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sparc: Support atomic64_dec_if_positive properly.

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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>
This commit is contained in:
David S. Miller 2012-11-09 19:37:59 -08:00
parent 0bce04be44
commit 193d2aadc0
4 changed files with 20 additions and 2 deletions
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1
arch/sparc/Kconfig
View file

@ -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

4
arch/sparc/include/asm/atomic_64.h
View file

@ -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()

16
arch/sparc/lib/atomic_64.S
View file

@ -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)

1
arch/sparc/lib/ksyms.c
View file

@ -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);