1 files changed, 71 insertions, 259 deletions

diff --git a/drivers/gpu/drm/i915/i915_active.h b/drivers/gpu/drm/i915/i915_active.h
index f95058f99057..44859356ce97 100644
--- a/drivers/gpu/drm/i915/i915_active.h
+++ b/drivers/gpu/drm/i915/i915_active.h
@@ -12,6 +12,10 @@
 #include "i915_active_types.h"
 #include "i915_request.h"
 
+struct i915_request;
+struct intel_engine_cs;
+struct intel_timeline;
+
 /*
  * We treat requests as fences. This is not be to confused with our
  * "fence registers" but pipeline synchronisation objects ala GL_ARB_sync.
@@ -28,308 +32,108 @@
  * write access so that we can perform concurrent read operations between
  * the CPU and GPU engines, as well as waiting for all rendering to
  * complete, or waiting for the last GPU user of a "fence register". The
- * object then embeds a #i915_active_request to track the most recent (in
+ * object then embeds a #i915_active_fence to track the most recent (in
  * retirement order) request relevant for the desired mode of access.
- * The #i915_active_request is updated with i915_active_request_set() to
+ * The #i915_active_fence is updated with i915_active_fence_set() to
  * track the most recent fence request, typically this is done as part of
  * i915_vma_move_to_active().
  *
- * When the #i915_active_request completes (is retired), it will
+ * When the #i915_active_fence completes (is retired), it will
  * signal its completion to the owner through a callback as well as mark
- * itself as idle (i915_active_request.request == NULL). The owner
+ * itself as idle (i915_active_fence.request == NULL). The owner
  * can then perform any action, such as delayed freeing of an active
  * resource including itself.
  */
 
-void i915_active_retire_noop(struct i915_active_request *active,
-			     struct i915_request *request);
+void i915_active_noop(struct dma_fence *fence, struct dma_fence_cb *cb);
 
 /**
- * i915_active_request_init - prepares the activity tracker for use
+ * __i915_active_fence_init - prepares the activity tracker for use
  * @active - the active tracker
- * @rq - initial request to track, can be NULL
+ * @fence - initial fence to track, can be NULL
  * @func - a callback when then the tracker is retired (becomes idle),
  *         can be NULL
  *
- * i915_active_request_init() prepares the embedded @active struct for use as
- * an activity tracker, that is for tracking the last known active request
- * associated with it. When the last request becomes idle, when it is retired
+ * i915_active_fence_init() prepares the embedded @active struct for use as
+ * an activity tracker, that is for tracking the last known active fence
+ * associated with it. When the last fence becomes idle, when it is retired
  * after completion, the optional callback @func is invoked.
  */
 static inline void
-i915_active_request_init(struct i915_active_request *active,
+__i915_active_fence_init(struct i915_active_fence *active,
 			 struct mutex *lock,
-			 struct i915_request *rq,
-			 i915_active_retire_fn retire)
+			 void *fence,
+			 dma_fence_func_t fn)
 {
-	RCU_INIT_POINTER(active->request, rq);
-	INIT_LIST_HEAD(&active->link);
-	active->retire = retire ?: i915_active_retire_noop;
+	RCU_INIT_POINTER(active->fence, fence);
+	active->cb.func = fn ?: i915_active_noop;
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
 	active->lock = lock;
 #endif
 }
 
-#define INIT_ACTIVE_REQUEST(name, lock) \
-	i915_active_request_init((name), (lock), NULL, NULL)
-
-/**
- * i915_active_request_set - updates the tracker to watch the current request
- * @active - the active tracker
- * @request - the request to watch
- *
- * __i915_active_request_set() watches the given @request for completion. Whilst
- * that @request is busy, the @active reports busy. When that @request is
- * retired, the @active tracker is updated to report idle.
- */
-static inline void
-__i915_active_request_set(struct i915_active_request *active,
-			  struct i915_request *request)
-{
-#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
-	lockdep_assert_held(active->lock);
-#endif
-	list_move(&active->link, &request->active_list);
-	rcu_assign_pointer(active->request, request);
-}
+#define INIT_ACTIVE_FENCE(A, LOCK) \
+	__i915_active_fence_init((A), (LOCK), NULL, NULL)
 
