atomic, arch: Audit atomic_{read,set}()

This patch makes sure that atomic_{read,set}() are at least
{READ,WRITE}_ONCE().

We already had the 'requirement' that atomic_read() should use
ACCESS_ONCE(), and most archs had this, but a few were lacking.
All are now converted to use READ_ONCE().

And, by a symmetry and general paranoia argument, upgrade atomic_set()
to use WRITE_ONCE().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: james.hogan@imgtec.com
Cc: linux-kernel@vger.kernel.org
Cc: oleg@redhat.com
Cc: will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/alpha/include/asm/atomic.h

@@ -17,11 +17,11 @@
 #define ATOMIC_INIT(i)		{ (i) }
 #define ATOMIC64_INIT(i)	{ (i) }
 
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
-#define atomic64_read(v)	ACCESS_ONCE((v)->counter)
+#define atomic_read(v)		READ_ONCE((v)->counter)
+#define atomic64_read(v)	READ_ONCE((v)->counter)
 
-#define atomic_set(v,i)		((v)->counter = (i))
-#define atomic64_set(v,i)	((v)->counter = (i))
+#define atomic_set(v,i)		WRITE_ONCE((v)->counter, (i))
+#define atomic64_set(v,i)	WRITE_ONCE((v)->counter, (i))
 
 /*
  * To get proper branch prediction for the main line, we must branch

arch/arc/include/asm/atomic.h

@@ -17,11 +17,11 @@
 #include <asm/barrier.h>
 #include <asm/smp.h>
 
-#define atomic_read(v)  ((v)->counter)
+#define atomic_read(v)  READ_ONCE((v)->counter)
 
 #ifdef CONFIG_ARC_HAS_LLSC
 
-#define atomic_set(v, i) (((v)->counter) = (i))
+#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
 
 #ifdef CONFIG_ARC_STAR_9000923308
 
@@ -107,7 +107,7 @@ static inline int atomic_##op##_return(int i, atomic_t *v)		\
 #ifndef CONFIG_SMP
 
  /* violating atomic_xxx API locking protocol in UP for optimization sake */
-#define atomic_set(v, i) (((v)->counter) = (i))
+#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
 
 #else
 
@@ -125,7 +125,7 @@ static inline void atomic_set(atomic_t *v, int i)
 	unsigned long flags;
 
 	atomic_ops_lock(flags);
-	v->counter = i;
+	WRITE_ONCE(v->counter, i);
 	atomic_ops_unlock(flags);
 }
 

arch/arm/include/asm/atomic.h

@@ -27,8 +27,8 @@
  * 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)	ACCESS_ONCE((v)->counter)
-#define atomic_set(v,i)	(((v)->counter) = (i))
+#define atomic_read(v)	READ_ONCE((v)->counter)
+#define atomic_set(v,i)	WRITE_ONCE(((v)->counter), (i))
 
 #if __LINUX_ARM_ARCH__ >= 6
 

arch/arm64/include/asm/atomic.h

@@ -54,7 +54,7 @@
 #define ATOMIC_INIT(i)	{ (i) }
 
 #define atomic_read(v)			READ_ONCE((v)->counter)
-#define atomic_set(v, i)		(((v)->counter) = (i))
+#define atomic_set(v, i)		WRITE_ONCE(((v)->counter), (i))
 #define atomic_xchg(v, new)		xchg(&((v)->counter), (new))
 #define atomic_cmpxchg(v, old, new)	cmpxchg(&((v)->counter), (old), (new))
 

arch/avr32/include/asm/atomic.h

@@ -19,8 +19,8 @@
 
 #define ATOMIC_INIT(i)  { (i) }
 
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
-#define atomic_set(v, i)	(((v)->counter) = i)
+#define atomic_read(v)		READ_ONCE((v)->counter)
+#define atomic_set(v, i)	WRITE_ONCE(((v)->counter), (i))
 
 #define ATOMIC_OP_RETURN(op, asm_op, asm_con)				\
 static inline int __atomic_##op##_return(int i, atomic_t *v)		\

arch/frv/include/asm/atomic.h

@@ -32,8 +32,8 @@
  */
 
 #define ATOMIC_INIT(i)		{ (i) }
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
-#define atomic_set(v, i)	(((v)->counter) = (i))
+#define atomic_read(v)		READ_ONCE((v)->counter)
+#define atomic_set(v, i)	WRITE_ONCE(((v)->counter), (i))
 
 static inline int atomic_inc_return(atomic_t *v)
 {

arch/h8300/include/asm/atomic.h

@@ -11,8 +11,8 @@
 
 #define ATOMIC_INIT(i)	{ (i) }
 
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
-#define atomic_set(v, i)	(((v)->counter) = i)
+#define atomic_read(v)		READ_ONCE((v)->counter)
+#define atomic_set(v, i)	WRITE_ONCE(((v)->counter), (i))
 
