From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752009AbdIEQS3 convert rfc822-to-8bit (ORCPT ); Tue, 5 Sep 2017 12:18:29 -0400 Received: from Chamillionaire.breakpoint.cc ([146.0.238.67]:59554 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751382AbdIEQS1 (ORCPT ); Tue, 5 Sep 2017 12:18:27 -0400 Date: Tue, 5 Sep 2017 18:18:21 +0200 From: Sebastian Andrzej Siewior To: Takashi Sakamoto Cc: Sebastian Andrzej Siewior , alsa-devel@alsa-project.org, keescook@chromium.org, Takashi Iwai , linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, john.stultz@linaro.org, tglx@linutronix.de, anna-maria@linutronix.de, hch@lst.de Subject: [PATCH 23/25 v3] ALSA/dummy: Replace tasklet with softirq hrtimer Message-ID: <20170905161820.jtysvxtfleunbbmf@breakpoint.cc> References: <20170901102537.8066-1-o-takashi@sakamocchi.jp> <19775981-a3f2-5f65-e934-bfe25db62a43@sakamocchi.jp> <20170905155351.2xmwyxrirndfwtgo@breakpoint.cc> <4cf46286-daf8-d52c-dacc-fa16052dcdb2@sakamocchi.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <4cf46286-daf8-d52c-dacc-fa16052dcdb2@sakamocchi.jp> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner 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 Signed-off-by: Anna-Maria Gleixner Cc: Jaroslav Kysela Cc: Takashi Iwai Cc: Takashi Sakamoto 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 Signed-off-by: Sebastian Andrzej Siewior --- 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(-) 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; } -- 2.14.1