On Thu, May 17, 2018 at 10:40 AM, Souptick Joarder <jrdr.linux@xxxxxxxxx> wrote:
> On Thu, May 17, 2018 at 12:48 AM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
>> Quoting Souptick Joarder (2018-05-16 20:12:20)
>>> 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.
>>>
>>> commit 1c8f422059ae ("mm: change return type to vm_fault_t")
>>>
>>> Fixed one checkpatch.pl warning inside WARN_ONCE.
>>>
>>> Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
>>> ---
>>
>>> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
>>> index dd89abd..732abdf 100644
>>> --- a/drivers/gpu/drm/i915/i915_gem.c
>>> +++ b/drivers/gpu/drm/i915/i915_gem.c
>>> @@ -1882,7 +1882,7 @@ int i915_gem_mmap_gtt_version(void)
>>> * The current feature set supported by i915_gem_fault() and thus GTT mmaps
>>> * is exposed via I915_PARAM_MMAP_GTT_VERSION (see i915_gem_mmap_gtt_version).
>>> */
>>> -int i915_gem_fault(struct vm_fault *vmf)
>>> +vm_fault_t i915_gem_fault(struct vm_fault *vmf)
>>> {
>>> #define MIN_CHUNK_PAGES ((1 << 20) >> PAGE_SHIFT) /* 1 MiB */
>>> struct vm_area_struct *area = vmf->vma;
>>> @@ -1894,7 +1894,8 @@ int i915_gem_fault(struct vm_fault *vmf)
>>> struct i915_vma *vma;
>>> pgoff_t page_offset;
>>> unsigned int flags;
>>> - int ret;
>>> + int err;
>>> + vm_fault_t ret = VM_FAULT_SIGBUS;
>>>
>>> /* We don't use vmf->pgoff since that has the fake offset */
>>> page_offset = (vmf->address - area->vm_start) >> PAGE_SHIFT;
>>> @@ -2027,8 +2028,7 @@ int i915_gem_fault(struct vm_fault *vmf)
>>> ret = VM_FAULT_SIGBUS;
>>> break;
>>> default:
>>> - WARN_ONCE(ret, "unhandled error in i915_gem_fault: %i\n", ret);
>>> - ret = VM_FAULT_SIGBUS;
>>> + WARN_ONCE(ret, "unhandled error in %s: %x\n", __func__, err);
>>> break;
>>
>> Even simpler would be to use e.g. return VM_FAULT_SIGBUS for each case
>> above. No early initialisation of use-once variables allowing the
>> compiler to do it's job. For a smaller patch, you can even skip the
>> s/ret/err/
>> -Chris
>
> Chris,
> I prefer to use return once at the end of the function rather than
> writing multiple return statement (Current code is doing similar).
> But if you think other way, I can make that change :)
If no further comment, we would like to get this patch
in queue for 4.18
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