[PATCH mptcp-next v11 0/4] mptcp: MSG_ERRQUEUE support on the parent socket

[PATCH mptcp-next v11 0/4] mptcp: MSG_ERRQUEUE support on the parent socket

[David Carlier]

This series lets MPTCP applications use poll(EPOLLERR) and
recvmsg(MSG_ERRQUEUE) on the parent socket to drain TX timestamps,
MSG_ZEROCOPY completion notifications and SO_EE_ORIGIN_LOCAL events
through the standard inet ABI, the same way they would on a plain TCP
socket. ICMP-derived errors stay on the subflow queue: the legacy
RECVERR ABI cannot convey their per-subflow peer identity, and they
are intended for a future MPTCP_RECERR channel.

Patch 1 factors the existing inet_flags subflow-propagation hard-coded
list into a mask, so subsequent patches can extend it without churn.

Patch 2 makes IP_RECVERR / IPV6_RECVERR (and the RFC4884 variants)
propagate to the subflows. The parent stores the bit so MPTCP-aware
helpers can branch on it.

Patch 3 splices subflow err-skbs onto the parent's sk_error_queue at
error-report time. All forwarded events go through sock_queue_err_skb(),
which re-homes skb->sk onto the parent and charges sk_rmem_alloc, so the
parent's error queue stays bounded by sk_rcvbuf and is dropped under rmem
pressure, matching tcp's tx-timestamp path and ip_icmp_error() /
ipv6_icmp_error(). MPTCP never originates MSG_ZEROCOPY or OPT_ID
tx-timestamp completions -- its data path copies into msk-owned pages and
bypasses tcp_sendmsg_locked() -- so no subflow-relative ee_data sequence
is ever forwarded. mptcp_recvmsg(MSG_ERRQUEUE) forwards directly to
inet_recv_error(), and mptcp_poll() advertises EPOLLERR purely on the
parent's sk_err / sk_error_queue, matching tcp_poll().

Patch 4 is a selftest covering the propagation path.

Changes in v11 (addresses sashiko v10 review,
https://sashiko.dev/#/patchset/20260529174524.260199-1-devnexen@gmail.com):
 - patch 3/4: route MSG_ZEROCOPY completions through sock_queue_err_skb()
   like every other forwarded event, rather than orphaning them and
   queueing to the parent by hand. The hand-rolled path ran the subflow
   destructor (refunding its memory charge) but never charged the parent,
   so completions could pile up unbounded on the parent err queue and
   exhaust memory (OOM). The "never drop or we leak pinned pages" premise
   was also wrong: __msg_zerocopy_callback() calls
   mm_unaccount_pinned_pages() before queueing, so a dropped notification
   loses only the notification, not the pages. (sashiko v10, High)
 - no functional change for the ee_data concern: MPTCP originates neither
   MSG_ZEROCOPY nor OPT_ID tx-timestamp completions, so no subflow-relative
   sequence is ever spliced to the parent. (sashiko v10, High)
 - patch 2/4: initialise val in mptcp_setsockopt_recverr() to silence a
   latent -Wmaybe-uninitialized on the switch without a default case.

v10: https://lore.kernel.org/mptcp/20260529174524.260199-1-devnexen@gmail.com/
v9: https://lore.kernel.org/mptcp/20260528055459.55133-1-devnexen@gmail.com/

David Carlier (4):
  mptcp: sockopt: factor inet_flags propagation into a mask
  mptcp: propagate RECVERR sockopts to subflows
  mptcp: support MSG_ERRQUEUE on the parent socket
  selftests: mptcp: cover IP_RECVERR sockopt propagation

 net/mptcp/protocol.c                          |  63 ++++++--
 net/mptcp/sockopt.c                           | 153 +++++++++++++++---
 .../selftests/net/mptcp/mptcp_sockopt.c       |  55 +++++++
 3 files changed, 237 insertions(+), 34 deletions(-)


base-commit: e05cbdb611ff815528cdf90e29a96663b9af48c6
-- 
2.53.0

[PATCH mptcp-next v11 1/4] mptcp: sockopt: factor inet_flags propagation into a mask

[David Carlier]

Introduce MPTCP_INET_FLAGS_MASK and replace the per-flag
inet_assign_bit() calls in sync_socket_options() with a loop driven
by the mask that calls assign_bit() per set bit, preserving the
per-bit atomicity of the original. 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 <pabeni@redhat.com>
Signed-off-by: David Carlier <devnexen@gmail.com>
---
 net/mptcp/sockopt.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index fcf6feb2a9eb..7be9a46cbdbe 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -16,6 +16,10 @@
 
