* [RFC PATCH 1/2] ASoC: soc-pcm: protect BE dailink state changes in trigger
[not found] <20210817164054.250028-1-pierre-louis.bossart@linux.intel.com>
@ 2021-08-17 16:40 ` Pierre-Louis Bossart
2021-08-26 18:30 ` Mark Brown
2021-08-17 16:40 ` [RFC PATCH 2/2] ASoC: soc-pcm: test refcount before triggering Pierre-Louis Bossart
1 sibling, 1 reply; 5+ messages in thread
From: Pierre-Louis Bossart @ 2021-08-17 16:40 UTC (permalink / raw)
To: alsa-devel
Cc: tiwai, broonie, vkoul, liam.r.girdwood, Kuninori Morimoto,
Pierre-Louis Bossart, Liam Girdwood, Jaroslav Kysela,
Takashi Iwai, open list
When more than one FE is connected to a BE, e.g. in a mixing use case,
the BE can be triggered multiple times when the FE are opened/started
concurrently. This race condition is problematic in the case of
SoundWire BE dailinks, and this is not desirable in a general
case. The code carefully checks when the BE can be stopped or
hw_free'ed, but the trigger code does not use any mutual exclusion.
Fix by using the same spinlock already used to check FE states, and
set the state before the trigger. In case of errors, the initial
state will be restored.
This patch does not change how the triggers are handled, it only makes
sure the states are handled in critical sections.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
sound/soc/soc-pcm.c | 103 ++++++++++++++++++++++++++++++++++++--------
1 file changed, 85 insertions(+), 18 deletions(-)
diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 48f71bb81a2f..0717f39d2eec 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1999,6 +1999,8 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
struct snd_soc_pcm_runtime *be;
struct snd_soc_dpcm *dpcm;
int ret = 0;
+ unsigned long flags;
+ enum snd_soc_dpcm_state state;
for_each_dpcm_be(fe, stream, dpcm) {
struct snd_pcm_substream *be_substream;
@@ -2015,76 +2017,141 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_PREPARE) &&
(be->dpcm[stream].state != SND_SOC_DPCM_STATE_STOP) &&
- (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))
+ (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED)) {
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
continue;
+ }
+ state = be->dpcm[stream].state;
+ be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ be->dpcm[stream].state = state;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
+ }
- be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
break;
case SNDRV_PCM_TRIGGER_RESUME:
- if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_SUSPEND))
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_SUSPEND) {
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
continue;
+ }
+
+ state = be->dpcm[stream].state;
+ be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ be->dpcm[stream].state = state;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
+ }
- be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
break;
case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
- if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED) {
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
continue;
+ }
+
+ state = be->dpcm[stream].state;
+ be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ be->dpcm[stream].state = state;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
+ }
- be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
break;
case SNDRV_PCM_TRIGGER_STOP:
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_START) &&
- (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))
+ (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED)) {
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
continue;
+ }
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
continue;
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ state = be->dpcm[stream].state;
+ be->dpcm[stream].state = SND_SOC_DPCM_STATE_STOP;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
+
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ be->dpcm[stream].state = state;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
+ }
- be->dpcm[stream].state = SND_SOC_DPCM_STATE_STOP;
break;
case SNDRV_PCM_TRIGGER_SUSPEND:
- if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START) {
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
continue;
+ }
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
continue;
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ state = be->dpcm[stream].state;
+ be->dpcm[stream].state = SND_SOC_DPCM_STATE_STOP;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
+
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ be->dpcm[stream].state = state;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
+ }
- be->dpcm[stream].state = SND_SOC_DPCM_STATE_SUSPEND;
break;
case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
- if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START) {
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
continue;
+ }
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
continue;
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ state = be->dpcm[stream].state;
+ be->dpcm[stream].state = SND_SOC_DPCM_STATE_PAUSED;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
+
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ spin_lock_irqsave(&fe->card->dpcm_lock, flags);
+ be->dpcm[stream].state = state;
+ spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
+ }
- be->dpcm[stream].state = SND_SOC_DPCM_STATE_PAUSED;
break;
}
}
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [RFC PATCH 2/2] ASoC: soc-pcm: test refcount before triggering
[not found] <20210817164054.250028-1-pierre-louis.bossart@linux.intel.com>
2021-08-17 16:40 ` [RFC PATCH 1/2] ASoC: soc-pcm: protect BE dailink state changes in trigger Pierre-Louis Bossart
@ 2021-08-17 16:40 ` Pierre-Louis Bossart
1 sibling, 0 replies; 5+ messages in thread
From: Pierre-Louis Bossart @ 2021-08-17 16:40 UTC (permalink / raw)
To: alsa-devel
Cc: tiwai, broonie, vkoul, liam.r.girdwood, Kuninori Morimoto,
Pierre-Louis Bossart, Liam Girdwood, Jaroslav Kysela,
Takashi Iwai, open list
On start/pause_release/resume, when more than one FE is connected to
the same BE, it's possible that the trigger is sent more than
once. This is not desirable, we only want to trigger a BE once, which
is straightforward to implement with a refcount.
