From 2ca06a2f65310aeef30bb69b7405437a14766e4d Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Mon, 13 Jan 2025 16:44:56 +0100 Subject: [PATCH 1/3] mptcp: be sure to send ack when mptcp-level window re-opens mptcp_cleanup_rbuf() is responsible to send acks when the user-space reads enough data to update the receive windows significantly. It tries hard to avoid acquiring the subflow sockets locks by checking conditions similar to the ones implemented at the TCP level. To avoid too much code duplication - the MPTCP protocol can't reuse the TCP helpers as part of the relevant status is maintained into the msk socket - and multiple costly window size computation, mptcp_cleanup_rbuf uses a rough estimate for the most recently advertised window size: the MPTCP receive free space, as recorded as at last-ack time. Unfortunately the above does not allow mptcp_cleanup_rbuf() to detect a zero to non-zero win change in some corner cases, skipping the tcp_cleanup_rbuf call and leaving the peer stuck. After commit ea66758c1795 ("tcp: allow MPTCP to update the announced window"), MPTCP has actually cheap access to the announced window value. Use it in mptcp_cleanup_rbuf() for a more accurate ack generation. Fixes: e3859603ba13 ("mptcp: better msk receive window updates") Cc: stable@vger.kernel.org Reported-by: Jakub Kicinski Closes: https://lore.kernel.org/20250107131845.5e5de3c5@kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250113-net-mptcp-connect-st-flakes-v1-1-0d986ee7b1b6@kernel.org Signed-off-by: Jakub Kicinski --- net/mptcp/options.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index a62bc874bf1e..123f3f297284 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -607,7 +607,6 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, } opts->ext_copy.use_ack = 1; opts->suboptions = OPTION_MPTCP_DSS; - WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk)); /* Add kind/length/subtype/flag overhead if mapping is not populated */ if (dss_size == 0) @@ -1288,7 +1287,7 @@ static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th) } MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICT); } - return; + goto update_wspace; } if (rcv_wnd_new != rcv_wnd_old) { @@ -1313,6 +1312,9 @@ static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th) th->window = htons(new_win); MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDSHARED); } + +update_wspace: + WRITE_ONCE(msk->old_wspace, tp->rcv_wnd); } __sum16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum) From e226d9259dc4f5d2c19e6682ad1356fa97cf38f4 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Mon, 13 Jan 2025 16:44:57 +0100 Subject: [PATCH 2/3] mptcp: fix spurious wake-up on under memory pressure The wake-up condition currently implemented by mptcp_epollin_ready() is wrong, as it could mark the MPTCP socket as readable even when no data are present and the system is under memory pressure. Explicitly check for some data being available in the receive queue. Fixes: 5684ab1a0eff ("mptcp: give rcvlowat some love") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250113-net-mptcp-connect-st-flakes-v1-2-0d986ee7b1b6@kernel.org Signed-off-by: Jakub Kicinski --- net/mptcp/protocol.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index a93e661ef5c4..73526f1d768f 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -760,10 +760,15 @@ static inline u64 mptcp_data_avail(const struct mptcp_sock *msk) static inline bool mptcp_epollin_ready(const struct sock *sk) { + u64 data_avail = mptcp_data_avail(mptcp_sk(sk)); + + if (!data_avail) + return false; + /* mptcp doesn't have to deal with small skbs in the receive queue, - * at it can always coalesce them + * as it can always coalesce them */ - return (mptcp_data_avail(mptcp_sk(sk)) >= sk->sk_rcvlowat) || + return (data_avail >= sk->sk_rcvlowat) || (mem_cgroup_sockets_enabled && sk->sk_memcg && mem_cgroup_under_socket_pressure(sk->sk_memcg)) || READ_ONCE(tcp_memory_pressure); From 