Re: [PATCH] drm/i915: Propagate error from drm_gem_object_init()

From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
To: Dave Gordon <david.s.gordon@intel.com>,
	intel-gfx@lists.freedesktop.org,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Matthew Auld <matthew.auld@intel.com>
Subject: Re: [PATCH] drm/i915: Propagate error from drm_gem_object_init()
Date: Fri, 22 Apr 2016 16:44:54 +0300	[thread overview]
Message-ID: <1461332694.28225.1.camel@linux.intel.com> (raw)
In-Reply-To: <571A122F.7000109@intel.com>

On pe, 2016-04-22 at 12:59 +0100, Dave Gordon wrote:
> On 22/04/16 11:57, Matthew Auld wrote:
> > 
> > From: Chris Wilson <chris@chris-wilson.co.uk>
> > 
> > Propagate the real error from drm_gem_object_init(). Note this also
> > fixes some confusion in the error return from i915_gem_alloc_object...
> > 
> > v2:
> > (Matthew Auld)
> >    - updated new users of gem_alloc_object from latest drm-nightly
> >    - replaced occurrences of IS_ERR_OR_NULL() with IS_ERR()
> > v3:
> > (Joonas Lahtinen)
> >    - fix double "From:" in commit message
> >    - add goto teardown path
> > 
> > Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > ---
> >   drivers/gpu/drm/i915/i915_gem.c              | 21 +++++++++++++--------
> >   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 |  7 +++++--
> >   drivers/gpu/drm/i915/i915_guc_submission.c   |  2 +-
> >   drivers/gpu/drm/i915/intel_display.c         |  4 ++--
> >   drivers/gpu/drm/i915/intel_fbdev.c           |  4 ++--
> >   drivers/gpu/drm/i915/intel_lrc.c             | 10 ++++++----
> >   drivers/gpu/drm/i915/intel_overlay.c         |  2 +-
> >   drivers/gpu/drm/i915/intel_ringbuffer.c      | 19 ++++++++++---------
> >   10 files changed, 44 insertions(+), 33 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index 261a3ef..c6c17dd 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -382,8 +382,8 @@ i915_gem_create(struct drm_file *file,
> > 
> >   	/* Allocate the new object */
> >   	obj = i915_gem_alloc_object(dev, size);
> > -	if (obj == NULL)
> > -		return -ENOMEM;
> > +	if (IS_ERR(obj))
> > +		return PTR_ERR(obj);
> > 
> >   	ret = drm_gem_handle_create(file, &obj->base, &handle);
> >   	/* drop reference from allocate - handle holds it now */
> > @@ -4498,15 +4498,15 @@ struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev,
> >   	struct drm_i915_gem_object *obj;
> >   	struct address_space *mapping;
> >   	gfp_t mask;
> > +	int ret;
> > 
> >   	obj = i915_gem_object_alloc(dev);
> >   	if (obj == NULL)
> > -		return NULL;
> > +		return ERR_PTR(-ENOMEM);
> The two changes above looked really really confusing, where one tests 
> the returned pointer and returns it if it's an ERR_PTR, and the other 
> tests for NULL and returns ERR_PTR(-ENOMEM).
> 
> Then I realised one was i915_gem_alloc_object() and the other was 
> i915_gem_object_alloc()!

Yep, noticed that a few days ago too, +1 on correcting it.

Regards, Joonas

> 
> Can we please get rid of one or the other? Since we generally use 
> subsystem_class_action naming, I'd suggest keeping (the low-level 
> memory-allocator) i915_gem_object_alloc(), and renaming the high-level 
> i915_gem_alloc_object() to i915_gem_object_create() or similar.
> 
> > 
> > -	if (drm_gem_object_init(dev, &obj->base, size) != 0) {
> > -		i915_gem_object_free(obj);
> > -		return NULL;
> > -	}
> > +	ret = drm_gem_object_init(dev, &obj->base, size);
> > +	if (ret)
> > +		goto fail;
> > 
> >   	mask = GFP_HIGHUSER | __GFP_RECLAIMABLE;
> >   	if (IS_CRESTLINE(dev) || IS_BROADWATER(dev)) {
> > @@ -4543,6 +4543,11 @@ struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev,
> >   	trace_i915_gem_object_create(obj);
> Oh and BTW i915_gem_alloc_object() already calls itself 
> i915_gem_object_create() in trace messages!
> 
> .Dave.
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> Intel-gfx@lists.freedesktop.org
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-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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