For stop/pause/suspend, the problem is more complicated: the check
implemented in snd_soc_dpcm_can_be_free_stop() may fail due to a
conceptual deadlock when we trigger the BE before the FE. In this
case, the FE states have not yet changed, so there are corner cases
where the TRIGGER_STOP is never sent - the dual case of start where
multiple triggers might be sent.
This patch suggests an unconditional trigger in all cases, without
checking the FE states, using a refcount protected by a spinlock.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
include/sound/soc-dpcm.h | 2 ++
sound/soc/soc-pcm.c | 46 ++++++++++++++++++++++++++++++++++++----
2 files changed, 44 insertions(+), 4 deletions(-)
diff --git a/include/sound/soc-dpcm.h b/include/sound/soc-dpcm.h
index e296a3949b18..6cc751002da7 100644
--- a/include/sound/soc-dpcm.h
+++ b/include/sound/soc-dpcm.h
@@ -101,6 +101,8 @@ struct snd_soc_dpcm_runtime {
enum snd_soc_dpcm_state state;
int trigger_pending; /* trigger cmd + 1 if pending, 0 if not */
+
+ int be_start; /* refcount protected by dpcm_lock */
};
#define for_each_dpcm_fe(be, stream, _dpcm) \
diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 0717f39d2eec..b2440f2f9bf5 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1534,7 +1534,7 @@ int dpcm_be_dai_startup(struct snd_soc_pcm_runtime *fe, int stream)
be->dpcm[stream].state = SND_SOC_DPCM_STATE_CLOSE;
goto unwind;
}
-
+ be->dpcm[stream].be_start = 0;
be->dpcm[stream].state = SND_SOC_DPCM_STATE_OPEN;
count++;
}
@@ -2001,6 +2001,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
int ret = 0;
unsigned long flags;
enum snd_soc_dpcm_state state;
+ bool do_trigger;
for_each_dpcm_be(fe, stream, dpcm) {
struct snd_pcm_substream *be_substream;
@@ -2015,6 +2016,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
dev_dbg(be->dev, "ASoC: trigger BE %s cmd %d\n",
be->dai_link->name, cmd);
+ do_trigger = false;
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
@@ -2025,13 +2027,20 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
continue;
}
state = be->dpcm[stream].state;
+ if (be->dpcm[stream].be_start == 0)
+ do_trigger = true;
+ be->dpcm[stream].be_start++;
be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
+ if (!do_trigger)
+ continue;
+
ret = soc_pcm_trigger(be_substream, cmd);
if (ret) {
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
be->dpcm[stream].state = state;
+ be->dpcm[stream].be_start--;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
}
@@ -2045,13 +2054,20 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
}
state = be->dpcm[stream].state;
+ if (be->dpcm[stream].be_start == 0)
+ do_trigger = true;
+ be->dpcm[stream].be_start++;
be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
+ if (!do_trigger)
+ continue;
+
ret = soc_pcm_trigger(be_substream, cmd);
if (ret) {
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
be->dpcm[stream].state = state;
+ be->dpcm[stream].be_start--;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
}
@@ -2065,13 +2081,20 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
}
state = be->dpcm[stream].state;
+ if (be->dpcm[stream].be_start == 0)
+ do_trigger = true;
+ be->dpcm[stream].be_start++;
be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
+ if (!do_trigger)
+ continue;
+
ret = soc_pcm_trigger(be_substream, cmd);
if (ret) {
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
be->dpcm[stream].state = state;
+ be->dpcm[stream].be_start--;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
}
@@ -2084,9 +2107,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
continue;
}
+ if ((be->dpcm[stream].state == SND_SOC_DPCM_STATE_START &&
+ be->dpcm[stream].be_start == 1) ||
+ (be->dpcm[stream].state == SND_SOC_DPCM_STATE_PAUSED &&
+ be->dpcm[stream].be_start == 0))
+ do_trigger = true;
+ be->dpcm[stream].be_start--;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
- if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
+ if (!do_trigger)
continue;
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
@@ -2098,6 +2127,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if (ret) {
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
be->dpcm[stream].state = state;
+ be->dpcm[stream].be_start++;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
}
@@ -2109,9 +2139,12 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
continue;
}
+ if (be->dpcm[stream].be_start == 1)
+ do_trigger = true;
+ be->dpcm[stream].be_start--;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
- if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
+ if (!do_trigger)
continue;
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
@@ -2123,6 +2156,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if (ret) {
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
be->dpcm[stream].state = state;
+ be->dpcm[stream].be_start++;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
}
@@ -2134,9 +2168,12 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
continue;
}
+ if (be->dpcm[stream].be_start == 1)
+ do_trigger = true;
+ be->dpcm[stream].be_start--;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
- if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
+ if (!do_trigger)
continue;
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
@@ -2148,6 +2185,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if (ret) {
spin_lock_irqsave(&fe->card->dpcm_lock, flags);
be->dpcm[stream].state = state;
+ be->dpcm[stream].be_start++;
spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
goto end;
}
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [RFC PATCH 1/2] ASoC: soc-pcm: protect BE dailink state changes in trigger
2021-08-17 16:40 ` [RFC PATCH 1/2] ASoC: soc-pcm: protect BE dailink state changes in trigger Pierre-Louis Bossart
@ 2021-08-26 18:30 ` Mark Brown
2021-08-26 19:24 ` Pierre-Louis Bossart
0 siblings, 1 reply; 5+ messages in thread
From: Mark Brown @ 2021-08-26 18:30 UTC (permalink / raw)
To: alsa-devel, Pierre-Louis Bossart
Cc: Mark, Brown, broonie, Takashi Iwai, open list, Liam Girdwood,
liam.r.girdwood, Jaroslav Kysela, vkoul, Kuninori Morimoto,
tiwai
From: Mark Brown,,, <broonie@kernel.org>
On Tue, 17 Aug 2021 11:40:53 -0500, Pierre-Louis Bossart wrote:
> When more than one FE is connected to a BE, e.g. in a mixing use case,
> the BE can be triggered multiple times when the FE are opened/started
> concurrently. This race condition is problematic in the case of
> SoundWire BE dailinks, and this is not desirable in a general
> case. The code carefully checks when the BE can be stopped or
> hw_free'ed, but the trigger code does not use any mutual exclusion.