-int __must_check
-i915_active_request_set(struct i915_active_request *active,
-			struct i915_request *rq);
+struct dma_fence *
+__i915_active_fence_set(struct i915_active_fence *active,
+			struct dma_fence *fence);
 
 /**
- * i915_active_request_raw - return the active request
+ * i915_active_fence_set - updates the tracker to watch the current fence
  * @active - the active tracker
+ * @rq - the request to watch
  *
- * i915_active_request_raw() returns the current request being tracked, or NULL.
- * It does not obtain a reference on the request for the caller, so the caller
- * must hold struct_mutex.
+ * i915_active_fence_set() watches the given @rq for completion. While
+ * that @rq is busy, the @active reports busy. When that @rq is signaled
+ * (or else retired) the @active tracker is updated to report idle.
  */
-static inline struct i915_request *
-i915_active_request_raw(const struct i915_active_request *active,
-			struct mutex *mutex)
-{
-	return rcu_dereference_protected(active->request,
-					 lockdep_is_held(mutex));
-}
-
-/**
- * i915_active_request_peek - report the active request being monitored
- * @active - the active tracker
- *
- * i915_active_request_peek() returns the current request being tracked if
- * still active, or NULL. It does not obtain a reference on the request
- * for the caller, so the caller must hold struct_mutex.
- */
-static inline struct i915_request *
-i915_active_request_peek(const struct i915_active_request *active,
-			 struct mutex *mutex)
-{
-	struct i915_request *request;
-
-	request = i915_active_request_raw(active, mutex);
-	if (!request || i915_request_completed(request))
-		return NULL;
-
-	return request;
-}
-
-/**
- * i915_active_request_get - return a reference to the active request
- * @active - the active tracker
- *
- * i915_active_request_get() returns a reference to the active request, or NULL
- * if the active tracker is idle. The caller must hold struct_mutex.
- */
-static inline struct i915_request *
-i915_active_request_get(const struct i915_active_request *active,
-			struct mutex *mutex)
-{
-	return i915_request_get(i915_active_request_peek(active, mutex));
-}
-
-/**
- * __i915_active_request_get_rcu - return a reference to the active request
- * @active - the active tracker
- *
- * __i915_active_request_get() returns a reference to the active request,
- * or NULL if the active tracker is idle. The caller must hold the RCU read
- * lock, but the returned pointer is safe to use outside of RCU.
- */
-static inline struct i915_request *
-__i915_active_request_get_rcu(const struct i915_active_request *active)
-{
-	/*
-	 * Performing a lockless retrieval of the active request is super
-	 * tricky. SLAB_TYPESAFE_BY_RCU merely guarantees that the backing
-	 * slab of request objects will not be freed whilst we hold the
-	 * RCU read lock. It does not guarantee that the request itself
-	 * will not be freed and then *reused*. Viz,
-	 *
-	 * Thread A			Thread B
-	 *
-	 * rq = active.request
-	 *				retire(rq) -> free(rq);
-	 *				(rq is now first on the slab freelist)
-	 *				active.request = NULL
-	 *
-	 *				rq = new submission on a new object
-	 * ref(rq)
-	 *
-	 * To prevent the request from being reused whilst the caller
-	 * uses it, we take a reference like normal. Whilst acquiring
-	 * the reference we check that it is not in a destroyed state
-	 * (refcnt == 0). That prevents the request being reallocated
-	 * whilst the caller holds on to it. To check that the request
-	 * was not reallocated as we acquired the reference we have to
-	 * check that our request remains the active request across
-	 * the lookup, in the same manner as a seqlock. The visibility
-	 * of the pointer versus the reference counting is controlled
-	 * by using RCU barriers (rcu_dereference and rcu_assign_pointer).
-	 *
-	 * In the middle of all that, we inspect whether the request is
-	 * complete. Retiring is lazy so the request may be completed long
-	 * before the active tracker is updated. Querying whether the
-	 * request is complete is far cheaper (as it involves no locked
