Re: [PATCH 3/6] drm/i915: Propagating correct error codes to the userspace

From: Dave Gordon <david.s.gordon@intel.com>
To: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/6] drm/i915: Propagating correct error codes to the userspace
Date: Fri, 9 Oct 2015 16:13:24 +0100	[thread overview]
Message-ID: <5617D994.7030004@intel.com> (raw)
In-Reply-To: <561643F5.1050308@linux.intel.com>

On 08/10/15 11:22, Tvrtko Ursulin wrote:
>
> Hi,
>
> On 08/10/15 07:24, ankitprasad.r.sharma@intel.com wrote:
>> From: Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>
>>
>> Propagating correct error codes to userspace by using ERR_PTR and
>> PTR_ERR macros for stolen memory based object allocation. We generally
>> return -ENOMEM to the user whenever there is a failure in object
>> allocation. This patch helps user to identify the correct reason for the
>> failure and not just -ENOMEM each time.
>>
>> v2: Moved the patch up in the series, added error propagation for
>> i915_gem_alloc_object too (Chris)
>>
>> Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>
>> ---
>>   drivers/gpu/drm/i915/i915_gem.c              | 15 +++++-----
>>   drivers/gpu/drm/i915/i915_gem_batch_pool.c   |  4 +--
>>   drivers/gpu/drm/i915/i915_gem_context.c      |  4 +--
>>   drivers/gpu/drm/i915/i915_gem_render_state.c |  4 +--
>>   drivers/gpu/drm/i915/i915_gem_stolen.c       | 43
>> ++++++++++++++++------------
>>   drivers/gpu/drm/i915/i915_guc_submission.c   |  4 +--
>>   drivers/gpu/drm/i915/intel_display.c         |  2 +-
>>   drivers/gpu/drm/i915/intel_fbdev.c           |  6 ++--
>>   drivers/gpu/drm/i915/intel_lrc.c             |  8 +++---
>>   drivers/gpu/drm/i915/intel_overlay.c         |  4 +--
>>   drivers/gpu/drm/i915/intel_pm.c              |  2 +-
>>   drivers/gpu/drm/i915/intel_ringbuffer.c      | 20 ++++++-------
>>   12 files changed, 61 insertions(+), 55 deletions(-)

[snip]

>> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c
>> b/drivers/gpu/drm/i915/i915_guc_submission.c
>> index 792d0b9..3901698 100644
>> --- a/drivers/gpu/drm/i915/i915_guc_submission.c
>> +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
>> @@ -646,8 +646,8 @@ static struct drm_i915_gem_object
>> *gem_allocate_guc_obj(struct drm_device *dev,
>>       struct drm_i915_gem_object *obj;
>>
>>       obj = i915_gem_alloc_object(dev, size);
>> -    if (!obj)
>> -        return NULL;
>> +    if (IS_ERR(obj))
>> +        return obj;
>
> You have to change kerneldoc for this function now.
> And even more importantly update error handling in the callers!

Or more simply, stop propagating the specific error at this level (it 
doesn't really help and probably can't even happen here), making this:

 >>       obj = i915_gem_alloc_object(dev, size);
 >> -    if (!obj)
 >> +    if (IS_ERR(obj))

leaving the "return NULL;" unchanged.

.Dave.
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