From c301211a511111caca29f3bd797eb13965026c78 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 26 Mar 2020 12:42:19 +0100 Subject: [PATCH] atomics: introduce smp_mb__[after|before]_atomic() barriers When using atomic variables for synchronization barriers are needed to ensure proper data serialization. Introduce smp_mb__before_atomic() and smp_mb__after_atomic() as in the Linux kernel for that purpose. Use the same definitions as in the Linux kernel. Suggested-by: Jan Beulich Signed-off-by: Juergen Gross Acked-by: Jan Beulich Acked-by: Julien Grall --- xen/include/asm-arm/system.h | 3 +++ xen/include/asm-x86/system.h | 3 +++ 2 files changed, 6 insertions(+) diff --git a/xen/include/asm-arm/system.h b/xen/include/asm-arm/system.h index e5d062667d..65d5c8e423 100644 --- a/xen/include/asm-arm/system.h +++ b/xen/include/asm-arm/system.h @@ -30,6 +30,9 @@ #define smp_wmb() dmb(ishst) +#define smp_mb__before_atomic() smp_mb() +#define smp_mb__after_atomic() smp_mb() + /* * This is used to ensure the compiler did actually allocate the register we * asked it for some inline assembly sequences. Apparently we can't trust diff --git a/xen/include/asm-x86/system.h b/xen/include/asm-x86/system.h index 069f422f0d..7e5891f3df 100644 --- a/xen/include/asm-x86/system.h +++ b/xen/include/asm-x86/system.h @@ -233,6 +233,9 @@ static always_inline unsigned long __xadd( #define set_mb(var, value) do { xchg(&var, value); } while (0) #define set_wmb(var, value) do { var = value; smp_wmb(); } while (0) +#define smp_mb__before_atomic() do { } while (0) +#define smp_mb__after_atomic() do { } while (0) + /** * array_index_mask_nospec() - generate a mask that is ~0UL when the * bounds check succeeds and 0 otherwise -- 2.30.2