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authorIngo Molnar <mingo@kernel.org>2016-09-21 15:01:57 +0200
committerIngo Molnar <mingo@kernel.org>2016-09-21 15:01:57 +0200
commit580498a23be1de55be55147eaee20a69249aeb13 (patch)
tree345f1a280812bf15969ae7097583b7dd59482636 /include/linux/compiler.h
parent3ec979658e5cc0fab86a42af79a650299e4d7135 (diff)
parent7d1e042314619115153a0f6f06e4552c09a50e13 (diff)
Merge branch 'linus' into x86/boot, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/compiler.h')
-rw-r--r--include/linux/compiler.h7
1 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 436aa4e42221..668569844d37 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -527,13 +527,14 @@ 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 size_t variable is to validate @p is indeed a pointer
- * type by making sure it can be dereferenced.
+ * The seemingly unused variable ___typecheck_p validates that @p is
+ * indeed a pointer type by using a pointer to typeof(*p) as the type.
+ * Taking a pointer to typeof(*p) again is needed in case p is void *.
*/
#define lockless_dereference(p) \
({ \
typeof(p) _________p1 = READ_ONCE(p); \
- size_t __maybe_unused __size_of_ptr = sizeof(*(p)); \
+ typeof(*(p)) *___typecheck_p __maybe_unused; \
smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
(_________p1); \
})