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From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm64: percpu: kill off final ACCESS_ONCE() uses
Date: Fri,  4 Nov 2016 18:17:06 +0000	[thread overview]
Message-ID: <1478283426-6649-1-git-send-email-mark.rutland@arm.com> (raw)

For several reasons it is preferable to use {READ,WRITE}_ONCE() rather than
ACCESS_ONCE(). For example, these handle aggregate types, result in shorter
source code, and better document the intended access (which may be useful for
instrumentation features such as the upcoming KTSAN).

Over a number of patches, most uses of ACCESS_ONCE() in arch/arm64 have been
migrated to {READ,WRITE}_ONCE(). For consistency, and the above reasons, this
patch migrates the final remaining uses.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/include/asm/percpu.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
index 5394c84..4afb6fc 100644
--- a/arch/arm64/include/asm/percpu.h
+++ b/arch/arm64/include/asm/percpu.h
@@ -101,16 +101,16 @@ static inline unsigned long __percpu_read(void *ptr, int size)
 
 	switch (size) {
 	case 1:
-		ret = ACCESS_ONCE(*(u8 *)ptr);
+		ret = READ_ONCE(*(u8 *)ptr);
 		break;
 	case 2:
-		ret = ACCESS_ONCE(*(u16 *)ptr);
+		ret = READ_ONCE(*(u16 *)ptr);
 		break;
 	case 4:
-		ret = ACCESS_ONCE(*(u32 *)ptr);
+		ret = READ_ONCE(*(u32 *)ptr);
 		break;
 	case 8:
-		ret = ACCESS_ONCE(*(u64 *)ptr);
+		ret = READ_ONCE(*(u64 *)ptr);
 		break;
 	default:
 		BUILD_BUG();
@@ -123,16 +123,16 @@ static inline void __percpu_write(void *ptr, unsigned long val, int size)
 {
 	switch (size) {
 	case 1:
-		ACCESS_ONCE(*(u8 *)ptr) = (u8)val;
+		WRITE_ONCE(*(u8 *)ptr, (u8)val);
 		break;
 	case 2:
-		ACCESS_ONCE(*(u16 *)ptr) = (u16)val;
+		WRITE_ONCE(*(u16 *)ptr, (u16)val);
 		break;
 	case 4:
-		ACCESS_ONCE(*(u32 *)ptr) = (u32)val;
+		WRITE_ONCE(*(u32 *)ptr, (u32)val);
 		break;
 	case 8:
-		ACCESS_ONCE(*(u64 *)ptr) = (u64)val;
+		WRITE_ONCE(*(u64 *)ptr, (u64)val);
 		break;
 	default:
 		BUILD_BUG();
-- 
2.7.4

             reply	other threads:[~2016-11-04 18:17 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-04 18:17 Mark Rutland [this message]
2016-11-07  1:44 ` [PATCH] arm64: percpu: kill off final ACCESS_ONCE() uses Dmitry Vyukov
2016-11-09 17:16 ` Catalin Marinas

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