From: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
To: "David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>
Cc: Benjamin Herrenschmidt <benh@amazon.com>,
Kuniyuki Iwashima <kuniyu@amazon.co.jp>,
Kuniyuki Iwashima <kuni1840@gmail.com>, <bpf@vger.kernel.org>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH v7 bpf-next 06/11] tcp: Migrate TCP_NEW_SYN_RECV requests at retransmitting SYN+ACKs.
Date: Sat, 22 May 2021 03:20:59 +0900 [thread overview]
Message-ID: <20210521182104.18273-7-kuniyu@amazon.co.jp> (raw)
In-Reply-To: <20210521182104.18273-1-kuniyu@amazon.co.jp>
As with the preceding patch, this patch changes reqsk_timer_handler() to
call reuseport_migrate_sock() and inet_reqsk_clone() to migrate in-flight
requests at retransmitting SYN+ACKs. If we can select a new listener and
clone the request, we resume setting the SYN+ACK timer for the new req. If
we can set the timer, we call inet_ehash_insert() to unhash the old req and
put the new req into ehash.
The noteworthy point here is that by unhashing the old req, another CPU
processing it may lose the "own_req" race in tcp_v[46]_syn_recv_sock() and
drop the final ACK packet. However, the new timer will recover this
situation.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
net/ipv4/inet_connection_sock.c | 75 ++++++++++++++++++++++++++++++---
1 file changed, 68 insertions(+), 7 deletions(-)
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 07e97b2f3635..c1f068464363 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -735,10 +735,20 @@ static struct request_sock *inet_reqsk_clone(struct request_sock *req,
return nreq;
}
+static void reqsk_queue_migrated(struct request_sock_queue *queue,
+ const struct request_sock *req)
+{
+ if (req->num_timeout == 0)
+ atomic_inc(&queue->young);
+ atomic_inc(&queue->qlen);
+}
+
static void reqsk_migrate_reset(struct request_sock *req)
{
+ req->saved_syn = NULL;
+ inet_rsk(req)->ireq_opt = NULL;
#if IS_ENABLED(CONFIG_IPV6)
- inet_rsk(req)->ipv6_opt = NULL;
+ inet_rsk(req)->pktopts = NULL;
#endif
}
@@ -782,15 +792,39 @@ EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
static void reqsk_timer_handler(struct timer_list *t)
{
struct request_sock *req = from_timer(req, t, rsk_timer);
+ struct request_sock *nreq = NULL, *oreq = req;
struct sock *sk_listener = req->rsk_listener;
- struct net *net = sock_net(sk_listener);
- struct inet_connection_sock *icsk = inet_csk(sk_listener);
- struct request_sock_queue *queue = &icsk->icsk_accept_queue;
+ struct inet_connection_sock *icsk;
+ struct request_sock_queue *queue;
+ struct net *net;
int max_syn_ack_retries, qlen, expire = 0, resend = 0;
- if (inet_sk_state_load(sk_listener) != TCP_LISTEN)
- goto drop;
+ if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
+ struct sock *nsk;
+
+ nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
+ if (!nsk)
+ goto drop;
+
+ nreq = inet_reqsk_clone(req, nsk);
+ if (!nreq)
+ goto drop;
+
+ /* The new timer for the cloned req can decrease the 2
+ * by calling inet_csk_reqsk_queue_drop_and_put(), so
+ * hold another count to prevent use-after-free and
+ * call reqsk_put() just before return.
+ */
+ refcount_set(&nreq->rsk_refcnt, 2 + 1);
+ timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
+ reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
+
+ req = nreq;
+ sk_listener = nsk;
+ }
+ icsk = inet_csk(sk_listener);
+ net = sock_net(sk_listener);
max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
/* Normally all the openreqs are young and become mature
* (i.e. converted to established socket) for first timeout.
@@ -809,6 +843,7 @@ static void reqsk_timer_handler(struct timer_list *t)
* embrions; and abort old ones without pity, if old
* ones are about to clog our table.