 #include <linux/kernel.h>
 

arch/hexagon/include/asm/atomic.h

@@ -48,7 +48,7 @@ static inline void atomic_set(atomic_t *v, int new)
  *
  * Assumes all word reads on our architecture are atomic.
  */
-#define atomic_read(v)		((v)->counter)
+#define atomic_read(v)		READ_ONCE((v)->counter)
 
 /**
  * atomic_xchg - atomic

arch/ia64/include/asm/atomic.h

@@ -21,11 +21,11 @@
 #define ATOMIC_INIT(i)		{ (i) }
 #define ATOMIC64_INIT(i)	{ (i) }
 
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
-#define atomic64_read(v)	ACCESS_ONCE((v)->counter)
+#define atomic_read(v)		READ_ONCE((v)->counter)
+#define atomic64_read(v)	READ_ONCE((v)->counter)
 
-#define atomic_set(v,i)		(((v)->counter) = (i))
-#define atomic64_set(v,i)	(((v)->counter) = (i))
+#define atomic_set(v,i)		WRITE_ONCE(((v)->counter), (i))
+#define atomic64_set(v,i)	WRITE_ONCE(((v)->counter), (i))
 
 #define ATOMIC_OP(op, c_op)						\
 static __inline__ int							\

arch/m32r/include/asm/atomic.h

@@ -28,7 +28,7 @@
  *
  * Atomically reads the value of @v.
  */
-#define atomic_read(v)	ACCESS_ONCE((v)->counter)
+#define atomic_read(v)	READ_ONCE((v)->counter)
 
 /**
  * atomic_set - set atomic variable
@@ -37,7 +37,7 @@
  *
  * Atomically sets the value of @v to @i.
  */
-#define atomic_set(v,i)	(((v)->counter) = (i))
+#define atomic_set(v,i)	WRITE_ONCE(((v)->counter), (i))
 
 #ifdef CONFIG_CHIP_M32700_TS1
 #define __ATOMIC_CLOBBER	, "r4"

arch/m68k/include/asm/atomic.h

@@ -17,8 +17,8 @@
 
 #define ATOMIC_INIT(i)	{ (i) }
 
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
-#define atomic_set(v, i)	(((v)->counter) = i)
+#define atomic_read(v)		READ_ONCE((v)->counter)
+#define atomic_set(v, i)	WRITE_ONCE(((v)->counter), (i))
 
 /*
  * The ColdFire parts cannot do some immediate to memory operations,

arch/metag/include/asm/atomic_lnkget.h

@@ -3,7 +3,7 @@
 
 #define ATOMIC_INIT(i)	{ (i) }
 
-#define atomic_set(v, i)		((v)->counter = (i))
+#define atomic_set(v, i)		WRITE_ONCE((v)->counter, (i))
 
 #include <linux/compiler.h>
 

arch/metag/include/asm/atomic_lock1.h

@@ -10,7 +10,7 @@
 
 static inline int atomic_read(const atomic_t *v)
 {
-	return (v)->counter;
+	return READ_ONCE((v)->counter);
 }
 
 /*

arch/mips/include/asm/atomic.h

@@ -30,7 +30,7 @@
  *
  * Atomically reads the value of @v.
  */
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
+#define atomic_read(v)		READ_ONCE((v)->counter)
 
 /*
  * atomic_set - set atomic variable
@@ -39,7 +39,7 @@
  *
  * Atomically sets the value of @v to @i.
  */
-#define atomic_set(v, i)		((v)->counter = (i))
+#define atomic_set(v, i)	WRITE_ONCE((v)->counter, (i))
 
 #define ATOMIC_OP(op, c_op, asm_op)					      \
 static __inline__ void atomic_##op(int i, atomic_t * v)			      \
@@ -315,14 +315,14 @@ static __inline__ int __atomic_add_unless(atomic_t *v, int a, int u)
  * @v: pointer of type atomic64_t
  *
  */
-#define atomic64_read(v)	ACCESS_ONCE((v)->counter)
+#define atomic64_read(v)	READ_ONCE((v)->counter)
 
 /*
  * atomic64_set - set atomic variable
  * @v: pointer of type atomic64_t
  * @i: required value
  */
-#define atomic64_set(v, i)	((v)->counter = (i))
+#define atomic64_set(v, i)	WRITE_ONCE((v)->counter, (i))
 
 #define ATOMIC64_OP(op, c_op, asm_op)					      \
 static __inline__ void atomic64_##op(long i, atomic64_t * v)		      \

arch/mn10300/include/asm/atomic.h

@@ -34,7 +34,7 @@
  *
  * Atomically reads the value of @v.  Note that the guaranteed
  */
-#define atomic_read(v)	(ACCESS_ONCE((v)->counter))
+#define atomic_read(v)	READ_ONCE((v)->counter)
 
 /**
  * atomic_set - set atomic variable
@@ -43,7 +43,7 @@
  *
  * Atomically sets the value of @v to @i.  Note that the guaranteed
  */
-#define atomic_set(v, i) (((v)->counter) = (i))
+#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
 
 #define ATOMIC_OP(op)							\
 static inline void atomic_##op(int i, atomic_t *v)			\

