Hi Nathan,

On 7/18/23 18:44, Nathan Chancellor wrote:
A proposed update to clang's -Wconstant-logical-operand to warn when the
left hand side is a constant shows the following instance in
nsecs_to_jiffies_timeout() when NSEC_PER_SEC is not a multiple of HZ,
such as CONFIG_HZ=300:

   In file included from drivers/gpu/drm/v3d/v3d_debugfs.c:12:
   drivers/gpu/drm/v3d/v3d_drv.h:343:24: warning: use of logical '&&' with 
constant operand [-Wconstant-logical-operand]
     343 |         if (NSEC_PER_SEC % HZ &&
         |             ~~~~~~~~~~~~~~~~~ ^
   drivers/gpu/drm/v3d/v3d_drv.h:343:24: note: use '&' for a bitwise operation
     343 |         if (NSEC_PER_SEC % HZ &&
         |                               ^~
         |                               &
   drivers/gpu/drm/v3d/v3d_drv.h:343:24: note: remove constant to silence this 
warning
   1 warning generated.

Turn this into an explicit comparison against zero to make the
expression a boolean to make it clear this should be a logical check,
not a bitwise one.

Link: https://reviews.llvm.org/D142609
Signed-off-by: Nathan Chancellor <nat...@kernel.org>

Reviewed-by: Maíra Canal <mca...@igalia.com>

Thanks for all the hard work with clang! Let me know if you need someone
to push it to drm-misc-next.

Best Regards,
- Maíra

---
  drivers/gpu/drm/v3d/v3d_drv.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
index b74b1351bfc8..7f664a4b2a75 100644
--- a/drivers/gpu/drm/v3d/v3d_drv.h
+++ b/drivers/gpu/drm/v3d/v3d_drv.h
@@ -340,7 +340,7 @@ struct v3d_submit_ext {
  static inline unsigned long nsecs_to_jiffies_timeout(const u64 n)
  {
        /* nsecs_to_jiffies64() does not guard against overflow */
-       if (NSEC_PER_SEC % HZ &&
+       if ((NSEC_PER_SEC % HZ) != 0 &&
            div_u64(n, NSEC_PER_SEC) >= MAX_JIFFY_OFFSET / HZ)
                return MAX_JIFFY_OFFSET;

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