From 5cef29aa5227e6347145940a7bccde92fd9a1afa Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Sat, 15 Jun 2013 00:13:16 +0200 Subject: [PATCH] drm: fix fb leak in setcrtc Drivers are allowed (actually have to) disable unrelated crtcs in their ->set_config callback (when we steal all the connectors from that crtc). If they do that they'll clear crtc->fb to NULL. Which results in a refcount leak, since the drm core is keeping track of that reference. To fix this track the old fb of all crtcs and adjust references for all of them. Of course, since we only hold an additional reference for the fb for the current crtc we need to increase refcounts before we drop the old one. This approach has the benefit that it inches us a bit closer to an atomic modeset world, where we want to update the config of all crtcs in one step. This regression has been introduce in the framebuffer refcount conversion, specifically in commit b0d1232589df5575c5971224ac4cb30e7e525884 Author: Daniel Vetter Date: Tue Dec 11 01:07:12 2012 +0100 drm: refcounting for crtc framebuffers Reported-by: Russell King Cc: Russell King Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_crtc.c | 22 ++++++++++++++++------ include/drm/drm_crtc.h | 4 ++++ 2 files changed, 20 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index a7dc1e2..02838e6 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -1972,21 +1972,31 @@ out: int drm_mode_set_config_internal(struct drm_mode_set *set) { struct drm_crtc *crtc = set->crtc; - struct drm_framebuffer *fb, *old_fb; + struct drm_framebuffer *fb; + struct drm_crtc *tmp; int ret; - old_fb = crtc->fb; + /* + * NOTE: ->set_config can also disable other crtcs (if we steal all + * connectors from it), hence we need to refcount the fbs across all + * crtcs. Atomic modeset will have saner semantics ... + */ + list_for_each_entry(tmp, &crtc->dev->mode_config.crtc_list, head) + tmp->old_fb = tmp->fb; + fb = set->fb; ret = crtc->funcs->set_config(set); if (ret == 0) { /* crtc->fb must be updated by ->set_config, enforces this. */ WARN_ON(fb != crtc->fb); + } - if (old_fb) - drm_framebuffer_unreference(old_fb); - if (fb) - drm_framebuffer_reference(fb); + list_for_each_entry(tmp, &crtc->dev->mode_config.crtc_list, head) { + if (tmp->fb) + drm_framebuffer_reference(tmp->fb); + if (tmp->old_fb) + drm_framebuffer_unreference(tmp->old_fb); } return ret; diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 9779ea1..b9ddd3d 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -409,6 +409,10 @@ struct drm_crtc { /* framebuffer the connector is currently bound to */ struct drm_framebuffer *fb; + /* Temporary tracking of the old fb while a modeset is ongoing. Used + * by drm_mode_set_config_internal to implement correct refcounting. */ + struct drm_framebuffer *old_fb; + bool enabled; /* Requested mode from modesetting. */ -- 2.7.4