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authorHelge Deller <deller@gmx.de>2013-05-06 19:13:33 +0000
committerHelge Deller <deller@gmx.de>2013-05-06 23:10:04 +0200
commitf21dda025ab00da197ac30b6c6690c380d838683 (patch)
tree3059c205f6fe3cbbf5e098524aab36a64aabeecc /arch/parisc
parentbbbfde782084b4f0d85ddffb88f1cf4650ff40e4 (diff)
downloadop-kernel-dev-f21dda025ab00da197ac30b6c6690c380d838683.zip
op-kernel-dev-f21dda025ab00da197ac30b6c6690c380d838683.tar.gz
parisc: implement atomic64_dec_if_positive()
Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch/parisc')
-rw-r--r--arch/parisc/Kconfig1
-rw-r--r--arch/parisc/include/asm/atomic.h23
2 files changed, 24 insertions, 0 deletions
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 433e75a..fe4afb0 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -13,6 +13,7 @@ config PARISC
select BUG
select HAVE_PERF_EVENTS
select GENERIC_ATOMIC64 if !64BIT
+ select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
select HAVE_GENERIC_HARDIRQS
select BROKEN_RODATA
select GENERIC_IRQ_PROBE
diff --git a/arch/parisc/include/asm/atomic.h b/arch/parisc/include/asm/atomic.h
index f38e198..472886c 100644
--- a/arch/parisc/include/asm/atomic.h
+++ b/arch/parisc/include/asm/atomic.h
@@ -229,6 +229,29 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
+/*
+ * atomic64_dec_if_positive - decrement by 1 if old value positive
+ * @v: pointer of type atomic_t
+ *
+ * The function returns the old value of *v minus 1, even if
+ * the atomic variable, v, was not decremented.
+ */
+static inline long atomic64_dec_if_positive(atomic64_t *v)
+{
+ 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 /* !CONFIG_64BIT */
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