>
> [...]
Applied, thanks!
[1/2] ASoC: soc-pcm: protect BE dailink state changes in trigger
commit: 0c75fc7193387776c10f7c7b440d93496e3d5e21
[2/2] ASoC: soc-pcm: test refcount before triggering
commit: 6479f7588651cbc9c91e61c20ff39119cbc8feba
Best regards,
--
Mark Brown,,, <broonie@kernel.org>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [RFC PATCH 1/2] ASoC: soc-pcm: protect BE dailink state changes in trigger
2021-08-26 18:30 ` Mark Brown
@ 2021-08-26 19:24 ` Pierre-Louis Bossart
2021-08-30 11:15 ` Mark Brown
0 siblings, 1 reply; 5+ messages in thread
From: Pierre-Louis Bossart @ 2021-08-26 19:24 UTC (permalink / raw)
To: Mark Brown, alsa-devel
Cc: Mark, Brown, Takashi Iwai, open list, Liam Girdwood,
liam.r.girdwood, Jaroslav Kysela, vkoul, Kuninori Morimoto,
tiwai
On 8/26/21 1:30 PM, Mark Brown wrote:
> From: Mark Brown,,, <broonie@kernel.org>
>
> On Tue, 17 Aug 2021 11:40:53 -0500, Pierre-Louis Bossart wrote:
>> When more than one FE is connected to a BE, e.g. in a mixing use case,
>> the BE can be triggered multiple times when the FE are opened/started
>> concurrently. This race condition is problematic in the case of
>> SoundWire BE dailinks, and this is not desirable in a general
>> case. The code carefully checks when the BE can be stopped or
>> hw_free'ed, but the trigger code does not use any mutual exclusion.
>>
>> [...]
>
> Applied, thanks!
>
> [1/2] ASoC: soc-pcm: protect BE dailink state changes in trigger
> commit: 0c75fc7193387776c10f7c7b440d93496e3d5e21
> [2/2] ASoC: soc-pcm: test refcount before triggering
> commit: 6479f7588651cbc9c91e61c20ff39119cbc8feba
Ah sorry, there were still some issues in this RFC, we did more testing
and came up with a lot of improvements. The intent of the RFC status was
also to make sure it wasn't applied before the merge window.
Can this be reverted in your branch Mark?
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [RFC PATCH 1/2] ASoC: soc-pcm: protect BE dailink state changes in trigger
2021-08-26 19:24 ` Pierre-Louis Bossart
@ 2021-08-30 11:15 ` Mark Brown
0 siblings, 0 replies; 5+ messages in thread
From: Mark Brown @ 2021-08-30 11:15 UTC (permalink / raw)
To: Pierre-Louis Bossart
Cc: alsa-devel, Mark, Brown, Takashi Iwai, open list, Liam Girdwood,
liam.r.girdwood, Jaroslav Kysela, vkoul, Kuninori Morimoto,
tiwai
[-- Attachment #1: Type: text/plain, Size: 341 bytes --]
On Thu, Aug 26, 2021 at 02:24:19PM -0500, Pierre-Louis Bossart wrote:
> Ah sorry, there were still some issues in this RFC, we did more testing
> and came up with a lot of improvements. The intent of the RFC status was
> also to make sure it wasn't applied before the merge window.
> Can this be reverted in your branch Mark?
Ugh, right.
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 5+ messages in thread
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[not found] <20210817164054.250028-1-pierre-louis.bossart@linux.intel.com>
2021-08-17 16:40 ` [RFC PATCH 1/2] ASoC: soc-pcm: protect BE dailink state changes in trigger Pierre-Louis Bossart
2021-08-26 18:30 ` Mark Brown
2021-08-26 19:24 ` Pierre-Louis Bossart
2021-08-30 11:15 ` Mark Brown
2021-08-17 16:40 ` [RFC PATCH 2/2] ASoC: soc-pcm: test refcount before triggering Pierre-Louis Bossart
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