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Recover from lost link when running in slave only mode. 

Under Linux, when the link goes down our multicast socket becomes stale.
We always poll(2) for events, but the link down does not trigger any event
to let us know that something is wrong. Once the port enters master mode
and starts announcing itself, the socket throws an error. This in turn
causes a fault, and we reopen the socket when clearing the fault.

However, in the case of slave only mode, if the port is listening then
it will never send, discover the link error, or repair the socket. This
patch fixes the issue by simply reopening the socket after an announce
timeout.

[ Another way would be to use a netlink socket, but that would add too
  much complexity as it poorly matches our port/interface model. ]

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
master
Richard Cochran 2012-07-06 21:17:45 +02:00
parent 3d7372d529
commit 646bf8bc26
1 changed files with 17 additions and 0 deletions
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17
port.c
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@ -690,6 +690,20 @@ no_timers:
return -1; return -1;
} }
static int port_renew_transport(struct port *p)
{
if (!port_is_enabled(p)) {
return 0;
}
clock_remove_fda(p->clock, p, p->fda);
transport_close(p->trp, &p->fda);
if (transport_open(p->trp, p->name, &p->fda, p->timestamping)) {
return -1;
}
clock_install_fda(p->clock, p, p->fda);
return 0;
}
/* /*
* Returns non-zero if the announce message is different than last. * Returns non-zero if the announce message is different than last.
*/ */
@ -1238,6 +1252,9 @@ enum fsm_event port_event(struct port *p, int fd_index)
if (p->best) if (p->best)
fc_clear(p->best); fc_clear(p->best);
port_set_announce_tmo(p); port_set_announce_tmo(p);
if (clock_slave_only(p->clock) && port_renew_transport(p)) {
return EV_FAULT_DETECTED;
}
return EV_ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES; return EV_ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES;
case FD_DELAY_TIMER: case FD_DELAY_TIMER: