| Message ID | 20170905161820.jtysvxtfleunbbmf@breakpoint.cc (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sep 6 2017 01:18, Sebastian Andrzej Siewior wrote: > From: Thomas Gleixner <tglx@linutronix.de> > > The tasklet is used to defer the execution of snd_pcm_period_elapsed() to > the softirq context. Using the CLOCK_MONOTONIC_SOFT base invokes the timer > callback in softirq context as well which renders the tasklet useless. > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> > Cc: Jaroslav Kysela <perex@perex.cz> > Cc: Takashi Iwai <tiwai@suse.com> > Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp> > Cc: alsa-devel@alsa-project.org > [o-takashi: avoid stall due to a call of hrtimer_cancel() on a callback > of hrtimer] > Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > On 2017-09-06 01:05:43 [+0900], Takashi Sakamoto wrote: >> As Iwai-san mentioned, in this function, .trigger can be called in two >> cases; XRUN occurs and draining is done. Thus, let you change the comment as >> 'In cases of XRUN and draining, this calls .trigger to stop PCM substream.'. >> I'm sorry to trouble you. >> >> snd_pcm_period_elapsed() >> ->snd_pcm_update_hw_ptr0() >> ->snd_pcm_update_state() >> ->snd_pcm_drain_done() >> ... >> ->.trigger(TRIGGER_STOP) >> ->xrun() >> ->snd_pcm_stop() >> ... >> ->.trigger(TRIGGER_STOP) >> > > I think you asked me just to update the comment. Did I do it right? > > v2…v3: updated the comment as per Takashi Sakamoto's suggestion. > v1…v2: merged Takashi Sakamoto fixup of the original patch into v2. > > sound/drivers/dummy.c | 25 +++++++++++-------------- > 1 file changed, 11 insertions(+), 14 deletions(-) This Looks good to me. I did quick test and confirmed that it brings no stalls. Tested-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> > diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c > index dd5ed037adf2..cdd851286f92 100644 > --- a/sound/drivers/dummy.c > +++ b/sound/drivers/dummy.c > @@ -376,17 +376,9 @@ 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; > @@ -394,7 +386,14 @@ 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; > } > @@ -414,14 +413,14 @@ 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 > @@ -466,12 +465,10 @@ 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_SOFT, HRTIMER_MODE_REL); > 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; > } Thanks Takashi Sakamoto
On Wed, 06 Sep 2017 06:30:03 +0200, Takashi Sakamoto wrote: > > On Sep 6 2017 01:18, Sebastian Andrzej Siewior wrote: > > From: Thomas Gleixner <tglx@linutronix.de> > > > > The tasklet is used to defer the execution of snd_pcm_period_elapsed() to > > the softirq context. Using the CLOCK_MONOTONIC_SOFT base invokes the timer > > callback in softirq context as well which renders the tasklet useless. > > > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > > Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> > > Cc: Jaroslav Kysela <perex@perex.cz> > > Cc: Takashi Iwai <tiwai@suse.com> > > Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp> > > Cc: alsa-devel@alsa-project.org > > [o-takashi: avoid stall due to a call of hrtimer_cancel() on a callback > > of hrtimer] > > Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > > --- > > On 2017-09-06 01:05:43 [+0900], Takashi Sakamoto wrote: > >> As Iwai-san mentioned, in this function, .trigger can be called in two > >> cases; XRUN occurs and draining is done. Thus, let you change the comment as > >> 'In cases of XRUN and draining, this calls .trigger to stop PCM substream.'. > >> I'm sorry to trouble you. > >> > >> snd_pcm_period_elapsed() > >> ->snd_pcm_update_hw_ptr0() > >> ->snd_pcm_update_state() > >> ->snd_pcm_drain_done() > >> ... > >> ->.trigger(TRIGGER_STOP) > >> ->xrun() > >> ->snd_pcm_stop() > >> ... > >> ->.trigger(TRIGGER_STOP) > >> > > > > I think you asked me just to update the comment. Did I do it right? > > > > v2…v3: updated the comment as per Takashi Sakamoto's suggestion. > > v1…v2: merged Takashi Sakamoto fixup of the original patch into v2. > > > > sound/drivers/dummy.c | 25 +++++++++++-------------- > > 1 file changed, 11 insertions(+), 14 deletions(-) > > This Looks good to me. I did quick test and confirmed that it brings > no stalls. > > Tested-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> I suppose you'd apply all together in some tree like tip or whatever? In anyway, feel free to take my ack for this patch: Reviewed-by: Takashi Iwai <tiwai@suse.de> Thanks! Takashi
diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c index dd5ed037adf2..cdd851286f92 100644 --- a/sound/drivers/dummy.c +++ b/sound/drivers/dummy.c @@ -376,17 +376,9 @@ 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; @@ -394,7 +386,14 @@ 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; } @@ -414,14 +413,14 @@ 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 @@ -466,12 +465,10 @@ 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_SOFT, HRTIMER_MODE_REL); 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; }