Hi Juergen,
On 25/03/2020 10:55, Juergen Gross wrote:
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 <jbeul...@suse.com>
Signed-off-by: Juergen Gross <jgr...@suse.com>
Acked-by: Julien Grall <jgr...@amazon.com>
Cheers,
---
V7:
- new patch
---
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
--
Julien Grall
