From fcfdebe70759c74e2e701f69aaa7f0e5e32cf5a6 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Fri, 11 Dec 2009 12:51:05 +0100 Subject: ALSA: hrtimer - Fix lock-up The timer stop callback can be called from snd_timer_interrupt(), which is called from the hrtimer callback. Since hrtimer_cancel() waits for the callback completion, this eventually results in a lock-up. This patch fixes the problem by just toggling a flag at stop callback and call hrtimer_cancel() later. Reported-and-tested-by: Wojtek Zabolotny Cc: Signed-off-by: Takashi Iwai --- sound/core/hrtimer.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'sound') diff --git a/sound/core/hrtimer.c b/sound/core/hrtimer.c index 34c7d48f5061..7f4d744ae40a 100644 --- a/sound/core/hrtimer.c +++ b/sound/core/hrtimer.c @@ -37,14 +37,22 @@ static unsigned int resolution; struct snd_hrtimer { struct snd_timer *timer; struct hrtimer hrt; + atomic_t running; }; static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt) { struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt); struct snd_timer *t = stime->timer; + + if (!atomic_read(&stime->running)) + return HRTIMER_NORESTART; + hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution)); snd_timer_interrupt(stime->timer, t->sticks); + + if (!atomic_read(&stime->running)) + return HRTIMER_NORESTART; return HRTIMER_RESTART; } @@ -58,6 +66,7 @@ static int snd_hrtimer_open(struct snd_timer *t) hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL); stime->timer = t; stime->hrt.function = snd_hrtimer_callback; + atomic_set(&stime->running, 0); t->private_data = stime; return 0; } @@ -78,16 +87,18 @@ static int snd_hrtimer_start(struct snd_timer *t) { struct snd_hrtimer *stime = t->private_data; + atomic_set(&stime->running, 0); + hrtimer_cancel(&stime->hrt); hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution), HRTIMER_MODE_REL); + atomic_set(&stime->running, 1); return 0; } static int snd_hrtimer_stop(struct snd_timer *t) { struct snd_hrtimer *stime = t->private_data; - - hrtimer_cancel(&stime->hrt); + atomic_set(&stime->running, 0); return 0; } -- cgit v1.2.3