drm: Fix locking gotcha in page_flip ioctl

We want to lock the primary plane, not the cursor (which might be
optional). Real bad case of copy-paste fail, unfortunately our CI
didn't catch that because i915 does have a cursor plane.

Reported-by: Eric Anholt <eric@anholt.net>
Fixes: 29dc0d1de182 ("drm: Roll out acquire context for the page_flip ioctl")
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170330204831.8225-1-daniel.vetter@ffwll.ch
Tested-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>

diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index 5eca3184a74786dd3e747ffa0a6fc26fbe698a49..bc71aa2b78728d1c241682ce9eee852faafade13 100644 (file)
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -872,7 +872,7 @@ retry:
        ret = drm_modeset_lock(&crtc->mutex, &ctx);
        if (ret)
                goto out;
-       ret = drm_modeset_lock(&crtc->cursor->mutex, &ctx);
+       ret = drm_modeset_lock(&crtc->primary->mutex, &ctx);
        if (ret)
                goto out;