From f17b3ea3d2df7c9bf3ce1dbd65b5fd7061f8e787 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 11 Aug 2016 11:50:21 +0200 Subject: [PATCH] Revert "drm/fb-helper: Reduce READ_ONCE(master) to lockless_dereference" This reverts commit: fa7d81bb3c269 ("drm/fb-helper: Reduce READ_ONCE(master) to lockless_dereference") As Peter explained: [...] lockless_dereference() is _stronger_ than READ_ONCE(), not weaker. [...] Also, clue is in the name: 'dereference', you don't actually dereference the pointer here, only load it. My next patch breaks the compile without this revert, because it assumes you want to deference and thus also need the struct type visible (which it isn't here), so revert it. Tested-by: Paul E. McKenney Signed-off-by: Johannes Berg Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Daniel Vetter Cc: Andrew Morton Cc: Chris Wilson Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1470909022-687-1-git-send-email-johannes@sipsolutions.net Signed-off-by: Ingo Molnar --- drivers/gpu/drm/drm_fb_helper.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ce54e985d91b..0a06f9120b5a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -464,7 +464,7 @@ static bool drm_fb_helper_is_bound(struct drm_fb_helper *fb_helper) /* Sometimes user space wants everything disabled, so don't steal the * display if there's a master. */ - if (lockless_dereference(dev->master)) + if (READ_ONCE(dev->master)) return false; drm_for_each_crtc(crtc, dev) { -- 2.20.1