# \[PATCH 03/18\] asm/rwonce: Allow \_\_READ\_ONCE to be overridden by the architecture - From: Will Deacon \ - Date: 2020-06-30 17:38:02 - List: linux-alpha - Page: https://ratatoskr.run/linux-alpha/2020/06/6020643 - Thread: https://ratatoskr.run/linux-arm-kernel/2020/06/6020640/t.md ```text The meat and potatoes of READ_ONCE() is defined by the __READ_ONCE() macro, which uses a volatile casts in an attempt to avoid tearing of byte, halfword, word and double-word accesses. Allow this to be overridden by the architecture code in the case that things like memory barriers are also required. Acked-by: Paul E. McKenney Signed-off-by: Will Deacon --- include/asm-generic/rwonce.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h index 92cc2f223cb3..f9dfa88fc04d 100644 --- a/include/asm-generic/rwonce.h +++ b/include/asm-generic/rwonce.h @@ -33,7 +33,9 @@ * atomicity or dependency ordering guarantees. Note that this may result * in tears! */ +#ifndef __READ_ONCE #define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x)) +#endif #define __READ_ONCE_SCALAR(x) \ ({ \ -- 2.27.0.212.ge8ba1cc988-goog ```