From: Dave Airlie Date: Mon, 22 Jun 2015 04:40:44 +0000 (+1000) Subject: drm/dp/mst: take lock around looking up the branch device on hpd irq X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=9eb1e57f564d4e6e10991402726cc83fe0b9172f;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git 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 Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie --- diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 1c9670665281..f7213497ad6c 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; }