[PATCH] drm: Fixup locking WARNINGs in drm_mode_config_reset

[Daniel Vetter]

With

commit 7a3f3d6667f5f9ffd1517f6b21d64bbf5312042c
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Thu Jul 9 23:44:28 2015 +0200

    drm: Check locking in drm_for_each_connector

we started checking the locking in drm_for_each_connector but somehow
I totally missed drm_mode_config_reset. There's no problem there since
this function should only be called in single-threaded contexts
(driver load or resume), so just wrap the loop with the right lock.

v2: Drink coffee and all that ...

Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Reported-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 drivers/gpu/drm/drm_crtc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index c91c18b2b1d4..10c1a0f6680c 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -5273,9 +5273,11 @@ void drm_mode_config_reset(struct drm_device *dev)
 		if (encoder->funcs->reset)
 			encoder->funcs->reset(encoder);
 
+	mutex_lock(&dev->mode_config.mutex);
 	drm_for_each_connector(connector, dev)
 		if (connector->funcs->reset)
 			connector->funcs->reset(connector);
+	mutex_unlock(&dev->mode_config.mutex);
 }
 EXPORT_SYMBOL(drm_mode_config_reset);
 
-- 
2.1.4