[Intel-gfx] [PATCH 2/2] drm/i915: Lift marking a lock as used to utils

[Chris Wilson]

After calling lock_set_subclass() the lock _must_ be used, or else
lockdep's internal nr_used_locks becomes unbalanced. Extract the little
utility function to i915_utils.c

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
---
 drivers/gpu/drm/i915/gt/intel_engine_cs.c | 13 +------------
 drivers/gpu/drm/i915/i915_utils.c         | 15 +++++++++++++++
 drivers/gpu/drm/i915/i915_utils.h         |  7 +++++++
 3 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 56fb9cece71b..f11ea72645ac 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -769,18 +769,7 @@ intel_engine_init_active(struct intel_engine_cs *engine, unsigned int subclass)
 
 	spin_lock_init(&engine->active.lock);
 	lockdep_set_subclass(&engine->active.lock, subclass);
-
-	/*
-	 * Due to an interesting quirk in lockdep's internal debug tracking,
-	 * after setting a subclass we must ensure the lock is used. Otherwise,
-	 * nr_unused_locks is incremented once too often.
-	 */
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	local_irq_disable();
-	lock_map_acquire(&engine->active.lock.dep_map);
-	lock_map_release(&engine->active.lock.dep_map);
-	local_irq_enable();
-#endif
+	mark_lock_used_irq(&engine->active.lock);
 }
 
 static struct intel_context *
diff --git a/drivers/gpu/drm/i915/i915_utils.c b/drivers/gpu/drm/i915/i915_utils.c
index 90c7f0c4838c..894de60833ec 100644
--- a/drivers/gpu/drm/i915/i915_utils.c
+++ b/drivers/gpu/drm/i915/i915_utils.c
@@ -127,3 +127,18 @@ void fs_reclaim_taints_mutex(struct mutex *mutex)
 
 	fs_reclaim_release(GFP_KERNEL);
 }
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void __mark_lock_used_irq(struct lockdep_map *lock)
+{
+	/*
+	 * Due to an interesting quirk in lockdep's internal debug tracking,
+	 * after setting a subclass we must ensure the lock is used. Otherwise,
+	 * nr_unused_locks is incremented once too often.
+	 */
+	local_irq_disable();
+	lock_map_acquire(lock);
+	lock_map_release(lock);
+	local_irq_enable();
+}
+#endif
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index 3f616d00de42..610616d6bf29 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -450,6 +450,13 @@ static inline bool timer_expired(const struct timer_list *t)
 	return timer_active(t) && !timer_pending(t);
 }
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void __mark_lock_used_irq(struct lockdep_map *lock);
+#define mark_lock_used_irq(lock) __mark_lock_used_irq(&(lock)->dep_map)
+#else
+#define mark_lock_used_irq(lock)
+#endif
+
 /*
  * 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
-- 
2.20.1