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authorThomas Gleixner <tglx@linutronix.de>2017-12-21 11:42:03 +0100
committerIngo Molnar <mingo@kernel.org>2018-01-16 09:51:22 +0100
commitb03bbbe08ff04d80136b6aac152954ef308a4909 (patch)
tree00eccdb20106c5f0f4fcf4cb26cdb5ebbc51eb5c
parent42f42da41b54c191ae6a775e84a86c100d66c5e8 (diff)
ALSA/dummy: Replace tasklet with softirq hrtimer
The tasklet is used to defer the execution of snd_pcm_period_elapsed() to the softirq context. Using the HRTIMER_MODE_SOFT mode invokes the timer callback in softirq context as well which renders the tasklet useless. [o-takashi: avoid stall due to a call of hrtimer_cancel() on a callback of hrtimer] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Takashi Iwai <tiwai@suse.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Jaroslav Kysela <perex@perex.cz> Cc: John Stultz <john.stultz@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Takashi Iwai <tiwai@suse.com> Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp> Cc: alsa-devel@alsa-project.org Cc: keescook@chromium.org Link: http://lkml.kernel.org/r/20171221104205.7269-35-anna-maria@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--sound/drivers/dummy.c27
1 files changed, 12 insertions, 15 deletions
diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
index 7b2b1f766b00..6ad2ff57833d 100644
--- a/sound/drivers/dummy.c
+++ b/sound/drivers/dummy.c
@@ -375,17 +375,9 @@ struct dummy_hrtimer_pcm {
ktime_t period_time;
atomic_t running;
struct hrtimer timer;
- struct tasklet_struct tasklet;
struct snd_pcm_substream *substream;
};
-static void dummy_hrtimer_pcm_elapsed(unsigned long priv)
-{
- struct dummy_hrtimer_pcm *dpcm = (struct dummy_hrtimer_pcm *)priv;
- if (atomic_read(&dpcm->running))
- snd_pcm_period_elapsed(dpcm->substream);
-}
-
static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
{
struct dummy_hrtimer_pcm *dpcm;
@@ -393,7 +385,14 @@ static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer);
if (!atomic_read(&dpcm->running))
return HRTIMER_NORESTART;
- tasklet_schedule(&dpcm->tasklet);
+ /*
+ * In cases of XRUN and draining, this calls .trigger to stop PCM
+ * substream.
+ */
+ snd_pcm_period_elapsed(dpcm->substream);
+ if (!atomic_read(&dpcm->running))
+ return HRTIMER_NORESTART;
+
hrtimer_forward_now(timer, dpcm->period_time);
return HRTIMER_RESTART;
}
@@ -403,7 +402,7 @@ static int dummy_hrtimer_start(struct snd_pcm_substream *substream)
struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
- hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL);
+ hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL_SOFT);
atomic_set(&dpcm->running, 1);
return 0;
}
@@ -413,14 +412,14 @@ static int dummy_hrtimer_stop(struct snd_pcm_substream *substream)
struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
atomic_set(&dpcm->running, 0);
- hrtimer_cancel(&dpcm->timer);
+ if (!hrtimer_callback_running(&dpcm->timer))
+ hrtimer_cancel(&dpcm->timer);
return 0;
}
static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
{
hrtimer_cancel(&dpcm->timer);
- tasklet_kill(&dpcm->tasklet);
}
static snd_pcm_uframes_t
@@ -465,12 +464,10 @@ static int dummy_hrtimer_create(struct snd_pcm_substream *substream)
if (!dpcm)
return -ENOMEM;
substream->runtime->private_data = dpcm;
- hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
dpcm->timer.function = dummy_hrtimer_callback;
dpcm->substream = substream;
atomic_set(&dpcm->running, 0);
- tasklet_init(&dpcm->tasklet, dummy_hrtimer_pcm_elapsed,
- (unsigned long)dpcm);
return 0;
}