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 <[email protected]> AuthorDate: Mon, 11 May 2020 21:41:45 +01:00 Committer: Thomas Gleixner <[email protected]> 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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Arnd Bergmann <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- 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
