drm/i915: Add ww locking to dma-buf ops, v2.

vmap is using pin_pages, but needs to use ww locking,
add pin_pages_unlocked to correctly lock the mapping.

Also add ww locking to begin/end cpu access.

Changes since v1:
- Fix i915_gem_map_dma_buf by using pin_pages_unlocked().
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-38-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c

@@ -25,7 +25,7 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme
 	struct scatterlist *src, *dst;
 	int ret, i;
 
-	ret = i915_gem_object_pin_pages(obj);
+	ret = i915_gem_object_pin_pages_unlocked(obj);
 	if (ret)
 		goto err;
 
@@ -82,7 +82,7 @@ static int i915_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct dma_buf_map *map
 	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
 	void *vaddr;
 
-	vaddr = i915_gem_object_pin_map(obj, I915_MAP_WB);
+	vaddr = i915_gem_object_pin_map_unlocked(obj, I915_MAP_WB);
 	if (IS_ERR(vaddr))
 		return PTR_ERR(vaddr);
 
@@ -123,42 +123,48 @@ static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_dire
 {
 	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
 	bool write = (direction == DMA_BIDIRECTIONAL || direction == DMA_TO_DEVICE);
+	struct i915_gem_ww_ctx ww;
 	int err;
 
-	err = i915_gem_object_pin_pages(obj);
-	if (err)
-		return err;
-
-	err = i915_gem_object_lock_interruptible(obj, NULL);
-	if (err)
-		goto out;
-
-	err = i915_gem_object_set_to_cpu_domain(obj, write);
-	i915_gem_object_unlock(obj);
-
-out:
-	i915_gem_object_unpin_pages(obj);
+	i915_gem_ww_ctx_init(&ww, true);
+retry:
+	err = i915_gem_object_lock(obj, &ww);
+	if (!err)
+		err = i915_gem_object_pin_pages(obj);
+	if (!err) {
+		err = i915_gem_object_set_to_cpu_domain(obj, write);
+		i915_gem_object_unpin_pages(obj);
+	}
+	if (err == -EDEADLK) {
+		err = i915_gem_ww_ctx_backoff(&ww);
+		if (!err)
+			goto retry;
+	}
+	i915_gem_ww_ctx_fini(&ww);
 	return err;
 }
 
 static int i915_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
 {
 	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
+	struct i915_gem_ww_ctx ww;
 	int err;
 
-	err = i915_gem_object_pin_pages(obj);
-	if (err)
-		return err;
-
-	err = i915_gem_object_lock_interruptible(obj, NULL);
-	if (err)
-		goto out;
-
-	err = i915_gem_object_set_to_gtt_domain(obj, false);
-	i915_gem_object_unlock(obj);
-
-out:
-	i915_gem_object_unpin_pages(obj);
+	i915_gem_ww_ctx_init(&ww, true);
+retry:
+	err = i915_gem_object_lock(obj, &ww);
+	if (!err)
+		err = i915_gem_object_pin_pages(obj);
+	if (!err) {
+		err = i915_gem_object_set_to_gtt_domain(obj, false);
+		i915_gem_object_unpin_pages(obj);
+	}
+	if (err == -EDEADLK) {
+		err = i915_gem_ww_ctx_backoff(&ww);
+		if (!err)
+			goto retry;
+	}
+	i915_gem_ww_ctx_fini(&ww);
 	return err;
 }