| Subject: timer-fd: Prevent live lock |
| From: Thomas Gleixner <tglx@linutronix.de> |
| 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 <sankara.m@gmail.com> |
| Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
| |
| --- |
| fs/timerfd.c | 5 ++++- |
| 1 file changed, 4 insertions(+), 1 deletion(-) |
| |
| --- a/fs/timerfd.c |
| +++ b/fs/timerfd.c |
| @@ -471,7 +471,10 @@ 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); |
| } |
| |
| /* |
