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Commit fc7dc61d authored by Oskar Schirmer's avatar Oskar Schirmer Committed by Mark Brown
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ASoC: fsl: imx-pcm-fiq: omit fiq counter to avoid harm in unbalanced situations 



Unbalanced calls to snd_imx_pcm_trigger() may result in endless
FIQ activity and thus provoke eternal sound. While on the first glance,
the switch statement looks pretty symmetric, the SUSPEND/RESUME
pair is not: the suspend case comes along snd_pcm_suspend_all(),
which for fsl/imx-pcm-fiq is called only at snd_soc_suspend(),
but the resume case originates straight from the SNDRV_PCM_IOCTL_RESUME.
This way userland may provoke an unbalanced resume, which might cause
the fiq_enable counter to increase and never return to zero again,
so eventually imx_pcm_fiq is never disabled.

Simply removing the fiq_enable will solve the problem, as long as
one never goes play and capture game simultaneously, but beware
trying both at once, the early TRIGGER_STOP will cut off the other
activity prematurely. So now playing and capturing is scrutinized
separately, instead of by counting.

Signed-off-by: default avatarOskar Schirmer <oskar@scara.com>
Signed-off-by: default avatarMark Brown <broonie@linaro.org>
Cc: stable@vger.kernel.org
parent 71d0c3a8

sound/soc/fsl/imx-pcm-fiq.c

+17 −12
Original line number Diff line number Diff line
@@ -44,7 +44,8 @@ struct imx_pcm_runtime_data { 
	struct hrtimer hrt;

	int poll_time_ns;

	struct snd_pcm_substream *substream;

	atomic_t running;

	atomic_t playing;

	atomic_t capturing;

};



static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
@@ -56,7 +57,7 @@ static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt) 
	struct pt_regs regs;

	unsigned long delta;



	if (!atomic_read(&iprtd->running))

	if (!atomic_read(&iprtd->playing) && !atomic_read(&iprtd->capturing))

		return HRTIMER_NORESTART;



	get_fiq_regs(&regs);
@@ -124,7 +125,6 @@ static int snd_imx_pcm_prepare(struct snd_pcm_substream *substream) 
	return 0;

}



static int fiq_enable;

static int imx_pcm_fiq;



static int snd_imx_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
@@ -136,23 +136,27 @@ static int snd_imx_pcm_trigger(struct snd_pcm_substream *substream, int cmd) 
	case SNDRV_PCM_TRIGGER_START:

	case SNDRV_PCM_TRIGGER_RESUME:

	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:

		atomic_set(&iprtd->running, 1);

		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

			atomic_set(&iprtd->playing, 1);

		else

			atomic_set(&iprtd->capturing, 1);

		hrtimer_start(&iprtd->hrt, ns_to_ktime(iprtd->poll_time_ns),

		      HRTIMER_MODE_REL);

		if (++fiq_enable == 1)

		enable_fiq(imx_pcm_fiq);



		break;



	case SNDRV_PCM_TRIGGER_STOP:

	case SNDRV_PCM_TRIGGER_SUSPEND:

	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:

		atomic_set(&iprtd->running, 0);



		if (--fiq_enable == 0)

		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

			atomic_set(&iprtd->playing, 0);

		else

			atomic_set(&iprtd->capturing, 0);

		if (!atomic_read(&iprtd->playing) &&

				!atomic_read(&iprtd->capturing))

			disable_fiq(imx_pcm_fiq);



		break;



	default:

		return -EINVAL;

	}
@@ -200,7 +204,8 @@ static int snd_imx_open(struct snd_pcm_substream *substream) 


	iprtd->substream = substream;



	atomic_set(&iprtd->running, 0);

	atomic_set(&iprtd->playing, 0);

	atomic_set(&iprtd->capturing, 0);

	hrtimer_init(&iprtd->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);

	iprtd->hrt.function = snd_hrtimer_callback;