[PATCH 1/2] drm/i915: Encapsulate kconfig constant values inside boolean predicates

* [PATCH 1/2] drm/i915: Encapsulate kconfig constant values inside boolean predicates
@ 2019-10-25 13:59 ` Chris Wilson
  0 siblings, 0 replies; 10+ messages in thread
From: Chris Wilson @ 2019-10-25 13:59 UTC (permalink / raw)
  To: intel-gfx; +Cc: Jani Nikula, Nathan Chancellor, Nick Desaulniers

Avoid angering clang and smatch by using a constant value in a '&&' test,
by forcing that constant value into a boolean.

E.g.,
drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c:159:13: warning: use of logical '&&' with constant operand [-Wconstant-logical-operand]
	if (!delay && CONFIG_DRM_I915_PREEMPT_TIMEOUT) {
                      ^  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c      |  3 ++-
 drivers/gpu/drm/i915/gem/i915_gem_mman.c         |  2 +-
 drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c |  4 ++--
 drivers/gpu/drm/i915/i915_request.c              |  2 +-
 drivers/gpu/drm/i915/i915_utils.h                | 13 +++++++++++++
 5 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 55f1f93c0925..414fc55c9dd0 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -325,7 +325,8 @@ static bool __cancel_engine(struct intel_engine_cs *engine)
 	 * kill the banned context, we fallback to doing a local reset
 	 * instead.
 	 */
-	if (CONFIG_DRM_I915_PREEMPT_TIMEOUT && !intel_engine_pulse(engine))
+	if (IS_ACTIVE(CONFIG_DRM_I915_PREEMPT_TIMEOUT) &&
+	    !intel_engine_pulse(engine))
 		return true;
 
 	/* If we are unable to send a pulse, try resetting this engine. */
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index fd4122d8c0a9..e3002849844b 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -312,7 +312,7 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf)
 		list_add(&obj->userfault_link, &i915->ggtt.userfault_list);
 	mutex_unlock(&i915->ggtt.vm.mutex);
 
-	if (CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND)
+	if (IS_ACTIVE(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND))
 		intel_wakeref_auto(&i915->ggtt.userfault_wakeref,
 				   msecs_to_jiffies_timeout(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND));
 
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
index 9977f59f6b53..5051f304705b 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
@@ -133,7 +133,7 @@ static void heartbeat(struct work_struct *wrk)
 
 void intel_engine_unpark_heartbeat(struct intel_engine_cs *engine)
 {
-	if (!CONFIG_DRM_I915_HEARTBEAT_INTERVAL)
+	if (!IS_ACTIVE(CONFIG_DRM_I915_HEARTBEAT_INTERVAL))
 		return;
 
 	next_heartbeat(engine);
@@ -156,7 +156,7 @@ int intel_engine_set_heartbeat(struct intel_engine_cs *engine,
 	int err;
 
 	/* Send one last pulse before to cleanup persistent hogs */
-	if (!delay && CONFIG_DRM_I915_PREEMPT_TIMEOUT) {
+	if (!delay && IS_ACTIVE(CONFIG_DRM_I915_PREEMPT_TIMEOUT)) {
 		err = intel_engine_pulse(engine);
 		if (err)
 			return err;
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 932c5cf190b5..19a1d447ab8d 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1447,7 +1447,7 @@ long i915_request_wait(struct i915_request *rq,
 	 * completion. That requires having a good predictor for the request
 	 * duration, which we currently lack.
 	 */
-	if (CONFIG_DRM_I915_SPIN_REQUEST &&
+	if (IS_ACTIVE(CONFIG_DRM_I915_SPIN_REQUEST) &&
 	    __i915_spin_request(rq, state, CONFIG_DRM_I915_SPIN_REQUEST)) {
 		dma_fence_signal(&rq->fence);
 		goto out;
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index 94f136d8a5fd..da205a4bdfdc 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -430,4 +430,17 @@ static inline bool timer_expired(const struct timer_list *t)
 	return READ_ONCE(t->expires) && !timer_pending(t);
 }
 
+/*
+ * This is a lookalike for IS_ENABLED() that takes a kconfig value,
+ * e.g. CONFIG_DRM_I915_SPIN_REQUEST, and evaluates whether it is non-zero
+ * i.e. active. Wrapping up the config inside a boolean context prevents
+ * clang and smatch from complaining about potential issues in confusing
+ * logical-&& with bitwise-& for constants.
+ *
+ * Sadly IS_ENABLED() itself does not work with kconfig values.
+ *
+ * Returns 0 if config is 0, 1 if set to any value.
+ */
+#define IS_ACTIVE(config) ((config) != 0)
+
 #endif /* !__I915_UTILS_H */
-- 
2.24.0.rc0

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