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ALSA: hrtimer - Fix lock-up

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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 <W.Zabolotny@elka.pw.edu.pl>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2009-12-11 12:51:05 +01:00
parent 5f60e49608
commit fcfdebe707
1 changed files with 13 additions and 2 deletions
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15
sound/core/hrtimer.c
View file

@ -37,14 +37,22 @@ static unsigned int resolution;
struct snd_hrtimer { struct snd_hrtimer {
struct snd_timer *timer; struct snd_timer *timer;
struct hrtimer hrt; struct hrtimer hrt;
atomic_t running;
}; };
static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt) static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
{ {
struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt); struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt);
struct snd_timer *t = stime->timer; struct snd_timer *t = stime->timer;
if (!atomic_read(&stime->running))
return HRTIMER_NORESTART;
hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution)); hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution));
snd_timer_interrupt(stime->timer, t->sticks); snd_timer_interrupt(stime->timer, t->sticks);
if (!atomic_read(&stime->running))
return HRTIMER_NORESTART;
return HRTIMER_RESTART; 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); hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
stime->timer = t; stime->timer = t;
stime->hrt.function = snd_hrtimer_callback; stime->hrt.function = snd_hrtimer_callback;
atomic_set(&stime->running, 0);
t->private_data = stime; t->private_data = stime;
return 0; return 0;
} }
@ -78,16 +87,18 @@ static int snd_hrtimer_start(struct snd_timer *t)
{ {
struct snd_hrtimer *stime = t->private_data; 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_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
HRTIMER_MODE_REL); HRTIMER_MODE_REL);
atomic_set(&stime->running, 1);
return 0; return 0;
} }
static int snd_hrtimer_stop(struct snd_timer *t) static int snd_hrtimer_stop(struct snd_timer *t)
{ {
struct snd_hrtimer *stime = t->private_data; struct snd_hrtimer *stime = t->private_data;
atomic_set(&stime->running, 0);
hrtimer_cancel(&stime->hrt);
return 0; return 0;
} }