drm/i915/fbdev: Check for existence of ifbdev->vma before operations
authorChris Wilson <chris@chris-wilson.co.uk>
Thu, 22 Jun 2017 16:02:11 +0000 (17:02 +0100)
committerJani Nikula <jani.nikula@intel.com>
Mon, 10 Jul 2017 07:33:03 +0000 (10:33 +0300)
commit7581d5ca2bb269cfc2ce2d0cb489aac513167f6b
treee2008a10d5fad5fa155dcc9b3459a6c41200f6d5
parent04941829b0049d2446c7042ab9686dd057d809a6
drm/i915/fbdev: Check for existence of ifbdev->vma before operations

Commit fabef825626d ("drm/i915: Drop struct_mutex around frontbuffer
flushes") adds a dependency to ifbdev->vma when flushing the framebufer,
but the checks are only against the existence of the ifbdev->fb and not
against ifbdev->vma. This leaves a window of opportunity where we may
try to operate on the fbdev prior to it being probed (thanks to
asynchronous booting).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101534
Fixes: fabef825626d ("drm/i915: Drop struct_mutex around frontbuffer flushes")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170622160211.783-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: stable@vger.kernel.org
(cherry picked from commit 15727ed0d944ce1dec8b9e1082dd3df29a0fdf44)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
drivers/gpu/drm/i915/intel_fbdev.c