[PATCH] powerpc: platform: cell: spufs: Change return type to vm_fault_t

[Souptick Joarder]

On Wed, Apr 18, 2018 at 2:17 AM, Matthew Wilcox <willy at infradead.org> wrote:
> On Wed, Apr 18, 2018 at 12:50:38AM +0530, Souptick Joarder wrote:
>> Use new return type vm_fault_t for fault handler. For
>> now, this is just documenting that the function returns
>> a VM_FAULT value rather than an errno. Once all instances
>> are converted, vm_fault_t will become a distinct type.
>>
>> Reference id -> 1c8f422059ae ("mm: change return type to
>> vm_fault_t")
>>
>> Previously vm_insert_pfn() returns err but driver returns
>> VM_FAULT_NOPAGE as default. The new function vmf_insert_pfn()
>> will replace this inefficiency by returning correct VM_FAULT_*
>> type.
>>
>> vmf_handle_error is a inline wrapper function which
>> will convert error number to vm_fault_t type err.
>
> I think you sent the wrong version of this one ...
>
> The commit message should mention that we're fixing a minor bug, that
> the error from vm_insert_pfn() was being ignored and the effect of this
> is likely to be only felt in OOM situations.

Ok, I will add this.
>
>> @@ -256,11 +257,11 @@ static ssize_t spufs_attr_write(struct file *file, const char __user *buf,
>>               vma->vm_page_prot = pgprot_noncached_wc(vma->vm_page_prot);
>>               pfn = (ctx->spu->local_store_phys + offset) >> PAGE_SHIFT;
>>       }
>> -     vm_insert_pfn(vma, vmf->address, pfn);
>> +     ret = vmf_insert_pfn(vma, vmf->address, pfn);
>>
>>       spu_release(ctx);
>>
>> -     return VM_FAULT_NOPAGE;
>> +     return ret;
>>  }
>
> I thought I said not to introduce vmf_handle_error(), because it's too
> trivial and obfuscates what's actually going on.
>
>> -static int spufs_ps_fault(struct vm_fault *vmf,
>> +static inline vm_fault_t vmf_handle_error(int err)
>> +{
>> +     return VM_FAULT_NOPAGE;
>> +}
>> +
>
> Re-reading spufs_ps_fault(), I wouldn't change anything inside it.  Just
> change its return type to vm_fault_t and call it done.

In that case, return value of spufs_wait() has to changed
to VM_FAULT_ type and we end with changing all the
references where spufs_wait() is called. I think we shouldn't
go with that approach. That's the reason I introduce inline
vmf_handle_error() and convert err to VM_FAULT_ type.