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 ACCESS_ONCE((v)->counter);
+	return READ_ONCE((v)->counter);
 }
 
 /* exported interface */

arch/sh/include/asm/atomic.h

@@ -14,8 +14,8 @@
 
 #define ATOMIC_INIT(i)	{ (i) }
 
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
-#define atomic_set(v,i)		((v)->counter = (i))
+#define atomic_read(v)		READ_ONCE((v)->counter)
+#define atomic_set(v,i)		WRITE_ONCE((v)->counter, (i))
 
 #if defined(CONFIG_GUSA_RB)
 #include <asm/atomic-grb.h>

arch/sparc/include/asm/atomic_64.h

@@ -14,11 +14,11 @@
 #define ATOMIC_INIT(i)		{ (i) }
 #define ATOMIC64_INIT(i)	{ (i) }
 
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
-#define atomic64_read(v)	ACCESS_ONCE((v)->counter)
+#define atomic_read(v)		READ_ONCE((v)->counter)
+#define atomic64_read(v)	READ_ONCE((v)->counter)
 
-#define atomic_set(v, i)	(((v)->counter) = i)
-#define atomic64_set(v, i)	(((v)->counter) = i)
+#define atomic_set(v, i)	WRITE_ONCE(((v)->counter), (i))
+#define atomic64_set(v, i)	WRITE_ONCE(((v)->counter), (i))
 
 #define ATOMIC_OP(op)							\
 void atomic_##op(int, atomic_t *);					\

arch/tile/include/asm/atomic.h

@@ -34,7 +34,7 @@
  */
 static inline int atomic_read(const atomic_t *v)
 {
-	return ACCESS_ONCE(v->counter);
+	return READ_ONCE(v->counter);
 }
 
 /**

arch/tile/include/asm/atomic_64.h

@@ -24,7 +24,7 @@
 
 /* First, the 32-bit atomic ops that are "real" on our 64-bit platform. */
 
-#define atomic_set(v, i) ((v)->counter = (i))
+#define atomic_set(v, i) WRITE_ONCE((v)->counter, (i))
 
 /*
  * The smp_mb() operations throughout are to support the fact that
@@ -82,8 +82,8 @@ static inline void atomic_xor(int i, atomic_t *v)
 
 #define ATOMIC64_INIT(i)	{ (i) }
 
-#define atomic64_read(v)		((v)->counter)
-#define atomic64_set(v, i) ((v)->counter = (i))
+#define atomic64_read(v)	READ_ONCE((v)->counter)
+#define atomic64_set(v, i)	WRITE_ONCE((v)->counter, (i))
 
 static inline void atomic64_add(long i, atomic64_t *v)
 {

arch/x86/include/asm/atomic.h

@@ -24,7 +24,7 @@
  */
 static __always_inline int atomic_read(const atomic_t *v)
 {
-	return ACCESS_ONCE((v)->counter);
+	return READ_ONCE((v)->counter);
 }
 
 /**
@@ -36,7 +36,7 @@ static __always_inline int atomic_read(const atomic_t *v)
  */
 static __always_inline void atomic_set(atomic_t *v, int i)
 {
-	v->counter = i;
+	WRITE_ONCE(v->counter, i);
 }
 
 /**

arch/x86/include/asm/atomic64_64.h

@@ -18,7 +18,7 @@
  */
 static inline long atomic64_read(const atomic64_t *v)
 {
-	return ACCESS_ONCE((v)->counter);
+	return READ_ONCE((v)->counter);
 }
 
 /**
@@ -30,7 +30,7 @@ static inline long atomic64_read(const atomic64_t *v)
  */
 static inline void atomic64_set(atomic64_t *v, long i)
 {
-	v->counter = i;
+	WRITE_ONCE(v->counter, i);
 }
 
 /**

arch/xtensa/include/asm/atomic.h

@@ -47,7 +47,7 @@
  *
  * Atomically reads the value of @v.
  */
-#define atomic_read(v)		ACCESS_ONCE((v)->counter)
+#define atomic_read(v)		READ_ONCE((v)->counter)
 
 /**
  * atomic_set - set atomic variable
@@ -56,7 +56,7 @@
  *
  * Atomically sets the value of @v to @i.
  */
-#define atomic_set(v,i)		((v)->counter = (i))
+#define atomic_set(v,i)		WRITE_ONCE((v)->counter, (i))
 
 #if XCHAL_HAVE_S32C1I
 #define ATOMIC_OP(op)							\

include/asm-generic/atomic.h

@@ -127,7 +127,7 @@ ATOMIC_OP(xor, ^)
  * Atomically reads the value of @v.
  */
 #ifndef atomic_read
-#define atomic_read(v)	ACCESS_ONCE((v)->counter)
+#define atomic_read(v)	READ_ONCE((v)->counter)
 #endif
 
 /**
@@ -137,7 +137,7 @@ ATOMIC_OP(xor, ^)
  *
  * Atomically sets the value of @v to @i.
  */
-#define atomic_set(v, i) (((v)->counter) = (i))
+#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
 
 #include <linux/irqflags.h>