drm/i915: Use vma->exec_entry as our double-entry placeholder

This has the benefit of not requiring us to manipulate the
vma->exec_link list when tearing down the execbuffer, and is a
marginally cheaper test to detect the user error.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170615081435.17699-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_evict.c

@@ -59,9 +59,6 @@ mark_free(struct drm_mm_scan *scan,
 	if (i915_vma_is_pinned(vma))
 		return false;
 
-	if (WARN_ON(!list_empty(&vma->exec_list)))
-		return false;
-
 	if (flags & PIN_NONFAULT && !list_empty(&vma->obj->userfault_link))
 		return false;
 
@@ -160,8 +157,6 @@ i915_gem_evict_something(struct i915_address_space *vm,
 	list_for_each_entry_safe(vma, next, &eviction_list, exec_list) {
 		ret = drm_mm_scan_remove_block(&scan, &vma->node);
 		BUG_ON(ret);
-
-		INIT_LIST_HEAD(&vma->exec_list);
 	}
 
 	/* Can we unpin some objects such as idle hw contents,
@@ -209,17 +204,12 @@ i915_gem_evict_something(struct i915_address_space *vm,
 		if (drm_mm_scan_remove_block(&scan, &vma->node))
 			__i915_vma_pin(vma);
 		else
-			list_del_init(&vma->exec_list);
+			list_del(&vma->exec_list);
 	}
 
 	/* Unbinding will emit any required flushes */
 	ret = 0;
-	while (!list_empty(&eviction_list)) {
-		vma = list_first_entry(&eviction_list,
-				       struct i915_vma,
-				       exec_list);
-
-		list_del_init(&vma->exec_list);
+	list_for_each_entry_safe(vma, next, &eviction_list, exec_list) {
 		__i915_vma_unpin(vma);
 		if (ret == 0)
 			ret = i915_vma_unbind(vma);
@@ -315,7 +305,7 @@ int i915_gem_evict_for_node(struct i915_address_space *vm,
 		}
 
 		/* Overlap of objects in the same batch? */
-		if (i915_vma_is_pinned(vma) || !list_empty(&vma->exec_list)) {
+		if (i915_vma_is_pinned(vma)) {
 			ret = -ENOSPC;
 			if (vma->exec_entry &&
 			    vma->exec_entry->flags & EXEC_OBJECT_PINNED)
@@ -336,7 +326,6 @@ int i915_gem_evict_for_node(struct i915_address_space *vm,
 	}
 
 	list_for_each_entry_safe(vma, next, &eviction_list, exec_list) {
-		list_del_init(&vma->exec_list);
 		__i915_vma_unpin(vma);
 		if (ret == 0)
 			ret = i915_vma_unbind(vma);

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -108,13 +108,40 @@ static int eb_create(struct i915_execbuffer *eb)
 		eb->and = -eb->args->buffer_count;
 	}
 
-	INIT_LIST_HEAD(&eb->vmas);
 	return 0;
 }
 
+static inline void
+__eb_unreserve_vma(struct i915_vma *vma,
+		   const struct drm_i915_gem_exec_object2 *entry)
+{
+	if (unlikely(entry->flags & __EXEC_OBJECT_HAS_FENCE))
+		i915_vma_unpin_fence(vma);
+
+	if (entry->flags & __EXEC_OBJECT_HAS_PIN)
+		__i915_vma_unpin(vma);
+}
+
+static void
+eb_unreserve_vma(struct i915_vma *vma)
+{
+	struct drm_i915_gem_exec_object2 *entry = vma->exec_entry;
+
+	__eb_unreserve_vma(vma, entry);
+	entry->flags &= ~(__EXEC_OBJECT_HAS_FENCE | __EXEC_OBJECT_HAS_PIN);
+}
+
 static void
 eb_reset(struct i915_execbuffer *eb)
 {
+	struct i915_vma *vma;
+
+	list_for_each_entry(vma, &eb->vmas, exec_list) {
+		eb_unreserve_vma(vma);
+		i915_vma_put(vma);
+		vma->exec_entry = NULL;
+	}
+
 	if (eb->and >= 0)
 		memset(eb->buckets, 0, (eb->and+1)*sizeof(struct hlist_head));
 }
@@ -146,6 +173,8 @@ eb_lookup_vmas(struct i915_execbuffer *eb)
 	struct list_head objects;
 	int i, ret;
 
+	INIT_LIST_HEAD(&eb->vmas);
+
 	INIT_LIST_HEAD(&objects);
 	spin_lock(&eb->file->table_lock);
 	/* Grab a reference to the object and release the lock so we can lookup
@@ -252,40 +281,23 @@ static struct i915_vma *eb_get_vma(struct i915_execbuffer *eb, unsigned long han
 	}
 }
 
-static void
-eb_unreserve_vma(struct i915_vma *vma)
-{
-	struct drm_i915_gem_exec_object2 *entry;
-
-	if (!drm_mm_node_allocated(&vma->node))
-		return;
-
-	entry = vma->exec_entry;
-
-	if (entry->flags & __EXEC_OBJECT_HAS_FENCE)
-		i915_vma_unpin_fence(vma);
-
-	if (entry->flags & __EXEC_OBJECT_HAS_PIN)
-		__i915_vma_unpin(vma);
-
-	entry->flags &= ~(__EXEC_OBJECT_HAS_FENCE | __EXEC_OBJECT_HAS_PIN);
-}
-
 static void eb_destroy(struct i915_execbuffer *eb)
 {
-	i915_gem_context_put(eb->ctx);
-
-	while (!list_empty(&eb->vmas)) {
 	struct i915_vma *vma;
 
-		vma = list_first_entry(&eb->vmas,
-				       struct i915_vma,
-				       exec_list);
-		list_del_init(&vma->exec_list);
-		eb_unreserve_vma(vma);
+	list_for_each_entry(vma, &eb->vmas, exec_list) {
+		if (!vma->exec_entry)
+			continue;
+
+		__eb_unreserve_vma(vma, vma->exec_entry);
 		vma->exec_entry = NULL;
 		i915_vma_put(vma);
 	}
+
+	i915_gem_context_put(eb->ctx);
+
+	if (eb->buckets)
+		kfree(eb->buckets);
 }
 
 static inline int use_cpu_reloc(struct drm_i915_gem_object *obj)
@@ -985,13 +997,7 @@ eb_relocate_slow(struct i915_execbuffer *eb)
 	int i, total, ret;
 
 	/* We may process another execbuffer during the unlock... */
-	while (!list_empty(&eb->vmas)) {
-		vma = list_first_entry(&eb->vmas, struct i915_vma, exec_list);
-		list_del_init(&vma->exec_list);
-		eb_unreserve_vma(vma);
-		i915_vma_put(vma);
-	}
-
+	eb_reset(eb);
 	mutex_unlock(&dev->struct_mutex);
 
 	total = 0;
@@ -1052,7 +1058,6 @@ eb_relocate_slow(struct i915_execbuffer *eb)
 	}
 
 	/* reacquire the objects */
-	eb_reset(eb);
 	ret = eb_lookup_vmas(eb);
 	if (ret)
 		goto err;

drivers/gpu/drm/i915/i915_vma.c

@@ -85,7 +85,6 @@ vma_create(struct drm_i915_gem_object *obj,
 	if (vma == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	INIT_LIST_HEAD(&vma->exec_list);
 	for (i = 0; i < ARRAY_SIZE(vma->last_read); i++)
 		init_request_active(&vma->last_read[i], i915_vma_retire);
 	init_request_active(&vma->last_fence, NULL);