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authorLinus Torvalds <torvalds@linux-foundation.org>2016-08-18 13:45:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-08-18 13:45:48 -0700
commitbd3fd451ff3b205f0bde4d1bf7a310552c40d6e0 (patch)
treeaceca2fab7b29490405bfda1597e43573ffe99f6 /include
parentf28535c100e3c3066ed3506d90948cf023dad21a (diff)
parent112dc0c8069e5554e0ad29c58228f1e6ca49e13d (diff)
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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"
Diffstat (limited to 'include')
-rw-r--r--include/linux/compiler.h6
1 files changed, 3 insertions, 3 deletions
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); \
})