From dca43c75e7e545694a9dd6288553f55c53e2a3a3 Mon Sep 17 00:00:00 2001 From: Jerry Chu Date: Fri, 27 Aug 2010 19:13:28 +0000 Subject: tcp: Add TCP_USER_TIMEOUT socket option. This patch provides a "user timeout" support as described in RFC793. The socket option is also needed for the the local half of RFC5482 "TCP User Timeout Option". TCP_USER_TIMEOUT is a TCP level socket option that takes an unsigned int, when > 0, to specify the maximum amount of time in ms that transmitted data may remain unacknowledged before TCP will forcefully close the corresponding connection and return ETIMEDOUT to the application. If 0 is given, TCP will continue to use the system default. Increasing the user timeouts allows a TCP connection to survive extended periods without end-to-end connectivity. Decreasing the user timeouts allows applications to "fail fast" if so desired. Otherwise it may take upto 20 minutes with the current system defaults in a normal WAN environment. The socket option can be made during any state of a TCP connection, but is only effective during the synchronized states of a connection (ESTABLISHED, FIN-WAIT-1, FIN-WAIT-2, CLOSE-WAIT, CLOSING, or LAST-ACK). Moreover, when used with the TCP keepalive (SO_KEEPALIVE) option, TCP_USER_TIMEOUT will overtake keepalive to determine when to close a connection due to keepalive failure. The option does not change in anyway when TCP retransmits a packet, nor when a keepalive probe will be sent. This option, like many others, will be inherited by an acceptor from its listener. Signed-off-by: H.K. Jerry Chu Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'net/ipv4/tcp.c') diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 176e11a..cf32545 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2391,7 +2391,12 @@ static int do_tcp_setsockopt(struct sock *sk, int level, err = tp->af_specific->md5_parse(sk, optval, optlen); break; #endif - + case TCP_USER_TIMEOUT: + /* Cap the max timeout in ms TCP will retry/retrans + * before giving up and aborting (ETIMEDOUT) a connection. + */ + icsk->icsk_user_timeout = msecs_to_jiffies(val); + break; default: err = -ENOPROTOOPT; break; @@ -2610,6 +2615,10 @@ static int do_tcp_getsockopt(struct sock *sk, int level, case TCP_THIN_DUPACK: val = tp->thin_dupack; break; + + case TCP_USER_TIMEOUT: + val = jiffies_to_msecs(icsk->icsk_user_timeout); + break; default: return -ENOPROTOOPT; } -- cgit v1.1