On Sun, 7 Mar 2010 16:16:56 +0100
Wim Van Sebroeck <wim@iguana.be> wrote:
At least on the system I run on, the watchdog is turned off by the
reboot itself, so it won't trigger on the next start anyway. But from
Padraigs mail earlier I understand that this isn't the case everywhere,
so it's a valid concern.
However, I still think it would be nice to have this option avaiable
for those that need it. Perhaps some option like "noshutdown" to keep
it running during reboots.
Sorry, I should have been more clear here: The system hangs during
shutdown (for reboot), not during the next bootup (when it's turned off
anyway). So what my patch was trying to protect for is a hang before
restart.
You are of course right - the core issue is the hang itself. The hang
occurs very rarely, and I don't have a way to reproduce it. We've seen
it on both an old 2.6.23 kernel and 2.6.31 (what we use currently).
I've manually inspected all shutdown calls and reboot notifiers which
gets called on reboot, but not seen any obvious places where the system
can hang. I'm suspecting some interaction with an interrupt handler or
similar, but I can't really tell.
The patch I sent provides protection against this hang, and it's
something we really need until we've found the real issue.
Unfortunately, iTCO_wdt is the first driver the shutdown() call is made
to, so the hang could be in any of the other shutdown() calls. I could
perhaps also go with a solution where the watchdog was guaranteed to be
turned off last right before reboot.
// Simon
--
