Re: [PATCH net-next] tcp: Add stats for socket migration.
From: Yuchung Cheng <hidden>
Date: 2021-06-23 16:35:08
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On Tue, Jun 22, 2021 at 4:36 PM Kuniyuki Iwashima [off-list ref] wrote:
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/ (local) Suggested-by: Yuchung Cheng <redacted>
Looks good. thanks Acked-by: Yuchung Cheng <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: Kuniyuki Iwashima <redacted> --- include/uapi/linux/snmp.h | 2 ++ net/core/sock_reuseport.c | 15 +++++++++++---- net/ipv4/inet_connection_sock.c | 15 +++++++++++++-- net/ipv4/proc.c | 2 ++ net/ipv4/tcp_minisocks.c | 3 +++ 5 files changed, 31 insertions(+), 6 deletions(-)diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h index 26fc60ce9298..904909d020e2 100644 --- a/include/uapi/linux/snmp.h +++ b/include/uapi/linux/snmp.h@@ -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 };diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c index de5ee3ae86d5..3f00a28fe762 100644 --- a/net/core/sock_reuseport.c +++ b/net/core/sock_reuseport.c@@ -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);diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 0eea878edc30..754013fa393b 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c@@ -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); }diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c index 6d46297a99f8..b0d3a09dc84e 100644 --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c@@ -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 };diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index f258a4c0da71..0a4f3f16140a 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c@@ -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; --2.30.2