diff options
Diffstat (limited to 'kernels/linux-libre-knock/0001-fixup-drm.patch')
| -rw-r--r-- | kernels/linux-libre-knock/0001-fixup-drm.patch | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/kernels/linux-libre-knock/0001-fixup-drm.patch b/kernels/linux-libre-knock/0001-fixup-drm.patch new file mode 100644 index 000000000..2acfb1ea6 --- /dev/null +++ b/kernels/linux-libre-knock/0001-fixup-drm.patch @@ -0,0 +1,70 @@ +From 8218c3f4df3bb1c637c17552405039a6dd3c1ee1 Mon Sep 17 00:00:00 2001 +From: Daniel Vetter <daniel.vetter@ffwll.ch> +Date: Fri, 27 Feb 2015 12:58:13 +0100 +Subject: drm: Fixup racy refcounting in plane_force_disable + +Originally it was impossible to be dropping the last refcount in this +function since there was always one around still from the idr. But in + +commit 83f45fc360c8e16a330474860ebda872d1384c8c +Author: Daniel Vetter <daniel.vetter@ffwll.ch> +Date: Wed Aug 6 09:10:18 2014 +0200 + + drm: Don't grab an fb reference for the idr + +we've switched to weak references, broke that assumption but forgot to +fix it up. + +Since we still force-disable planes it's only possible to hit this +when racing multiple rmfb with fbdev restoring or similar evil things. +As long as userspace is nice it's impossible to hit the BUG_ON. + +But the BUG_ON would most likely be hit from fbdev code, which usually +invovles the console_lock besides all modeset locks. So very likely +we'd never get the bug reports if this was hit in the wild, hence +better be safe than sorry and backport. + +Spotted by Matt Roper while reviewing other patches. + +[airlied: pull this back into 4.0 - the oops happens there] + +Cc: stable@vger.kernel.org +Cc: Matt Roper <matthew.d.roper@intel.com> +Reviewed-by: Matt Roper <matthew.d.roper@intel.com> +Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> +Signed-off-by: Dave Airlie <airlied@redhat.com> + +diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c +index f6d04c7..679b10e 100644 +--- a/drivers/gpu/drm/drm_crtc.c ++++ b/drivers/gpu/drm/drm_crtc.c +@@ -525,17 +525,6 @@ void drm_framebuffer_reference(struct drm_framebuffer *fb) + } + EXPORT_SYMBOL(drm_framebuffer_reference); + +-static void drm_framebuffer_free_bug(struct kref *kref) +-{ +- BUG(); +-} +- +-static void __drm_framebuffer_unreference(struct drm_framebuffer *fb) +-{ +- DRM_DEBUG("%p: FB ID: %d (%d)\n", fb, fb->base.id, atomic_read(&fb->refcount.refcount)); +- kref_put(&fb->refcount, drm_framebuffer_free_bug); +-} +- + /** + * drm_framebuffer_unregister_private - unregister a private fb from the lookup idr + * @fb: fb to unregister +@@ -1320,7 +1309,7 @@ void drm_plane_force_disable(struct drm_plane *plane) + return; + } + /* disconnect the plane from the fb and crtc: */ +- __drm_framebuffer_unreference(plane->old_fb); ++ drm_framebuffer_unreference(plane->old_fb); + plane->old_fb = NULL; + plane->fb = NULL; + plane->crtc = NULL; +-- +cgit v0.10.2 + |