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tile: support atomic64_dec_if_positive()

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Use the normal cmpxchg() idiom to implement this functionality.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
This commit is contained in:
Chris Metcalf 2013-02-01 12:37:48 -05:00
parent ef567f25d5
commit adf6d9b30f
2 changed files with 22 additions and 0 deletions
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1
arch/tile/Kconfig
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@ -24,6 +24,7 @@ config TILE
select MODULES_USE_ELF_RELA
select HAVE_ARCH_TRACEHOOK
select HAVE_SYSCALL_TRACEPOINTS
select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
# FIXME: investigate whether we need/want these options.
# select HAVE_IOREMAP_PROT

21
arch/tile/include/asm/atomic.h
View File

@ -131,4 +131,25 @@ static inline int atomic_read(const atomic_t *v)
#include <asm/atomic_64.h>
#endif
#ifndef __ASSEMBLY__
static inline long long atomic64_dec_if_positive(atomic64_t *v)
{
long long c, old, dec;
c = atomic64_read(v);
for (;;) {
dec = c - 1;
if (unlikely(dec < 0))
break;
old = atomic64_cmpxchg((v), c, dec);
if (likely(old == c))
break;
c = old;
}
return dec;
}
#endif /* __ASSEMBLY__ */
#endif /* _ASM_TILE_ATOMIC_H */