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61d0a8e6a8
[[resending with correct cc: - "vfs.kernel.org" just isn't right!]]
xprt->reestablish_timeout is used to cause TCP connection attempts to
back off if the connection fails so as not to hammer the network,
but to still allow immediate connections when there is no reason to
believe there is a problem.
It is not used for the first connection (when transport->sock is NULL)
but only on reconnects.
It is currently set:
a/ to 0 when xs_tcp_state_change finds a state of TCP_FIN_WAIT1
on the assumption that the client has closed the connection
so the reconnect should be immediate when needed.
b/ to at least XS_TCP_INIT_REEST_TO when xs_tcp_state_change
detects TCP_CLOSING or TCP_CLOSE_WAIT on the assumption that the
server closed the connection so a small delay at least is
required.
c/ as above when xs_tcp_state_change detects TCP_SYN_SENT, so that
it is never 0 while a connection has been attempted, else
the doubling will produce 0 and there will be no backoff.
d/ to double is value (up to a limit) when delaying a connection,
thus providing exponential backoff and
e/ to XS_TCP_INIT_REEST_TO in xs_setup_tcp as simple initialisation.
So you can see it is highly dependant on xs_tcp_state_change being
called as expected. However experimental evidence shows that
xs_tcp_state_change does not see all state changes.
("rpcdebug -m rpc trans" can help show what actually happens).
Results show:
TCP_ESTABLISHED is reported when a connection is made. TCP_SYN_SENT
is never reported, so rule 'c' above is never effective.
When the server closes the connection, TCP_CLOSE_WAIT and
TCP_LAST_ACK *might* be reported, and TCP_CLOSE is always
reported. This rule 'b' above will sometimes be effective, but
not reliably.
When the client closes the connection, it used to result in
TCP_FIN_WAIT1, TCP_FIN_WAIT2, TCP_CLOSE. However since commit
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| appletalk | ||
| atm | ||
| ax25 | ||
| bluetooth | ||
| bridge | ||
| can | ||
| core | ||
| dcb | ||
| dccp | ||
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| ethernet | ||
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| irda | ||
| iucv | ||
| key | ||
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| netlabel | ||
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| packet | ||
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| x25 | ||
| xfrm | ||
| compat.c | ||
| Kconfig | ||
| Makefile | ||
| nonet.c | ||
| socket.c | ||
| sysctl_net.c | ||
| TUNABLE | ||