timerfd: Fix wakeup of processes when timer is cancelled on clock change

[~andy/linux] / fs / timerfd.c

diff --git a/fs/timerfd.c b/fs/timerfd.c
index f67acbdda5e8c13fce54e51f72fe0882f2fa94da..dffeb3795af1d4204f8554447dbb2d2c33992429 100644 (file)
--- 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);