Mike Frysinger ha scritto:
On Mon, Sep 29, 2008 at 08:59, damico wrote:
Mike Frysinger ha scritto:
When the reboot program runs, it sends SIGHUP right after SIGTERM, so we
need to handle it as well.
I'm not sure that SIGHUP signal should be handled while rebooting system.
IMHO: sending SIGHUP signal while reboot system is not correct. Maybe, only
reboot from sysutils issue a SIGHUP to all process before sending SIGKILL.
For instance reboot from busybox don't issue any SIGHUP signal but just
SIGTERM and finally a SIGKILL.
that doesnt make any sense. if watchdogd does not handle SIGHUP, the
default signal handler takes over which means the program exits
uncleanly and the watchdog device may kick in. if you want an unclean
exit, send watchdogd SIGKILL. which is what the default
sysutils/reboot.c does after a delay.
OK, I understand. It is clear and right : watchdogd MUST catch SIGHUP.
I was looking for some specification on shutdown and signals in the net but
I haven't found any reliable note on that topic.
there is no such spec
Just at http://linux.die.net/man/8/shutdown I read about SIGTERM but nowhere
I found anything about SIGHUP.
Anyway, on dhcpcd README there is a note:
[quote]
7. Other Information
dhcpcd sends DHCP_RELEASE message to the DHCP server, deletes the
/etc/dhcpc/dhcpcd-interface.cache file and brings the attached
network interface down when it gets SIGHUP signal. It will
not send DHCP_RELEASE message and will not delete
/etc/dhcpc/dhcpcd-interface.cache file in a case it gets
SIGTERM as normally happens upon reboot.
[quote]
So, when the system reboot if a SIGHUP signal is sent to dhcpcd the result
is that we lost the ip address.
I think that the only thing to do is remove from sysutils/reboot.c
kill(-1, SIGHUP);
I did it one year ago .... Now my devices preserve the ip address when I
reboot them ... :)
let me know If you have some specifications about the signals that should
issue while rebooting system. I can revert my modifications and modify
dhcpcd to change its behaviour.
what happens with sysutils/reboot.c doesnt really matter to me. if
you want to know what the "correct" behavior is, you should just look
at the sysvinit implementation of reboot. which does send SIGTERM and
SIGHUP when rebooting.
-mike
I took a look to sysvinit's source code I wasn't able to find where the
SIGHUP signal does send... but I wrote a test code to see what happens
on my debian box and I can see the SIGHUP signal when rebooting.
So, I'm not smart enough to understand sysvinit's source code :)
Just a question. What is the correct signal that dhcpcd should handle in
order to send a DHCP_RELEASE to the DHCP server?
Thank you very much.
Regards
--Michele
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