Current implementation of 'atomic64_add_unless' function
(and hence 'atomic64_inc_not_zero') return incorrect value
if lover 32 bits of compared 64-bit number are equal and
higher 32 bits aren't.
For in following example atomic64_add_unless must return '1'
but it actually returns '0':
--------->8---------
atomic64_t val = ATOMIC64_INIT(0x4444000000000000LL);
int ret = atomic64_add_unless(&val, 1LL, 0LL)
--------->8---------
This happens because we write '0' to returned variable regardless
of higher 32 bits comparison result.
So fix it.
NOTE:
this change was tested with atomic64_test.
Signed-off-by: Eugeniy Paltsev <eugeniy.palt...@synopsys.com>
---
arch/arc/include/asm/atomic.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arc/include/asm/atomic.h b/arch/arc/include/asm/atomic.h
index 11859287c52a..e840cb1763b2 100644
--- a/arch/arc/include/asm/atomic.h
+++ b/arch/arc/include/asm/atomic.h
@@ -578,11 +578,11 @@ static inline int atomic64_add_unless(atomic64_t *v, long
long a, long long u)
__asm__ __volatile__(
"1: llockd %0, [%2] \n"
- " mov %1, 1 \n"
" brne %L0, %L4, 2f # continue to add since v != u \n"
" breq.d %H0, %H4, 3f # return since v == u \n"
" mov %1, 0 \n"
"2: \n"
+ " mov %1, 1 \n"
" add.f %L0, %L0, %L3 \n"
" adc %H0, %H0, %H3 \n"
" scondd %0, [%2] \n"
--
2.14.4
_______________________________________________
linux-snps-arc mailing list
linux-snps-arc@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-snps-arc
