tipc: remove implicit message delivery in node_unlock()

After the most recent changes, all access calls to a link which
may entail addition of messages to the link's input queue are
postpended by an explicit call to tipc_sk_rcv(), using a reference
to the correct queue.

This means that the potentially hazardous implicit delivery, using
tipc_node_unlock() in combination with a binary flag and a cached
queue pointer, now has become redundant.

This commit removes this implicit delivery mechanism both for regular
data messages and for binding table update messages.

Tested-by: Ying Xue <[email protected]>
Signed-off-by: Jon Maloy <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Jon Paul Maloy

net/tipc/link.c

@@ -559,8 +559,6 @@ void link_prepare_wakeup(struct tipc_link *l)
 			break;
 		skb_unlink(skb, &l->wakeupq);
 		skb_queue_tail(l->inputq, skb);
-		l->owner->inputq = l->inputq;
-		l->owner->action_flags |= TIPC_MSG_EVT;
 	}
 }
 
@@ -598,8 +596,6 @@ void tipc_link_purge_queues(struct tipc_link *l_ptr)
 
 void tipc_link_reset(struct tipc_link *l)
 {
-	struct tipc_node *owner = l->owner;
-
 	tipc_link_fsm_evt(l, LINK_RESET_EVT);
 
 	/* Link is down, accept any session */
@@ -611,14 +607,10 @@ void tipc_link_reset(struct tipc_link *l)
 	/* Prepare for renewed mtu size negotiation */
 	l->mtu = l->advertised_mtu;
 
-	/* Clean up all queues, except inputq: */
+	/* Clean up all queues: */
 	__skb_queue_purge(&l->transmq);
 	__skb_queue_purge(&l->deferdq);
-	if (!owner->inputq)
-		owner->inputq = l->inputq;
-	skb_queue_splice_init(&l->wakeupq, owner->inputq);
-	if (!skb_queue_empty(owner->inputq))
-		owner->action_flags |= TIPC_MSG_EVT;
+	skb_queue_splice_init(&l->wakeupq, l->inputq);
 
 	tipc_link_purge_backlog(l);
 	kfree_skb(l->reasm_buf);
@@ -972,25 +964,18 @@ static bool tipc_data_input(struct tipc_link *link, struct sk_buff *skb)
 {
 	struct tipc_node *node = link->owner;
 	struct tipc_msg *msg = buf_msg(skb);
-	u32 dport = msg_destport(msg);
 
 	switch (msg_user(msg)) {
 	case TIPC_LOW_IMPORTANCE:
 	case TIPC_MEDIUM_IMPORTANCE:
 	case TIPC_HIGH_IMPORTANCE:
 	case TIPC_CRITICAL_IMPORTANCE:
 	case CONN_MANAGER:
-		if (tipc_skb_queue_tail(link->inputq, skb, dport)) {
-			node->inputq = link->inputq;
-			node->action_flags |= TIPC_MSG_EVT;
-		}
+		skb_queue_tail(link->inputq, skb);
 		return true;
 	case NAME_DISTRIBUTOR:
 		node->bclink.recv_permitted = true;
-		node->namedq = link->namedq;
 		skb_queue_tail(link->namedq, skb);
-		if (skb_queue_len(link->namedq) == 1)
-			node->action_flags |= TIPC_NAMED_MSG_EVT;
 		return true;
 	case MSG_BUNDLER:
 	case TUNNEL_PROTOCOL:

net/tipc/msg.h

@@ -862,28 +862,6 @@ static inline struct sk_buff *tipc_skb_dequeue(struct sk_buff_head *list,
 	return skb;
 }
 
-/* tipc_skb_queue_tail(): add buffer to tail of list;
- * @list: list to be appended to
- * @skb: buffer to append. Always appended
- * @dport: the destination port of the buffer
- * returns true if dport differs from previous destination
- */
-static inline bool tipc_skb_queue_tail(struct sk_buff_head *list,
-				       struct sk_buff *skb, u32 dport)
-{
-	struct sk_buff *_skb = NULL;
-	bool rv = false;
-
-	spin_lock_bh(&list->lock);
-	_skb = skb_peek_tail(list);
-	if (!_skb || (msg_destport(buf_msg(_skb)) != dport) ||
-	    (skb_queue_len(list) > 32))
-		rv = true;
-	__skb_queue_tail(list, skb);
-	spin_unlock_bh(&list->lock);
-	return rv;
-}
-
 /* tipc_skb_queue_sorted(); sort pkt into list according to sequence number
  * @list: list to be appended to
  * @skb: buffer to add

