[PATCH v5 4/4] powerpc/papr_scm: Force a scm-unbind if initial scm-bind fails

[Oliver O'Halloran]

On Wed, Jul 24, 2019 at 7:27 PM Laurent Dufour
<ldufour at linux.vnet.ibm.com> wrote:
>
> Le 24/07/2019 à 11:24, Oliver O'Halloran a écrit :
> > On Wed, Jul 24, 2019 at 7:17 PM Laurent Dufour
> > <ldufour at linux.vnet.ibm.com> wrote:
> >>
> >> Le 23/07/2019 à 18:13, Vaibhav Jain a écrit :
> >>> *snip*
> >>> @@ -404,6 +409,14 @@ static int papr_scm_probe(struct platform_device *pdev)
> >>>
> >>>        /* request the hypervisor to bind this region to somewhere in memory */
> >>>        rc = drc_pmem_bind(p);
> >>> +
> >>> +     /* If phyp says drc memory still bound then force unbound and retry */
> >>> +     if (rc == -EBUSY) {
> >>> +             dev_warn(&pdev->dev, "Retrying bind after unbinding\n");
> >>> +             drc_pmem_unbind(p);
> >>> +             rc = drc_pmem_bind(p);
> >>
> >> In the unlikely case where H_SCM_BIND_MEM is returning H_OVERLAP once the
> >> unbinding has been done, the error would be silently processed. That sounds
> >> really unlikely, but should an error message be displayed in this
> >> particular case ?
> >
> > drc_pmem_bind() prints the h-call error code if we get one, so it's not silent
>
> That's no more the case whith this patch, H_OVERLAP is handled before
> writing the error message, which would make sense for the first try.
>
> For the record, the patch introduces:
>
> @@ -65,6 +66,10 @@ static int drc_pmem_bind(struct papr_scm_priv *p)
>         } while (rc == H_BUSY);
>
>         if (rc) {
> +               /* H_OVERLAP needs a separate error path */
> +               if (rc == H_OVERLAP)
> +                       return -EBUSY;
> +
>                 dev_err(&p->pdev->dev, "bind err: %lld\n", rc);
>                 return -ENXIO;
>         }

Ah, good point. Getting H_OVERLAP is still an error case so I think
it's reasonable to still print the message in that case.