rxrpc: Fix conn expiry timers

Fix the rxrpc connection expiry timers so that connections for closed
AF_RXRPC sockets get deleted in a more timely fashion, freeing up the
transport UDP port much more quickly.

 (1) Replace the delayed work items with work items plus timers so that
     timer_reduce() can be used to shorten them and so that the timer
     doesn't requeue the work item if the net namespace is dead.

 (2) Don't use queue_delayed_work() as that won't alter the timeout if the
     timer is already running.

 (3) Don't rearm the timers if the network namespace is dead.
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/af_rxrpc.c

@@ -895,6 +895,8 @@ static int rxrpc_release_sock(struct sock *sk)
 	rxrpc_release_calls_on_socket(rx);
 	flush_workqueue(rxrpc_workqueue);
 	rxrpc_purge_queue(&sk->sk_receive_queue);
+	rxrpc_queue_work(&rx->local->rxnet->service_conn_reaper);
+	rxrpc_queue_work(&rx->local->rxnet->client_conn_reaper);
 
 	rxrpc_put_local(rx->local);
 	rx->local = NULL;

net/rxrpc/ar-internal.h

@@ -79,7 +79,8 @@ struct rxrpc_net {
 	struct list_head	conn_proc_list;	/* List of conns in this namespace for proc */
 	struct list_head	service_conns;	/* Service conns in this namespace */
 	rwlock_t		conn_lock;	/* Lock for ->conn_proc_list, ->service_conns */
-	struct delayed_work	service_conn_reaper;
+	struct work_struct	service_conn_reaper;
+	struct timer_list	service_conn_reap_timer;
 
 	unsigned int		nr_client_conns;
 	unsigned int		nr_active_client_conns;
@@ -90,7 +91,8 @@ struct rxrpc_net {
 	struct list_head	waiting_client_conns;
 	struct list_head	active_client_conns;
 	struct list_head	idle_client_conns;
-	struct delayed_work	client_conn_reaper;
+	struct work_struct	client_conn_reaper;
+	struct timer_list	client_conn_reap_timer;
 
 	struct list_head	local_endpoints;
 	struct mutex		local_mutex;	/* Lock for ->local_endpoints */

net/rxrpc/conn_client.c

@@ -691,7 +691,7 @@ int rxrpc_connect_call(struct rxrpc_call *call,
 
 	_enter("{%d,%lx},", call->debug_id, call->user_call_ID);
 
-	rxrpc_discard_expired_client_conns(&rxnet->client_conn_reaper.work);
+	rxrpc_discard_expired_client_conns(&rxnet->client_conn_reaper);
 	rxrpc_cull_active_client_conns(rxnet);
 
 	ret = rxrpc_get_client_conn(call, cp, srx, gfp);
@@ -756,6 +756,18 @@ void rxrpc_expose_client_call(struct rxrpc_call *call)
 	}
 }
 
+/*
+ * Set the reap timer.
+ */
+static void rxrpc_set_client_reap_timer(struct rxrpc_net *rxnet)
+{
+	unsigned long now = jiffies;
+	unsigned long reap_at = now + rxrpc_conn_idle_client_expiry;
+
+	if (rxnet->live)
+		timer_reduce(&rxnet->client_conn_reap_timer, reap_at);
+}
+
 /*
  * Disconnect a client call.
  */
@@ -896,9 +908,7 @@ void rxrpc_disconnect_client_call(struct rxrpc_call *call)
 		list_move_tail(&conn->cache_link, &rxnet->idle_client_conns);
 		if (rxnet->idle_client_conns.next == &conn->cache_link &&
 		    !rxnet->kill_all_client_conns)
-			queue_delayed_work(rxrpc_workqueue,
-					   &rxnet->client_conn_reaper,
-					   rxrpc_conn_idle_client_expiry);
+			rxrpc_set_client_reap_timer(rxnet);
 	} else {
 		trace_rxrpc_client(conn, channel, rxrpc_client_to_inactive);
 		conn->cache_state = RXRPC_CONN_CLIENT_INACTIVE;
@@ -1036,8 +1046,7 @@ void rxrpc_discard_expired_client_conns(struct work_struct *work)
 {
 	struct rxrpc_connection *conn;
 	struct rxrpc_net *rxnet =
-		container_of(to_delayed_work(work),
-			     struct rxrpc_net, client_conn_reaper);
+		container_of(work, struct rxrpc_net, client_conn_reaper);
 	unsigned long expiry, conn_expires_at, now;
 	unsigned int nr_conns;
 	bool did_discard = false;
@@ -1116,9 +1125,8 @@ void rxrpc_discard_expired_client_conns(struct work_struct *work)
 	 */
 	_debug("not yet");
 	if (!rxnet->kill_all_client_conns)
-		queue_delayed_work(rxrpc_workqueue,
-				   &rxnet->client_conn_reaper,
-				   conn_expires_at - now);
+		timer_reduce(&rxnet->client_conn_reap_timer,
+			     conn_expires_at);
 
 out:
 	spin_unlock(&rxnet->client_conn_cache_lock);
@@ -1138,9 +1146,9 @@ void rxrpc_destroy_all_client_connections(struct rxrpc_net *rxnet)
 	rxnet->kill_all_client_conns = true;
 	spin_unlock(&rxnet->client_conn_cache_lock);
 
-	cancel_delayed_work(&rxnet->client_conn_reaper);
+	del_timer_sync(&rxnet->client_conn_reap_timer);
 
