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drm/dp/mst: close deadlock in connector destruction.

Browse source 
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 <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Dave Airlie 2015-06-15 10:34:28 +10:00
commit 6b8eeca65b
3 changed files with 44 additions and 2 deletions
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2
include/drm/drm_crtc.h
View file

@ -743,6 +743,8 @@ 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;
};
/**

4
include/drm/drm_dp_mst_helper.h
View file

@ -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);