net: qrtr: Release distant nodes along the bridge node

Distant QRTR nodes can be accessed via an other node that acts as
a bridge. When the a QRTR endpoint associated to a bridge node is
released, all the linked distant nodes should also be released.

This patch fixes endpoint release by:
- Submitting QRTR BYE message locally on behalf of all the nodes
accessible through the endpoint.
- Removing all the routable node IDs from radix tree pointing to
the released node endpoint.
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/qrtr/qrtr.c

@@ -171,8 +171,13 @@ static void __qrtr_node_release(struct kref *kref)
 	void __rcu **slot;
 
 	spin_lock_irqsave(&qrtr_nodes_lock, flags);
-	if (node->nid != QRTR_EP_NID_AUTO)
-		radix_tree_delete(&qrtr_nodes, node->nid);
+	/* If the node is a bridge for other nodes, there are possibly
+	 * multiple entries pointing to our released node, delete them all.
+	 */
+	radix_tree_for_each_slot(slot, &qrtr_nodes, &iter, 0) {
+		if (*slot == node)
+			radix_tree_iter_delete(&qrtr_nodes, &iter, slot);
+	}
 	spin_unlock_irqrestore(&qrtr_nodes_lock, flags);
 
 	list_del(&node->item);
@@ -602,6 +607,7 @@ void qrtr_endpoint_unregister(struct qrtr_endpoint *ep)
 	struct qrtr_ctrl_pkt *pkt;
 	struct qrtr_tx_flow *flow;
 	struct sk_buff *skb;
+	unsigned long flags;
 	void __rcu **slot;
 
 	mutex_lock(&node->ep_lock);
@@ -609,11 +615,18 @@ void qrtr_endpoint_unregister(struct qrtr_endpoint *ep)
 	mutex_unlock(&node->ep_lock);
 
 	/* Notify the local controller about the event */
-	skb = qrtr_alloc_ctrl_packet(&pkt, GFP_KERNEL);
+	spin_lock_irqsave(&qrtr_nodes_lock, flags);
+	radix_tree_for_each_slot(slot, &qrtr_nodes, &iter, 0) {
+		if (*slot != node)
+			continue;
+		src.sq_node = iter.index;
+		skb = qrtr_alloc_ctrl_packet(&pkt, GFP_ATOMIC);
 		if (skb) {
 			pkt->cmd = cpu_to_le32(QRTR_TYPE_BYE);
 			qrtr_local_enqueue(NULL, skb, QRTR_TYPE_BYE, &src, &dst);
 		}
+	}
+	spin_unlock_irqrestore(&qrtr_nodes_lock, flags);
 
 	/* Wake up any transmitters waiting for resume-tx from the node */
 	mutex_lock(&node->qrtr_tx_lock);