Messages in this thread |  | | From | Jason Xing <> | Date | Mon, 16 Jan 2023 08:36:14 +0800 | Subject | Re: [PATCH v2 net] tcp: avoid the lookup process failing to get sk in ehash table |
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On Mon, Jan 16, 2023 at 12:12 AM Eric Dumazet <edumazet@google.com> wrote: > > On Sat, Jan 14, 2023 at 2:27 PM Jason Xing <kerneljasonxing@gmail.com> wrote: > > > > From: Jason Xing <kernelxing@tencent.com> > > > > > > Fixes: 5e0724d027f0 ("tcp/dccp: fix hashdance race for passive sessions") > > Suggested-by: Eric Dumazet <edumazet@google.com> > > Signed-off-by: Jason Xing <kernelxing@tencent.com> > > Link: https://lore.kernel.org/lkml/20230112065336.41034-1-kerneljasonxing@gmail.com/ > > --- > > v2: > > 1) adding the sk node into the tail of list to prevent the race. > > 2) fix the race condition when handling time-wait socket hashdance. > > --- > > net/ipv4/inet_hashtables.c | 10 ++++++++++ > > net/ipv4/inet_timewait_sock.c | 6 +++--- > > 2 files changed, 13 insertions(+), 3 deletions(-) > > > > diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c > > index 24a38b56fab9..b0b54ad55507 100644 > > --- a/net/ipv4/inet_hashtables.c > > +++ b/net/ipv4/inet_hashtables.c > > @@ -650,7 +650,16 @@ bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk) > > spin_lock(lock); > > if (osk) { > > WARN_ON_ONCE(sk->sk_hash != osk->sk_hash); > > + if (sk_hashed(osk)) > > > nit: this should be: > > if (sk_hashed(osk)) { [1] > /* multi-line .... > * .... comment. > */ > ret = sk_nulls_del_node_init_rcu(osk); > goto unlock; > } > if (found_dup_sk) { [2] > > 1) parentheses needed in [1] > 2) No else if in [2], since you added a "goto unlock;" >
I'll do that. It looks much better.
Thanks, Jason
> > + /* Before deleting the node, we insert a new one to make > > + * sure that the look-up-sk process would not miss either > > + * of them and that at least one node would exist in ehash > > + * table all the time. Otherwise there's a tiny chance > > + * that lookup process could find nothing in ehash table. > > + */ > > + __sk_nulls_add_node_tail_rcu(sk, list); > > ret = sk_nulls_del_node_init_rcu(osk); > > + goto unlock; > > } else if (found_dup_sk) { > > *found_dup_sk = inet_ehash_lookup_by_sk(sk, list); > > if (*found_dup_sk) > > @@ -660,6 +669,7 @@ bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk) > > if (ret) > > __sk_nulls_add_node_rcu(sk, list); > > > > +unlock: > > spin_unlock(lock); > > Thanks.
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