*/
+ queue = &icsk->icsk_accept_queue;
qlen = reqsk_queue_len(queue);
if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
int young = reqsk_queue_len_young(queue) << 1;
@@ -833,10 +868,36 @@ static void reqsk_timer_handler(struct timer_list *t)
atomic_dec(&queue->young);
timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
mod_timer(&req->rsk_timer, jiffies + timeo);
+
+ if (!nreq)
+ return;
+
+ if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
+ /* delete timer */
+ inet_csk_reqsk_queue_drop(sk_listener, nreq);
+ goto drop;
+ }
+
+ reqsk_migrate_reset(oreq);
+ reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
+ reqsk_put(oreq);
+
+ reqsk_put(nreq);
return;
}
+
drop:
- inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
+ /* Even if we can clone the req, we may need not retransmit any more
+ * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
+ * CPU may win the "own_req" race so that inet_ehash_insert() fails.
+ */
+ if (nreq) {
+ reqsk_migrate_reset(nreq);
+ reqsk_queue_removed(queue, nreq);
+ __reqsk_free(nreq);
+ }
+
+ inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
}
static void reqsk_queue_hash_req(struct request_sock *req,
--
2.30.2
next prev parent reply other threads:[~2021-05-21 18:23 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-21 18:20 [PATCH v7 bpf-next 00/11] Socket migration for SO_REUSEPORT Kuniyuki Iwashima
2021-05-21 18:20 ` [PATCH v7 bpf-next 01/11] net: Introduce net.ipv4.tcp_migrate_req Kuniyuki Iwashima
2021-06-10 17:24 ` Eric Dumazet
2021-06-10 22:31 ` Kuniyuki Iwashima
2021-05-21 18:20 ` [PATCH v7 bpf-next 02/11] tcp: Add num_closed_socks to struct sock_reuseport Kuniyuki Iwashima
2021-06-10 17:38 ` Eric Dumazet
2021-06-10 22:33 ` Kuniyuki Iwashima
2021-05-21 18:20 ` [PATCH v7 bpf-next 03/11] tcp: Keep TCP_CLOSE sockets in the reuseport group Kuniyuki Iwashima
2021-06-10 17:59 ` Eric Dumazet
2021-06-10 22:37 ` Kuniyuki Iwashima
2021-05-21 18:20 ` [PATCH v7 bpf-next 04/11] tcp: Add reuseport_migrate_sock() to select a new listener Kuniyuki Iwashima
2021-06-10 18:09 ` Eric Dumazet
2021-06-10 22:39 ` Kuniyuki Iwashima
2021-05-21 18:20 ` [PATCH v7 bpf-next 05/11] tcp: Migrate TCP_ESTABLISHED/TCP_SYN_RECV sockets in accept queues Kuniyuki Iwashima
2021-06-10 18:20 ` Eric Dumazet
2021-06-10 22:45 ` Kuniyuki Iwashima
2021-05-21 18:20 ` Kuniyuki Iwashima [this message]
2021-06-10 20:21 ` [PATCH v7 bpf-next 06/11] tcp: Migrate TCP_NEW_SYN_RECV requests at retransmitting SYN+ACKs Eric Dumazet
2021-06-10 22:52 ` Kuniyuki Iwashima
2021-05-21 18:21 ` [PATCH v7 bpf-next 07/11] tcp: Migrate TCP_NEW_SYN_RECV requests at receiving the final ACK Kuniyuki Iwashima
2021-06-10 20:36 ` Eric Dumazet
2021-06-10 22:56 ` Kuniyuki Iwashima
2021-05-21 18:21 ` [PATCH v7 bpf-next 08/11] bpf: Support BPF_FUNC_get_socket_cookie() for BPF_PROG_TYPE_SK_REUSEPORT Kuniyuki Iwashima
2021-05-21 18:21 ` [PATCH v7 bpf-next 09/11] bpf: Support socket migration by eBPF Kuniyuki Iwashima
2021-05-21 18:21 ` [PATCH v7 bpf-next 10/11] libbpf: Set expected_attach_type for BPF_PROG_TYPE_SK_REUSEPORT Kuniyuki Iwashima
2021-05-21 18:21 ` [PATCH v7 bpf-next 11/11] bpf: Test BPF_SK_REUSEPORT_SELECT_OR_MIGRATE Kuniyuki Iwashima
2021-05-26 6:42 ` [PATCH v7 bpf-next 00/11] Socket migration for SO_REUSEPORT Daniel Borkmann
2021-06-08 3:13 ` Alexei Starovoitov
2021-06-08 17:48 ` Yuchung Cheng
2021-06-08 23:03 ` Kuniyuki Iwashima
2021-06-08 23:47 ` Yuchung Cheng
2021-06-09 0:34 ` Kuniyuki Iwashima
2021-06-09 17:04 ` Eric Dumazet
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