tipc: clean up skb list lock handling on send path

commit e654f9f53b45fde3fcc8051830b212c7a8f36148 upstream.

The policy for handling the skb list locks on the send and receive paths
is simple.

- On the send path we never need to grab the lock on the 'xmitq' list
  when the destination is an exernal node.

- On the receive path we always need to grab the lock on the 'inputq'
  list, irrespective of source node.

However, when transmitting node local messages those will eventually
end up on the receive path of a local socket, meaning that the argument
'xmitq' in tipc_node_xmit() will become the 'ínputq' argument in  the
function tipc_sk_rcv(). This has been handled by always initializing
the spinlock of the 'xmitq' list at message creation, just in case it
may end up on the receive path later, and despite knowing that the lock
in most cases never will be used.

This approach is inaccurate and confusing, and has also concealed the
fact that the stated 'no lock grabbing' policy for the send path is
violated in some cases.

We now clean up this by never initializing the lock at message creation,
instead doing this at the moment we find that the message actually will
enter the receive path. At the same time we fix the four locations
where we incorrectly access the spinlock on the send/error path.

This patch also reverts commit d12cffe9329f ("tipc: ensure head->lock
is initialised") which has now become redundant.

CC: Eric Dumazet <edumazet@google.com>
Reported-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[acj: backport v4.19 -stable
- adjust context
- skipped the hunk modifying non-existent function tipc_mcast_send_sync
- additional comment ]
Signed-off-by: Aviraj CJ <acj@cisco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

5 files changed, 22 insertions, 21 deletions

diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index d8026543bf4c..68107bf92c7e 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -181,7 +181,7 @@ static void tipc_bcbase_xmit(struct net *net, struct sk_buff_head *xmitq)
 	}
 
 	/* We have to transmit across all bearers */
-	skb_queue_head_init(&_xmitq);
+	__skb_queue_head_init(&_xmitq);
 	for (bearer_id = 0; bearer_id < MAX_BEARERS; bearer_id++) {
 		if (!bb->dests[bearer_id])
 			continue;
@@ -237,7 +237,7 @@ static int tipc_bcast_xmit(struct net *net, struct sk_buff_head *pkts,
 	struct sk_buff_head xmitq;
 	int rc = 0;
 
-	skb_queue_head_init(&xmitq);
+	__skb_queue_head_init(&xmitq);
 	tipc_bcast_lock(net);
 	if (tipc_link_bc_peers(l))
 		rc = tipc_link_xmit(l, pkts, &xmitq);
@@ -267,7 +267,7 @@ static int tipc_rcast_xmit(struct net *net, struct sk_buff_head *pkts,
 	u32 dnode, selector;
 
 	selector = msg_link_selector(buf_msg(skb_peek(pkts)));
-	skb_queue_head_init(&_pkts);
+	__skb_queue_head_init(&_pkts);
 
 	list_for_each_entry_safe(dst, tmp, &dests->list, list) {
 		dnode = dst->node;
@@ -299,7 +299,7 @@ int tipc_mcast_xmit(struct net *net, struct sk_buff_head *pkts,
 	int rc = 0;
 
 	skb_queue_head_init(&inputq);
-	skb_queue_head_init(&localq);
+	__skb_queue_head_init(&localq);
 
 	/* Clone packets before they are consumed by next call */
 	if (dests->local && !tipc_msg_reassemble(pkts, &localq)) {
diff --git a/net/tipc/group.c b/net/tipc/group.c
index 3ee93b5c19b6..9a9138de4eca 100644
--- a/net/tipc/group.c
+++ b/net/tipc/group.c
@@ -199,7 +199,7 @@ void tipc_group_join(struct net *net, struct tipc_group *grp, int *sk_rcvbuf)
 	struct tipc_member *m, *tmp;
 	struct sk_buff_head xmitq;
 
-	skb_queue_head_init(&xmitq);
+	__skb_queue_head_init(&xmitq);
 	rbtree_postorder_for_each_entry_safe(m, tmp, tree, tree_node) {
 		tipc_group_proto_xmit(grp, m, GRP_JOIN_MSG, &xmitq);
 		tipc_group_update_member(m, 0);
@@ -435,7 +435,7 @@ bool tipc_group_cong(struct tipc_group *grp, u32 dnode, u32 dport,
 		return true;
 	if (state == MBR_PENDING && adv == ADV_IDLE)
 		return true;
-	skb_queue_head_init(&xmitq);
+	__skb_queue_head_init(&xmitq);
 	tipc_group_proto_xmit(grp, m, GRP_ADV_MSG, &xmitq);
 	tipc_node_distr_xmit(grp->net, &xmitq);
 	return true;
diff --git a/net/tipc/link.c b/net/tipc/link.c
index cc9a0485536b..f756b721f93e 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -928,7 +928,7 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
 	int rc = 0;
 
 	if (unlikely(msg_size(hdr) > mtu)) {
-		skb_queue_purge(list);
+		__skb_queue_purge(list);
 		return -EMSGSIZE;
 	}
 
@@ -957,7 +957,7 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
 		if (likely(skb_queue_len(transmq) < maxwin)) {
 			_skb = skb_clone(skb, GFP_ATOMIC);
 			if (!_skb) {
-				skb_queue_purge(list);
+				__skb_queue_purge(list);
 				return -ENOBUFS;
 			}
 			__skb_dequeue(list);
@@ -1429,7 +1429,7 @@ void tipc_link_create_dummy_tnl_msg(struct tipc_link *l,
 	struct sk_buff *skb;
 	u32 dnode = l->addr;
 
