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authorJerry Chu <hkchu@google.com>2010-08-27 19:13:28 +0000
committerDavid S. Miller <davem@davemloft.net>2010-08-30 13:23:33 -0700
commitdca43c75e7e545694a9dd6288553f55c53e2a3a3 (patch)
tree4df6b0b295ecd571fa95004b486d9af1636d6a30 /net/ipv4/tcp.c
parent409456b10f87b28303643fec37543103f9ada00c (diff)
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 <hkchu@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp.c')
-rw-r--r--net/ipv4/tcp.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 176e11aaea77..cf3254528753 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;
}