[tip:locking/arch] locking,arch: Use ACCESS_ONCE() instead of cast to volatile in atomic_read()

From: tip-bot for Pranith Kumar
Date: Fri Oct 03 2014 - 01:30:24 EST

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Commit-ID: 2291059c852706c6f5ffb400366042b7625066cd
Gitweb: http://git.kernel.org/tip/2291059c852706c6f5ffb400366042b7625066cd
Author: Pranith Kumar <bobby.prani@xxxxxxxxx>
AuthorDate: Tue, 23 Sep 2014 10:29:50 -0400
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 3 Oct 2014 06:06:23 +0200

locking,arch: Use ACCESS_ONCE() instead of cast to volatile in atomic_read()

Use the much more reader friendly ACCESS_ONCE() instead of the cast to volatile.
This is purely a stylistic change.

Signed-off-by: Pranith Kumar <bobby.prani@xxxxxxxxx>
Acked-by: Jesper Nilsson <jesper.nilsson@xxxxxxxx>
Acked-by: Hans-Christian Egtvedt <egtvedt@xxxxxxxxxxxx>
Acked-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-arch@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1411482607-20948-1-git-send-email-bobby.prani@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/alpha/include/asm/atomic.h | 4 ++--
arch/arm/include/asm/atomic.h | 2 +-
arch/arm64/include/asm/atomic.h | 4 ++--
arch/avr32/include/asm/atomic.h | 2 +-
arch/cris/include/asm/atomic.h | 2 +-
arch/frv/include/asm/atomic.h | 2 +-
arch/ia64/include/asm/atomic.h | 4 ++--
arch/m32r/include/asm/atomic.h | 2 +-
arch/m68k/include/asm/atomic.h | 2 +-
arch/mips/include/asm/atomic.h | 4 ++--
arch/parisc/include/asm/atomic.h | 4 ++--
arch/sh/include/asm/atomic.h | 2 +-
arch/sparc/include/asm/atomic_32.h | 2 +-
arch/sparc/include/asm/atomic_64.h | 4 ++--
arch/x86/include/asm/atomic.h | 2 +-
arch/x86/include/asm/atomic64_64.h | 2 +-
arch/xtensa/include/asm/atomic.h | 2 +-
include/asm-generic/atomic.h | 2 +-
18 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/arch/alpha/include/asm/atomic.h b/arch/alpha/include/asm/atomic.h
index 6fbb53a..8f8eafb 100644
--- a/arch/alpha/include/asm/atomic.h
+++ b/arch/alpha/include/asm/atomic.h
@@ -17,8 +17,8 @@
#define ATOMIC_INIT(i) { (i) }
#define ATOMIC64_INIT(i) { (i) }

-#define atomic_read(v) (*(volatile int *)&(v)->counter)
-#define atomic64_read(v) (*(volatile long *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
+#define atomic64_read(v) ACCESS_ONCE((v)->counter)

#define atomic_set(v,i) ((v)->counter = (i))
#define atomic64_set(v,i) ((v)->counter = (i))
diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
index 832f1cd..e22c119 100644
--- a/arch/arm/include/asm/atomic.h
+++ b/arch/arm/include/asm/atomic.h
@@ -27,7 +27,7 @@
* strex/ldrex monitor on some implementations. The reason we can use it for
* atomic_set() is the clrex or dummy strex done on every exception return.
*/
-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
#define atomic_set(v,i) (((v)->counter) = (i))

#if __LINUX_ARM_ARCH__ >= 6
diff --git a/arch/arm64/include/asm/atomic.h b/arch/arm64/include/asm/atomic.h
index b83c325..7047051 100644
--- a/arch/arm64/include/asm/atomic.h
+++ b/arch/arm64/include/asm/atomic.h
@@ -35,7 +35,7 @@
* strex/ldrex monitor on some implementations. The reason we can use it for
* atomic_set() is the clrex or dummy strex done on every exception return.
*/
-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
#define atomic_set(v,i) (((v)->counter) = (i))

/*
@@ -139,7 +139,7 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u)
*/
#define ATOMIC64_INIT(i) { (i) }