-	 * instructions setting cachelines to exclusive) than acquiring
-	 * the reference, so we do it first. The RCU read lock ensures the
-	 * pointer dereference is valid, but does not ensure that the
-	 * seqno nor HWS is the right one! However, if the request was
-	 * reallocated, that means the active tracker's request was complete.
-	 * If the new request is also complete, then both are and we can
-	 * just report the active tracker is idle. If the new request is
-	 * incomplete, then we acquire a reference on it and check that
-	 * it remained the active request.
-	 *
-	 * It is then imperative that we do not zero the request on
-	 * reallocation, so that we can chase the dangling pointers!
-	 * See i915_request_alloc().
-	 */
-	do {
-		struct i915_request *request;
-
-		request = rcu_dereference(active->request);
-		if (!request || i915_request_completed(request))
-			return NULL;
-
-		/*
-		 * An especially silly compiler could decide to recompute the
-		 * result of i915_request_completed, more specifically
-		 * re-emit the load for request->fence.seqno. A race would catch
-		 * a later seqno value, which could flip the result from true to
-		 * false. Which means part of the instructions below might not
-		 * be executed, while later on instructions are executed. Due to
-		 * barriers within the refcounting the inconsistency can't reach
-		 * past the call to i915_request_get_rcu, but not executing
-		 * that while still executing i915_request_put() creates
-		 * havoc enough.  Prevent this with a compiler barrier.
-		 */
-		barrier();
-
-		request = i915_request_get_rcu(request);
-
-		/*
-		 * What stops the following rcu_access_pointer() from occurring
-		 * before the above i915_request_get_rcu()? If we were
-		 * to read the value before pausing to get the reference to
-		 * the request, we may not notice a change in the active
-		 * tracker.
-		 *
-		 * The rcu_access_pointer() is a mere compiler barrier, which
-		 * means both the CPU and compiler are free to perform the
-		 * memory read without constraint. The compiler only has to
-		 * ensure that any operations after the rcu_access_pointer()
-		 * occur afterwards in program order. This means the read may
-		 * be performed earlier by an out-of-order CPU, or adventurous
-		 * compiler.
-		 *
-		 * The atomic operation at the heart of
-		 * i915_request_get_rcu(), see dma_fence_get_rcu(), is
-		 * atomic_inc_not_zero() which is only a full memory barrier
-		 * when successful. That is, if i915_request_get_rcu()
-		 * returns the request (and so with the reference counted
-		 * incremented) then the following read for rcu_access_pointer()
-		 * must occur after the atomic operation and so confirm
-		 * that this request is the one currently being tracked.
-		 *
-		 * The corresponding write barrier is part of
-		 * rcu_assign_pointer().
-		 */
-		if (!request || request == rcu_access_pointer(active->request))
-			return rcu_pointer_handoff(request);
-
-		i915_request_put(request);
-	} while (1);
-}
-
+int __must_check
+i915_active_fence_set(struct i915_active_fence *active,
+		      struct i915_request *rq);
 /**
- * i915_active_request_get_unlocked - return a reference to the active request
+ * i915_active_fence_get - return a reference to the active fence
  * @active - the active tracker
  *
- * i915_active_request_get_unlocked() returns a reference to the active request,
+ * i915_active_fence_get() returns a reference to the active fence,
  * or NULL if the active tracker is idle. The reference is obtained under RCU,
  * so no locking is required by the caller.
  *
- * The reference should be freed with i915_request_put().
+ * The reference should be freed with dma_fence_put().
  */
-static inline struct i915_request *
-i915_active_request_get_unlocked(const struct i915_active_request *active)
+static inline struct dma_fence *
+i915_active_fence_get(struct i915_active_fence *active)
 {
-	struct i915_request *request;
+	struct dma_fence *fence;
 
 	rcu_read_lock();
-	request = __i915_active_request_get_rcu(active);
+	fence = dma_fence_get_rcu_safe(&active->fence);
 	rcu_read_unlock();
 
