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Date: Sat, 27 Mar 2010 14:05:34 +0100
From: Aurelien Jarno <aurelien@aurel32.net>
Subject: Re: [Qemu-devel] [PATCH] fix race between timer firing vs.
	alarm_timer->pending = 0
Message-ID: <20100327130534.GN15194@volta.aurel32.net>
References: <a38b25541003190247g1a34df71g40dc6a6ca709c53a@mail.gmail.com>
	<1268994635-5788-1-git-send-email-pbonzini@redhat.com>
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: geleman@gmail.com, aliguori@us.ibm.com, qemu-devel@nongnu.org

On Fri, Mar 19, 2010 at 11:30:35AM +0100, Paolo Bonzini wrote:
> The period for Win32 timers is very short and always the same
> independent of dynticks, so it's possible that the timer fires
> before qemu_run_all_timers has reset alarm_timer->pending to zero.
> Reset alarm_timer->pending before rearming.

Thanks, applied.

> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  qemu-timer.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/qemu-timer.c b/qemu-timer.c
> index 329d3a4..49eac86 100644
> --- a/qemu-timer.c
> +++ b/qemu-timer.c
> @@ -706,14 +706,14 @@ void configure_icount(const char *option)
>  
>  void qemu_run_all_timers(void)
>  {
> +    alarm_timer->pending = 0;
> +
>      /* rearm timer, if not periodic */
>      if (alarm_timer->expired) {
>          alarm_timer->expired = 0;
>          qemu_rearm_alarm_timer(alarm_timer);
>      }
>  
> -    alarm_timer->pending = 0;
> -
>      /* vm time timers */
>      if (vm_running) {
>          qemu_run_timers(vm_clock);
> -- 
> 1.6.6.1
> 
> 
> 
> 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net