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ASoC: fsl: imx-pcm-fiq: omit fiq counter to avoid harm in unbalanced situations

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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: Oskar Schirmer <oskar@scara.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Cc: stable@vger.kernel.org
This commit is contained in:
Oskar Schirmer 2013-11-12 15:46:38 +00:00 committed by Mark Brown
parent 71d0c3a876
commit fc7dc61d9a
1 changed files with 17 additions and 12 deletions
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29
sound/soc/fsl/imx-pcm-fiq.c
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@ -44,7 +44,8 @@ struct imx_pcm_runtime_data {
struct hrtimer hrt; struct hrtimer hrt;
int poll_time_ns; int poll_time_ns;
struct snd_pcm_substream *substream; struct snd_pcm_substream *substream;
atomic_t running; atomic_t playing;
atomic_t capturing;
}; };
static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt) 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; struct pt_regs regs;
unsigned long delta; unsigned long delta;
if (!atomic_read(&iprtd->running)) if (!atomic_read(&iprtd->playing) && !atomic_read(&iprtd->capturing))
return HRTIMER_NORESTART; return HRTIMER_NORESTART;
get_fiq_regs(&regs); get_fiq_regs(&regs);
@ -124,7 +125,6 @@ static int snd_imx_pcm_prepare(struct snd_pcm_substream *substream)
return 0; return 0;
} }
static int fiq_enable;
static int imx_pcm_fiq; static int imx_pcm_fiq;
static int snd_imx_pcm_trigger(struct snd_pcm_substream *substream, int cmd) 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_START:
case SNDRV_PCM_TRIGGER_RESUME: case SNDRV_PCM_TRIGGER_RESUME:
case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: 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_start(&iprtd->hrt, ns_to_ktime(iprtd->poll_time_ns),
HRTIMER_MODE_REL); HRTIMER_MODE_REL);
if (++fiq_enable == 1) enable_fiq(imx_pcm_fiq);
enable_fiq(imx_pcm_fiq);
break; break;
case SNDRV_PCM_TRIGGER_STOP: case SNDRV_PCM_TRIGGER_STOP:
case SNDRV_PCM_TRIGGER_SUSPEND: case SNDRV_PCM_TRIGGER_SUSPEND:
case SNDRV_PCM_TRIGGER_PAUSE_PUSH: case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
atomic_set(&iprtd->running, 0); if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
atomic_set(&iprtd->playing, 0);
if (--fiq_enable == 0) else
atomic_set(&iprtd->capturing, 0);
if (!atomic_read(&iprtd->playing) &&
!atomic_read(&iprtd->capturing))
disable_fiq(imx_pcm_fiq); disable_fiq(imx_pcm_fiq);
break; break;
default: default:
return -EINVAL; return -EINVAL;
} }
@ -200,7 +204,8 @@ static int snd_imx_open(struct snd_pcm_substream *substream)
iprtd->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); hrtimer_init(&iprtd->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
iprtd->hrt.function = snd_hrtimer_callback; iprtd->hrt.function = snd_hrtimer_callback;