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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4463d5ee9ecsm1107145f8f.16.2026.04.27.14.10.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2026 14:10:10 -0700 (PDT) From: David Carlier To: mptcp@lists.linux.dev Cc: Matthieu Baerts , Mat Martineau , Geliang Tang , Paolo Abeni , David Carlier Subject: [PATCH mptcp-next v4 1/4] mptcp: sockopt: factor inet_flags propagation into a mask Date: Mon, 27 Apr 2026 22:10:03 +0100 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: <20260421223338.52743-1-devnexen@gmail.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Replace the per-flag inet_assign_bit() calls in sync_socket_options() with a masked word-level copy of inet_sk()->inet_flags. Introduce MPTCP_INET_FLAGS_MASK so further flags propagated by MPTCP can be added by extending the mask rather than touching the call site. No functional change. Suggested-by: Paolo Abeni Signed-off-by: David Carlier --- net/mptcp/sockopt.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index 0efe40be2fde..41c9dc9cf95e 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -16,6 +16,10 @@ =20 #define MIN_INFO_OPTLEN_SIZE 16 #define MIN_FULL_INFO_OPTLEN_SIZE 40 +#define MPTCP_INET_FLAGS_MASK \ + (BIT(INET_FLAGS_TRANSPARENT) | \ + BIT(INET_FLAGS_FREEBIND) | \ + BIT(INET_FLAGS_BIND_ADDRESS_NO_PORT)) =20 static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk) { @@ -1536,6 +1540,7 @@ static void sync_socket_options(struct mptcp_sock *ms= k, struct sock *ssk) { static const unsigned int tx_rx_locks =3D SOCK_RCVBUF_LOCK | SOCK_SNDBUF_= LOCK; struct sock *sk =3D (struct sock *)msk; + unsigned long flags; bool keep_open; =20 keep_open =3D sock_flag(sk, SOCK_KEEPOPEN); @@ -1582,9 +1587,10 @@ static void sync_socket_options(struct mptcp_sock *m= sk, struct sock *ssk) tcp_sock_set_keepcnt(ssk, msk->keepalive_cnt); 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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4463d5ee9ecsm1107145f8f.16.2026.04.27.14.10.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2026 14:10:11 -0700 (PDT) From: David Carlier To: mptcp@lists.linux.dev Cc: Matthieu Baerts , Mat Martineau , Geliang Tang , Paolo Abeni , David Carlier Subject: [PATCH mptcp-next v4 2/4] mptcp: propagate RECVERR sockopts to subflows Date: Mon, 27 Apr 2026 22:10:04 +0100 Message-ID: <21762831cbe0d70fd963dd7f0ed9e05b050a7d1f.1777324037.git.devnexen@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: <20260421223338.52743-1-devnexen@gmail.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Propagate IP_RECVERR/IP_RECVERR_RFC4884 and IPV6_RECVERR/IPV6_RECVERR_RFC4884 from the MPTCP socket to existing and future subflows. The setsockopt path forwards each option to every subflow via mptcp_setsockopt_all_sf(); newly-joining subflows inherit the four RECVERR bits through sync_socket_options() now that MPTCP_INET_FLAGS_MASK covers them. Suggested-by: Paolo Abeni Assisted-by: Codex:gpt-5 Signed-off-by: David Carlier --- net/mptcp/sockopt.c | 97 ++++++++++++++++++++++++++++++++++++--------- 1 file changed, 79 insertions(+), 18 deletions(-) diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index 41c9dc9cf95e..171e83e66a97 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -8,6 +8,8 @@ =20 #include #include +#include +#include #include #include #include @@ -19,7 +21,11 @@ #define MPTCP_INET_FLAGS_MASK \ (BIT(INET_FLAGS_TRANSPARENT) | \ BIT(INET_FLAGS_FREEBIND) | \ - BIT(INET_FLAGS_BIND_ADDRESS_NO_PORT)) + BIT(INET_FLAGS_BIND_ADDRESS_NO_PORT) | \ + BIT(INET_FLAGS_RECVERR) | \ + BIT(INET_FLAGS_RECVERR_RFC4884) | \ + BIT(INET_FLAGS_RECVERR6) | \ + BIT(INET_FLAGS_RECVERR6_RFC4884)) =20 static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk) { @@ -388,6 +394,41 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_so= ck *msk, int optname, return -EOPNOTSUPP; } =20 +static int mptcp_setsockopt_all_sf(struct mptcp_sock *msk, int level, + int optname, sockptr_t optval, + unsigned int optlen) +{ + struct mptcp_subflow_context *subflow; + int ret =3D 0; + + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); + + ret =3D tcp_setsockopt(ssk, level, optname, optval, optlen); + if (ret) + break; + } + return ret; +} + +#if IS_ENABLED(CONFIG_IPV6) +static int mptcp_setsockopt_v6_recverr(struct mptcp_sock *msk, int optname, + sockptr_t optval, unsigned int optlen) +{ + struct sock *sk =3D (struct sock *)msk; + int ret; + + ret =3D ipv6_setsockopt(sk, SOL_IPV6, optname, optval, optlen); + if (ret) + return ret; + + lock_sock(sk); + ret =3D mptcp_setsockopt_all_sf(msk, SOL_IPV6, optname, optval, optlen); + release_sock(sk); + return ret; +} +#endif + static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname, sockptr_t optval, unsigned int optlen) { @@ -430,6 +471,12 @@ static int mptcp_setsockopt_v6(struct mptcp_sock *msk,= int optname, =20 release_sock(sk); break; +#if IS_ENABLED(CONFIG_IPV6) + case IPV6_RECVERR: + case IPV6_RECVERR_RFC4884: + ret =3D mptcp_setsockopt_v6_recverr(msk, optname, optval, optlen); + break; +#endif } =20 return ret; @@ -764,6 +811,22 @@ static int mptcp_setsockopt_v4_set_tos(struct mptcp_so= ck *msk, int optname, return 0; } =20 +static int mptcp_setsockopt_v4_recverr(struct mptcp_sock *msk, int optname, + sockptr_t optval, unsigned int optlen) +{ + struct sock *sk =3D (struct sock *)msk; + int ret; + + ret =3D ip_setsockopt(sk, SOL_IP, optname, optval, optlen); + if (ret) + return ret; + + lock_sock(sk); + ret =3D mptcp_setsockopt_all_sf(msk, SOL_IP, optname, optval, optlen); + release_sock(sk); + return ret; +} + static int mptcp_setsockopt_v4(struct mptcp_sock *msk, int optname, sockptr_t optval, unsigned int optlen) { @@ -775,6 +838,9 @@ static int mptcp_setsockopt_v4(struct mptcp_sock *msk, = int optname, return mptcp_setsockopt_sol_ip_set(msk, optname, optval, optlen); case IP_TOS: return mptcp_setsockopt_v4_set_tos(msk, optname, optval, optlen); + case IP_RECVERR: + case IP_RECVERR_RFC4884: + return mptcp_setsockopt_v4_recverr(msk, optname, optval, optlen); } =20 return -EOPNOTSUPP; @@ -802,23 +868,6 @@ static int mptcp_setsockopt_first_sf_only(struct mptcp= _sock *msk, int level, int return ret; } =20 -static int mptcp_setsockopt_all_sf(struct mptcp_sock *msk, int level, - int optname, sockptr_t optval, - unsigned int optlen) -{ - struct mptcp_subflow_context *subflow; - int ret =3D 0; - - mptcp_for_each_subflow(msk, subflow) { - struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); - - ret =3D tcp_setsockopt(ssk, level, optname, optval, optlen); - if (ret) - break; - } - return ret; -} - static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname, sockptr_t optval, unsigned int optlen) { @@ -1463,6 +1512,12 @@ static int mptcp_getsockopt_v4(struct mptcp_sock *ms= k, int optname, case IP_LOCAL_PORT_RANGE: return mptcp_put_int_option(msk, optval, optlen, READ_ONCE(inet_sk(sk)->local_port_range)); + case IP_RECVERR: + return mptcp_put_int_option(msk, optval, optlen, + inet_test_bit(RECVERR, sk)); + case IP_RECVERR_RFC4884: + return mptcp_put_int_option(msk, optval, optlen, + inet_test_bit(RECVERR_RFC4884, sk)); 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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4463d5ee9ecsm1107145f8f.16.2026.04.27.14.10.