Re: [PATCH] drm/i915: Don't unregister fbdev twice

From: Lukas Wunner <lukas@wunner.de>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Don't unregister fbdev twice
Date: Wed, 8 Jun 2016 19:03:02 +0200	[thread overview]
Message-ID: <20160608170302.GB18955@wunner.de> (raw)
In-Reply-To: <20160608120940.GC3363@phenom.ffwll.local>

On Wed, Jun 08, 2016 at 02:09:40PM +0200, Daniel Vetter wrote:
> On Wed, Jun 08, 2016 at 01:15:22PM +0200, Lukas Wunner wrote:
> > Calling drm_framebuffer_unregister_private() in intel_fbdev_destroy() is
> > superfluous because the framebuffer will subsequently be unregistered by
> > drm_framebuffer_free() when unreferenced in drm_framebuffer_remove().
> > The call is a leftover, when it was introduced by commit 362063619cf6
> > ("drm: revamp framebuffer cleanup interfaces"), struct intel_framebuffer
> > was still embedded in struct intel_fbdev rather than being a pointer as
> > it is today, and drm_framebuffer_remove() wasn't used yet.
> > 
> > As a bonus, the ID of the framebuffer is no longer 0 in the debug log:
> > 
> > Before:
> >     [   39.680874] [drm:drm_mode_object_unreference] OBJ ID: 0 (3)
> >     [   39.680878] [drm:drm_mode_object_unreference] OBJ ID: 0 (2)
> >     [   39.680884] [drm:drm_mode_object_unreference] OBJ ID: 0 (1)
> > 
> > After:
> >     [  102.504649] [drm:drm_mode_object_unreference] OBJ ID: 45 (3)
> >     [  102.504651] [drm:drm_mode_object_unreference] OBJ ID: 45 (2)
> >     [  102.504654] [drm:drm_mode_object_unreference] OBJ ID: 45 (1)
> > 
> > Signed-off-by: Lukas Wunner <lukas@wunner.de>
> 
> Hm yeah. But there's a pile of that particaluar cargo-culting copied all
> over the place, would be really good to audit all callers of
> unregister_private and fix them all up. A few older drivers still embed
> the fbdev fb, but most don't but still use the unregister_private +
> cleanup combo.

Yes, I noticed that but i915 was the only one that I could actually test,
the others I can only compile test. So fixing those up requires very
careful examination and takes more time, but I'll keep it on my todo list.

> Nitpick in your subject: s/fbdev/fbdev's fb/

Right, should I post a v2 or are you going to fix it up if/when merging?

Thanks,

Lukas

> 
> > ---
> >  drivers/gpu/drm/i915/intel_fbdev.c | 2 --
> >  1 file changed, 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> > index ef8e676..4c7ea46 100644
> > --- a/drivers/gpu/drm/i915/intel_fbdev.c
> > +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> > @@ -552,8 +552,6 @@ static void intel_fbdev_destroy(struct drm_device *dev,
> >  	drm_fb_helper_fini(&ifbdev->helper);
> >  
> >  	if (ifbdev->fb) {
> > -		drm_framebuffer_unregister_private(&ifbdev->fb->base);
> > -
> >  		mutex_lock(&dev->struct_mutex);
> >  		intel_unpin_fb_obj(&ifbdev->fb->base, BIT(DRM_ROTATE_0));
> >  		mutex_unlock(&dev->struct_mutex);
> > -- 
> > 2.8.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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