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authorThomas Graf <tgraf@infradead.org>2011-07-07 00:28:35 +0000
committerDavid S. Miller <davem@davemloft.net>2011-07-07 14:08:44 -0700
commitf8d9605243280f1870dd2c6c37a735b925c15f3c (patch)
tree2d6a3ce33c503bce8fca71489d4c4dc266579469 /include
parent31cb852809c86541c817538c98003678546dfa58 (diff)
sctp: Enforce retransmission limit during shutdown
When initiating a graceful shutdown while having data chunks on the retransmission queue with a peer which is in zero window mode the shutdown is never completed because the retransmission error count is reset periodically by the following two rules: - Do not timeout association while doing zero window probe. - Reset overall error count when a heartbeat request has been acknowledged. The graceful shutdown will wait for all outstanding TSN to be acknowledged before sending the SHUTDOWN request. This never happens due to the peer's zero window not acknowledging the continuously retransmitted data chunks. Although the error counter is incremented for each failed retransmission, the receiving of the SACK announcing the zero window clears the error count again immediately. Also heartbeat requests continue to be sent periodically. The peer acknowledges these requests causing the error counter to be reset as well. This patch changes behaviour to only reset the overall error counter for the above rules while not in shutdown. After reaching the maximum number of retransmission attempts, the T5 shutdown guard timer is scheduled to give the receiver some additional time to recover. The timer is stopped as soon as the receiver acknowledges any data. The issue can be easily reproduced by establishing a sctp association over the loopback device, constantly queueing data at the sender while not reading any at the receiver. Wait for the window to reach zero, then initiate a shutdown by killing both processes simultaneously. The association will never be freed and the chunks on the retransmission queue will be retransmitted indefinitely. Signed-off-by: Thomas Graf <tgraf@infradead.org> Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/net/sctp/command.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/net/sctp/command.h b/include/net/sctp/command.h
index dd6847e5d6e4..6506458ccd33 100644
--- a/include/net/sctp/command.h
+++ b/include/net/sctp/command.h
@@ -63,6 +63,7 @@ typedef enum {
SCTP_CMD_ECN_ECNE, /* Do delayed ECNE processing. */
SCTP_CMD_ECN_CWR, /* Do delayed CWR processing. */
SCTP_CMD_TIMER_START, /* Start a timer. */
+ SCTP_CMD_TIMER_START_ONCE, /* Start a timer once */
SCTP_CMD_TIMER_RESTART, /* Restart a timer. */
SCTP_CMD_TIMER_STOP, /* Stop a timer. */
SCTP_CMD_INIT_CHOOSE_TRANSPORT, /* Choose transport for an INIT. */