Commit 55d444b3 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller
Browse files

tcp: Add stats for socket migration. 

This commit adds two stats for the socket migration feature to evaluate the
effectiveness: LINUX_MIB_TCPMIGRATEREQ(SUCCESS|FAILURE).

If the migration fails because of the own_req race in receiving ACK and
sending SYN+ACK paths, we do not increment the failure stat. Then another
CPU is responsible for the req.

Link: https://lore.kernel.org/bpf/CAK6E8=cgFKuGecTzSCSQ8z3YJ_163C0uwO9yRvfDSE7vOe9mJA@mail.gmail.com/


Suggested-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7525de25

include/uapi/linux/snmp.h

+2 −0
Original line number Diff line number Diff line
@@ -290,6 +290,8 @@ enum 
	LINUX_MIB_TCPDUPLICATEDATAREHASH,	/* TCPDuplicateDataRehash */

	LINUX_MIB_TCPDSACKRECVSEGS,		/* TCPDSACKRecvSegs */

	LINUX_MIB_TCPDSACKIGNOREDDUBIOUS,	/* TCPDSACKIgnoredDubious */

	LINUX_MIB_TCPMIGRATEREQSUCCESS,		/* TCPMigrateReqSuccess */

	LINUX_MIB_TCPMIGRATEREQFAILURE,		/* TCPMigrateReqFailure */

	__LINUX_MIB_MAX

};

net/core/sock_reuseport.c

+11 −4
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
 * selecting the socket index from the array of available sockets.

 */



#include <net/ip.h>

#include <net/sock_reuseport.h>

#include <linux/bpf.h>

#include <linux/idr.h>
@@ -536,7 +537,7 @@ struct sock *reuseport_migrate_sock(struct sock *sk, 


	socks = READ_ONCE(reuse->num_socks);

	if (unlikely(!socks))

		goto out;

		goto failure;



	/* paired with smp_wmb() in __reuseport_add_sock() */

	smp_rmb();
@@ -546,13 +547,13 @@ struct sock *reuseport_migrate_sock(struct sock *sk, 
	if (!prog || prog->expected_attach_type != BPF_SK_REUSEPORT_SELECT_OR_MIGRATE) {

		if (sock_net(sk)->ipv4.sysctl_tcp_migrate_req)

			goto select_by_hash;

		goto out;

		goto failure;

	}



	if (!skb) {

		skb = alloc_skb(0, GFP_ATOMIC);

		if (!skb)

			goto out;

			goto failure;

		allocated = true;

	}
@@ -565,12 +566,18 @@ struct sock *reuseport_migrate_sock(struct sock *sk, 
	if (!nsk)

		nsk = reuseport_select_sock_by_hash(reuse, hash, socks);



	if (IS_ERR_OR_NULL(nsk) || unlikely(!refcount_inc_not_zero(&nsk->sk_refcnt)))

	if (IS_ERR_OR_NULL(nsk) || unlikely(!refcount_inc_not_zero(&nsk->sk_refcnt))) {

		nsk = NULL;

		goto failure;

	}



out:

	rcu_read_unlock();

	return nsk;



failure:

	__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);

	goto out;

}

EXPORT_SYMBOL(reuseport_migrate_sock);

net/ipv4/inet_connection_sock.c

+13 −2
Original line number Diff line number Diff line
@@ -703,6 +703,8 @@ static struct request_sock *inet_reqsk_clone(struct request_sock *req, 


	nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);

	if (!nreq) {

		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);



		/* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */

		sock_put(sk);

		return NULL;
@@ -876,9 +878,10 @@ static void reqsk_timer_handler(struct timer_list *t) 
		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;

			goto no_ownership;

		}



		__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);

		reqsk_migrate_reset(oreq);

		reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);

		reqsk_put(oreq);
@@ -887,17 +890,19 @@ static void reqsk_timer_handler(struct timer_list *t) 
		return;

	}



drop:

	/* 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) {

		__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);

no_ownership:

		reqsk_migrate_reset(nreq);

		reqsk_queue_removed(queue, nreq);

		__reqsk_free(nreq);

	}



drop:

	inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);

}
@@ -1135,11 +1140,13 @@ struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child, 


			refcount_set(&nreq->rsk_refcnt, 1);

			if (inet_csk_reqsk_queue_add(sk, nreq, child)) {

				__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);

				reqsk_migrate_reset(req);

				reqsk_put(req);

				return child;

			}



			__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);

			reqsk_migrate_reset(nreq);

			__reqsk_free(nreq);

		} else if (inet_csk_reqsk_queue_add(sk, req, child)) {
@@ -1188,8 +1195,12 @@ void inet_csk_listen_stop(struct sock *sk) 
				refcount_set(&nreq->rsk_refcnt, 1);



				if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {

					__NET_INC_STATS(sock_net(nsk),

							LINUX_MIB_TCPMIGRATEREQSUCCESS);

					reqsk_migrate_reset(req);

				} else {

					__NET_INC_STATS(sock_net(nsk),

							LINUX_MIB_TCPMIGRATEREQFAILURE);

					reqsk_migrate_reset(nreq);

					__reqsk_free(nreq);

				}

net/ipv4/proc.c

+2 −0
Original line number Diff line number Diff line
@@ -295,6 +295,8 @@ static const struct snmp_mib snmp4_net_list[] = { 
	SNMP_MIB_ITEM("TcpDuplicateDataRehash", LINUX_MIB_TCPDUPLICATEDATAREHASH),

	SNMP_MIB_ITEM("TCPDSACKRecvSegs", LINUX_MIB_TCPDSACKRECVSEGS),

	SNMP_MIB_ITEM("TCPDSACKIgnoredDubious", LINUX_MIB_TCPDSACKIGNOREDDUBIOUS),

	SNMP_MIB_ITEM("TCPMigrateReqSuccess", LINUX_MIB_TCPMIGRATEREQSUCCESS),

	SNMP_MIB_ITEM("TCPMigrateReqFailure", LINUX_MIB_TCPMIGRATEREQFAILURE),

	SNMP_MIB_SENTINEL

};

net/ipv4/tcp_minisocks.c

+3 −0
Original line number Diff line number Diff line
@@ -786,6 +786,9 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 
	return inet_csk_complete_hashdance(sk, child, req, own_req);



listen_overflow:

	if (sk != req->rsk_listener)

		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);



	if (!sock_net(sk)->ipv4.sysctl_tcp_abort_on_overflow) {

		inet_rsk(req)->acked = 1;

		return NULL;