[Intel-gfx] [PATCH 2/2] drm/fb-helper: Fix fb refcounting in pan_display_atomic

[Daniel Vetter]

On Fri, Oct 16, 2015 at 07:48:37PM +0300, Ville Syrjälä wrote:
> On Fri, Oct 16, 2015 at 06:23:14PM +0200, Daniel Vetter wrote:
> > In
> > 
> > commit bbb1e52402b2a288b09ae37e8182599931c7e9df
> > Author: Rob Clark <robdclark at gmail.com>
> > Date:   Tue Aug 25 15:35:58 2015 -0400
> > 
> >     drm/fb-helper: atomic restore_fbdev_mode()..
> > 
> > we've forgotten to do the plane->old_fb refcount dance for
> > pan_display_atomic, which can result in refcount leaks if the current
> > configuration is not from fbcon. Which apparently can happen when
> > vt-switching - fbcon does a pan first before a set_par.
> > 
> > OCD-align function parameters while at it.
> > 
> > Cc: Rob Clark <robdclark at gmail.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi at gmail.com>
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92483
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> >  drivers/gpu/drm/drm_fb_helper.c | 27 +++++++++++++++++++++++++--
> >  1 file changed, 25 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> > index 0ac0fcc9b0d2..b2cf28dd90fe 100644
> > --- a/drivers/gpu/drm/drm_fb_helper.c
> > +++ b/drivers/gpu/drm/drm_fb_helper.c
> > @@ -1249,6 +1249,8 @@ retry:
> >  
> >  		mode_set = &fb_helper->crtc_info[i].mode_set;
> >  
> > +		mode_set->crtc->primary->old_fb = mode_set->crtc->primary->fb;
> > +
> >  		mode_set->x = var->xoffset;
> >  		mode_set->y = var->yoffset;
> >  
> > @@ -1264,13 +1266,34 @@ retry:
> >  	info->var.xoffset = var->xoffset;
> >  	info->var.yoffset = var->yoffset;
> >  
> > -	return 0;
> >  
> >  fail:
> 
> Time to rename the label too?

Other atomic functions use fail: too. I guess we could do a large-scale
rename to out: or something ...
-Daniel

> 
> > +	for(i = 0; i < fb_helper->crtc_count; i++) {
> > +		struct drm_mode_set *mode_set;
> > +		struct drm_plane *plane;
> > +
> > +		mode_set = &fb_helper->crtc_info[i].mode_set;
> > +		plane = mode_set->crtc->primary;
> > +
> > +		if (ret == 0) {
> > +			struct drm_framebuffer *new_fb = plane->state->fb;
> > +
> > +			if (new_fb)
> > +				drm_framebuffer_reference(new_fb);
> > +			plane->fb = new_fb;
> > +			plane->crtc = plane->state->crtc;
> > +
> > +			if (plane->old_fb)
> > +				drm_framebuffer_unreference(plane->old_fb);
> > +		}
> > +		plane->old_fb = NULL;
> > +	}
> > +
> >  	if (ret == -EDEADLK)
> >  		goto backoff;
> >  
> > -	drm_atomic_state_free(state);
> > +	if (ret != 0)
> > +		drm_atomic_state_free(state);
> >  
> >  	return ret;
> >  
> > -- 
> > 2.5.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
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> dri-devel at lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch