTIME_MAX;
+ ctx->ticks++;
wake_up_locked(&ctx->wqh);
}
spin_unlock_irqrestore(&ctx->wqh.lock, flags);