From: Adam Richter <adamrichter4@gmail.com>
Date: Fri, 16 Oct 2015 10:33:02 +0000 (-0700)
Subject: drm: fix mutex leak in drm_dp_get_mst_branch_device
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=6749c9f023d49adca3ca4773e93282b95ceebfb5;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

drm: fix mutex leak in drm_dp_get_mst_branch_device

In Linux 4.3-rc5, there is an error case in drm_dp_get_branch_device
that returns without releasing mgr->lock, resulting a spew of kernel
messages about a kernel work function possibly having leaked a mutex
and presumably more serious adverse consequences later.  This patch
changes the error to "goto out" to unlock the mutex before returning.

Signed-off-by: Adam J. Richter <adam_richter2004@yahoo.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index e23df5fd3836..e4c9b4a68c04 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1182,17 +1182,18 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
 
 		list_for_each_entry(port, &mstb->ports, next) {
 			if (port->port_num == port_num) {
-				if (!port->mstb) {
+				mstb = port->mstb;
+				if (!mstb) {
 					DRM_ERROR("failed to lookup MSTB with lct %d, rad %02x\n", lct, rad[0]);
-					return NULL;
+					goto out;
 				}
 
-				mstb = port->mstb;
 				break;
 			}
 		}
 	}
 	kref_get(&mstb->kref);
+out:
 	mutex_unlock(&mgr->lock);
 	return mstb;
 }