-#define atomic64_read(v) (*(volatile long *)&(v)->counter)
+#define atomic64_read(v) ACCESS_ONCE((v)->counter)
#define atomic64_set(v,i) (((v)->counter) = (i))

#define ATOMIC64_OP(op, asm_op) \
diff --git a/arch/avr32/include/asm/atomic.h b/arch/avr32/include/asm/atomic.h
index 83e980a..2d07ce1 100644
--- a/arch/avr32/include/asm/atomic.h
+++ b/arch/avr32/include/asm/atomic.h
@@ -19,7 +19,7 @@

#define ATOMIC_INIT(i) { (i) }

-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
#define atomic_set(v, i) (((v)->counter) = i)

#define ATOMIC_OP_RETURN(op, asm_op, asm_con) \
diff --git a/arch/cris/include/asm/atomic.h b/arch/cris/include/asm/atomic.h
index 0033f9d..279766a 100644
--- a/arch/cris/include/asm/atomic.h
+++ b/arch/cris/include/asm/atomic.h
@@ -17,7 +17,7 @@

#define ATOMIC_INIT(i) { (i) }

-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
#define atomic_set(v,i) (((v)->counter) = (i))

/* These should be written in asm but we do it in C for now. */
diff --git a/arch/frv/include/asm/atomic.h b/arch/frv/include/asm/atomic.h
index f6c3a16..102190a 100644
--- a/arch/frv/include/asm/atomic.h
+++ b/arch/frv/include/asm/atomic.h
@@ -31,7 +31,7 @@
*/

#define ATOMIC_INIT(i) { (i) }
-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
#define atomic_set(v, i) (((v)->counter) = (i))

#ifndef CONFIG_FRV_OUTOFLINE_ATOMIC_OPS
diff --git a/arch/ia64/include/asm/atomic.h b/arch/ia64/include/asm/atomic.h
index 42919a8..0bf0350 100644
--- a/arch/ia64/include/asm/atomic.h
+++ b/arch/ia64/include/asm/atomic.h
@@ -21,8 +21,8 @@
#define ATOMIC_INIT(i) { (i) }
#define ATOMIC64_INIT(i) { (i) }

-#define atomic_read(v) (*(volatile int *)&(v)->counter)
-#define atomic64_read(v) (*(volatile long *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
+#define atomic64_read(v) ACCESS_ONCE((v)->counter)

#define atomic_set(v,i) (((v)->counter) = (i))
#define atomic64_set(v,i) (((v)->counter) = (i))
diff --git a/arch/m32r/include/asm/atomic.h b/arch/m32r/include/asm/atomic.h
index 3946b2c..31bb74a 100644
--- a/arch/m32r/include/asm/atomic.h
+++ b/arch/m32r/include/asm/atomic.h
@@ -28,7 +28,7 @@
*
* Atomically reads the value of @v.
*/
-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)

/**
* atomic_set - set atomic variable
diff --git a/arch/m68k/include/asm/atomic.h b/arch/m68k/include/asm/atomic.h
index 663d4ba..e85f047 100644
--- a/arch/m68k/include/asm/atomic.h
+++ b/arch/m68k/include/asm/atomic.h
@@ -17,7 +17,7 @@

#define ATOMIC_INIT(i) { (i) }

-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
#define atomic_set(v, i) (((v)->counter) = i)

/*
diff --git a/arch/mips/include/asm/atomic.h b/arch/mips/include/asm/atomic.h
index f3ee721..6dd6bfc 100644
--- a/arch/mips/include/asm/atomic.h
+++ b/arch/mips/include/asm/atomic.h
@@ -29,7 +29,7 @@
*
* Atomically reads the value of @v.
*/
-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)

/*
* atomic_set - set atomic variable
@@ -306,7 +306,7 @@ static __inline__ int __atomic_add_unless(atomic_t *v, int a, int u)
* @v: pointer of type atomic64_t
*
*/
-#define atomic64_read(v) (*(volatile long *)&(v)->counter)
+#define atomic64_read(v) ACCESS_ONCE((v)->counter)

