X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=arch%2Farc%2Finclude%2Fasm%2Fcmpxchg.h;h=44fd531f4d7b93a9df7bff6dec976af5e571506c;hb=83dcf400be7165af938dbd6b8ce6805c754701db;hp=90de5c528da221f5f5929f731962f675b6787a90;hpb=d57f727264f1425a94689bafc7e99e502cb135b5;p=karo-tx-linux.git

diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
index 90de5c528da2..44fd531f4d7b 100644
--- a/arch/arc/include/asm/cmpxchg.h
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -10,6 +10,8 @@
 #define __ASM_ARC_CMPXCHG_H
 
 #include <linux/types.h>
+
+#include <asm/barrier.h>
 #include <asm/smp.h>
 
 #ifdef CONFIG_ARC_HAS_LLSC
@@ -19,6 +21,12 @@ __cmpxchg(volatile void *ptr, unsigned long expected, unsigned long new)
 {
 	unsigned long prev;
 
+	/*
+	 * Explicit full memory barrier needed before/after as
+	 * LLOCK/SCOND thmeselves don't provide any such semantics
+	 */
+	smp_mb();
+
 	__asm__ __volatile__(
 	"1:	llock   %0, [%1]	\n"
 	"	brne    %0, %2, 2f	\n"
@@ -31,6 +39,8 @@ __cmpxchg(volatile void *ptr, unsigned long expected, unsigned long new)
 	  "r"(new)	/* can't be "ir". scond can't take LIMM for "b" */
 	: "cc", "memory"); /* so that gcc knows memory is being written here */
 
+	smp_mb();
+
 	return prev;
 }
 
@@ -43,6 +53,9 @@ __cmpxchg(volatile void *ptr, unsigned long expected, unsigned long new)
 	int prev;
 	volatile unsigned long *p = ptr;
 
+	/*
+	 * spin lock/unlock provide the needed smp_mb() before/after
+	 */
 	atomic_ops_lock(flags);
 	prev = *p;
 	if (prev == expected)
@@ -78,12 +91,16 @@ static inline unsigned long __xchg(unsigned long val, volatile void *ptr,
 
 	switch (size) {
 	case 4:
+		smp_mb();
+
 		__asm__ __volatile__(
 		"	ex  %0, [%1]	\n"
 		: "+r"(val)
 		: "r"(ptr)
 		: "memory");
 
+		smp_mb();
+
 		return val;
 	}
 	return __xchg_bad_pointer();