Subject: timer-fd: Prevent live lock From: Thomas Gleixner Date: Wed, 25 Jan 2012 11:08:40 +0100 Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.9/older/patches-4.9.20-rt16.tar.xz 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 --- fs/timerfd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/fs/timerfd.c +++ b/fs/timerfd.c @@ -460,7 +460,10 @@ static int do_timerfd_settime(int ufd, i break; } spin_unlock_irq(&ctx->wqh.lock); - cpu_relax(); + if (isalarm(ctx)) + hrtimer_wait_for_timer(&ctx->t.alarm.timer); + else + hrtimer_wait_for_timer(&ctx->t.tmr); } /*