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authorLinus Torvalds <torvalds@linux-foundation.org>2016-09-13 12:13:58 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-09-13 12:13:58 -0700
commit504cb1c25b63ca434e9ced4226c026b54097391d (patch)
tree7bdf8c7076ede1dcad22c318948c4312bbedfd0f /include
parent7c2c1144164c0a6fd91642909042862db907e053 (diff)
parentd7127b5e5fa0551be21b86640f1648b224e36d43 (diff)
downloadlinux-stericsson-504cb1c25b63ca434e9ced4226c026b54097391d.tar.gz
Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fix from Ingo Molnar: "Another lockless_dereference() Sparse fix" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/barriers: Don't use sizeof(void) in lockless_dereference()
Diffstat (limited to 'include')
-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); \
})