[Qemu-devel] Re: [PATCH 01/22] Prevent abortion on multiple VCPU kicks

[Avi Kivity]

On 01/31/2011 01:19 PM, Jan Kiszka wrote:
> On 2011-01-31 10:44, Avi Kivity wrote:
> >  On 01/27/2011 03:09 PM, Jan Kiszka wrote:
> >>  If we call qemu_cpu_kick more than once before the target was able to
> >>  process the signal, pthread_kill will fail, and qemu will abort. Prevent
> >>  this by avoiding the redundant signal.
> >>
> >
> >  Doesn't fit with the manual page (or with the idea that signals are
> >  asynchronous):
> >
> >  NAME
> >          pthread_kill - send a signal to a thread
> >
> >
> >  ...
> >
> >  ERRORS
> >          ESRCH  No thread with the ID thread could be found.
> >
> >          EINVAL An invalid signal was specified.
> >
>
> Valid remark, but I was receiving EAGAIN for blocked RT signals. Don't
> know if this is Linux-specific. A quick glance at the man pages did not
> reveal if this is allowed or at least gray area.

    } else if (!is_si_special(info)) {
        if (sig >= SIGRTMIN && info->si_code != SI_USER) {
            /*
             * Queue overflow, abort.  We may abort if the
             * signal was rt and sent by user using something
             * other than kill().
             */
            trace_signal_overflow_fail(sig, group, info);
            return -EAGAIN;
        }

> However, even when selectively ignoring this, it's more efficient to
> catch the redundant signaling in user space.

Yes.

--
error compiling committee.c: too many arguments to function