On Sun, 22 Oct 2017 23:40:12 +0200, Anna-Maria Gleixner wrote: > > From: Thomas Gleixner <t...@linutronix.de> > > 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 <t...@linutronix.de> > Signed-off-by: Anna-Maria Gleixner <anna-ma...@linutronix.de> > Cc: Jaroslav Kysela <pe...@perex.cz> > Cc: Takashi Iwai <ti...@suse.com>
Feel free to take my ack: Reviewed-by: Takashi Iwai <ti...@suse.de> thanks, Takashi > Cc: Takashi Sakamoto <o-taka...@sakamocchi.jp> > Cc: alsa-de...@alsa-project.org > Link: http://lkml.kernel.org/r/20170905161820.jtysvxtfleunb...@breakpoint.cc > > --- > 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 | 27 ++++++++++++--------------- > 1 file changed, 12 insertions(+), 15 deletions(-) > > --- 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_hrtime > 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; > } > @@ -404,7 +403,7 @@ static int dummy_hrtimer_start(struct sn > 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; > } > @@ -414,14 +413,14 @@ static int dummy_hrtimer_stop(struct snd > 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 s > 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; > } > > > >
