| Message ID | 20201203222956.1091606-1-arnd@kernel.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | media: i2c: fix an uninitialized error code | expand |
Hi Arnd, Thanks for the patch. On Thu, 2020-12-03 at 23:29 +0100, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > Clang points out that the error handling in ov02a10_s_stream() is > broken, and just returns a random error code: > > drivers/media/i2c/ov02a10.c:537:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] > if (ov02a10->streaming == on) > ^~~~~~~~~~~~~~~~~~~~~~~~ > drivers/media/i2c/ov02a10.c:568:9: note: uninitialized use occurs here > return ret; > ^~~ > drivers/media/i2c/ov02a10.c:537:2: note: remove the 'if' if its condition is always false > if (ov02a10->streaming == on) > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/media/i2c/ov02a10.c:533:9: note: initialize the variable 'ret' to silence this warning > int ret; > > I assume that -EBUSY is the intended error code, so use that. > > Fixes: 91807efbe8ec ("media: i2c: add OV02A10 image sensor driver") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/media/i2c/ov02a10.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/i2c/ov02a10.c b/drivers/media/i2c/ov02a10.c > index 391718136ade..7ee9c904d9b5 100644 > --- a/drivers/media/i2c/ov02a10.c > +++ b/drivers/media/i2c/ov02a10.c > @@ -534,8 +534,10 @@ static int ov02a10_s_stream(struct v4l2_subdev *sd, int on) > > mutex_lock(&ov02a10->mutex); > > - if (ov02a10->streaming == on) > + if (ov02a10->streaming == on) { > + ret = -EBUSY; > goto unlock_and_return; > + } > > if (on) { > ret = pm_runtime_get_sync(&client->dev); Only if sensor fails to stream on, ret can return a negative error code. Thus ret above needs to be initialized to '0'. Also you could fix the clang error like this. static int ov02a10_s_stream(struct v4l2_subdev *sd, int on) { struct ov02a10 *ov02a10 = to_ov02a10(sd); ... int ret = 0; ... if (ov02a10->streaming == on) goto unlock_and_return; ... }
On Fri, Dec 4, 2020 at 3:10 AM Dongchun Zhu <dongchun.zhu@mediatek.com> wrote: > > Hi Arnd, > > Thanks for the patch. > > On Thu, 2020-12-03 at 23:29 +0100, Arnd Bergmann wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > > > Clang points out that the error handling in ov02a10_s_stream() is > > broken, and just returns a random error code: > > > > drivers/media/i2c/ov02a10.c:537:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] > > if (ov02a10->streaming == on) > > ^~~~~~~~~~~~~~~~~~~~~~~~ > > drivers/media/i2c/ov02a10.c:568:9: note: uninitialized use occurs here > > return ret; > > ^~~ > > drivers/media/i2c/ov02a10.c:537:2: note: remove the 'if' if its condition is always false > > if (ov02a10->streaming == on) > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > drivers/media/i2c/ov02a10.c:533:9: note: initialize the variable 'ret' to silence this warning > > int ret; > > > > I assume that -EBUSY is the intended error code, so use that. > > > > Fixes: 91807efbe8ec ("media: i2c: add OV02A10 image sensor driver") > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > --- > > drivers/media/i2c/ov02a10.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/media/i2c/ov02a10.c b/drivers/media/i2c/ov02a10.c > > index 391718136ade..7ee9c904d9b5 100644 > > --- a/drivers/media/i2c/ov02a10.c > > +++ b/drivers/media/i2c/ov02a10.c > > @@ -534,8 +534,10 @@ static int ov02a10_s_stream(struct v4l2_subdev *sd, int on) > > > > mutex_lock(&ov02a10->mutex); > > > > - if (ov02a10->streaming == on) > > + if (ov02a10->streaming == on) { > > + ret = -EBUSY; > > goto unlock_and_return; > > + } > > > > if (on) { > > ret = pm_runtime_get_sync(&client->dev); > > Only if sensor fails to stream on, ret can return a negative error code. > Thus ret above needs to be initialized to '0'. Ok, I sent a version 2. > Also you could fix the clang error like this. > > static int ov02a10_s_stream(struct v4l2_subdev *sd, int on) > { > struct ov02a10 *ov02a10 = to_ov02a10(sd); > ... > int ret = 0; > > ... > if (ov02a10->streaming == on) > goto unlock_and_return; > > ... > } Sorry, I should have removed the last line of the output from clang that suggested doing that. Initializing a local variable in the declaration is generally a bad idea precisely because it prevents the compiler from warning about a case like this where the author forgot to set the correct error value. We should really fix clang to not propagate that nonsense. Arnd
diff --git a/drivers/media/i2c/ov02a10.c b/drivers/media/i2c/ov02a10.c index 391718136ade..7ee9c904d9b5 100644 --- a/drivers/media/i2c/ov02a10.c +++ b/drivers/media/i2c/ov02a10.c @@ -534,8 +534,10 @@ static int ov02a10_s_stream(struct v4l2_subdev *sd, int on) mutex_lock(&ov02a10->mutex); - if (ov02a10->streaming == on) + if (ov02a10->streaming == on) { + ret = -EBUSY; goto unlock_and_return; + } if (on) { ret = pm_runtime_get_sync(&client->dev);