1 files changed, 64 insertions, 39 deletions

diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index b1c71bad510b..72a6e12a9304 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c
@@ -79,6 +79,7 @@ static struct rxrpc_local *rxrpc_alloc_local(struct rxrpc_net *rxnet,
 	local = kzalloc(sizeof(struct rxrpc_local), GFP_KERNEL);
 	if (local) {
 		atomic_set(&local->usage, 1);
+		atomic_set(&local->active_users, 1);
 		local->rxnet = rxnet;
 		INIT_LIST_HEAD(&local->link);
 		INIT_WORK(&local->processor, rxrpc_local_processor);
@@ -92,7 +93,7 @@ static struct rxrpc_local *rxrpc_alloc_local(struct rxrpc_net *rxnet,
 		local->debug_id = atomic_inc_return(&rxrpc_debug_id);
 		memcpy(&local->srx, srx, sizeof(*srx));
 		local->srx.srx_service = 0;
-		trace_rxrpc_local(local, rxrpc_local_new, 1, NULL);
+		trace_rxrpc_local(local->debug_id, rxrpc_local_new, 1, NULL);
 	}
 
 	_leave(" = %p", local);
@@ -266,11 +267,8 @@ struct rxrpc_local *rxrpc_lookup_local(struct net *net,
 		 * bind the transport socket may still fail if we're attempting
 		 * to use a local address that the dying object is still using.
 		 */
-		if (!rxrpc_get_local_maybe(local)) {
-			cursor = cursor->next;
-			list_del_init(&local->link);
+		if (!rxrpc_use_local(local))
 			break;
-		}
 
 		age = "old";
 		goto found;
@@ -284,7 +282,10 @@ struct rxrpc_local *rxrpc_lookup_local(struct net *net,
 	if (ret < 0)
 		goto sock_error;
 
-	list_add_tail(&local->link, cursor);
+	if (cursor != &rxnet->local_endpoints)
+		list_replace_init(cursor, &local->link);
+	else
+		list_add_tail(&local->link, cursor);
 	age = "new";
 
 found:
@@ -320,7 +321,7 @@ struct rxrpc_local *rxrpc_get_local(struct rxrpc_local *local)
 	int n;
 
 	n = atomic_inc_return(&local->usage);
-	trace_rxrpc_local(local, rxrpc_local_got, n, here);
+	trace_rxrpc_local(local->debug_id, rxrpc_local_got, n, here);
 	return local;
 }
 
@@ -334,7 +335,8 @@ struct rxrpc_local *rxrpc_get_local_maybe(struct rxrpc_local *local)
 	if (local) {
 		int n = atomic_fetch_add_unless(&local->usage, 1, 0);
 		if (n > 0)
-			trace_rxrpc_local(local, rxrpc_local_got, n + 1, here);
+			trace_rxrpc_local(local->debug_id, rxrpc_local_got,
+					  n + 1, here);
 		else
 			local = NULL;
 	}
@@ -342,24 +344,18 @@ struct rxrpc_local *rxrpc_get_local_maybe(struct rxrpc_local *local)
 }
 
 /*
- * Queue a local endpoint.
+ * Queue a local endpoint and pass the caller's reference to the work item.
  */
 void rxrpc_queue_local(struct rxrpc_local *local)
 {
 	const void *here = __builtin_return_address(0);
+	unsigned int debug_id = local->debug_id;
+	int n = atomic_read(&local->usage);
 
 	if (rxrpc_queue_work(&local->processor))
-		trace_rxrpc_local(local, rxrpc_local_queued,
-				  atomic_read(&local->usage), here);
-}
-
-/*
- * A local endpoint reached its end of life.
- */
-static void __rxrpc_put_local(struct rxrpc_local *local)
-{
-	_enter("%d", local->debug_id);
-	rxrpc_queue_work(&local->processor);
+		trace_rxrpc_local(debug_id, rxrpc_local_queued, n, here);
+	else
+		rxrpc_put_local(local);
 }
 
 /*
@@ -372,10 +368,47 @@ void rxrpc_put_local(struct rxrpc_local *local)
 
 	if (local) {
 		n = atomic_dec_return(&local->usage);
-		trace_rxrpc_local(local, rxrpc_local_put, n, here);
+		trace_rxrpc_local(local->debug_id, rxrpc_local_put, n, here);
 
 		if (n == 0)
-			__rxrpc_put_local(local);
+			call_rcu(&local->rcu, rxrpc_local_rcu);
+	}
+}
+
+/*
+ * Start using a local endpoint.
+ */
+struct rxrpc_local *rxrpc_use_local(struct rxrpc_local *local)
+{
+	unsigned int au;
+
+	local = rxrpc_get_local_maybe(local);
+	if (!local)
+		return NULL;
+
+	au = atomic_fetch_add_unless(&local->active_users, 1, 0);
+	if (au == 0) {
+		rxrpc_put_local(local);
+		return NULL;
+	}
+
+	return local;
+}
+
+/*
+ * Cease using a local endpoint.  Once the number of active users reaches 0, we
+ * start the closure of the transport in the work processor.
+ */
+void rxrpc_unuse_local(struct rxrpc_local *local)
+{
+	unsigned int au;
+
+	if (local) {
+		au = atomic_dec_return(&local->active_users);
+		if (au == 0)
+			rxrpc_queue_local(local);
+		else
+			rxrpc_put_local(local);
 	}
 }
 
@@ -393,16 +426,6 @@ static void rxrpc_local_destroyer(struct rxrpc_local *local)
 
 	_enter("%d", local->debug_id);
 
-	/* We can get a race between an incoming call packet queueing the
-	 * processor again and the work processor starting the destruction
-	 * process which will shut down the UDP socket.
-	 */
-	if (local->dead) {
-		_leave(" [already dead]");
-		return;
-	}
-	local->dead = true;
-
 	mutex_lock(&rxnet->local_mutex);
 	list_del_init(&local->link);
 	mutex_unlock(&rxnet->local_mutex);
@@ -422,13 +445,11 @@ static void rxrpc_local_destroyer(struct rxrpc_local *local)
 	 */
 	rxrpc_purge_queue(&local->reject_queue);
 	rxrpc_purge_queue(&local->event_queue);
-
-	_debug("rcu local %d", local->debug_id);
-	call_rcu(&local->rcu, rxrpc_local_rcu);
 }
 
 /*
- * Process events on an endpoint
+ * Process events on an endpoint.  The work item carries a ref which
+ * we must release.
  */
 static void rxrpc_local_processor(struct work_struct *work)
 {
@@ -436,13 +457,15 @@ static void rxrpc_local_processor(struct work_struct *work)
 		container_of(work, struct rxrpc_local, processor);
 	bool again;
 
-	trace_rxrpc_local(local, rxrpc_local_processing,
+	trace_rxrpc_local(local->debug_id, rxrpc_local_processing,
 			  atomic_read(&local->usage), NULL);
 
 	do {
 		again = false;
-		if (atomic_read(&local->usage) == 0)
-			return rxrpc_local_destroyer(local);
+		if (atomic_read(&local->active_users) == 0) {
+			rxrpc_local_destroyer(local);
+			break;
+		}
 
 		if (!skb_queue_empty(&local->reject_queue)) {
 			rxrpc_reject_packets(local);
@@ -454,6 +477,8 @@ static void rxrpc_local_processor(struct work_struct *work)
 			again = true;
 		}
 	} while (again);
+
+	rxrpc_put_local(local);
 }
 
 /*