* [PATCH] media: i2c: fix an uninitialized error code
@ 2020-12-03 22:29 Arnd Bergmann
2020-12-04 2:10 ` Dongchun Zhu
0 siblings, 1 reply; 3+ messages in thread
From: Arnd Bergmann @ 2020-12-03 22:29 UTC (permalink / raw)
To: Dongchun Zhu, Mauro Carvalho Chehab, Nathan Chancellor,
Nick Desaulniers, Andy Shevchenko, Sakari Ailus
Cc: Arnd Bergmann, linux-media, linux-kernel, clang-built-linux
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);
--
2.27.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] media: i2c: fix an uninitialized error code
2020-12-03 22:29 [PATCH] media: i2c: fix an uninitialized error code Arnd Bergmann
@ 2020-12-04 2:10 ` Dongchun Zhu
2020-12-04 8:22 ` Arnd Bergmann
0 siblings, 1 reply; 3+ messages in thread
From: Dongchun Zhu @ 2020-12-04 2:10 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Mauro Carvalho Chehab, Nathan Chancellor, Nick Desaulniers,
Andy Shevchenko, Sakari Ailus, Arnd Bergmann, linux-media,
linux-kernel, clang-built-linux, tfiga, sj.huang
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;
...
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] media: i2c: fix an uninitialized error code
2020-12-04 2:10 ` Dongchun Zhu
@ 2020-12-04 8:22 ` Arnd Bergmann
0 siblings, 0 replies; 3+ messages in thread
From: Arnd Bergmann @ 2020-12-04 8:22 UTC (permalink / raw)
To: Dongchun Zhu
Cc: Mauro Carvalho Chehab, Nathan Chancellor, Nick Desaulniers,
Andy Shevchenko, Sakari Ailus, Arnd Bergmann,
Linux Media Mailing List, linux-kernel, clang-built-linux, tfiga,
sj.huang
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
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-12-04 2:10 ` Dongchun Zhu
2020-12-04 8:22 ` Arnd Bergmann
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