dhcp: rtems_event_receive() doesn't return

[Tim Cussins]

Hi all,

We use the DHCP mechanism provided by RTEMS, and have noticed a curious
issue that manifests in long-running devices.

The method 'dhcp_task' uses rtems_event_receive() with a timeout of
1000ms to measure time (receiving the event itself causes dhcp_task to
exit). We're using 4.9 but with dhcp related files backported from 4.10,
so we look like this:

http://git.rtems.org/rtems/tree/cpukit/libnetworking/rtems/rtems_dhcp.c?h=4.10#n705

Our problem is that the software can get into a state where
rtems_event_receive() never returns - in a recent case, the count was
25287 seconds - well into the lease, but not of any particular significance.

I had a network monitor interposed, recording all inbound and outbound
traffic to the device: There is no network traffic of note at the time
of failure.

I've scanned bugzilla and the mailing list, but couldn't find a mention
of a similar issue.

Has anyone spotted behaviour like this before? The rarity of the issue
feels like a subtle race to me - better thought would be very welcome :)

FWIW: We're using the virtex bsp (ppc405).

Any tips or thoughts would be much appreciated!

Cheers,
Tim