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| author | Jerry Chu <hkchu@google.com> | 2010-08-27 19:13:28 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-08-30 13:23:33 -0700 |
| commit | dca43c75e7e545694a9dd6288553f55c53e2a3a3 (patch) | |
| tree | 4df6b0b295ecd571fa95004b486d9af1636d6a30 /include/linux | |
| parent | 409456b10f87b28303643fec37543103f9ada00c (diff) | |
| download | linux-dca43c75e7e545694a9dd6288553f55c53e2a3a3.tar.gz linux-dca43c75e7e545694a9dd6288553f55c53e2a3a3.tar.bz2 linux-dca43c75e7e545694a9dd6288553f55c53e2a3a3.zip | |
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 'include/linux')
| -rw-r--r-- | include/linux/tcp.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index a778ee024590..e64f4c67d0ef 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -105,6 +105,7 @@ enum { #define TCP_COOKIE_TRANSACTIONS 15 /* TCP Cookie Transactions */ #define TCP_THIN_LINEAR_TIMEOUTS 16 /* Use linear timeouts for thin streams*/ #define TCP_THIN_DUPACK 17 /* Fast retrans. after 1 dupack */ +#define TCP_USER_TIMEOUT 18 /* How long for loss retry before timeout */ /* for TCP_INFO socket option */ #define TCPI_OPT_TIMESTAMPS 1 |