/*
* atomic64_set - set atomic variable
diff --git a/arch/parisc/include/asm/atomic.h b/arch/parisc/include/asm/atomic.h
index 219750b..226f8ca 100644
--- a/arch/parisc/include/asm/atomic.h
+++ b/arch/parisc/include/asm/atomic.h
@@ -67,7 +67,7 @@ static __inline__ void atomic_set(atomic_t *v, int i)

static __inline__ int atomic_read(const atomic_t *v)
{
- return (*(volatile int *)&(v)->counter);
+ return ACCESS_ONCE((v)->counter);
}

/* exported interface */
@@ -204,7 +204,7 @@ atomic64_set(atomic64_t *v, s64 i)
static __inline__ s64
atomic64_read(const atomic64_t *v)
{
- return (*(volatile long *)&(v)->counter);
+ return ACCESS_ONCE((v)->counter);
}

#define atomic64_inc(v) (atomic64_add( 1,(v)))
diff --git a/arch/sh/include/asm/atomic.h b/arch/sh/include/asm/atomic.h
index f57b8a6..05b9f74 100644
--- a/arch/sh/include/asm/atomic.h
+++ b/arch/sh/include/asm/atomic.h
@@ -14,7 +14,7 @@

#define ATOMIC_INIT(i) { (i) }

-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
#define atomic_set(v,i) ((v)->counter = (i))

#if defined(CONFIG_GUSA_RB)
diff --git a/arch/sparc/include/asm/atomic_32.h b/arch/sparc/include/asm/atomic_32.h
index 7b024f0..765c177 100644
--- a/arch/sparc/include/asm/atomic_32.h
+++ b/arch/sparc/include/asm/atomic_32.h
@@ -26,7 +26,7 @@ int atomic_cmpxchg(atomic_t *, int, int);
int __atomic_add_unless(atomic_t *, int, int);
void atomic_set(atomic_t *, int);

-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)

#define atomic_add(i, v) ((void)atomic_add_return( (int)(i), (v)))
#define atomic_sub(i, v) ((void)atomic_add_return(-(int)(i), (v)))
diff --git a/arch/sparc/include/asm/atomic_64.h b/arch/sparc/include/asm/atomic_64.h
index 7e4ca1e..4082749 100644
--- a/arch/sparc/include/asm/atomic_64.h
+++ b/arch/sparc/include/asm/atomic_64.h
@@ -14,8 +14,8 @@
#define ATOMIC_INIT(i) { (i) }
#define ATOMIC64_INIT(i) { (i) }

-#define atomic_read(v) (*(volatile int *)&(v)->counter)
-#define atomic64_read(v) (*(volatile long *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
+#define atomic64_read(v) ACCESS_ONCE((v)->counter)

#define atomic_set(v, i) (((v)->counter) = i)
#define atomic64_set(v, i) (((v)->counter) = i)
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
index bf20c81..5e5cd12 100644
--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -24,7 +24,7 @@
*/
static inline int atomic_read(const atomic_t *v)
{
- return (*(volatile int *)&(v)->counter);
+ return ACCESS_ONCE((v)->counter);
}

/**
diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h
index 46e9052..f8d273e 100644
--- a/arch/x86/include/asm/atomic64_64.h
+++ b/arch/x86/include/asm/atomic64_64.h
@@ -18,7 +18,7 @@
*/
static inline long atomic64_read(const atomic64_t *v)
{
- return (*(volatile long *)&(v)->counter);
+ return ACCESS_ONCE((v)->counter);
}

/**
diff --git a/arch/xtensa/include/asm/atomic.h b/arch/xtensa/include/asm/atomic.h
index 6266766..00b7d46 100644
--- a/arch/xtensa/include/asm/atomic.h
+++ b/arch/xtensa/include/asm/atomic.h
@@ -47,7 +47,7 @@
*
* Atomically reads the value of @v.
*/
-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)

/**
* atomic_set - set atomic variable
diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
index 56d4d36..1973ad2 100644
--- a/include/asm-generic/atomic.h
+++ b/include/asm-generic/atomic.h
@@ -126,7 +126,7 @@ ATOMIC_OP(or, |)
* Atomically reads the value of @v.
*/
#ifndef atomic_read
-#define atomic_read(v) (*(volatile int *)&(v)->counter)
+#define atomic_read(v) ACCESS_ONCE((v)->counter)
#endif

/**
--
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