[PATCH 3.16.y-ckt 082/180] drm/nouveau/kms: take mode_config mutex in connector hotplug path

[Luis Henriques]

3.16.7-ckt24 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Ben Skeggs <bskeggs at redhat.com>

commit 0a882cadbc63fd2da3994af7115b4ada2fcbd638 upstream.

fdo#93634

Signed-off-by: Ben Skeggs <bskeggs at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 1fa222e8f007..6b2057dbbcd6 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -954,10 +954,13 @@ nouveau_connector_hotplug_work(struct work_struct *work)
 
 		NV_DEBUG(drm, "%splugged %s\n", plugged ? "" : "un", name);
 
+		mutex_lock(&drm->dev->mode_config.mutex);
 		if (plugged)
 			drm_helper_connector_dpms(connector, DRM_MODE_DPMS_ON);
 		else
 			drm_helper_connector_dpms(connector, DRM_MODE_DPMS_OFF);
+		mutex_unlock(&drm->dev->mode_config.mutex);
+
 		drm_helper_hpd_irq_event(connector->dev);
 	}