Re: [Xen-devel] [PATCH 03/16] xen: sched: make implementing .alloc_pdata optional

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

On Mon, 2016-04-04 at 00:13 -0600, Jan Beulich wrote:
> > > > On 01.04.16 at 19:01, <dario.faggioli@xxxxxxxxxx> wrote:
> > Ok, I'll do:
> > 
> >     sd->sched_priv = SCHED_OP(&ops, alloc_pdata, cpu);
> >     if ( IS_ERR(sd->sched_priv) )
> >     {
> >         int err = PTR_ERR(sd->sched_priv);
> > 
> >         sd->sched_priv = NULL;
> >         return err;
> >     }
> > 
> > Is this ok?
> Depends: Can ->sched_priv be looked at by another CPU between
> the first and second assignments? If yes, you need to use an
> intermediary local variable.
> 
Mmm... good point. I don't see this happening, but using a local
variable is more "defensive programming oriented", so I'm going for it.

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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