diff mbox series

[v3] media: v4l2-device.h: Explicitly compare grp{id,mask} to zero in v4l2_device macros

Message ID 20191208211139.18514-1-natechancellor@gmail.com (mailing list archive)
State New, archived
Headers show
Series [v3] media: v4l2-device.h: Explicitly compare grp{id,mask} to zero in v4l2_device macros | expand

Commit Message

Nathan Chancellor Dec. 8, 2019, 9:11 p.m. UTC 
When building with Clang + -Wtautological-constant-compare, several of
the ivtv and cx18 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 warning happens 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. The ultimate goal is to enable
-Wtautological-compare globally because there are several subwarnings
that would be helpful to have.

For visual consistency and avoidance of these warnings in the future,
all of the implicitly boolean conversions in the v4l2_device macros
are converted to explicit ones as well.

Link: https://github.com/ClangBuiltLinux/linux/issues/752
Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>
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.

v2 -> v3: https://lore.kernel.org/lkml/20191105045907.26123-1-natechancellor@gmail.com/

* Improve reasoning for change (Ezequiel)
* Patch all implicit boolean conversions (Ezequiel)
* Add Ezequiel's reviewed-by.

 include/media/v4l2-device.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h
index 5f36e0d2ede6..95353ae476a1 100644
--- a/include/media/v4l2-device.h
+++ b/include/media/v4l2-device.h
@@ -371,7 +371,7 @@  static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev)
 		struct v4l2_subdev *__sd;				\
 									\
 		__v4l2_device_call_subdevs_p(v4l2_dev, __sd,		\
-			!(grpid) || __sd->grp_id == (grpid), o, f ,	\
+			(grpid) == 0 || __sd->grp_id == (grpid), o, f ,	\
 			##args);					\
 	} while (0)
 
@@ -403,7 +403,7 @@  static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev)
 ({									\
 	struct v4l2_subdev *__sd;					\
 	__v4l2_device_call_subdevs_until_err_p(v4l2_dev, __sd,		\
-			!(grpid) || __sd->grp_id == (grpid), o, f ,	\
+			(grpid) == 0 || __sd->grp_id == (grpid), o, f ,	\
 			##args);					\
 })
 
@@ -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)
 
 /**
@@ -462,8 +462,8 @@  static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev)
 ({									\
 	struct v4l2_subdev *__sd;					\
 	__v4l2_device_call_subdevs_until_err_p(v4l2_dev, __sd,		\
-			!(grpmsk) || (__sd->grp_id & (grpmsk)), o, f ,	\
-			##args);					\
+			(grpmsk) == 0 || (__sd->grp_id & (grpmsk)), o,	\
+			f , ##args);					\
 })