On Fri, 14 May 2021 16:36:16 -0700 Cong Wang wrote:
> > @@ -176,8 +202,15 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc)
> > static inline void qdisc_run_end(struct Qdisc *qdisc)
> > {
> > write_seqcount_end(&qdisc->running);
> > - if (qdisc->flags & TCQ_F_NOLOCK)
> > + if (qdisc->flags & TCQ_F_NOLOCK) {
> > spin_unlock(&qdisc->seqlock);
> > +
> > + if (unlikely(test_bit(__QDISC_STATE_MISSED,
> > + &qdisc->state))) {
> > + clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
>
> We have test_and_clear_bit() which is atomic, test_bit()+clear_bit()
> is not.
It doesn't have to be atomic, right? I asked to split the test because
test_and_clear is a locked op on x86, test by itself is not.
