ASoC: soc-pcm: add a check for unsupported commands to the soc_pcm_trigger

Commit Message

xuhanwu March 11, 2024, 7:05 a.m. UTC

From: xuhanwu <[e-mail]>

The function soc_pcm_trigger needs to return an error(-EINVAL)
if the cmd parameter is not supported.

Signed-off-by: xuhanwu <[e-mail]>
---
Dear Brown

Thank you for your guidance.
The issue with characters exceeding 80 has been resolved.

>	As can be seen from inspection of the immediately
>	preceeding handling of start, we're deliberately
>        ignoring half the values in each switch.

In kernel version 6.2, when the soc_pcm_trigger function receives a
command parameter cmd set to SNDRV_PCM_TRIGGER_DRAIN,
it returns a value of -EINVAL.The function snd_pcm_drain checks
the returned error value and exits accordingly.

kernel-version6.2 Function call relationship
		  snd_pcm_drain->
			snd_pcm_action->
				snd_pcm_do_drain_init->
					    soc_pcm_trigger->

    snd_pcm_drain
	result = snd_pcm_action(&snd_pcm_action_drain_init, substream,
				ACTION_ARG_IGNORE);
	if (result < 0)
		goto unlock;

     snd_pcm_do_drain_init
	if (runtime->state == SNDRV_PCM_STATE_DRAINING &&
	    runtime->trigger_master == substream &&
	    (runtime->hw.info & SNDRV_PCM_INFO_DRAIN_TRIGGER))
		return substream->ops->trigger(substream,
					       SNDRV_PCM_TRIGGER_DRAIN);

In the latest code, when the cmd parameter is set to SNDRV_PCM_TRIGGER_DRAIN,
the return value is 0. If snd_pcm_drain finds that the return value is 0,
it will not execute the goto unlock;

The above is my understanding of the code, please help me correct it.

Thanks
Xuhanwu
---
 sound/soc/soc-pcm.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Mark Brown March 12, 2024, 2:31 p.m. UTC | #1

On Mon, Mar 11, 2024 at 03:05:48PM +0800, xuhanwu wrote:

> >	As can be seen from inspection of the immediately
> >	preceeding handling of start, we're deliberately
> >        ignoring half the values in each switch.

> In kernel version 6.2, when the soc_pcm_trigger function receives a
> command parameter cmd set to SNDRV_PCM_TRIGGER_DRAIN,
> it returns a value of -EINVAL.The function snd_pcm_drain checks
> the returned error value and exits accordingly.

The current kernel version is v6.8 (we're in the merge window for v6.9
now) - any changes that you're submitting should be submitted against
current code, not v6.2.

> In the latest code, when the cmd parameter is set to SNDRV_PCM_TRIGGER_DRAIN,
> the return value is 0. If snd_pcm_drain finds that the return value is 0,
> it will not execute the goto unlock;

Well, it will get to the unlock eventually after going through the for
loop so the lock doesn't get leaked AFAICT?  I'm not sure what the issue
you're seeing here is.

xuhanwu March 15, 2024, 8:18 a.m. UTC | #2

Dear broonie

Issue: Before and after Linux version 6.2, when the cmd is 
SNDRV_PCM_TRIGGER_DRAIN, calling the function soc_pcm_trigger results 
in different return values.
Through your guidance, I've realized that the code logic has been adjusted. 
I will further deepen my study of the code. Thank you for your guidance.

Thank you for your help.
xuhanwu

Patch

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 77ee103b7..eba737729 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1173,6 +1173,9 @@  static int soc_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 			if (r < 0)
 				break;
 		}
+		break;
+	default:
+		return -EINVAL;
 	}
 
 	/*