Re: [alsa-devel] [PATCH] ASoC: fsl_audmix: Add spin lock to protect tdms

[Daniel Baluta]

On Thu, Nov 7, 2019 at 8:54 AM S.j. Wang <shengjiu.wang@xxxxxxx> wrote:
>
> Hi
> >
> > Hi Shengjiu,
> >
> > Comments inline.
> >
> > On Wed, Nov 6, 2019 at 9:30 AM Shengjiu Wang <shengjiu.wang@xxxxxxx>
> > wrote:
> > >
> > > Audmix support two substream, When two substream start to run, the
> > > trigger function may be called by two substream in same time, that the
> > > priv->tdms may be updated wrongly.
> > >
> > > The expected priv->tdms is 0x3, but sometimes the result is 0x2, or
> > > 0x1.
> > >
> > > Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxx>
> > > ---
> > >  sound/soc/fsl/fsl_audmix.c | 6 ++++++  sound/soc/fsl/fsl_audmix.h | 1
> > > +
> > >  2 files changed, 7 insertions(+)
> > >
> > > diff --git a/sound/soc/fsl/fsl_audmix.c b/sound/soc/fsl/fsl_audmix.c
> > > index c7e4e9757dce..a1db1bce330f 100644
> > > --- a/sound/soc/fsl/fsl_audmix.c
> > > +++ b/sound/soc/fsl/fsl_audmix.c
> > > @@ -286,6 +286,7 @@ static int fsl_audmix_dai_trigger(struct
> > snd_pcm_substream *substream, int cmd,
> > >                                   struct snd_soc_dai *dai)  {
> > >         struct fsl_audmix *priv = snd_soc_dai_get_drvdata(dai);
> > > +       unsigned long lock_flags;
> > >
> > >         /* Capture stream shall not be handled */
> > >         if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
> > > @@ -295,12 +296,16 @@ static int fsl_audmix_dai_trigger(struct
> > snd_pcm_substream *substream, int cmd,
> > >         case SNDRV_PCM_TRIGGER_START:
> > >         case SNDRV_PCM_TRIGGER_RESUME:
> > >         case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
> > > +               spin_lock_irqsave(&priv->lock, lock_flags);
> >
> > Why do we need to disable interrupts here? I assume that lock is only
> > used in process context.
> >
> It is in atomic context, so I think it is ok to disable interrupt.

All right thanks for the explanation. Added my Reviewed-by to v2.