drm/i915: Add gem object locking to madvise.

Doesn't need the full ww lock, only checking if pages are bound.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> #irc
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-7-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/i915/i915_gem.c

@@ -963,10 +963,14 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
 	if (!obj)
 		return -ENOENT;
 
-	err = mutex_lock_interruptible(&obj->mm.lock);
+	err = i915_gem_object_lock_interruptible(obj, NULL);
 	if (err)
 		goto out;
 
+	err = mutex_lock_interruptible(&obj->mm.lock);
+	if (err)
+		goto out_ww;
+
 	if (i915_gem_object_has_pages(obj) &&
 	    i915_gem_object_is_tiled(obj) &&
 	    i915->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
@@ -1011,6 +1015,8 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
 	args->retained = obj->mm.madv != __I915_MADV_PURGED;
 	mutex_unlock(&obj->mm.lock);
 
+out_ww:
+	i915_gem_object_unlock(obj);
 out:
 	i915_gem_object_put(obj);
 	return err;