drm/i915: Avoid -Wconstant-logical-operand in nsecs_to_jiffies_timeout()

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:

  drivers/gpu/drm/i915/gem/i915_gem_wait.c:189:24: warning: use of logical '&&' with constant operand [-Wconstant-logical-operand]
    189 |         if (NSEC_PER_SEC % HZ &&
        |             ~~~~~~~~~~~~~~~~~ ^
  drivers/gpu/drm/i915/gem/i915_gem_wait.c:189:24: note: use '&' for a bitwise operation
    189 |         if (NSEC_PER_SEC % HZ &&
        |                               ^~
        |                               &
  drivers/gpu/drm/i915/gem/i915_gem_wait.c:189:24: 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 <nathan@kernel.org>
Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230718-nsecs_to_jiffies_timeout-constant-logical-operand-v1-2-36ed8fc8faea@kernel.org

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
index 4a33ad2d122bd01b57849c81a05873e8fb661cdb..d4b918fb11cebd73b1e5368b6fa1319bce3a653f 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
@@ -186,7 +186,7 @@ i915_gem_object_wait(struct drm_i915_gem_object *obj,
 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;