Re: [Xen-devel] [PATCH v3 6/8] x86/vm-event: minor ASSERT fix, add 'unlikely'

[Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>]

On 7/7/2016 11:27 AM, Jan Beulich wrote:
> > > > On 06.07.16 at 17:54, <czuzu@xxxxxxxxxxxxxxx> wrote:
> > --- a/xen/arch/x86/hvm/hvm.c
> > +++ b/xen/arch/x86/hvm/hvm.c
> > @@ -475,7 +475,7 @@ void hvm_do_resume(struct vcpu *v)
> >   
> >       if ( unlikely(v->arch.vm_event) )
> >       {
> > -        if ( v->arch.vm_event->emulate_flags )
> > +        if ( unlikely(v->arch.vm_event->emulate_flags) )
> >           {
> >               enum emul_kind kind = EMUL_KIND_NORMAL;
> >   
> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> > --- a/xen/arch/x86/vm_event.c
> > +++ b/xen/arch/x86/vm_event.c
> > @@ -96,14 +96,16 @@ void vm_event_register_write_resume(struct vcpu *v,
> > vm_event_response_t *rsp)
> >   {
> >       if ( rsp->flags & VM_EVENT_FLAG_DENY )
> >       {
> > -        struct monitor_write_data *w = &v->arch.vm_event->write_data;
> > +        struct monitor_write_data *w;
> >   
> > -        ASSERT(w);
> > +        ASSERT(v->arch.vm_event);
> >   
> >           /* deny flag requires the vCPU to be paused */
> >           if ( !atomic_read(&v->vm_event_pause_count) )
> >               return;
> >   
> > +        w = &v->arch.vm_event->write_data;
> > +
> >           switch ( rsp->reason )
> >           {
> >           case VM_EVENT_REASON_MOV_TO_MSR:
> I'd have preferred for you to leave alone the initializer, but we'll see
> what the maintainers are going to say.
>
> Jan
It's 'cleaner' this way, doesn't it? Not assigning a pointer to a 
possibly invalid address...
Anyway, I'm preparing a v4, I'll probably drop this change if you won't 
*subdue* to ack it (kidding).
Thanks,
Corneliu.

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