-	return request;
+	return fence;
 }
 
 /**
- * i915_active_request_isset - report whether the active tracker is assigned
+ * i915_active_fence_isset - report whether the active tracker is assigned
  * @active - the active tracker
  *
- * i915_active_request_isset() returns true if the active tracker is currently
- * assigned to a request. Due to the lazy retiring, that request may be idle
+ * i915_active_fence_isset() returns true if the active tracker is currently
+ * assigned to a fence. Due to the lazy retiring, that fence may be idle
  * and this may report stale information.
  */
 static inline bool
-i915_active_request_isset(const struct i915_active_request *active)
+i915_active_fence_isset(const struct i915_active_fence *active)
 {
-	return rcu_access_pointer(active->request);
+	return rcu_access_pointer(active->fence);
 }
 
-/**
- * i915_active_request_retire - waits until the request is retired
- * @active - the active request on which to wait
- *
- * i915_active_request_retire() waits until the request is completed,
- * and then ensures that at least the retirement handler for this
- * @active tracker is called before returning. If the @active
- * tracker is idle, the function returns immediately.
- */
-static inline int __must_check
-i915_active_request_retire(struct i915_active_request *active,
-			   struct mutex *mutex)
+static inline void
+i915_active_fence_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 {
-	struct i915_request *request;
-	long ret;
-
-	request = i915_active_request_raw(active, mutex);
-	if (!request)
-		return 0;
-
-	ret = i915_request_wait(request,
-				I915_WAIT_INTERRUPTIBLE,
-				MAX_SCHEDULE_TIMEOUT);
-	if (ret < 0)
-		return ret;
+	struct i915_active_fence *active =
+		container_of(cb, typeof(*active), cb);
 
-	list_del_init(&active->link);
-	RCU_INIT_POINTER(active->request, NULL);
-
-	active->retire(active, request);
-
-	return 0;
+	RCU_INIT_POINTER(active->fence, NULL);
 }
 
 /*
@@ -358,34 +162,40 @@ i915_active_request_retire(struct i915_active_request *active,
  * synchronisation.
  */
 
-void __i915_active_init(struct drm_i915_private *i915,
-			struct i915_active *ref,
+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);
-#define i915_active_init(i915, ref, active, retire) do {		\
+#define i915_active_init(ref, active, retire) do {		\
 	static struct lock_class_key __key;				\
 									\
-	__i915_active_init(i915, ref, active, retire, &__key);		\
+	__i915_active_init(ref, active, retire, &__key);		\
 } while (0)
 
 int i915_active_ref(struct i915_active *ref,
 		    struct intel_timeline *tl,
-		    struct i915_request *rq);
+		    struct dma_fence *fence);
+
+static inline int
+i915_active_add_request(struct i915_active *ref, struct i915_request *rq)
+{
+	return i915_active_ref(ref, i915_request_timeline(rq), &rq->fence);
+}
+
+void i915_active_set_exclusive(struct i915_active *ref, struct dma_fence *f);
+
+static inline bool i915_active_has_exclusive(struct i915_active *ref)
+{
+	return rcu_access_pointer(ref->excl.fence);
+}
 
 int i915_active_wait(struct i915_active *ref);
 
-int i915_request_await_active(struct i915_request *rq,
-			      struct i915_active *ref);
-int i915_request_await_active_request(struct i915_request *rq,
-				      struct i915_active_request *active);
+int i915_request_await_active(struct i915_request *rq, struct i915_active *ref);
 
 int i915_active_acquire(struct i915_active *ref);
+bool i915_active_acquire_if_busy(struct i915_active *ref);
 void i915_active_release(struct i915_active *ref);
-void __i915_active_release_nested(struct i915_active *ref, int subclass);
-
-bool i915_active_trygrab(struct i915_active *ref);
-void i915_active_ungrab(struct i915_active *ref);
 
 static inline bool
 i915_active_is_idle(const struct i915_active *ref)
@@ -404,4 +214,6 @@ int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
 void i915_active_acquire_barrier(struct i915_active *ref);
 void i915_request_add_active_barriers(struct i915_request *rq);
 
+void i915_active_print(struct i915_active *ref, struct drm_printer *m);
+
 #endif /* _I915_ACTIVE_H_ */