 #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))
 
 static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk)
 {
@@ -1551,6 +1555,9 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 {
 	static const unsigned int tx_rx_locks = SOCK_RCVBUF_LOCK | SOCK_SNDBUF_LOCK;
 	struct sock *sk = (struct sock *)msk;
+	unsigned long mask = MPTCP_INET_FLAGS_MASK;
+	unsigned long src;
+	int b;
 	bool keep_open;
 
 	keep_open = sock_flag(sk, SOCK_KEEPOPEN);
@@ -1597,9 +1604,11 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 	tcp_sock_set_keepcnt(ssk, msk->keepalive_cnt);
 	tcp_sock_set_maxseg(ssk, msk->maxseg);
 
-	inet_assign_bit(TRANSPARENT, ssk, inet_test_bit(TRANSPARENT, sk));
-	inet_assign_bit(FREEBIND, ssk, inet_test_bit(FREEBIND, sk));
-	inet_assign_bit(BIND_ADDRESS_NO_PORT, ssk, inet_test_bit(BIND_ADDRESS_NO_PORT, sk));
+	src = READ_ONCE(inet_sk(sk)->inet_flags);
+
+	for_each_set_bit(b, &mask, BITS_PER_LONG)
+		assign_bit(b, &inet_sk(ssk)->inet_flags, src & BIT(b));
+
 	WRITE_ONCE(inet_sk(ssk)->local_port_range, READ_ONCE(inet_sk(sk)->local_port_range));
 }
 
-- 
2.53.0

[PATCH mptcp-next v11 2/4] mptcp: propagate RECVERR sockopts to subflows

[David Carlier]

Propagate IP_RECVERR/IP_RECVERR_RFC4884 and
IPV6_RECVERR/IPV6_RECVERR_RFC4884 from the MPTCP socket to existing
and future subflows.

mptcp_setsockopt_recverr() snapshots optval into a local int, applies
it to the parent socket via ip_setsockopt() / ipv6_setsockopt(), bumps
msk->setsockopt_seq, and forwards to every subflow via
mptcp_setsockopt_all_sf(). Newly-joining subflows pick up the four
RECVERR bits through sync_socket_options() now that
MPTCP_INET_FLAGS_MASK covers them.

mptcp_setsockopt_all_sf() skips IPv4 subflows when called with
SOL_IPV6: ipv6_setsockopt() on a sock with sk_family != AF_INET6
returns an error, which would abort the loop and leave the remaining
subflows desynchronised. This branch was unreachable before this
patch (the only caller was TCP_MAXSEG, family-agnostic); it becomes
live with the new IPV6_RECVERR / IPV6_RECVERR_RFC4884 caller and the
v4-subflow-on-AF_INET6-msk case (v4 MP_JOIN, or userspace PM grafting
a v4 subflow onto a v6 msk).

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Assisted-by: Codex:gpt-5
Signed-off-by: David Carlier <devnexen@gmail.com>
---
 net/mptcp/sockopt.c | 140 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 117 insertions(+), 23 deletions(-)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 7be9a46cbdbe..a2a980304660 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -8,6 +8,7 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <net/ipv6.h>
 #include <net/sock.h>
 #include <net/protocol.h>
 #include <net/tcp.h>
@@ -19,7 +20,11 @@
 #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))
 
 static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk)
 {
@@ -398,6 +403,86 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
 	return -EOPNOTSUPP;
 }
 
