sparc: Support atomic64_dec_if_positive properly.
Sparc32 already supported it, as a consequence of using the
generic atomic64 implementation. And the sparc64 implementation
is rather trivial.
This allows us to set ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE for all
of sparc, and avoid the annoying warning from lib/atomic64_test.c
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/lib/atomic_64.S b/arch/sparc/lib/atomic_64.S
index 4d502da..85c233d 100644
--- a/arch/sparc/lib/atomic_64.S
+++ b/arch/sparc/lib/atomic_64.S
@@ -1,6 +1,6 @@
/* atomic.S: These things are too big to do inline.
*
- * Copyright (C) 1999, 2007 David S. Miller (davem@davemloft.net)
+ * Copyright (C) 1999, 2007 2012 David S. Miller (davem@davemloft.net)
*/
#include <linux/linkage.h>
@@ -117,3 +117,17 @@
sub %g1, %o0, %o0
2: BACKOFF_SPIN(%o2, %o3, 1b)
ENDPROC(atomic64_sub_ret)
+
+ENTRY(atomic64_dec_if_positive) /* %o0 = atomic_ptr */
+ BACKOFF_SETUP(%o2)
+1: ldx [%o0], %g1
+ brlez,pn %g1, 3f
+ sub %g1, 1, %g7
+ casx [%o0], %g1, %g7
+ cmp %g1, %g7
+ bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
+ nop
+3: retl
+ sub %g1, 1, %o0
+2: BACKOFF_SPIN(%o2, %o3, 1b)
+ENDPROC(atomic64_dec_if_positive)