drm/i915: Mark up all locked waiters

In the next patch we want to handle reset directly by a locked waiter in
order to avoid issues with returning before the reset is handled. To
handle the reset, we must first know whether we hold the struct_mutex.
If we do not hold the struct_mtuex we can not perform the reset, but we do
not block the reset worker either (and so we can just continue to wait for
request completion) - otherwise we must relinquish the mutex.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160909131201.16673-10-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_debugfs.c

@@ -4794,7 +4794,9 @@ i915_drop_caches_set(void *data, u64 val)
 		return ret;
 
 	if (val & DROP_ACTIVE) {
-		ret = i915_gem_wait_for_idle(dev_priv, I915_WAIT_INTERRUPTIBLE);
+		ret = i915_gem_wait_for_idle(dev_priv,
+					     I915_WAIT_INTERRUPTIBLE |
+					     I915_WAIT_LOCKED);
 		if (ret)
 			goto unlock;
 	}

drivers/gpu/drm/i915/i915_gem.c

@@ -2802,7 +2802,8 @@ __i915_gem_object_sync(struct drm_i915_gem_request *to,
 
 	if (!i915.semaphores) {
 		ret = i915_wait_request(from,
-					from->i915->mm.interruptible,
+					from->i915->mm.interruptible |
+					I915_WAIT_LOCKED,
 					NULL,
 					NO_WAITBOOST);
 		if (ret)
@@ -4304,7 +4305,9 @@ int i915_gem_suspend(struct drm_device *dev)
 	if (ret)
 		goto err;
 
-	ret = i915_gem_wait_for_idle(dev_priv, I915_WAIT_INTERRUPTIBLE);
+	ret = i915_gem_wait_for_idle(dev_priv,
+				     I915_WAIT_INTERRUPTIBLE |
+				     I915_WAIT_LOCKED);
 	if (ret)
 		goto err;
 

drivers/gpu/drm/i915/i915_gem_evict.c

@@ -170,7 +170,9 @@ i915_gem_evict_something(struct i915_address_space *vm,
 	if (ret)
 		return ret;
 
-	ret = i915_gem_wait_for_idle(dev_priv, I915_WAIT_INTERRUPTIBLE);
+	ret = i915_gem_wait_for_idle(dev_priv,
+				     I915_WAIT_INTERRUPTIBLE |
+				     I915_WAIT_LOCKED);
 	if (ret)
 		return ret;
 
@@ -275,7 +277,9 @@ int i915_gem_evict_vm(struct i915_address_space *vm, bool do_idle)
 				return ret;
 		}
 
-		ret = i915_gem_wait_for_idle(dev_priv, I915_WAIT_INTERRUPTIBLE);
+		ret = i915_gem_wait_for_idle(dev_priv,
+					     I915_WAIT_INTERRUPTIBLE |
+					     I915_WAIT_LOCKED);
 		if (ret)
 			return ret;
 

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -2683,7 +2683,7 @@ void i915_gem_gtt_finish_object(struct drm_i915_gem_object *obj)
 	struct i915_ggtt *ggtt = &dev_priv->ggtt;
 
 	if (unlikely(ggtt->do_idle_maps)) {
-		if (i915_gem_wait_for_idle(dev_priv, 0)) {
+		if (i915_gem_wait_for_idle(dev_priv, I915_WAIT_LOCKED)) {
 			DRM_ERROR("Failed to wait for idle; VT'd may hang.\n");
 			/* Wait a bit, in hopes it avoids the hang */
 			udelay(10);

drivers/gpu/drm/i915/i915_gem_request.c

@@ -260,7 +260,9 @@ static int i915_gem_init_seqno(struct drm_i915_private *dev_priv, u32 seqno)
 
 	/* Carefully retire all requests without writing to the rings */
 	for_each_engine(engine, dev_priv) {
-		ret = intel_engine_idle(engine, I915_WAIT_INTERRUPTIBLE);
+		ret = intel_engine_idle(engine,
+					I915_WAIT_INTERRUPTIBLE |
+					I915_WAIT_LOCKED);
 		if (ret)
 			return ret;
 	}
@@ -625,6 +627,10 @@ int i915_wait_request(struct drm_i915_gem_request *req,
 	int ret = 0;
 
 	might_sleep();
+#if IS_ENABLED(CONFIG_LOCKDEP)
+	GEM_BUG_ON(!!lockdep_is_held(&req->i915->drm.struct_mutex) !=
+		   !!(flags & I915_WAIT_LOCKED));
+#endif
 
 	if (i915_gem_request_completed(req))
 		return 0;
@@ -667,6 +673,7 @@ int i915_wait_request(struct drm_i915_gem_request *req,
 		goto complete;
 
 	set_current_state(state);
+	if (flags & I915_WAIT_LOCKED)
 		add_wait_queue(&req->i915->gpu_error.wait_queue, &reset);
 
 	intel_wait_init(&wait, req->fence.seqno);
@@ -707,10 +714,12 @@ int i915_wait_request(struct drm_i915_gem_request *req,
 		if (i915_spin_request(req, state, 2))
 			break;
 	}
-	remove_wait_queue(&req->i915->gpu_error.wait_queue, &reset);
 
 	intel_engine_remove_wait(req->engine, &wait);
+	if (flags & I915_WAIT_LOCKED)
+		remove_wait_queue(&req->i915->gpu_error.wait_queue, &reset);
 	__set_current_state(TASK_RUNNING);
+
 complete:
 	trace_i915_gem_request_wait_end(req);
 

drivers/gpu/drm/i915/i915_gem_request.h

@@ -223,6 +223,7 @@ int i915_wait_request(struct drm_i915_gem_request *req,
 		      struct intel_rps_client *rps)
 	__attribute__((nonnull(1)));
 #define I915_WAIT_INTERRUPTIBLE	BIT(0)
+#define I915_WAIT_LOCKED	BIT(1) /* struct_mutex held, handle GPU reset */
 
 static inline u32 intel_engine_get_seqno(struct intel_engine_cs *engine);
 
@@ -576,7 +577,9 @@ i915_gem_active_wait(const struct i915_gem_active *active, struct mutex *mutex)
 	if (!request)
 		return 0;
 
-	return i915_wait_request(request, I915_WAIT_INTERRUPTIBLE, NULL, NULL);
+	return i915_wait_request(request,
+				 I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED,
+				 NULL, NULL);
 }
 
 /**
@@ -639,7 +642,9 @@ i915_gem_active_retire(struct i915_gem_active *active,
 	if (!request)
 		return 0;
 
-	ret = i915_wait_request(request, I915_WAIT_INTERRUPTIBLE, NULL, NULL);
+	ret = i915_wait_request(request,
+				I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED,
+				NULL, NULL);
 	if (ret)
 		return ret;
 

drivers/gpu/drm/i915/i915_gem_shrinker.c

@@ -414,7 +414,7 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
 		return NOTIFY_DONE;
 
 	/* Force everything onto the inactive lists */
-	ret = i915_gem_wait_for_idle(dev_priv, 0);
+	ret = i915_gem_wait_for_idle(dev_priv, I915_WAIT_LOCKED);
 	if (ret)
 		goto out;
 

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -2223,7 +2223,8 @@ static int wait_for_space(struct drm_i915_gem_request *req, int bytes)
 	if (WARN_ON(&target->ring_link == &ring->request_list))
 		return -ENOSPC;
 
-	ret = i915_wait_request(target, I915_WAIT_INTERRUPTIBLE,
+	ret = i915_wait_request(target,
+				I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED,
 				NULL, NO_WAITBOOST);
 	if (ret)
 		return ret;