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Groups > linux.kernel > #1726826

[PATCH 23/25 v2] ALSA/dummy: Replace tasklet with softirq hrtimer

From Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Newsgroups linux.kernel
Subject [PATCH 23/25 v2] ALSA/dummy: Replace tasklet with softirq hrtimer
Date 2017-09-05 18:00 +0200
Message-ID <umoqB-4Dm-5@gated-at.bofh.it> (permalink)
References <ukzJv-7ng-3@gated-at.bofh.it> <ukRn4-2DU-13@gated-at.bofh.it> <ukSMb-3T0-31@gated-at.bofh.it> <ul5q1-4ET-1@gated-at.bofh.it>
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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 2017-09-02 10:19:45 [+0900], Takashi Sakamoto wrote:
> Yep. I request the authors to include this 
Thank you for providing a fix.

v1…v2: merged Takashi Sakamoto fixup of the original patch into v2.

So this patch now is okay?

 sound/drivers/dummy.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
index dd5ed037adf2..3d01fe17ed36 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 +386,12 @@ 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 a case of XRUN, 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 +411,14 @@ 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 +463,10 @@ 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

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Thread

[PATCH 00/25] hrtimer: Provide softirq context hrtimers Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 07/25] hrtimer: Reduce conditional code (hres_active) Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 05/25] hrtimer: Switch for loop to _ffs() evaluation Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 24/25] net/cdc_ncm: Replace tasklet with softirq hrtimer Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
    Re: [PATCH 24/25] net/cdc_ncm: Replace tasklet with softirq hrtimer Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-08-31 15:40 +0200
    Re: [PATCH 24/25] net/cdc_ncm: Replace tasklet with softirq hrtimer Bjørn Mork <bjorn@mork.no> - 2017-08-31 16:00 +0200
      [PATCH 24/25 v2] net/cdc_ncm: Replace tasklet with softirq hrtimer Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-09-05 17:50 +0200
  [PATCH 23/25] ALSA/dummy: Replace tasklet with softirq hrtimer Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
    Re: [PATCH 23/25] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Iwai <tiwai@suse.de> - 2017-08-31 16:30 +0200
    Re: [PATCH 23/25] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Sakamoto <o-takashi@sakamocchi.jp> - 2017-08-31 16:30 +0200
    Re: [PATCH 23/25] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Iwai <tiwai@suse.de> - 2017-08-31 17:40 +0200
      Re: [PATCH 23/25] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Sakamoto <o-takashi@sakamocchi.jp> - 2017-09-01 12:30 +0200
        Re: [PATCH 23/25] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Iwai <tiwai@suse.de> - 2017-09-01 14:00 +0200
          Re: [PATCH 23/25] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Sakamoto <o-takashi@sakamocchi.jp> - 2017-09-02 03:30 +0200
            Re: [PATCH 23/25] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Sakamoto <o-takashi@sakamocchi.jp> - 2017-09-04 14:50 +0200
            [PATCH 23/25 v2] ALSA/dummy: Replace tasklet with softirq hrtimer Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-09-05 18:00 +0200
              Re: [PATCH 23/25 v2] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Iwai <tiwai@suse.de> - 2017-09-05 18:10 +0200
              Re: [PATCH 23/25 v2] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Sakamoto <o-takashi@sakamocchi.jp> - 2017-09-05 18:10 +0200
                [PATCH 23/25 v3] ALSA/dummy: Replace tasklet with softirq hrtimer Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-09-05 18:20 +0200
                Re: [PATCH 23/25 v3] ALSA/dummy: Replace tasklet with softirq hrtimer Takashi Sakamoto <o-takashi@sakamocchi.jp> - 2017-09-06 06:40 +0200
                Re: [alsa-devel] [PATCH 23/25 v3] ALSA/dummy: Replace tasklet with     softirq hrtimer Takashi Iwai <tiwai@suse.de> - 2017-09-08 10:30 +0200
  [PATCH 22/25] softirq: Remove tasklet_hrtimer Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 21/25] xfrm: Replace hrtimer tasklet with softirq hrtimer Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 06/25] hrtimer: Store running timer in hrtimer_clock_base Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 19/25] can/bcm: Replace hrtimer_tasklet with softirq based  hrtimer Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
    Re: [PATCH 19/25] can/bcm: Replace hrtimer_tasklet with softirq  based hrtimer Thomas Gleixner <tglx@linutronix.de> - 2017-09-01 18:00 +0200
      Re: [PATCH 19/25] can/bcm: Replace hrtimer_tasklet with softirq based  hrtimer Oliver Hartkopp <socketcan@hartkopp.net> - 2017-09-01 19:10 +0200
    Re: [PATCH 19/25] can/bcm: Replace hrtimer_tasklet with softirq based  hrtimer Oliver Hartkopp <socketcan@hartkopp.net> - 2017-09-01 18:00 +0200
    Re: [PATCH 19/25] can/bcm: Replace hrtimer_tasklet with softirq based  hrtimer Oliver Hartkopp <socketcan@hartkopp.net> - 2017-09-02 20:10 +0200
  [PATCH 10/25] hrtimer: Make handling of hrtimer reprogramming and  enqueuing not conditional Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 14/25] hrtimer: Split out code from __hrtimer_get_next_event()  for reuse Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 25/25] usb/gadget/NCM: Replace tasklet with softirq hrtimer Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 03/25] hrtimer: Fix kerneldoc for struct hrtimer_cpu_base Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  [PATCH 09/25] hrtimer: Reduce conditional code (hrtimer_reprogram()) Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:30 +0200
  Re: [PATCH 00/25] hrtimer: Provide softirq context hrtimers Anna-Maria Gleixner <anna-maria@linutronix.de> - 2017-08-31 14:40 +0200

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