Re: [libvirt] [PATCH 2/5] daemonize qemu processes

[Daniel Veillard <veillard redhat com>]

On Mon, Dec 15, 2008 at 11:21:20AM +0000, Daniel P. Berrange wrote:
> On Fri, Dec 12, 2008 at 07:26:32PM +0100, Guido G?nther wrote:
> > +    if (kill(vm->pid, SIGTERM) < 0)
> > +        qemudLog(QEMUD_ERROR, _("Failed to send SIGTERM to %s (%d): %s\n"),
> > +                 vm->def->name, vm->pid, strerror(errno));
> 
> We should add a guard around all the kill() statements for
> 
>   if (vm->pid > 1)
>      kill..
> 
> One of the bugs I found when doing the LXC/UML drivers is that when relying 
> on an external PID file, some things can go wrong in unexpected ways that
> just don't happen when getting the PID straight back from fork. This often
> ended up with vm->pid being -1, 0 with horrific results - 
> 
>    "If  pid equals -1, then sig is sent to every process for which the calling
>     process has permission to send signals, except for process 1 (init)"
> 
> Yes, I killed every single process on my dev machine several times before
> discovering this isues :-)

  This call for an utility function
    int virKillProcess(pid_t pid, int sig)
call checking for this, could also help on debugging/logging

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/