On 08/11/2018 09:09 AM, Eugeniy Paltsev wrote: > 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.Paltsev at synopsys.com> LGTM. Curious, was this from code review or did u actually run into this ? Thx, -Vineet > --- > 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"