218cc166321fb3cc8786677ffe0d09a78778a910 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Mon, 13 Jan 2025 16:44:58 +0100 Subject: [PATCH 3/3] selftests: mptcp: avoid spurious errors on disconnect MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The disconnect test-case generates spurious errors: INFO: disconnect INFO: extra options: -I 3 -i /tmp/tmp.r43niviyoI 01 ns1 MPTCP -> ns1 (10.0.1.1:10000 ) MPTCP (duration 140ms) [FAIL] file received by server does not match (in, out): Unexpected revents: POLLERR/POLLNVAL(19) -rw-r--r-- 1 root root 10028676 Jan 10 10:47 /tmp/tmp.r43niviyoI.disconnect Trailing bytes are: ��\����R���!8��u2��5N% -rw------- 1 root root 9992290 Jan 10 10:47 /tmp/tmp.Os4UbnWbI1 Trailing bytes are: ��\����R���!8��u2��5N% 02 ns1 MPTCP -> ns1 (dead:beef:1::1:10001) MPTCP (duration 206ms) [ OK ] 03 ns1 MPTCP -> ns1 (dead:beef:1::1:10002) TCP (duration 31ms) [ OK ] 04 ns1 TCP -> ns1 (dead:beef:1::1:10003) MPTCP (duration 26ms) [ OK ] [FAIL] Tests of the full disconnection have failed Time: 2 seconds The root cause is actually in the user-space bits: the test program currently disconnects as soon as all the pending data has been spooled, generating an FASTCLOSE. If such option reaches the peer before the latter has reached the closed status, the msk socket will report an error to the user-space, as per protocol specification, causing the above failure. Address the issue explicitly waiting for all the relevant sockets to reach a closed status before performing the disconnect. Fixes: 05be5e273c84 ("selftests: mptcp: add disconnect tests") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250113-net-mptcp-connect-st-flakes-v1-3-0d986ee7b1b6@kernel.org Signed-off-by: Jakub Kicinski --- .../selftests/net/mptcp/mptcp_connect.c | 43 ++++++++++++++----- 1 file changed, 32 insertions(+), 11 deletions(-) diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/testing/selftests/net/mptcp/mptcp_connect.c index 4209b9569039..414addef9a45 100644 --- a/tools/testing/selftests/net/mptcp/mptcp_connect.c +++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c @@ -25,6 +25,8 @@ #include #include +#include + #include #include @@ -1211,23 +1213,42 @@ static void parse_setsock_options(const char *name) exit(1); } -void xdisconnect(int fd, int addrlen) +void xdisconnect(int fd) { - struct sockaddr_storage empty; + socklen_t addrlen = sizeof(struct sockaddr_storage); + struct sockaddr_storage addr, empty; int msec_sleep = 10; - int queued = 1; - int i; + void *raw_addr; + int i, cmdlen; + char cmd[128]; + + /* get the local address and convert it to string */ + if (getsockname(fd, (struct sockaddr *)&addr, &addrlen) < 0) + xerror("getsockname"); + + if (addr.ss_family == AF_INET) + raw_addr = &(((struct sockaddr_in *)&addr)->sin_addr); + else if (addr.ss_family == AF_INET6) + raw_addr = &(((struct sockaddr_in6 *)&addr)->sin6_addr); + else + xerror("bad family"); + + strcpy(cmd, "ss -M | grep -q "); + cmdlen = strlen(cmd); + if (!inet_ntop(addr.ss_family, raw_addr, &cmd[cmdlen], + sizeof(cmd) - cmdlen)) + xerror("inet_ntop"); shutdown(fd, SHUT_WR); - /* while until the pending data is completely flushed, the later + /* + * wait until the pending data is completely flushed and all + * the MPTCP sockets reached the closed status. * disconnect will bypass/ignore/drop any pending data. */ for (i = 0; ; i += msec_sleep) { - if (ioctl(fd, SIOCOUTQ, &queued) < 0) - xerror("can't query out socket queue: %d", errno); - - if (!queued) + /* closed socket are not listed by 'ss' */ + if (system(cmd) != 0) break; if (i > poll_timeout) @@ -1281,9 +1302,9 @@ int main_loop(void) return ret; if (cfg_truncate > 0) { - xdisconnect(fd, peer->ai_addrlen); + xdisconnect(fd); } else if (--cfg_repeat > 0) { - xdisconnect(fd, peer->ai_addrlen); + xdisconnect(fd); /* the socket could be unblocking at this point, we need the * connect to be blocking