On Thu, Apr 1, 2021 at 8:44 PM Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
>
> On Thu, Mar 25, 2021 at 04:32:58PM +0100, Gioh Kim wrote:
> > diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> > index 42f49208b8f7..1519191d7154 100644
> > +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> > @@ -808,6 +808,9 @@ static struct rtrs_clt_sess *get_next_path_min_inflight(struct path_it *it)
> > int inflight;
> >
> > list_for_each_entry_rcu(sess, &clt->paths_list, s.entry) {
> > + if (unlikely(READ_ONCE(sess->state) != RTRS_CLT_CONNECTED))
> > + continue;
>
> There is no way this could be right, a READ_ONCE can't guarentee that
> a following load is not going to happen without races.
>
> You need locking.
Hi Jason,
rtrs_clt_request() calls rcu_read_lock() before calling
get_next_path_min_inflight().
And rtrs_clt_change_state_from_to(), that changes the sess->state,
calls spin_lock_irq() before changing it.
I think that is enough, isn't it?
>
> Jason
