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authorDaniel Vetter <daniel.vetter@ffwll.ch>2017-05-22 15:59:45 +0200
committerDaniel Vetter <daniel.vetter@ffwll.ch>2017-05-23 09:39:14 +0200
commitf928543404bdf6bb4e8d6a6c3ced5edebd0d6f38 (patch)
treee467518f1cc1b361a99cfc5cb8bcab1733a530f9 /drivers/gpu/drm/drm_plane.c
parent429030bc944ee9a8bbe5d9bb23dcda0ae2205450 (diff)
drm: Fix deadlock retry loop in page_flip_ioctl
I failed to properly onion-wrap the unwind code: We acquire the vblank reference before we start with the wait-wound locking dance, hence we must make sure we retry before we drop the reference. Oops. v2: The vblank_put must be after the frambuffer_put (Michel). I suck at unwrapping code that doesn't use separate labels for each stage, but checks each pointer first ... While re-reading everything I also realized that we must clean up the fb refcounts, and specifically plane->old_fb before we drop the locks, either in the final unlocking, or in the w/w retry path. Hence the correct fix is to drop the vblank_put to the very bottom. Fixes: 29dc0d1de182 ("drm: Roll out acquire context for the page_flip ioctl") Cc: Harry Wentland <harry.wentland@amd.com> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Sean Paul <seanpaul@chromium.org> Cc: David Airlie <airlied@linux.ie> Cc: dri-devel@lists.freedesktop.org Reported-by: Tommi Rantala <tt.rantala@gmail.com> Cc: Tommi Rantala <tt.rantala@gmail.com> Cc: Michel Dänzer <michel@daenzer.net> Tested-by: Tommi Rantala <tt.rantala@gmail.com> Reviewed-by: Michel Dänzer <michel.daenzer@amd.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170522135945.28831-1-daniel.vetter@ffwll.ch
Diffstat (limited to 'drivers/gpu/drm/drm_plane.c')
-rw-r--r--drivers/gpu/drm/drm_plane.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index fedd4d60d9cd..5dc8c4350602 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -948,8 +948,6 @@ retry:
}
out:
- if (ret && crtc->funcs->page_flip_target)
- drm_crtc_vblank_put(crtc);
if (fb)
drm_framebuffer_put(fb);
if (crtc->primary->old_fb)
@@ -964,5 +962,8 @@ out:
drm_modeset_drop_locks(&ctx);
drm_modeset_acquire_fini(&ctx);
+ if (ret && crtc->funcs->page_flip_target)
+ drm_crtc_vblank_put(crtc);
+
return ret;
}