Patch "drm/dp/mst: fixup handling hotplug on port removal." has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    drm/dp/mst: fixup handling hotplug on port removal.

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-dp-mst-fixup-handling-hotplug-on-port-removal.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From df4839fdc9b3c922586b945f062f38cbbda022bb Mon Sep 17 00:00:00 2001
From: Dave Airlie <airlied@redhat.com>
Date: Wed, 16 Sep 2015 10:37:28 +1000
Subject: drm/dp/mst: fixup handling hotplug on port removal.

From: Dave Airlie <airlied@redhat.com>

commit df4839fdc9b3c922586b945f062f38cbbda022bb upstream.

output ports should always have a connector, unless
in the rare case connector allocation fails in the
driver.

In this case we only need to teardown the pdt,
and free the struct, and there is no need to
send a hotplug msg.

In the case were we add the port to the destroy
list we need to send a hotplug if we destroy
any connectors, so userspace knows to reprobe
stuff.

this patch also handles port->connector allocation
failing which should be a rare event, but makes
the code consistent.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/drm_dp_mst_topology.c |   36 ++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -863,29 +863,33 @@ static void drm_dp_destroy_port(struct k
 {
 	struct drm_dp_mst_port *port = container_of(kref, struct drm_dp_mst_port, kref);
 	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
+
 	if (!port->input) {
 		port->vcpi.num_slots = 0;
 
 		kfree(port->cached_edid);
 
-		/* we can't destroy the connector here, as
-		   we might be holding the mode_config.mutex
-		   from an EDID retrieval */
+		/*
+		 * 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 */
+
 			mutex_lock(&mgr->destroy_connector_lock);
 			list_add(&port->next, &mgr->destroy_connector_list);
 			mutex_unlock(&mgr->destroy_connector_lock);
 			schedule_work(&mgr->destroy_connector_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);
-
-		if (!port->input && port->vcpi.vcpi > 0)
-			drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
 	}
 	kfree(port);
-
-	(*mgr->cbs->hotplug)(mgr);
 }
 
 static void drm_dp_put_port(struct drm_dp_mst_port *port)
@@ -1115,12 +1119,21 @@ static void drm_dp_add_port(struct drm_d
 		char proppath[255];
 		build_mst_prop_path(port, mstb, proppath, sizeof(proppath));
 		port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr, port, proppath);
-
+		if (!port->connector) {
+			/* remove it from the port list */
+			mutex_lock(&mstb->mgr->lock);
+			list_del(&port->next);
+			mutex_unlock(&mstb->mgr->lock);
+			/* drop port list reference */
+			drm_dp_put_port(port);
+			goto out;
+		}
 		if (port->port_num >= 8) {
 			port->cached_edid = drm_get_edid(port->connector, &port->aux.ddc);
 		}
 	}
 
+out:
 	/* put reference to this port */
 	drm_dp_put_port(port);
 }
@@ -2661,7 +2674,7 @@ static void drm_dp_destroy_connector_wor
 {
 	struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, destroy_connector_work);
 	struct drm_dp_mst_port *port;
-
+	bool send_hotplug = false;
 	/*
 	 * Not a regular list traverse as we have to drop the destroy
 	 * connector lock before destroying the connector, to avoid AB->BA
@@ -2684,7 +2697,10 @@ static void drm_dp_destroy_connector_wor
 		if (!port->input && port->vcpi.vcpi > 0)
 			drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
 		kfree(port);
+		send_hotplug = true;
 	}
+	if (send_hotplug)
+		(*mgr->cbs->hotplug)(mgr);
 }
 
 /**


Patches currently in stable-queue which might be from airlied@redhat.com are

queue-4.2/drm-qxl-only-report-first-monitor-as-connected-if-we-have-no-state.patch
queue-4.2/drm-qxl-recreate-the-primary-surface-when-the-bo-is-not-primary.patch
queue-4.2/drm-dp-mst-fixup-handling-hotplug-on-port-removal.patch
queue-4.2/drm-dp-mst-drop-cancel-work-sync-in-the-mstb-destroy-path-v2.patch