From 5c507167d2ef467ecd2ec4ad40a0bd70b4fad814 Mon Sep 17 00:00:00 2001 From: Dave Airlie Date: Mon, 15 Jun 2015 10:34:28 +1000 Subject: drm/dp/mst: close deadlock in connector destruction. commit 6b8eeca65b18ae77e175cc2b6571731f0ee413bf upstream. I've only seen this once, and I failed to capture the lockdep backtrace, but I did some investigations. If we are calling into the MST layer from EDID probing, we have the mode_config mutex held, if during that EDID probing, the MST hub goes away, then we can get a deadlock where the connector destruction function in the driver tries to retake the mode config mutex. This offloads connector destruction to a workqueue, and avoid the subsequenct lock ordering issue. Acked-by: Daniel Vetter Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- include/drm/drm_crtc.h | 2 ++ include/drm/drm_dp_mst_helper.h | 4 ++++ 2 files changed, 6 insertions(+) (limited to 'include') diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index ca71c03143d1..54233583c6cb 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -731,6 +731,8 @@ struct drm_connector { uint8_t num_h_tile, num_v_tile; uint8_t tile_h_loc, tile_v_loc; uint16_t tile_h_size, tile_v_size; + + struct list_head destroy_list; }; /** diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h index a2507817be41..86d0b25ed054 100644 --- a/include/drm/drm_dp_mst_helper.h +++ b/include/drm/drm_dp_mst_helper.h @@ -463,6 +463,10 @@ struct drm_dp_mst_topology_mgr { struct work_struct work; struct work_struct tx_work; + + struct list_head destroy_connector_list; + struct mutex destroy_connector_lock; + struct work_struct destroy_connector_work; }; int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr, struct device *dev, struct drm_dp_aux *aux, int max_dpcd_transaction_bytes, int max_payloads, int conn_base_id); -- cgit v1.2.3