[PATCH v5 02/14] drm/dp_mst: Remove PDT teardown in drm_dp_destroy_port() and refactor

Lyude Paul
2019-10-22T02:35:57Z

This will allow us to add some locking for port->* members, in
particular the PDT and ->connector, which can't be done from
drm_dp_destroy_port() since we don't know what locks the caller might be
holding.

Note that we already do this in delayed_destroy_work (renamed from
destroy_connector_work in this patch) for ports, we're just making it so
mstbs are also destroyed in this worker.

Changes since v2:
* Clarify commit message
Changes since v4:
* Clarify commit message more

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sean Paul <sean@poorly.run>
Signed-off-by: Lyude Paul <lyude@redhat.com>
---
drivers/gpu/drm/drm_dp_mst_topology.c | 40 +++++++++++----------------
1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 66ff226d8c86..204d0c832c65 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1510,31 +1510,22 @@ static void drm_dp_destroy_port(struct kref *kref)
container_of(kref, struct drm_dp_mst_port, topology_kref);
struct drm_dp_mst_topology_mgr *mgr = port->mgr;

- if (!port->input) {
- kfree(port->cached_edid);
+ /* There's nothing that needs locking to destroy an input port yet */
+ if (port->input) {
+ drm_dp_mst_put_port_malloc(port);
+ return;
+ }

- /*
- * The only time we don't have a connector
- * on an output port is if the connector init
- * fails.
- */
- if (port->connector) {
- /* we can't destroy the connector here, as
- * we might be holding the mode_config.mutex
- * from an EDID retrieval */
+ kfree(port->cached_edid);

- mutex_lock(&mgr->delayed_destroy_lock);
- list_add(&port->next, &mgr->destroy_port_list);
- mutex_unlock(&mgr->delayed_destroy_lock);
- schedule_work(&mgr->delayed_destroy_work);
- return;
- }
- /* no need to clean up vcpi
- * as if we have no connector we never setup a vcpi */
- drm_dp_port_teardown_pdt(port, port->pdt);
- port->pdt = DP_PEER_DEVICE_NONE;
- }
- drm_dp_mst_put_port_malloc(port);
+ /*
+ * we can't destroy the connector here, as we might be holding the
+ * mode_config.mutex from an EDID retrieval
+ */
+ mutex_lock(&mgr->delayed_destroy_lock);
+ list_add(&port->next, &mgr->destroy_port_list);
+ mutex_unlock(&mgr->delayed_destroy_lock);
+ schedule_work(&mgr->delayed_destroy_work);
}

/**
@@ -3981,7 +3972,8 @@ static void drm_dp_tx_work(struct work_struct *work)
static inline void
drm_dp_delayed_destroy_port(struct drm_dp_mst_port *port)
{
- port->mgr->cbs->destroy_connector(port->mgr, port->connector);
+ if (port->connector)
+ port->mgr->cbs->destroy_connector(port->mgr, port->connector);

drm_dp_port_teardown_pdt(port, port->pdt);
port->pdt = DP_PEER_DEVICE_NONE;
--
2.21.0