[alsa-devel] [PATCH] sound: Don't assume i2c device probing always succeeds
Jean Delvare
khali at linux-fr.org
Sun Oct 4 11:35:21 CEST 2009
Hi Takashi,
On Thu, 01 Oct 2009 08:52:59 +0200, Takashi Iwai wrote:
> At Wed, 30 Sep 2009 18:55:05 +0200,
> Jean Delvare wrote:
> >
> > On Wed, 30 Sep 2009 17:15:49 +0200, Takashi Iwai wrote:
> > > Yes, indeed I prefer NULL check because the user can know the error
> > > at the right place. I share your concern about the code addition,
> > > though :)
> > >
> > > I already made a patch below, but it's totally untested.
> > > It'd be helpful if someone can do review and build-test it.
> > >
> > >
> > > thanks,
> > >
> > > Takashi
> > >
> > > ---
> > > diff --git a/sound/aoa/codecs/tas.c b/sound/aoa/codecs/tas.c
> > > index f0ebc97..0f810c8 100644
> > > --- a/sound/aoa/codecs/tas.c
> > > +++ b/sound/aoa/codecs/tas.c
> > > @@ -897,6 +897,10 @@ static int tas_create(struct i2c_adapter *adapter,
> > > client = i2c_new_device(adapter, &info);
> > > if (!client)
> > > return -ENODEV;
> > > + if (!client->driver) {
> > > + i2c_unregister_device(client);
> > > + return -ENODEV;
> > > + }
> > >
> > > /*
> > > * Let i2c-core delete that device on driver removal.
> > > diff --git a/sound/ppc/keywest.c b/sound/ppc/keywest.c
> > > index 835fa19..473c5a6 100644
> > > --- a/sound/ppc/keywest.c
> > > +++ b/sound/ppc/keywest.c
> > > @@ -59,6 +59,13 @@ static int keywest_attach_adapter(struct i2c_adapter *adapter)
> > > strlcpy(info.type, "keywest", I2C_NAME_SIZE);
> > > info.addr = keywest_ctx->addr;
> > > keywest_ctx->client = i2c_new_device(adapter, &info);
> > > + if (!keywest_ctx->client)
> > > + return -ENODEV;
> > > + if (!keywest_ctx->client->driver) {
> > > + i2c_unregister_device(keywest_ctx->client);
> > > + keywest_ctx->client = NULL;
> > > + return -ENODEV;
> > > + }
> > >
> > > /*
> > > * Let i2c-core delete that device on driver removal.
> >
> > This looks good to me. Please add the following comment before the
> > client->driver check in both drivers:
> >
> > /*
> > * We know the driver is already loaded, so the device should be
> > * already bound. If not it means binding failed, and then there
> > * is no point in keeping the device instantiated.
> > */
> >
> > Otherwise it's a little difficult to understand why the check is there.
>
> Fair enough. I applied the patch with the comment now.
> Thanks!
I see this is upstream now. While the keywest fix was essentially
theoretical, the tas one addresses a crash which really could happen,
so I think it would be worth sending to stable for 2.6.31. What do you
think? Will you take care, or do you want me to?
Thanks,
--
Jean Delvare
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