+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 = 0;
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		int err;
+
+		/* SOL_IPV6 options on a v4 subflow (v4 MP_JOIN, or userspace PM
+		 * grafting a v4 subflow onto an AF_INET6 msk) would otherwise
+		 * abort the loop with -EAFNOSUPPORT from ipv6_setsockopt().
+		 */
+		if (level == SOL_IPV6 && ssk->sk_family != AF_INET6)
+			continue;
+
+		err = tcp_setsockopt(ssk, level, optname, optval, optlen);
+		if (err < 0 && ret == 0)
+			ret = err;
+	}
+
+	if (!ret)
+		sockopt_seq_inc(msk);
+
+	return ret;
+}
+
+static int mptcp_setsockopt_recverr(struct mptcp_sock *msk, int level,
+				    int optname, sockptr_t optval,
+				    unsigned int optlen)
+{
+	struct sock *sk = (struct sock *)msk;
+	int val = 0, ret;
+
+	/* Let ip_setsockopt() / ipv6_setsockopt() validate optval and optlen
+	 * (so 1-byte boolean writes keep the same ABI as plain TCP) and update
+	 * the parent's RECVERR bit. Re-read that bit under lock_sock() and
+	 * push it to the subflows: concurrent setsockopt callers cannot leave
+	 * parent and subflows desynchronized this way.
+	 */
+	if (level == SOL_IP)
+		ret = ip_setsockopt(sk, level, optname, optval, optlen);
+#if IS_ENABLED(CONFIG_IPV6)
+	else if (level == SOL_IPV6) {
+		if (sk->sk_family != AF_INET6)
+			return -ENOPROTOOPT;
+		ret = ipv6_setsockopt(sk, level, optname, optval, optlen);
+	}
+#endif
+	else
+		return -EOPNOTSUPP;
+	if (ret)
+		return ret;
+
+	lock_sock(sk);
+	switch (optname) {
+	case IP_RECVERR:
+		val = inet_test_bit(RECVERR, sk);
+		break;
+	case IP_RECVERR_RFC4884:
+		val = inet_test_bit(RECVERR_RFC4884, sk);
+		break;
+#if IS_ENABLED(CONFIG_IPV6)
+	case IPV6_RECVERR:
+		val = inet6_test_bit(RECVERR6, sk);
+		break;
+	case IPV6_RECVERR_RFC4884:
+		val = inet6_test_bit(RECVERR6_RFC4884, sk);
+		break;
+#endif
+	}
+
+	ret = mptcp_setsockopt_all_sf(msk, level, optname,
+				      KERNEL_SOCKPTR(&val), sizeof(val));
+	release_sock(sk);
+	return ret;
+}
+
 static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname,
 			       sockptr_t optval, unsigned int optlen)
 {
@@ -440,6 +525,10 @@ static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname,
 
 		release_sock(sk);
 		break;
+	case IPV6_RECVERR:
+	case IPV6_RECVERR_RFC4884:
+		ret = mptcp_setsockopt_recverr(msk, SOL_IPV6, optname, optval, optlen);
+		break;
 	}
 
 	return ret;
@@ -785,6 +874,9 @@ 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_recverr(msk, SOL_IP, optname, optval, optlen);
 	}
 
 	return -EOPNOTSUPP;
@@ -812,28 +904,6 @@ static int mptcp_setsockopt_first_sf_only(struct mptcp_sock *msk, int level, int
 	return ret;
 }
 
-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 = 0;
-
-	mptcp_for_each_subflow(msk, subflow) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-		int err;
-
-		err = tcp_setsockopt(ssk, level, optname, optval, optlen);
-		if (err < 0 && ret == 0)
-			ret = err;
-	}
-
-	if (!ret)
-		sockopt_seq_inc(msk);
-
-	return ret;
-}
-
 static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
 				    sockptr_t optval, unsigned int optlen)
 {
@@ -1478,6 +1548,12 @@ static int mptcp_getsockopt_v4(struct mptcp_sock *msk, 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));
 	}
 
 	return -EOPNOTSUPP;
@@ -1498,6 +1574,16 @@ static int mptcp_getsockopt_v6(struct mptcp_sock *msk, int optname,
 	case IPV6_FREEBIND:
 		return mptcp_put_int_option(msk, optval, optlen,
 					    inet_test_bit(FREEBIND, sk));
+	case IPV6_RECVERR:
+		if (sk->sk_family != AF_INET6)
+			return -ENOPROTOOPT;
+		return mptcp_put_int_option(msk, optval, optlen,
+					    inet6_test_bit(RECVERR6, sk));
+	case IPV6_RECVERR_RFC4884:
+		if (sk->sk_family != AF_INET6)
+			return -ENOPROTOOPT;
+		return mptcp_put_int_option(msk, optval, optlen,
+					    inet6_test_bit(RECVERR6_RFC4884, sk));
 	}
 
 	return -EOPNOTSUPP;
@@ -1606,6 +1692,14 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 
 	src = READ_ONCE(inet_sk(sk)->inet_flags);
 
