diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-08-18 13:45:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-08-18 13:45:48 -0700 |
| commit | bd3fd451ff3b205f0bde4d1bf7a310552c40d6e0 (patch) | |
| tree | aceca2fab7b29490405bfda1597e43573ffe99f6 | |
| parent | f28535c100e3c3066ed3506d90948cf023dad21a (diff) | |
| parent | 112dc0c8069e5554e0ad29c58228f1e6ca49e13d (diff) | |
Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
"Two lockless_dereference() related fixes"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/barriers: Suppress sparse warnings in lockless_dereference()
Revert "drm/fb-helper: Reduce READ_ONCE(master) to lockless_dereference"
| -rw-r--r-- | drivers/gpu/drm/drm_fb_helper.c | 2 | ||||
| -rw-r--r-- | include/linux/compiler.h | 6 |
2 files changed, 4 insertions, 4 deletions
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) { diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 1bb954842725..436aa4e42221 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -527,13 +527,13 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s * object's lifetime is managed by something other than RCU. That * "something other" might be reference counting or simple immortality. * - * The seemingly unused void * variable is to validate @p is indeed a pointer - * type. All pointer types silently cast to void *. + * The seemingly unused size_t variable is to validate @p is indeed a pointer + * type by making sure it can be dereferenced. */ #define lockless_dereference(p) \ ({ \ typeof(p) _________p1 = READ_ONCE(p); \ - __maybe_unused const void * const _________p2 = _________p1; \ + size_t __maybe_unused __size_of_ptr = sizeof(*(p)); \ smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ (_________p1); \ }) |