From 9eb1e57f564d4e6e10991402726cc83fe0b9172f Mon Sep 17 00:00:00 2001
From: Dave Airlie <airlied@redhat.com>
Date: Mon, 22 Jun 2015 14:40:44 +1000
Subject: [PATCH] drm/dp/mst: take lock around looking up the branch device on
hpd irq
If we are doing an MST transaction and we've gotten HPD and we
lookup the device from the incoming msg, we should take the mgr
lock around it, so that mst_primary and mstb->ports are valid.
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
---
drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 1c967066528138..f7213497ad6c40 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1163,6 +1163,8 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
struct drm_dp_mst_port *port;
int i;
/* find the port by iterating down */
+
+ mutex_lock(&mgr->lock);
mstb = mgr->mst_primary;
for (i = 0; i < lct - 1; i++) {
@@ -1182,6 +1184,7 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
}
}
kref_get(&mstb->kref);
+ mutex_unlock(&mgr->lock);
return mstb;
}
--
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