Commit ae303004 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Specialise i915_active.work lock classes 



Similar to for i915_active.mutex, we require each class of i915_active
to have distinct lockdep chains as some, but by no means all,
i915_active are used within the shrinker and so have much more severe
usage constraints. By using a lockclass local to i915_active_init() all
i915_active workers have the same lock class, and we may generate false
positives when waiting for the i915_active. If we push the lockclass
into the caller, each class of i915_active will have distinct lockdep
chains.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Acked-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191202140133.2444217-1-chris@chris-wilson.co.uk
parent 7d0aa0db

drivers/gpu/drm/i915/i915_active.c

+6 −2
Original line number Diff line number Diff line
@@ -277,7 +277,8 @@ active_instance(struct i915_active *ref, struct intel_timeline *tl) 
void __i915_active_init(struct i915_active *ref,

			int (*active)(struct i915_active *ref),

			void (*retire)(struct i915_active *ref),

			struct lock_class_key *key)

			struct lock_class_key *mkey,

			struct lock_class_key *wkey)

{

	unsigned long bits;
@@ -295,9 +296,12 @@ void __i915_active_init(struct i915_active *ref, 


	init_llist_head(&ref->preallocated_barriers);

	atomic_set(&ref->count, 0);

	__mutex_init(&ref->mutex, "i915_active", key);

	__mutex_init(&ref->mutex, "i915_active", mkey);

	__i915_active_fence_init(&ref->excl, NULL, excl_retire);

	INIT_WORK(&ref->work, active_work);

#if IS_ENABLED(CONFIG_LOCKDEP)

	lockdep_init_map(&ref->work.lockdep_map, "i915_active.work", wkey, 0);

#endif

}



static bool ____active_del_barrier(struct i915_active *ref,

drivers/gpu/drm/i915/i915_active.h

+7 −3
Original line number Diff line number Diff line
@@ -152,11 +152,15 @@ i915_active_fence_isset(const struct i915_active_fence *active) 
void __i915_active_init(struct i915_active *ref,

			int (*active)(struct i915_active *ref),

			void (*retire)(struct i915_active *ref),

			struct lock_class_key *key);

			struct lock_class_key *mkey,

			struct lock_class_key *wkey);



/* Specialise each class of i915_active to avoid impossible lockdep cycles. */

#define i915_active_init(ref, active, retire) do {		\

	static struct lock_class_key __key;				\

	static struct lock_class_key __mkey;				\

	static struct lock_class_key __wkey;				\

									\

	__i915_active_init(ref, active, retire, &__key);		\

	__i915_active_init(ref, active, retire, &__mkey, &__wkey);	\

} while (0)



int i915_active_ref(struct i915_active *ref,