arch,mips: Convert smp_mb__*()

MIPS is interesting and has hardware variants that reorder over ll/sc
as well as those that do not.

Implement the 2 new barrier functions as per the old barriers.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-9ph49jbae3hol9v721sbc2g6@git.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maciej W. Rozycki" <macro@codesourcery.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/mips/include/asm/atomic.h

@@ -761,13 +761,4 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
 
 #endif /* CONFIG_64BIT */
 
-/*
- * atomic*_return operations are serializing but not the non-*_return
- * versions.
- */
-#define smp_mb__before_atomic_dec()	smp_mb__before_llsc()
-#define smp_mb__after_atomic_dec()	smp_llsc_mb()
-#define smp_mb__before_atomic_inc()	smp_mb__before_llsc()
-#define smp_mb__after_atomic_inc()	smp_llsc_mb()
-
 #endif /* _ASM_ATOMIC_H */

arch/mips/include/asm/barrier.h

@@ -195,4 +195,7 @@ do {									\
 	___p1;								\
 })
 
+#define smp_mb__before_atomic()	smp_mb__before_llsc()
+#define smp_mb__after_atomic()	smp_llsc_mb()
+
 #endif /* __ASM_BARRIER_H */

arch/mips/include/asm/bitops.h

@@ -37,13 +37,6 @@
 #define __EXT		"dext	 "
 #endif
 
-/*
- * clear_bit() doesn't provide any barrier for the compiler.
- */
-#define smp_mb__before_clear_bit()	smp_mb__before_llsc()
-#define smp_mb__after_clear_bit()	smp_llsc_mb()
-
-
 /*
  * These are the "slower" versions of the functions and are in bitops.c.
  * These functions call raw_local_irq_{save,restore}().
@@ -120,7 +113,7 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *addr)
  *
  * clear_bit() is atomic and may not be reordered.  However, it does
  * not contain a memory barrier, so if it is used for locking purposes,
- * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
+ * you should call smp_mb__before_atomic() and/or smp_mb__after_atomic()
  * in order to ensure changes are visible on other processors.
  */
 static inline void clear_bit(unsigned long nr, volatile unsigned long *addr)
@@ -175,7 +168,7 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *addr)
  */
 static inline void clear_bit_unlock(unsigned long nr, volatile unsigned long *addr)
 {
-	smp_mb__before_clear_bit();
+	smp_mb__before_atomic();
 	clear_bit(nr, addr);
 }
 

arch/mips/kernel/irq.c

@@ -62,9 +62,9 @@ void __init alloc_legacy_irqno(void)
 
 void free_irqno(unsigned int irq)
 {
-	smp_mb__before_clear_bit();
+	smp_mb__before_atomic();
 	clear_bit(irq, irq_map);
-	smp_mb__after_clear_bit();
+	smp_mb__after_atomic();
 }
 
 /*