On Fri, Feb 15, 2013 at 11:24:35AM +0100, Daniel Vetter wrote:
/me grabs a few brown paper bags
So it looks like I've broken compilation in
commit 6aed8ec3f76a22217c9ae183d32b1aa990bed069 Author: Daniel Vetter daniel.vetter@ffwll.ch Date: Sun Jan 20 17:32:21 2013 +0100
drm: review locking for drm_fb_helper_restore_fbdev_modeFix it up again.
Reported-by: Wu Fengguang fengguang.wu@intel.com Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch
drivers/gpu/drm/drm_fb_cma_helper.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c index e851658..ef68e34 100644 --- a/drivers/gpu/drm/drm_fb_cma_helper.c +++ b/drivers/gpu/drm/drm_fb_cma_helper.c @@ -377,6 +377,8 @@ EXPORT_SYMBOL_GPL(drm_fbdev_cma_fini); */ void drm_fbdev_cma_restore_mode(struct drm_fbdev_cma *fbdev_cma) {
- struct drm_device *dev = fbdev_cma->fb_helper.dev;
- drm_modeset_lock_all(dev); if (fbdev_cma) drm_fb_helper_restore_fbdev_mode(&fbdev_cma->fb_helper);
The above check indicates that fbdev_cma might be NULL, so you're potentially dereferencing NULL when assigning the dev variable.
Perhaps a better way would be to move the locking into the if block, as in the patch below.
Thierry
diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c index e851658..54a250f 100644 --- a/drivers/gpu/drm/drm_fb_cma_helper.c +++ b/drivers/gpu/drm/drm_fb_cma_helper.c @@ -377,10 +377,11 @@ EXPORT_SYMBOL_GPL(drm_fbdev_cma_fini); */ void drm_fbdev_cma_restore_mode(struct drm_fbdev_cma *fbdev_cma) { - drm_modeset_lock_all(dev); - if (fbdev_cma) + if (fbdev_cma) { + drm_modeset_lock_all(fbdev_cma->fb_helper.dev); drm_fb_helper_restore_fbdev_mode(&fbdev_cma->fb_helper); - drm_modeset_unlock_all(dev); + drm_modeset_unlock_all(fbdev_cma->fb_helper.dev); + } } EXPORT_SYMBOL_GPL(drm_fbdev_cma_restore_mode);