Re: [Qemu-devel] [RFC v2 3/5] timer: make qemu_clock_enable sync between disable and timer's cb

[Stefan Hajnoczi <stefanha@redhat.com>]

On Fri, Aug 02, 2013 at 11:33:40AM +0800, liu ping fan wrote:
> On Thu, Aug 1, 2013 at 9:28 PM, Alex Bligh <alex@alex.org.uk> wrote:
> > Paolo,
> >
> >
> > --On 1 August 2013 08:19:34 -0400 Paolo Bonzini <pbonzini@redhat.com> wrote:
> >
> >>> > True, qemu_event basically works only when a single thread resets it.
> >>> > But there is no race condition here because qemu_run_timers cannot be
> >>> > executed concurrently by multiple threads (like aio_poll in your
> >>> > bottom half patches).
> >>>
> >>> ... or, if rebasing on top of my patches, qemu_run_timers *can* be
> >>> executed concurrently by mulitple threads, but in respect of any given
> >>> QEMUTimerList, it will only be executed by one thread.
> >>
> >>
> >> ... so the event would be placed in QEMUTimerList, not QEMUClock.
> >
> >
> > Correct
> >
> >
> >> qemu_clock_enable then will have to visit all timer lists. That's
> >> not hard to do,
> >
> >
> > Correct, v4 of my patch does this.
> >
> >
> >> but as locks proliferate we need to have a clear
> >> policy (e.g. BQL -> clock -> timerlist).
> >
> >
> > But doesn't do the locking bit yet (Pingfan is going to do that I hope)
> >
> Seem that Stefanha had been involved in this, and sent out his patches :)

Hi Ping Fan,
I dropped the series where I added locks to qemu-timer.c from a few
weeks ago.

With your series rebased onto Alex's series, I think my patches are no
longer needed?

Stefan