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2026 14:10:12 -0700 (PDT) From: David Carlier To: mptcp@lists.linux.dev Cc: Matthieu Baerts , Mat Martineau , Geliang Tang , Paolo Abeni , David Carlier Subject: [PATCH mptcp-next v4 3/4] mptcp: support MSG_ERRQUEUE on the parent socket Date: Mon, 27 Apr 2026 22:10:05 +0100 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: <20260421223338.52743-1-devnexen@gmail.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Splice pending err skbs from each subflow's error queue onto the parent msk's error queue at error-report time, so poll() and recvmsg(MSG_ERRQUEUE) on the parent socket observe ICMP, tx timestamp, and zerocopy completion notifications through the standard inet ABI. If sock_queue_err_skb() on the parent fails (rmem-limited), the skb is left on the subflow queue and retried on the next error report, avoiding silent loss. Suggested-by: Paolo Abeni Signed-off-by: David Carlier --- net/mptcp/protocol.c | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 0db50e3715c3..131fb6ddfcd9 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -815,21 +815,39 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk) return moved; } =20 +static bool __mptcp_subflow_splice_errqueue(struct sock *sk, struct sock *= ssk) +{ + struct sk_buff *skb; + bool moved =3D false; + + while ((skb =3D skb_dequeue(&ssk->sk_error_queue))) { + if (sock_queue_err_skb(sk, skb)) { + skb_queue_head(&ssk->sk_error_queue, skb); + break; + } + moved =3D true; + } + + return moved; +} + static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk) { int ssk_state; + bool report; int err; =20 + report =3D __mptcp_subflow_splice_errqueue(sk, ssk); + /* only propagate errors on fallen-back sockets or * on MPC connect */ if (sk->sk_state !=3D TCP_SYN_SENT && !__mptcp_check_fallback(mptcp_sk(sk= ))) - return false; + goto out; =20 err =3D sock_error(ssk); if (!err) - return false; - + goto out; /* We need to propagate only transition to CLOSE state. * Orphaned socket will see such state change via * subflow_sched_work_if_closed() and that path will properly @@ -839,6 +857,11 @@ static bool __mptcp_subflow_error_report(struct sock *= sk, struct sock *ssk) if (ssk_state =3D=3D TCP_CLOSE && !sock_flag(sk, SOCK_DEAD)) mptcp_set_state(sk, ssk_state); WRITE_ONCE(sk->sk_err, -err); + report =3D true; + +out: + if (!report) + return false; =20 /* This barrier is coupled with smp_rmb() in mptcp_poll() */ smp_wmb(); @@ -2295,7 +2318,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msgh= dr *msg, size_t len, int target; long timeo; =20 - /* MSG_ERRQUEUE is really a no-op till we support IP_RECVERR */ if (unlikely(flags & MSG_ERRQUEUE)) return inet_recv_error(sk, msg, len); =20 @@ -4340,7 +4362,8 @@ static __poll_t mptcp_poll(struct file *file, struct = socket *sock, =20 /* This barrier is coupled with smp_wmb() in __mptcp_error_report() */ smp_rmb(); - if (READ_ONCE(sk->sk_err)) + if (READ_ONCE(sk->sk_err) || + !skb_queue_empty_lockless(&sk->sk_error_queue)) mask |=3D EPOLLERR; =20 return mask; --=20 2.53.0 From nobody Tue May 5 11:26:39 2026 Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AE973373BE9 for ; Mon, 27 Apr 2026 21:10:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777324217; cv=none; b=CYmLB8XLqt0t7Il46jMez/vFrN17iKkoVwSP2MRi3urohTDHLW7n/k1YACdK7S5IiRt+JZDGQHQutySRxTXKftmi3SHyGTpkP1XUQeJtPXZbXCzzF4WzmDxyHiSaxNCZDpqMRjn3o+ARMv8oEU1ycFNL4mWLCXBWquX5lVJNWv8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777324217; c=relaxed/simple; bh=QcNVzrHJDmzDhVBtHzMTu8HUGMD/QTYlMSpRK5EIoOU=; 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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4463d5ee9ecsm1107145f8f.16.2026.04.27.14.10.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2026 14:10:13 -0700 (PDT) From: David Carlier To: mptcp@lists.linux.dev Cc: Matthieu Baerts , Mat Martineau , Geliang Tang , Paolo Abeni , David Carlier Subject: [PATCH mptcp-next v4 4/4] selftests: mptcp: cover IP_RECVERR sockopt propagation Date: Mon, 27 Apr 2026 22:10:06 +0100 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: <20260421223338.52743-1-devnexen@gmail.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Exercise setsockopt/getsockopt of IP_RECVERR and IPV6_RECVERR on the MPTCP parent socket, including the empty-errqueue EAGAIN contract on MSG_ERRQUEUE|MSG_DONTWAIT. End-to-end errqueue delivery (ICMP, TX timestamps, zerocopy) depends on subflow-side producers that are out of scope for this series and will be covered by follow-up work. Assisted-by: Codex:gpt-5 Signed-off-by: David Carlier --- .../selftests/net/mptcp/mptcp_sockopt.c | 55 +++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c b/tools/test= ing/selftests/net/mptcp/mptcp_sockopt.c index b6e58d936ebe..95bb2cc8e2ff 100644 --- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c +++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c @@ -769,6 +769,60 @@ static void test_ip_tos_sockopt(int fd) xerror("expect socklen_t =3D=3D -1"); } =20 +static void test_ip_recverr_sockopt(int fd) +{ + struct iovec iov =3D { + .iov_base =3D &(char){ 0 }, + .iov_len =3D 1, + }; + struct msghdr msg =3D { + .msg_iov =3D &iov, + .msg_iovlen =3D 1, + }; + int one =3D 1, zero =3D 0, val =3D -1; + socklen_t s =3D sizeof(val); + int level, optname, r; + + switch (pf) { + case AF_INET: + level =3D SOL_IP; + optname =3D IP_RECVERR; + break; + case AF_INET6: + level =3D SOL_IPV6; + optname =3D IPV6_RECVERR; + break; + default: + xerror("Unknown pf %d\n", pf); + } + + r =3D setsockopt(fd, level, optname, &one, sizeof(one)); + if (r) + die_perror("setsockopt recverr on"); + + r =3D getsockopt(fd, level, optname, &val, &s); + if (r) + die_perror("getsockopt recverr on"); + if (s !=3D sizeof(val) || val !=3D one) + xerror("recverr on mismatch val=3D%d len=3D%u", val, s); + + r =3D recvmsg(fd, &msg, MSG_ERRQUEUE | MSG_DONTWAIT); + if (r !=3D -1 || errno !=3D EAGAIN) + xerror("expected empty errqueue to return EAGAIN, ret=3D%d errno=3D%d", = r, errno); + + r =3D setsockopt(fd, level, optname, &zero, sizeof(zero)); + if (r) + die_perror("setsockopt recverr off"); + + val =3D -1; + s =3D sizeof(val); + r =3D getsockopt(fd, level, optname, &val, &s); + if (r) + die_perror("getsockopt recverr off"); + if (s !=3D sizeof(val) || val !=3D zero) + xerror("recverr off mismatch val=3D%d len=3D%u", val, s); +} + static int client(int pipefd) { int fd =3D -1; @@ -787,6 +841,7 @@ static int client(int pipefd) } =20 test_ip_tos_sockopt(fd); + test_ip_recverr_sockopt(fd); =20 connect_one_server(fd, pipefd); =20 --=20 2.53.0