drm/i915: Take obj lock around set_domain ioctl

We need to lock the object to move it to the correct domain,
add the missing lock.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
[danvet: Pick version from an older patch series.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210128162612.927917-29-maarten.lankhorst@linux.intel.com
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-29-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/i915/gem/i915_gem_domain.c

@@ -541,6 +541,10 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
 		goto out;
 	}
 
+	err = i915_gem_object_lock_interruptible(obj, NULL);
+	if (err)
+		goto out;
+
 	/*
 	 * Flush and acquire obj->pages so that we are coherent through
 	 * direct access in memory with previous cached writes through
@@ -552,7 +556,7 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
 	 */
 	err = i915_gem_object_pin_pages(obj);
 	if (err)
-		goto out;
+		goto out_unlock;
 
 	/*
 	 * Already in the desired write domain? Nothing for us to do!
@@ -567,10 +571,6 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
 	if (READ_ONCE(obj->write_domain) == read_domains)
 		goto out_unpin;
 
-	err = i915_gem_object_lock_interruptible(obj, NULL);
-	if (err)
-		goto out_unpin;
-
 	if (read_domains & I915_GEM_DOMAIN_WC)
 		err = i915_gem_object_set_to_wc_domain(obj, write_domain);
 	else if (read_domains & I915_GEM_DOMAIN_GTT)
@@ -578,13 +578,15 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
 	else
 		err = i915_gem_object_set_to_cpu_domain(obj, write_domain);
 
+out_unpin:
+	i915_gem_object_unpin_pages(obj);
+
+out_unlock:
 	i915_gem_object_unlock(obj);
 
-	if (write_domain)
+	if (!err && write_domain)
 		i915_gem_object_invalidate_frontbuffer(obj, ORIGIN_CPU);
 
-out_unpin:
-	i915_gem_object_unpin_pages(obj);
 out:
 	i915_gem_object_put(obj);
 	return err;