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

[Laurent Dufour <ldufour@linux.vnet.ibm.com>]

Le 24/07/2019 à 11:24, Oliver O'Halloran a écrit :
> On Wed, Jul 24, 2019 at 7:17 PM Laurent Dufour
> <ldufour@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;
  	}