Subject: timer-fd: Prevent live lock From: Thomas Gleixner Date: Wed, 25 Jan 2012 11:08:40 +0100 If hrtimer_try_to_cancel() requires a retry, then depending on the priority setting te retry loop might prevent timer callback completion on RT. Prevent that by waiting for completion on RT, no change for a non RT kernel. Reported-by: Sankara Muthukrishnan Signed-off-by: Thomas Gleixner Cc: stable-rt@vger.kernel.org --- fs/timerfd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-stable/fs/timerfd.c =================================================================== --- linux-stable.orig/fs/timerfd.c +++ linux-stable/fs/timerfd.c @@ -313,7 +313,7 @@ SYSCALL_DEFINE4(timerfd_settime, int, uf if (hrtimer_try_to_cancel(&ctx->tmr) >= 0) break; spin_unlock_irq(&ctx->wqh.lock); - cpu_relax(); + hrtimer_wait_for_timer(&ctx->tmr); } /*