+	/* RECVERR6 bits are only read on AF_INET6 sockets; copying them onto a
+	 * v4 subflow is dead state and diverges from the SOL_IPV6 skip in
+	 * mptcp_setsockopt_all_sf().
+	 */
+	if (ssk->sk_family != AF_INET6)
+		mask &= ~(BIT(INET_FLAGS_RECVERR6) |
+			BIT(INET_FLAGS_RECVERR6_RFC4884));
+
 	for_each_set_bit(b, &mask, BITS_PER_LONG)
 		assign_bit(b, &inet_sk(ssk)->inet_flags, src & BIT(b));
 
-- 
2.53.0

[PATCH mptcp-next v11 3/4] mptcp: support MSG_ERRQUEUE on the parent socket

[David Carlier]

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 TX timestamps and MSG_ZEROCOPY completion
notifications through the standard inet ABI.

The splice filters by SO_EE_ORIGIN: TIMESTAMPING / ZEROCOPY / LOCAL
events forward to the parent because they are tied to user-handed data,
not to a specific path; subflow-level ICMP errors are dropped because
the legacy RECVERR ABI cannot meaningfully convey their per-subflow peer
identity to single-path-aware userspace. Such events will be carried by
a future MPTCP_RECERR channel.

Forwarded events all go through sock_queue_err_skb(), which re-homes
skb->sk onto the parent and charges sk_rmem_alloc, so the parent's error
queue stays bounded by sk_rcvbuf and is dropped under rmem pressure
(sk_rmem_alloc + truesize >= sk_rcvbuf), matching tcp's sk_rcvbuf-gated
tx-timestamp path and ip_icmp_error() / ipv6_icmp_error(). MPTCP itself
never originates MSG_ZEROCOPY or OPT_ID tx-timestamp completions -- its
data path copies into msk-owned pages and bypasses tcp_sendmsg_locked()
-- so no subflow-relative ee_data sequence is ever forwarded to the
parent. The MSG_ERRQUEUE branch of mptcp_recvmsg() forwards to
inet_recv_error() directly, and poll() advertises EPOLLERR purely on the
parent's sk_err / sk_error_queue, matching tcp_poll().

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David Carlier <devnexen@gmail.com>
---
 net/mptcp/protocol.c | 63 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 54 insertions(+), 9 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f1d74d4b28cf..42a355311c81 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -11,6 +11,7 @@
 #include <linux/netdevice.h>
 #include <linux/sched/signal.h>
 #include <linux/atomic.h>
+#include <linux/errqueue.h>
 #include <net/aligned_data.h>
 #include <net/rps.h>
 #include <net/sock.h>
@@ -894,21 +895,61 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk)
 	return moved;
 }
 
+static bool mptcp_errqueue_skb_forwardable(const struct sk_buff *skb)
+{
+	u8 origin = SKB_EXT_ERR(skb)->ee.ee_origin;
+
+	return origin == SO_EE_ORIGIN_TIMESTAMPING ||
+		origin == SO_EE_ORIGIN_ZEROCOPY ||
+		origin == SO_EE_ORIGIN_LOCAL;
+}
+
+static bool __mptcp_subflow_splice_errqueue(struct sock *sk, struct sock *ssk)
+{
+	struct sk_buff *skb;
+	bool moved = false;
+
+	while ((skb = skb_dequeue(&ssk->sk_error_queue))) {
+		if (!mptcp_errqueue_skb_forwardable(skb)) {
+			kfree_skb(skb);  /* path-specific (ICMP) — belongs in MPTCP_RECERR */
+			continue;
+		}
+		/* sock_queue_err_skb() re-homes skb->sk onto the parent and
+		 * charges its sk_rmem_alloc, so the error queue stays bounded by
+		 * sk_rcvbuf; drop on overflow, matching tcp's tx-timestamp path.
+		 * MPTCP never originates MSG_ZEROCOPY or OPT_ID tx-timestamp
+		 * completions (the data path copies and bypasses
+		 * tcp_sendmsg_locked()), so no subflow-relative ee_data sequence
+		 * is ever forwarded.
+		 */
+		if (sock_queue_err_skb(sk, skb)) {
+			kfree_skb(skb);
+			continue;
+		}
+		moved = true;
+	}
+
+	return moved;
+}
+
 static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk)
 {
+	bool propagated = false;
 	int ssk_state;
+	bool report;
 	int err;
 
