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authorDavid S. Miller <davem@davemloft.net>2012-11-09 19:37:59 -0800
committerDavid S. Miller <davem@davemloft.net>2012-11-09 19:37:59 -0800
commit193d2aadc0ff5c687f6f0d5ef1d38c86ab511a14 (patch)
tree294286e259a08c977e3e71819b2c1d763b13312f /arch
parent0bce04be442cf4d6e4ba9dac2f0a4c5ee88af5c5 (diff)
downloadlinux-193d2aadc0ff5c687f6f0d5ef1d38c86ab511a14.tar.gz
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/sparc/Kconfig1
-rw-r--r--arch/sparc/include/asm/atomic_64.h4
-rw-r--r--arch/sparc/lib/atomic_64.S16
-rw-r--r--arch/sparc/lib/ksyms.c1
4 files changed, 20 insertions, 2 deletions
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index b6b442b0d793..9f2edb5c5551 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -20,6 +20,7 @@ config SPARC
select HAVE_ARCH_TRACEHOOK
select SYSCTL_EXCEPTION_TRACE
select ARCH_WANT_OPTIONAL_GPIOLIB
+ select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
select RTC_CLASS
select RTC_DRV_M48T59
select HAVE_IRQ_WORK
diff --git a/arch/sparc/include/asm/atomic_64.h b/arch/sparc/include/asm/atomic_64.h
index ce35a1cf1a20..be56a244c9cf 100644
--- a/arch/sparc/include/asm/atomic_64.h
+++ b/arch/sparc/include/asm/atomic_64.h
@@ -1,7 +1,7 @@
/* atomic.h: Thankfully the V9 is at least reasonable for this
* stuff.
*
- * Copyright (C) 1996, 1997, 2000 David S. Miller (davem@redhat.com)
+ * Copyright (C) 1996, 1997, 2000, 2012 David S. Miller (davem@redhat.com)
*/
#ifndef __ARCH_SPARC64_ATOMIC__
@@ -106,6 +106,8 @@ static inline long atomic64_add_unless(atomic64_t *v, long a, long u)
#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
+extern long atomic64_dec_if_positive(atomic64_t *v);
+
/* Atomic operations are already serializing */
#define smp_mb__before_atomic_dec() barrier()
#define smp_mb__after_atomic_dec() barrier()
diff --git a/arch/sparc/lib/atomic_64.S b/arch/sparc/lib/atomic_64.S
index 4d502da3de78..85c233d0a340 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 @@ ENTRY(atomic64_sub_ret) /* %o0 = decrement, %o1 = atomic_ptr */
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)
diff --git a/arch/sparc/lib/ksyms.c b/arch/sparc/lib/ksyms.c
index ee31b884c61b..0c4e35e522fa 100644
--- a/arch/sparc/lib/ksyms.c
+++ b/arch/sparc/lib/ksyms.c
@@ -116,6 +116,7 @@ EXPORT_SYMBOL(atomic64_add);
EXPORT_SYMBOL(atomic64_add_ret);
EXPORT_SYMBOL(atomic64_sub);
EXPORT_SYMBOL(atomic64_sub_ret);
+EXPORT_SYMBOL(atomic64_dec_if_positive);
/* Atomic bit operations. */
EXPORT_SYMBOL(test_and_set_bit);