Signed-off-by: Helge Deller <deller@xxxxxx>
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 0339181..967d727 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -12,6 +12,7 @@ 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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