+	report = __mptcp_subflow_splice_errqueue(sk, ssk);
+
 	/* only propagate errors on fallen-back sockets or
 	 * on MPC connect
 	 */
 	if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(mptcp_sk(sk)))
-		return false;
+		goto out;
 
 	err = 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
@@ -918,11 +959,15 @@ static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk)
 	if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
 		mptcp_set_state(sk, ssk_state);
 	WRITE_ONCE(sk->sk_err, -err);
+	report = propagated = true;
 
-	/* This barrier is coupled with smp_rmb() in mptcp_poll() */
-	smp_wmb();
-	sk_error_report(sk);
-	return true;
+out:
+	if (report) {
+		/* This barrier is coupled with smp_rmb() in mptcp_poll() */
+		smp_wmb();
+		sk_error_report(sk);
+	}
+	return propagated;
 }
 
 void __mptcp_error_report(struct sock *sk)
@@ -2363,7 +2408,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	int target;
 	long timeo;
 
-	/* MSG_ERRQUEUE is really a no-op till we support IP_RECVERR */
 	if (unlikely(flags & MSG_ERRQUEUE))
 		return inet_recv_error(sk, msg, len);
 
@@ -4413,7 +4457,8 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
 
 	/* 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 |= EPOLLERR;
 
 	return mask;
-- 
2.53.0

[PATCH mptcp-next v11 4/4] selftests: mptcp: cover IP_RECVERR sockopt propagation

[David Carlier]

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 <devnexen@gmail.com>
---
 .../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/testing/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 == -1");
 }
 
+static void test_ip_recverr_sockopt(int fd)
+{
+	struct iovec iov = {
+		.iov_base = &(char){ 0 },
+		.iov_len = 1,
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	int one = 1, zero = 0, val = -1;
+	socklen_t s = sizeof(val);
+	int level, optname, r;
+
+	switch (pf) {
+	case AF_INET:
+		level = SOL_IP;
+		optname = IP_RECVERR;
+		break;
+	case AF_INET6:
+		level = SOL_IPV6;
+		optname = IPV6_RECVERR;
+		break;
+	default:
+		xerror("Unknown pf %d\n", pf);
+	}
+
+	r = setsockopt(fd, level, optname, &one, sizeof(one));
+	if (r)
+		die_perror("setsockopt recverr on");
+
+	r = getsockopt(fd, level, optname, &val, &s);
+	if (r)
+		die_perror("getsockopt recverr on");
+	if (s != sizeof(val) || val != one)
+		xerror("recverr on mismatch val=%d len=%u", val, s);
+
+	r = recvmsg(fd, &msg, MSG_ERRQUEUE | MSG_DONTWAIT);
+	if (r != -1 || errno != EAGAIN)
+		xerror("expected empty errqueue to return EAGAIN, ret=%d errno=%d", r, errno);
+
+	r = setsockopt(fd, level, optname, &zero, sizeof(zero));
+	if (r)
+		die_perror("setsockopt recverr off");
+
+	val = -1;
+	s = sizeof(val);
+	r = getsockopt(fd, level, optname, &val, &s);
+	if (r)
+		die_perror("getsockopt recverr off");
+	if (s != sizeof(val) || val != zero)
+		xerror("recverr off mismatch val=%d len=%u", val, s);
+}
+
 static int client(int pipefd)
 {
 	int fd = -1;
@@ -787,6 +841,7 @@ static int client(int pipefd)
 	}
 
 	test_ip_tos_sockopt(fd);
+	test_ip_recverr_sockopt(fd);
 
 	connect_one_server(fd, pipefd);
 
-- 
2.53.0

Re: [PATCH mptcp-next v11 0/4] mptcp: MSG_ERRQUEUE support on the parent socket

[MPTCP CI]

Hi David,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal (except selftest_mptcp_join): Unstable: 1 failed test(s): packetdrill_add_addr ⚠️ 
- KVM Validation: normal (only selftest_mptcp_join): Success! ✅
- KVM Validation: debug (except selftest_mptcp_join): Unstable: 1 failed test(s): selftest_mptcp_connect_checksum ⚠️ 
- KVM Validation: debug (only selftest_mptcp_join): Success! ✅
- KVM Validation: btf-normal (only bpftest_all): Success! ✅
- KVM Validation: btf-debug (only bpftest_all): Success! ✅
- Task: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/26716494041

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/5dd33dfffc0d
Patchwork: https://patchwork.kernel.org/project/mptcp/list/?series=1103609


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-normal

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)