-	if (!queue_delayed_work(rxrpc_workqueue, &rxnet->client_conn_reaper, 0))
+	if (!rxrpc_queue_work(&rxnet->client_conn_reaper))
 		_debug("destroy: queue failed");
 
 	_leave("");

net/rxrpc/conn_object.c

@@ -310,22 +310,30 @@ rxrpc_get_connection_maybe(struct rxrpc_connection *conn)
 	return conn;
 }
 
+/*
+ * Set the service connection reap timer.
+ */
+static void rxrpc_set_service_reap_timer(struct rxrpc_net *rxnet,
+					 unsigned long reap_at)
+{
+	if (rxnet->live)
+		timer_reduce(&rxnet->service_conn_reap_timer, reap_at);
+}
+
 /*
  * Release a service connection
  */
 void rxrpc_put_service_conn(struct rxrpc_connection *conn)
 {
-	struct rxrpc_net *rxnet;
 	const void *here = __builtin_return_address(0);
 	int n;
 
 	n = atomic_dec_return(&conn->usage);
 	trace_rxrpc_conn(conn, rxrpc_conn_put_service, n, here);
 	ASSERTCMP(n, >=, 0);
-	if (n == 1) {
-		rxnet = conn->params.local->rxnet;
-		rxrpc_queue_delayed_work(&rxnet->service_conn_reaper, 0);
-	}
+	if (n == 1)
+		rxrpc_set_service_reap_timer(conn->params.local->rxnet,
+					     jiffies + rxrpc_connection_expiry);
 }
 
 /*
@@ -362,8 +370,7 @@ void rxrpc_service_connection_reaper(struct work_struct *work)
 {
 	struct rxrpc_connection *conn, *_p;
 	struct rxrpc_net *rxnet =
-		container_of(to_delayed_work(work),
-			     struct rxrpc_net, service_conn_reaper);
+		container_of(work, struct rxrpc_net, service_conn_reaper);
 	unsigned long expire_at, earliest, idle_timestamp, now;
 
 	LIST_HEAD(graveyard);
@@ -417,8 +424,7 @@ void rxrpc_service_connection_reaper(struct work_struct *work)
 	if (earliest != now + MAX_JIFFY_OFFSET) {
 		_debug("reschedule reaper %ld", (long)earliest - (long)now);
 		ASSERT(time_after(earliest, now));
-		rxrpc_queue_delayed_work(&rxnet->service_conn_reaper,
-					 earliest - now);
+		rxrpc_set_service_reap_timer(rxnet, earliest);		
 	}
 
 	while (!list_empty(&graveyard)) {
@@ -446,8 +452,8 @@ void rxrpc_destroy_all_connections(struct rxrpc_net *rxnet)
 
 	rxrpc_destroy_all_client_connections(rxnet);
 
-	cancel_delayed_work(&rxnet->client_conn_reaper);
-	rxrpc_queue_delayed_work(&rxnet->client_conn_reaper, 0);
+	del_timer_sync(&rxnet->service_conn_reap_timer);
+	rxrpc_queue_work(&rxnet->service_conn_reaper);
 	flush_workqueue(rxrpc_workqueue);
 
 	write_lock(&rxnet->conn_lock);

net/rxrpc/net_ns.c

@@ -14,6 +14,24 @@
 
 unsigned int rxrpc_net_id;
 
+static void rxrpc_client_conn_reap_timeout(struct timer_list *timer)
+{
+	struct rxrpc_net *rxnet =
+		container_of(timer, struct rxrpc_net, client_conn_reap_timer);
+
+	if (rxnet->live)
+		rxrpc_queue_work(&rxnet->client_conn_reaper);
+}
+
+static void rxrpc_service_conn_reap_timeout(struct timer_list *timer)
+{
+	struct rxrpc_net *rxnet =
+		container_of(timer, struct rxrpc_net, service_conn_reap_timer);
+
+	if (rxnet->live)
+		rxrpc_queue_work(&rxnet->service_conn_reaper);
+}
+
 /*
  * Initialise a per-network namespace record.
  */
@@ -32,8 +50,10 @@ static __net_init int rxrpc_init_net(struct net *net)
 	INIT_LIST_HEAD(&rxnet->conn_proc_list);
 	INIT_LIST_HEAD(&rxnet->service_conns);
 	rwlock_init(&rxnet->conn_lock);
-	INIT_DELAYED_WORK(&rxnet->service_conn_reaper,
-			  rxrpc_service_connection_reaper);
+	INIT_WORK(&rxnet->service_conn_reaper,
+		  rxrpc_service_connection_reaper);
+	timer_setup(&rxnet->service_conn_reap_timer,
+		    rxrpc_service_conn_reap_timeout, 0);
 
 	rxnet->nr_client_conns = 0;
 	rxnet->nr_active_client_conns = 0;
@@ -43,8 +63,10 @@ static __net_init int rxrpc_init_net(struct net *net)
 	INIT_LIST_HEAD(&rxnet->waiting_client_conns);
 	INIT_LIST_HEAD(&rxnet->active_client_conns);
 	INIT_LIST_HEAD(&rxnet->idle_client_conns);
-	INIT_DELAYED_WORK(&rxnet->client_conn_reaper,
-			  rxrpc_discard_expired_client_conns);
+	INIT_WORK(&rxnet->client_conn_reaper,
+		  rxrpc_discard_expired_client_conns);
+	timer_setup(&rxnet->client_conn_reap_timer,
+		    rxrpc_client_conn_reap_timeout, 0);
 
 	INIT_LIST_HEAD(&rxnet->local_endpoints);
 	mutex_init(&rxnet->local_mutex);