The following commit has been merged into the locking/kcsan branch of tip:
Commit-ID: 0229d80867ef27b3e41585a784d5f78695a58f95
Gitweb: https://git.kernel.org/tip/0229d80867ef27b3e41585a784d5f78695a58f95
Author: Will Deacon <will@xxxxxxxxxx>
AuthorDate: Mon, 11 May 2020 21:41:45 +01:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 12 May 2020 11:04:15 +02:00
locking/barriers: Use '__unqual_scalar_typeof' for load-acquire macros
Passing volatile-qualified pointers to the asm-generic implementations of
the load-acquire macros results in a re-load from the stack due to the
temporary result variable inheriting the volatile semantics thanks to the
use of 'typeof()'.
Define these temporary variables using 'unqual_scalar_typeof' to drop
the volatile qualifier in the case that they are scalar types.
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Link: https://lkml.kernel.org/r/20200511204150.27858-14-will@xxxxxxxxxx
---
include/asm-generic/barrier.h | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 85b28eb..2eacaf7 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -128,10 +128,10 @@ do { \
#ifndef __smp_load_acquire
#define __smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = READ_ONCE(*p); \
+ __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
__smp_mb(); \
- ___p1; \
+ (typeof(*p))___p1; \
})
#endif
@@ -183,10 +183,10 @@ do { \
#ifndef smp_load_acquire
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = READ_ONCE(*p); \
+ __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
- ___p1; \
+ (typeof(*p))___p1; \
})
#endif
@@ -229,14 +229,14 @@ do { \
#ifndef smp_cond_load_relaxed
#define smp_cond_load_relaxed(ptr, cond_expr) ({ \
typeof(ptr) __PTR = (ptr); \
- typeof(*ptr) VAL; \
+ __unqual_scalar_typeof(*ptr) VAL; \
for (;;) { \
VAL = READ_ONCE(*__PTR); \
if (cond_expr) \
break; \
cpu_relax(); \
} \
- VAL; \
+ (typeof(*ptr))VAL; \
})
#endif
@@ -250,10 +250,10 @@ do { \
*/
#ifndef smp_cond_load_acquire
#define smp_cond_load_acquire(ptr, cond_expr) ({ \
- typeof(*ptr) _val; \
+ __unqual_scalar_typeof(*ptr) _val; \
_val = smp_cond_load_relaxed(ptr, cond_expr); \
smp_acquire__after_ctrl_dep(); \
- _val; \
+ (typeof(*ptr))_val; \
})
#endif
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