Re: [Qemu-devel] [PATCH] virtio: abort on fatal error instead of just exiting

[Igor Mammedov]

On Thu, 30 Jun 2016 07:12:08 +0200
Markus Armbruster <address@hidden> wrote:

> Igor Mammedov <address@hidden> writes:
> 
> > On Wed, 29 Jun 2016 14:49:59 +0200
> > Markus Armbruster <address@hidden> wrote:
> >  
> >> Igor Mammedov <address@hidden> writes:
> >>   
> >> > replace mainly useless exit(1) on fatal error path with
> >> > abort(), so that it would be possible to generate core
> >> > dump, that could be used to analyse cause of problem.
> >> >
> >> > Signed-off-by: Igor Mammedov <address@hidden>
> >> > ---
> >> >  hw/virtio/virtio.c | 24 ++++++++++++------------
> >> >  1 file changed, 12 insertions(+), 12 deletions(-)
> >> >
> >> > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> >> > index 7ed06ea..9d3ac72 100644
> >> > --- a/hw/virtio/virtio.c
> >> > +++ b/hw/virtio/virtio.c
> >> > @@ -315,7 +315,7 @@ static int virtqueue_num_heads(VirtQueue *vq,
> >> > unsigned int idx) if (num_heads > vq->vring.num) {
> >> >          error_report("Guest moved used index from %u to %u",
> >> >                       idx, vq->shadow_avail_idx);
> >> > -        exit(1);
> >> > +        abort();  
> >> 
> >> What's wrong with a simple assert(num_heads <= vq->vring.num)?  
> > Nothing, it should work to as we don't use NDEBUG.
> > My intent was to make core dump at the point and no to remove
> > error message
> > (though message's mostly useless for me as virtio is unfamiliar to me
> > and  I had to dig into core dump to analyze issue).  
> 
> Understand.
> 
> The solution we really want is of course putting the device in an error
> state, where it stays until reset.
As Cornelia has mentioned earlier, there is/were a series on list for it,
aborting is just an interim step until those patches are ready.