From 92d2c905b404d8d056ce35a0ce645e23529742c2 Mon Sep 17 00:00:00 2001 From: Allan Stephens Date: Tue, 25 Oct 2011 11:20:26 -0400 Subject: [PATCH] tipc: Prevent transmission of outdated link protocol messages Ensures that a link endpoint discards any previously deferred link protocol message whenever it attempts to send a new one. Previously, it was possible for a link protocol message that was unsent due to congestion to be transmitted after newer protocol messages had been sent. The stale link protocol message might then cause the receiving link endpoint to malfunction because of its outdated conent. Thanks to Osamu Kaminuma [okaminum@avaya.com] for diagnosing the problem and contributing a prototype patch. Signed-off-by: Allan Stephens Signed-off-by: Paul Gortmaker --- net/tipc/link.c | 53 +++++++++++++++++++++++++------------------------ 1 file changed, 27 insertions(+), 26 deletions(-) diff --git a/net/tipc/link.c b/net/tipc/link.c index c317abf74a78..bee316ce387c 100644 --- a/net/tipc/link.c +++ b/net/tipc/link.c @@ -1954,6 +1954,13 @@ void tipc_link_send_proto_msg(struct tipc_link *l_ptr, u32 msg_typ, u32 msg_size = sizeof(l_ptr->proto_msg); int r_flag; + /* Discard any previous message that was deferred due to congestion */ + + if (l_ptr->proto_msg_queue) { + buf_discard(l_ptr->proto_msg_queue); + l_ptr->proto_msg_queue = NULL; + } + if (link_blocked(l_ptr)) return; @@ -1962,6 +1969,8 @@ void tipc_link_send_proto_msg(struct tipc_link *l_ptr, u32 msg_typ, if ((l_ptr->owner->block_setup) && (msg_typ != RESET_MSG)) return; + /* Create protocol message with "out-of-sequence" sequence number */ + msg_set_type(msg, msg_typ); msg_set_net_plane(msg, l_ptr->b_ptr->net_plane); msg_set_bcast_ack(msg, mod(l_ptr->owner->bclink.last_in)); @@ -2018,44 +2027,36 @@ void tipc_link_send_proto_msg(struct tipc_link *l_ptr, u32 msg_typ, r_flag = (l_ptr->owner->working_links > tipc_link_is_up(l_ptr)); msg_set_redundant_link(msg, r_flag); msg_set_linkprio(msg, l_ptr->priority); - - /* Ensure sequence number will not fit : */ + msg_set_size(msg, msg_size); msg_set_seqno(msg, mod(l_ptr->next_out_no + (0xffff/2))); - /* Congestion? */ - - if (tipc_bearer_congested(l_ptr->b_ptr, l_ptr)) { - if (!l_ptr->proto_msg_queue) { - l_ptr->proto_msg_queue = - tipc_buf_acquire(sizeof(l_ptr->proto_msg)); - } - buf = l_ptr->proto_msg_queue; - if (!buf) - return; - skb_copy_to_linear_data(buf, msg, sizeof(l_ptr->proto_msg)); - return; - } - - /* Message can be sent */ - buf = tipc_buf_acquire(msg_size); if (!buf) return; skb_copy_to_linear_data(buf, msg, sizeof(l_ptr->proto_msg)); - msg_set_size(buf_msg(buf), msg_size); - if (tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr)) { - l_ptr->unacked_window = 0; - buf_discard(buf); + /* Defer message if bearer is already congested */ + + if (tipc_bearer_congested(l_ptr->b_ptr, l_ptr)) { + l_ptr->proto_msg_queue = buf; return; } - /* New congestion */ - tipc_bearer_schedule(l_ptr->b_ptr, l_ptr); - l_ptr->proto_msg_queue = buf; - l_ptr->stats.bearer_congs++; + /* Defer message if attempting to send results in bearer congestion */ + + if (!tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr)) { + tipc_bearer_schedule(l_ptr->b_ptr, l_ptr); + l_ptr->proto_msg_queue = buf; + l_ptr->stats.bearer_congs++; + return; + } + + /* Discard message if it was sent successfully */ + + l_ptr->unacked_window = 0; + buf_discard(buf); } /*