| Message ID | 20191105045907.26123-1-natechancellor@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] media: v4l2-device.h: Explicitly compare grpmask to zero in v4l2_device_mask_call_all | expand |
Bumping for review. On Mon, Nov 4, 2019 at 9:00 PM Nathan Chancellor <natechancellor@gmail.com> wrote: > > When building with Clang + -Wtautological-constant-compare, several of > the ivtv drivers warn along the lines of: > > drivers/media/pci/cx18/cx18-driver.c:1005:21: warning: converting the > result of '<<' to a boolean always evaluates to true > [-Wtautological-constant-compare] > cx18_call_hw(cx, CX18_HW_GPIO_RESET_CTRL, > ^ > drivers/media/pci/cx18/cx18-cards.h:18:37: note: expanded from macro > 'CX18_HW_GPIO_RESET_CTRL' > #define CX18_HW_GPIO_RESET_CTRL (1 << 6) > ^ > 1 warning generated. > > This is because the shift operation is implicitly converted to a boolean > in v4l2_device_mask_call_all before being negated. This can be solved by > just comparing the mask result to 0 explicitly so that there is no > boolean conversion. > > Link: https://github.com/ClangBuiltLinux/linux/issues/752 > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- > > v1 -> v2: https://lore.kernel.org/lkml/20191024201240.49063-1-natechancellor@gmail.com/ > > * Fix typo in commit message > * Add Nick's Reviewed-by. > > include/media/v4l2-device.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h > index e0b8f2602670..8564b3227887 100644 > --- a/include/media/v4l2-device.h > +++ b/include/media/v4l2-device.h > @@ -431,8 +431,8 @@ static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev) > struct v4l2_subdev *__sd; \ > \ > __v4l2_device_call_subdevs_p(v4l2_dev, __sd, \ > - !(grpmsk) || (__sd->grp_id & (grpmsk)), o, f , \ > - ##args); \ > + (grpmsk) == 0 || (__sd->grp_id & (grpmsk)), o, \ > + f , ##args); \ > } while (0) > > /** > -- > 2.24.0 >
(Adding Hans) Hi Nathan, Nick, Thanks for the patch (and the patience). On Mon, 2019-11-04 at 21:59 -0700, Nathan Chancellor wrote: > When building with Clang + -Wtautological-constant-compare, several of > the ivtv drivers warn along the lines of: > Nitpick: s/ivtv/ivtv and cx18 > drivers/media/pci/cx18/cx18-driver.c:1005:21: warning: converting the > result of '<<' to a boolean always evaluates to true > [-Wtautological-constant-compare] > cx18_call_hw(cx, CX18_HW_GPIO_RESET_CTRL, > ^ > drivers/media/pci/cx18/cx18-cards.h:18:37: note: expanded from macro > 'CX18_HW_GPIO_RESET_CTRL' > #define CX18_HW_GPIO_RESET_CTRL (1 << 6) > ^ > 1 warning generated. > > This is because the shift operation is implicitly converted to a boolean > in v4l2_device_mask_call_all before being negated. This can be solved by > just comparing the mask result to 0 explicitly so that there is no > boolean conversion. > Perhaps it's interesting to mention the reason for this change, which you mentioned as a comment before: """ The ultimate goal is to get -Wtautological-compare enabled because there are several subwarnings that would be helpful to have and right now they are all disabled. """ > Link: https://github.com/ClangBuiltLinux/linux/issues/752 > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- > > v1 -> v2: https://lore.kernel.org/lkml/20191024201240.49063-1-natechancellor@gmail.com/ > > * Fix typo in commit message > * Add Nick's Reviewed-by. > > include/media/v4l2-device.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h > index e0b8f2602670..8564b3227887 100644 > --- a/include/media/v4l2-device.h > +++ b/include/media/v4l2-device.h > @@ -431,8 +431,8 @@ static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev) > struct v4l2_subdev *__sd; \ > \ > __v4l2_device_call_subdevs_p(v4l2_dev, __sd, \ > - !(grpmsk) || (__sd->grp_id & (grpmsk)), o, f , \ > - ##args); \ > + (grpmsk) == 0 || (__sd->grp_id & (grpmsk)), o, \ > + f , ##args); \ > } while (0) > > /** The change is small enough and if it helps enabling helpful warnings, then it seems a good idea. Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com> For consistency, it would be good to also patch the other case(s). Thanks, Ezequiel
diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h index e0b8f2602670..8564b3227887 100644 --- a/include/media/v4l2-device.h +++ b/include/media/v4l2-device.h @@ -431,8 +431,8 @@ static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev) struct v4l2_subdev *__sd; \ \ __v4l2_device_call_subdevs_p(v4l2_dev, __sd, \ - !(grpmsk) || (__sd->grp_id & (grpmsk)), o, f , \ - ##args); \ + (grpmsk) == 0 || (__sd->grp_id & (grpmsk)), o, \ + f , ##args); \ } while (0) /**
When building with Clang + -Wtautological-constant-compare, several of the ivtv drivers warn along the lines of: drivers/media/pci/cx18/cx18-driver.c:1005:21: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare] cx18_call_hw(cx, CX18_HW_GPIO_RESET_CTRL, ^ drivers/media/pci/cx18/cx18-cards.h:18:37: note: expanded from macro 'CX18_HW_GPIO_RESET_CTRL' #define CX18_HW_GPIO_RESET_CTRL (1 << 6) ^ 1 warning generated. This is because the shift operation is implicitly converted to a boolean in v4l2_device_mask_call_all before being negated. This can be solved by just comparing the mask result to 0 explicitly so that there is no boolean conversion. Link: https://github.com/ClangBuiltLinux/linux/issues/752 Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> --- v1 -> v2: https://lore.kernel.org/lkml/20191024201240.49063-1-natechancellor@gmail.com/ * Fix typo in commit message * Add Nick's Reviewed-by. include/media/v4l2-device.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)