add explicit barrier operation to internal atomic.h API

arch/arm/atomic.h

@@ -101,7 +101,9 @@ static inline void a_store(volatile int *p, int x)
 	while (__k_cas(*p, x, p));
 }
 
-static inline void a_spin()
+#define a_spin a_barrier
+
+static inline void a_barrier()
 {
 	__k_cas(0, 0, &(int){0});
 }

arch/i386/atomic.h

@@ -96,6 +96,11 @@ static inline void a_spin()
 	__asm__ __volatile__( "pause" : : : "memory" );
 }
 
+static inline void a_barrier()
+{
+	__asm__ __volatile__( "" : : : "memory" );
+}
+
 static inline void a_crash()
 {
 	__asm__ __volatile__( "hlt" : : : "memory" );

arch/microblaze/atomic.h

@@ -95,7 +95,9 @@ static inline void a_store(volatile int *p, int x)
 		: "=m"(*p) : "r"(x) : "memory" );
 }
 
-static inline void a_spin()
+#define a_spin a_barrier
+
+static inline void a_barrier()
 {
 	a_cas(&(int){0}, 0, 0);
 }

arch/mips/atomic.h

@@ -135,7 +135,9 @@ static inline void a_store(volatile int *p, int x)
 		: "+m"(*p) : "r"(x) : "memory" );
 }
 
-static inline void a_spin()
+#define a_spin a_barrier
+
+static inline void a_barrier()
 {
 	a_cas(&(int){0}, 0, 0);
 }

arch/or1k/atomic.h

@@ -72,7 +72,9 @@ static inline void a_store(volatile int *p, int x)
 	a_swap(p, x);
 }
 
-static inline void a_spin()
+#define a_spin a_barrier
+
+static inline void a_barrier()
 {
 	a_cas(&(int){0}, 0, 0);
 }

arch/powerpc/atomic.h

@@ -78,7 +78,9 @@ static inline void a_store(volatile int *p, int x)
 		: "=m"(*p) : "r"(x) : "memory" );
 }
 
-static inline void a_spin()
+#define a_spin a_barrier
+
+static inline void a_barrier()
 {
 	a_cas(&(int){0}, 0, 0);
 }

arch/sh/atomic.h

@@ -51,7 +51,9 @@ static inline void a_dec(volatile int *x)
 	a_fetch_add(x, -1);
 }
 
-static inline void a_spin()
+#define a_spin a_barrier
+
+static inline void a_barrier()
 {
 	a_cas(&(int){0}, 0, 0);
 }

arch/x32/atomic.h

@@ -91,6 +91,11 @@ static inline void a_spin()
 	__asm__ __volatile__( "pause" : : : "memory" );
 }
 
+static inline void a_barrier()
+{
+	__asm__ __volatile__( "" : : : "memory" );
+}
+
 static inline void a_crash()
 {
 	__asm__ __volatile__( "hlt" : : : "memory" );

arch/x86_64/atomic.h

@@ -91,6 +91,11 @@ static inline void a_spin()
 	__asm__ __volatile__( "pause" : : : "memory" );
 }
 
+static inline void a_barrier()
+{
+	__asm__ __volatile__( "" : : : "memory" );
+}
+
 static inline void a_crash()
 {
 	__asm__ __volatile__( "hlt" : : : "memory" );