path: root/net/tipc
diff options
authorTuong Lien <tuong.t.lien@dektech.com.au>2019-12-10 15:21:03 +0700
committerDavid S. Miller <davem@davemloft.net>2019-12-10 17:45:04 -0800
commitdca4a17d24ee9d878836ce5eb8dc25be1ffa5729 (patch)
tree3792939ecf7a1008b22002426ef454adce03c094 /net/tipc
parenttipc: fix name table rbtree issues (diff)
tipc: fix potential hanging after b/rcast changing
In commit c55c8edafa91 ("tipc: smooth change between replicast and broadcast"), we allow instant switching between replicast and broadcast by sending a dummy 'SYN' packet on the last used link to synchronize packets on the links. The 'SYN' message is an object of link congestion also, so if that happens, a 'SOCK_WAKEUP' will be scheduled to be sent back to the socket... However, in that commit, we simply use the same socket 'cong_link_cnt' counter for both the 'SYN' & normal payload message sending. Therefore, if both the replicast & broadcast links are congested, the counter will be not updated correctly but overwritten by the latter congestion. Later on, when the 'SOCK_WAKEUP' messages are processed, the counter is reduced one by one and eventually overflowed. Consequently, further activities on the socket will only wait for the false congestion signal to disappear but never been met. Because sending the 'SYN' message is vital for the mechanism, it should be done anyway. This commit fixes the issue by marking the message with an error code e.g. 'TIPC_ERR_NO_PORT', so its sending should not face a link congestion, there is no need to touch the socket 'cong_link_cnt' either. In addition, in the event of any error (e.g. -ENOBUFS), we will purge the entire payload message queue and make a return immediately. Fixes: c55c8edafa91 ("tipc: smooth change between replicast and broadcast") Acked-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc')
1 files changed, 15 insertions, 9 deletions
diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 55aeba681cf4..656ebc79c64e 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -305,17 +305,17 @@ static int tipc_rcast_xmit(struct net *net, struct sk_buff_head *pkts,
* @skb: socket buffer to copy
* @method: send method to be used
* @dests: destination nodes for message.
- * @cong_link_cnt: returns number of encountered congested destination links
* Returns 0 if success, otherwise errno
static int tipc_mcast_send_sync(struct net *net, struct sk_buff *skb,
struct tipc_mc_method *method,
- struct tipc_nlist *dests,
- u16 *cong_link_cnt)
+ struct tipc_nlist *dests)
struct tipc_msg *hdr, *_hdr;
struct sk_buff_head tmpq;
struct sk_buff *_skb;
+ u16 cong_link_cnt;
+ int rc = 0;
/* Is a cluster supporting with new capabilities ? */
if (!(tipc_net(net)->capabilities & TIPC_MCAST_RBCTL))
@@ -343,18 +343,19 @@ static int tipc_mcast_send_sync(struct net *net, struct sk_buff *skb,
_hdr = buf_msg(_skb);
msg_set_size(_hdr, MCAST_H_SIZE);
msg_set_is_rcast(_hdr, !msg_is_rcast(hdr));
+ msg_set_errcode(_hdr, TIPC_ERR_NO_PORT);
__skb_queue_tail(&tmpq, _skb);
if (method->rcast)
- tipc_bcast_xmit(net, &tmpq, cong_link_cnt);
+ rc = tipc_bcast_xmit(net, &tmpq, &cong_link_cnt);
- tipc_rcast_xmit(net, &tmpq, dests, cong_link_cnt);
+ rc = tipc_rcast_xmit(net, &tmpq, dests, &cong_link_cnt);
/* This queue should normally be empty by now */
- return 0;
+ return rc;
/* tipc_mcast_xmit - deliver message to indicated destination nodes
@@ -396,9 +397,14 @@ int tipc_mcast_xmit(struct net *net, struct sk_buff_head *pkts,
msg_set_is_rcast(hdr, method->rcast);
/* Switch method ? */
- if (rcast != method->rcast)
- tipc_mcast_send_sync(net, skb, method,
- dests, cong_link_cnt);
+ if (rcast != method->rcast) {
+ rc = tipc_mcast_send_sync(net, skb, method, dests);
+ if (unlikely(rc)) {
+ pr_err("Unable to send SYN: method %d, rc %d\n",
+ rcast, rc);
+ goto exit;
+ }
+ }
if (method->rcast)
rc = tipc_rcast_xmit(net, pkts, dests, cong_link_cnt);