arch,blackfin: Convert smp_mb__*()

Blackfin's atomic primitives do not imply a full barrier as whitnessed
from its SMP smp_mb__{before,after}_clear_bit() implementations.

However since !SMP smp_mb() reduces to barrier() remove everything and
rely on the asm-generic/barrier.h implentation.
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-1widdkdsb3c1titq8jez6g3g@git.kernel.org
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Steven Miao <realmz6@gmail.com>
Cc: adi-buildroot-devel@lists.sourceforge.net
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/blackfin/include/asm/barrier.h

@@ -27,6 +27,9 @@
 
 #endif /* !CONFIG_SMP */
 
+#define smp_mb__before_atomic()	barrier()
+#define smp_mb__after_atomic()	barrier()
+
 #include <asm-generic/barrier.h>
 
 #endif /* _BLACKFIN_BARRIER_H */

arch/blackfin/include/asm/bitops.h

@@ -27,21 +27,17 @@
 
 #include <asm-generic/bitops/ext2-atomic.h>
 
+#include <asm/barrier.h>
+
 #ifndef CONFIG_SMP
 #include <linux/irqflags.h>
-
 /*
  * clear_bit may not imply a memory barrier
  */
-#ifndef smp_mb__before_clear_bit
-#define smp_mb__before_clear_bit()	smp_mb()
-#define smp_mb__after_clear_bit()	smp_mb()
-#endif
 #include <asm-generic/bitops/atomic.h>
 #include <asm-generic/bitops/non-atomic.h>
 #else
 
-#include <asm/barrier.h>
 #include <asm/byteorder.h>	/* swab32 */
 #include <linux/linkage.h>
 
@@ -101,12 +97,6 @@ static inline int test_and_change_bit(int nr, volatile unsigned long *addr)
 	return __raw_bit_test_toggle_asm(a, nr & 0x1f);
 }
 
-/*
- * clear_bit() doesn't provide any barrier for the compiler.
- */
-#define smp_mb__before_clear_bit()	barrier()
-#define smp_mb__after_clear_bit()	barrier()
-
 #define test_bit __skip_test_bit
 #include <asm-generic/bitops/non-atomic.h>
 #undef test_bit