-	skb_queue_head_init(&tnlq);
+	__skb_queue_head_init(&tnlq);
 	skb = tipc_msg_create(TUNNEL_PROTOCOL, FAILOVER_MSG,
 			      INT_H_SIZE, BASIC_H_SIZE,
 			      dnode, onode, 0, 0, 0);
@@ -1465,8 +1465,8 @@ void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
 	if (!tnl)
 		return;
 
-	skb_queue_head_init(&tnlq);
-	skb_queue_head_init(&tmpxq);
+	__skb_queue_head_init(&tnlq);
+	__skb_queue_head_init(&tmpxq);
 
 	/* At least one packet required for safe algorithm => add dummy */
 	skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
@@ -1476,7 +1476,7 @@ void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
 		return;
 	}
-	skb_queue_tail(&tnlq, skb);
+	__skb_queue_tail(&tnlq, skb);
 	tipc_link_xmit(l, &tnlq, &tmpxq);
 	__skb_queue_purge(&tmpxq);
 
diff --git a/net/tipc/node.c b/net/tipc/node.c
index e67ffd194927..a188c2590137 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -1368,13 +1368,14 @@ int tipc_node_xmit(struct net *net, struct sk_buff_head *list,
 	int rc;
 
 	if (in_own_node(net, dnode)) {
+		spin_lock_init(&list->lock);
 		tipc_sk_rcv(net, list);
 		return 0;
 	}
 
 	n = tipc_node_find(net, dnode);
 	if (unlikely(!n)) {
-		skb_queue_purge(list);
+		__skb_queue_purge(list);
 		return -EHOSTUNREACH;
 	}
 
@@ -1383,7 +1384,7 @@ int tipc_node_xmit(struct net *net, struct sk_buff_head *list,
 	if (unlikely(bearer_id == INVALID_BEARER_ID)) {
 		tipc_node_read_unlock(n);
 		tipc_node_put(n);
-		skb_queue_purge(list);
+		__skb_queue_purge(list);
 		return -EHOSTUNREACH;
 	}
 
@@ -1415,7 +1416,7 @@ int tipc_node_xmit_skb(struct net *net, struct sk_buff *skb, u32 dnode,
 {
 	struct sk_buff_head head;
 
-	skb_queue_head_init(&head);
+	__skb_queue_head_init(&head);
 	__skb_queue_tail(&head, skb);
 	tipc_node_xmit(net, &head, dnode, selector);
 	return 0;
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 40947ad90222..f0184a5e83aa 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -800,7 +800,7 @@ static int tipc_sendmcast(struct  socket *sock, struct tipc_name_seq *seq,
 	msg_set_nameupper(hdr, seq->upper);
 
 	/* Build message as chain of buffers */
-	skb_queue_head_init(&pkts);
+	__skb_queue_head_init(&pkts);
 	rc = tipc_msg_build(hdr, msg, 0, dlen, mtu, &pkts);
 
 	/* Send message if build was successful */
@@ -841,7 +841,7 @@ static int tipc_send_group_msg(struct net *net, struct tipc_sock *tsk,
 	msg_set_grp_bc_seqno(hdr, bc_snd_nxt);
 
 	/* Build message as chain of buffers */
-	skb_queue_head_init(&pkts);
+	__skb_queue_head_init(&pkts);
 	mtu = tipc_node_get_mtu(net, dnode, tsk->portid);
 	rc = tipc_msg_build(hdr, m, 0, dlen, mtu, &pkts);
 	if (unlikely(rc != dlen))
@@ -1046,7 +1046,7 @@ static int tipc_send_group_bcast(struct socket *sock, struct msghdr *m,
 	msg_set_grp_bc_ack_req(hdr, ack);
 
 	/* Build message as chain of buffers */
-	skb_queue_head_init(&pkts);
+	__skb_queue_head_init(&pkts);
 	rc = tipc_msg_build(hdr, m, 0, dlen, mtu, &pkts);
 	if (unlikely(rc != dlen))
 		return rc;
@@ -1372,7 +1372,7 @@ static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dlen)
 	if (unlikely(rc))
 		return rc;
 
-	skb_queue_head_init(&pkts);
+	__skb_queue_head_init(&pkts);
 	mtu = tipc_node_get_mtu(net, dnode, tsk->portid);
 	rc = tipc_msg_build(hdr, m, 0, dlen, mtu, &pkts);
 	if (unlikely(rc != dlen))
@@ -1427,7 +1427,7 @@ static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dlen)
 	int send, sent = 0;
 	int rc = 0;
 
-	skb_queue_head_init(&pkts);
+	__skb_queue_head_init(&pkts);
 
 	if (unlikely(dlen > INT_MAX))
 		return -EMSGSIZE;
@@ -1782,7 +1782,7 @@ static int tipc_recvmsg(struct socket *sock, struct msghdr *m,
 
 	/* Send group flow control advertisement when applicable */
 	if (tsk->group && msg_in_group(hdr) && !grp_evt) {
-		skb_queue_head_init(&xmitq);
+		__skb_queue_head_init(&xmitq);
 		tipc_group_update_rcv_win(tsk->group, tsk_blocks(hlen + dlen),
 					  msg_orignode(hdr), msg_origport(hdr),
 					  &xmitq);