net/tipc/node.c

@@ -873,10 +873,8 @@ static void node_lost_contact(struct tipc_node *n_ptr,
 				      SHORT_H_SIZE, 0, tn->own_addr,
 				      conn->peer_node, conn->port,
 				      conn->peer_port, TIPC_ERR_NO_NODE);
-		if (likely(skb)) {
+		if (likely(skb))
 			skb_queue_tail(inputq, skb);
-			n_ptr->action_flags |= TIPC_MSG_EVT;
-		}
 		list_del(&conn->list);
 		kfree(conn);
 	}
@@ -923,27 +921,20 @@ void tipc_node_unlock(struct tipc_node *node)
 	u32 flags = node->action_flags;
 	u32 link_id = 0;
 	struct list_head *publ_list;
-	struct sk_buff_head *inputq = node->inputq;
-	struct sk_buff_head *namedq;
 
-	if (likely(!flags || (flags == TIPC_MSG_EVT))) {
-		node->action_flags = 0;
+	if (likely(!flags)) {
 		spin_unlock_bh(&node->lock);
-		if (flags == TIPC_MSG_EVT)
-			tipc_sk_rcv(net, inputq);
 		return;
 	}
 
 	addr = node->addr;
 	link_id = node->link_id;
-	namedq = node->namedq;
 	publ_list = &node->publ_list;
 
-	node->action_flags &= ~(TIPC_MSG_EVT |
-				TIPC_NOTIFY_NODE_DOWN | TIPC_NOTIFY_NODE_UP |
+	node->action_flags &= ~(TIPC_NOTIFY_NODE_DOWN | TIPC_NOTIFY_NODE_UP |
 				TIPC_NOTIFY_LINK_DOWN | TIPC_NOTIFY_LINK_UP |
 				TIPC_WAKEUP_BCAST_USERS | TIPC_BCAST_MSG_EVT |
-				TIPC_NAMED_MSG_EVT | TIPC_BCAST_RESET);
+				TIPC_BCAST_RESET);
 
 	spin_unlock_bh(&node->lock);
 
@@ -964,12 +955,6 @@ void tipc_node_unlock(struct tipc_node *node)
 		tipc_nametbl_withdraw(net, TIPC_LINK_STATE, addr,
 				      link_id, addr);
 
-	if (flags & TIPC_MSG_EVT)
-		tipc_sk_rcv(net, inputq);
-
-	if (flags & TIPC_NAMED_MSG_EVT)
-		tipc_named_rcv(net, namedq);
-
 	if (flags & TIPC_BCAST_MSG_EVT)
 		tipc_bclink_input(net);
 
@@ -1270,6 +1255,9 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b)
 	if (unlikely(rc & TIPC_LINK_DOWN_EVT))
 		tipc_node_link_down(n, bearer_id, false);
 
+	if (unlikely(!skb_queue_empty(&n->bclink.namedq)))
+		tipc_named_rcv(net, &n->bclink.namedq);
+
 	if (!skb_queue_empty(&le->inputq))
 		tipc_sk_rcv(net, &le->inputq);
 

net/tipc/node.h

@@ -53,13 +53,11 @@
  * TIPC_DISTRIBUTE_NAME: publish or withdraw link state name type
  */
 enum {
-	TIPC_MSG_EVT                    = 1,
 	TIPC_NOTIFY_NODE_DOWN		= (1 << 3),
 	TIPC_NOTIFY_NODE_UP		= (1 << 4),
 	TIPC_WAKEUP_BCAST_USERS		= (1 << 5),
 	TIPC_NOTIFY_LINK_UP		= (1 << 6),
 	TIPC_NOTIFY_LINK_DOWN		= (1 << 7),
-	TIPC_NAMED_MSG_EVT		= (1 << 8),
 	TIPC_BCAST_MSG_EVT		= (1 << 9),
 	TIPC_BCAST_RESET		= (1 << 10)
 };
@@ -124,8 +122,6 @@ struct tipc_node {
 	spinlock_t lock;
 	struct net *net;
 	struct hlist_node hash;
-	struct sk_buff_head *inputq;
-	struct sk_buff_head *namedq;
 	int active_links[2];
 	struct tipc_link_entry links[MAX_BEARERS];
 	int action_flags;