From: Eric Dumazet edumazet@google.com
commit 1c4e97dd2d3c9a3e84f7e26346aa39bc426d3249 upstream
inet_twsk_purge() uses rcu to find TIME_WAIT and NEW_SYN_RECV objects to purge.
These objects use SLAB_TYPESAFE_BY_RCU semantic and need special care. We need to use refcount_inc_not_zero(&sk->sk_refcnt).
Reuse the existing correct logic I wrote for TIME_WAIT, because both structures have common locations for sk_state, sk_family, and netns pointer.
If after the refcount_inc_not_zero() the object fields longer match the keys, use sock_gen_put(sk) to release the refcount.
Then we can call inet_twsk_deschedule_put() for TIME_WAIT, inet_csk_reqsk_queue_drop_and_put() for NEW_SYN_RECV sockets, with BH disabled.
Then we need to restart the loop because we had drop rcu_read_lock().
Fixes: 740ea3c4a0b2 ("tcp: Clean up kernel listener's reqsk in inet_twsk_purge()") Link: https://lore.kernel.org/netdev/CANn89iLvFuuihCtt9PME2uS1WJATnf5fKjDToa1WzVnR... Signed-off-by: Eric Dumazet edumazet@google.com Link: https://lore.kernel.org/r/20240308200122.64357-2-kuniyu@amazon.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Zhengchao Shao shaozhengchao@huawei.com --- net/ipv4/inet_timewait_sock.c | 41 ++++++++++++++++------------------- 1 file changed, 19 insertions(+), 22 deletions(-)
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c index 9b891d6296ec..25809e06f111 100644 --- a/net/ipv4/inet_timewait_sock.c +++ b/net/ipv4/inet_timewait_sock.c @@ -254,12 +254,12 @@ void __inet_twsk_schedule(struct inet_timewait_sock *tw, int timeo, bool rearm) } EXPORT_SYMBOL_GPL(__inet_twsk_schedule);
+/* Remove all non full sockets (TIME_WAIT and NEW_SYN_RECV) for dead netns */ void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family) { - struct inet_timewait_sock *tw; - struct sock *sk; struct hlist_nulls_node *node; unsigned int slot; + struct sock *sk;
for (slot = 0; slot <= hashinfo->ehash_mask; slot++) { struct inet_ehash_bucket *head = &hashinfo->ehash[slot]; @@ -268,38 +268,35 @@ void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family) rcu_read_lock(); restart: sk_nulls_for_each_rcu(sk, node, &head->chain) { - if (sk->sk_state != TCP_TIME_WAIT) { - /* A kernel listener socket might not hold refcnt for net, - * so reqsk_timer_handler() could be fired after net is - * freed. Userspace listener and reqsk never exist here. - */ - if (unlikely(sk->sk_state == TCP_NEW_SYN_RECV && - hashinfo->pernet)) { - struct request_sock *req = inet_reqsk(sk); - - inet_csk_reqsk_queue_drop_and_put(req->rsk_listener, req); - } + int state = inet_sk_state_load(sk);
+ if ((1 << state) & ~(TCPF_TIME_WAIT | + TCPF_NEW_SYN_RECV)) continue; - }
- tw = inet_twsk(sk); - if ((tw->tw_family != family) || - refcount_read(&twsk_net(tw)->ns.count)) + if (sk->sk_family != family || + refcount_read(&sock_net(sk)->ns.count)) continue;
- if (unlikely(!refcount_inc_not_zero(&tw->tw_refcnt))) + if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt))) continue;
- if (unlikely((tw->tw_family != family) || - refcount_read(&twsk_net(tw)->ns.count))) { - inet_twsk_put(tw); + if (unlikely(sk->sk_family != family || + refcount_read(&sock_net(sk)->ns.count))) { + sock_gen_put(sk); goto restart; }
rcu_read_unlock(); local_bh_disable(); - inet_twsk_deschedule_put(tw); + if (state == TCP_TIME_WAIT) { + inet_twsk_deschedule_put(inet_twsk(sk)); + } else { + struct request_sock *req = inet_reqsk(sk); + + inet_csk_reqsk_queue_drop_and_put(req->rsk_listener, + req); + } local_bh_enable(); goto restart_rcu; }