Re: [Qemu-devel] [PATCH] vl.c/exit: pause cpus before closing block devices

[Stefan Hajnoczi]

On Thu, Jul 13, 2017 at 08:01:16PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
> 
> There's a rare exit seg if the guest is accessing
> IO during exit.
> It's always hitting the atomic_inc(&bs->in_flight) with a NULL
> bs. This was added recently in 99723548  but I don't see it
> as the cause.
> 
> Flip vl.c around so we pause the cpus before closing the block devices,
> that way we shouldn't have anything trying to access them when
> they're gone.
> 
> This was originally Red Hat bz 
> https://bugzilla.redhat.com/show_bug.cgi?id=1451015
> 
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> Reported-by: Cong Li <address@hidden>
> 
> --
> This is a very rare race, I'll leave it running in a loop to see if
> we hit anything else and to check this really fixes it.
> 
> I do worry if there are other cases that can trigger this - e.g.
> hot-unplug or ejecting a CD.
> 
> ---
>  vl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Stefan Hajnoczi <address@hidden>

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