[PATCH net-next 0/5] mptcp: improve code coverage and small optimisations

[PATCH net-next 0/5] mptcp: improve code coverage and small optimisations

[Matthieu Baerts (NGI0)]

This small series have various unrelated patches:

- Patch 1 and 2: improve code coverage by validating mptcp_diag_dump_one
  thanks to a new tool displaying MPTCP info for a specific token.

- Patch 3: a fix for a commit which is only in net-next.

- Patch 4: reduce parameters for one in-kernel PM helper.

- Patch 5: exit early when processing an ADD_ADDR echo to avoid unneeded
  operations.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Gang Yan (2):
      selftests: mptcp: Add a tool to get specific msk_info
      selftests: mptcp: add a test for mptcp_diag_dump_one

Geliang Tang (2):
      mptcp: pm: in-kernel: avoid access entry without lock
      mptcp: pm: in-kernel: reduce parameters of set_flags

Matthieu Baerts (NGI0) (1):
      mptcp: pm: exit early with ADD_ADDR echo if possible

 net/mptcp/pm.c                                 |   3 +
 net/mptcp/pm_netlink.c                         |  15 +-
 tools/testing/selftests/net/mptcp/Makefile     |   2 +-
 tools/testing/selftests/net/mptcp/diag.sh      |  27 +++
 tools/testing/selftests/net/mptcp/mptcp_diag.c | 272 +++++++++++++++++++++++++
 5 files changed, 311 insertions(+), 8 deletions(-)
---
base-commit: 56794b5862c5a9aefcf2b703257c6fb93f76573e
change-id: 20250228-net-next-mptcp-coverage-small-opti-70d8dc1d329d

Best regards,
-- 
Matthieu Baerts (NGI0) <matttbe@kernel.org>

[PATCH net-next 1/5] selftests: mptcp: Add a tool to get specific msk_info

[Matthieu Baerts (NGI0)]

From: Gang Yan <yangang@kylinos.cn>

This patch enables the retrieval of the mptcp_info structure corresponding
to a specified MPTCP socket (msk). When multiple MPTCP connections are
present, specific information can be obtained for a given connection
through the 'mptcp_diag_dump_one' by using the 'token' associated with
the msk.

Signed-off-by: Gang Yan <yangang@kylinos.cn>
Co-developed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/mptcp/Makefile     |   2 +-
 tools/testing/selftests/net/mptcp/mptcp_diag.c | 272 +++++++++++++++++++++++++
 2 files changed, 273 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/mptcp/Makefile b/tools/testing/selftests/net/mptcp/Makefile
index c76525fe2b84d503646429d1ddfb4a323a722ae9..340e1a777e16a893300e01d19fdb5191fab8e00b 100644
--- a/tools/testing/selftests/net/mptcp/Makefile
+++ b/tools/testing/selftests/net/mptcp/Makefile
@@ -7,7 +7,7 @@ CFLAGS += -Wall -Wl,--no-as-needed -O2 -g -I$(top_srcdir)/usr/include $(KHDR_INC
 TEST_PROGS := mptcp_connect.sh pm_netlink.sh mptcp_join.sh diag.sh \
 	      simult_flows.sh mptcp_sockopt.sh userspace_pm.sh
 
-TEST_GEN_FILES = mptcp_connect pm_nl_ctl mptcp_sockopt mptcp_inq
+TEST_GEN_FILES = mptcp_connect pm_nl_ctl mptcp_sockopt mptcp_inq mptcp_diag
 
 TEST_FILES := mptcp_lib.sh settings
 
diff --git a/tools/testing/selftests/net/mptcp/mptcp_diag.c b/tools/testing/selftests/net/mptcp/mptcp_diag.c
new file mode 100644
index 0000000000000000000000000000000000000000..284286c524cfeff5f49b0af1a4da5a376c9e3140
--- /dev/null
+++ b/tools/testing/selftests/net/mptcp/mptcp_diag.c
@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025, Kylin Software */
+
+#include <linux/sock_diag.h>
+#include <linux/rtnetlink.h>
+#include <linux/inet_diag.h>
+#include <linux/netlink.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <linux/tcp.h>
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <stdio.h>
+
+#ifndef IPPROTO_MPTCP
+#define IPPROTO_MPTCP 262
+#endif
+
+struct mptcp_info {
+	__u8	mptcpi_subflows;
+	__u8	mptcpi_add_addr_signal;
+	__u8	mptcpi_add_addr_accepted;
+	__u8	mptcpi_subflows_max;
+	__u8	mptcpi_add_addr_signal_max;
+	__u8	mptcpi_add_addr_accepted_max;
+	__u32	mptcpi_flags;
+	__u32	mptcpi_token;
+	__u64	mptcpi_write_seq;
+	__u64	mptcpi_snd_una;
+	__u64	mptcpi_rcv_nxt;
+	__u8	mptcpi_local_addr_used;
+	__u8	mptcpi_local_addr_max;
+	__u8	mptcpi_csum_enabled;
+	__u32	mptcpi_retransmits;
+	__u64	mptcpi_bytes_retrans;
+	__u64	mptcpi_bytes_sent;
+	__u64	mptcpi_bytes_received;
+	__u64	mptcpi_bytes_acked;
+	__u8	mptcpi_subflows_total;
+	__u8	reserved[3];
+	__u32	mptcpi_last_data_sent;
+	__u32	mptcpi_last_data_recv;
+	__u32	mptcpi_last_ack_recv;
+};
+
+static void die_perror(const char *msg)
+{
+	perror(msg);
+	exit(1);
+}
+
+static void die_usage(int r)
+{
+	fprintf(stderr, "Usage: mptcp_diag -t\n");
+	exit(r);
+}
+
+static void send_query(int fd, __u32 token)
+{
+	struct sockaddr_nl nladdr = {
+		.nl_family = AF_NETLINK
+	};
+	struct {
+		struct nlmsghdr nlh;
+		struct inet_diag_req_v2 r;
+	} req = {
+		.nlh = {
+			.nlmsg_len = sizeof(req),
+			.nlmsg_type = SOCK_DIAG_BY_FAMILY,
+			.nlmsg_flags = NLM_F_REQUEST
+		},
+		.r = {
+			.sdiag_family = AF_INET,
+			/* Real proto is set via INET_DIAG_REQ_PROTOCOL */
+			.sdiag_protocol = IPPROTO_TCP,
+			.id.idiag_cookie[0] = token,
+		}
+	};
+	struct rtattr rta_proto;
+	struct iovec iov[6];
+	int iovlen = 1;
+	__u32 proto;
+
+	req.r.idiag_ext |= (1 << (INET_DIAG_INFO - 1));
+	proto = IPPROTO_MPTCP;
+	rta_proto.rta_type = INET_DIAG_REQ_PROTOCOL;
+	rta_proto.rta_len = RTA_LENGTH(sizeof(proto));
+
+	iov[0] = (struct iovec) {
+		.iov_base = &req,
+		.iov_len = sizeof(req)
+	};
+	iov[iovlen] = (struct iovec){ &rta_proto, sizeof(rta_proto)};
+	iov[iovlen + 1] = (struct iovec){ &proto, sizeof(proto)};
+	req.nlh.nlmsg_len += RTA_LENGTH(sizeof(proto));
+	iovlen += 2;
+	struct msghdr msg = {
+		.msg_name = &nladdr,
+		.msg_namelen = sizeof(nladdr),
+		.msg_iov = iov,
+		.msg_iovlen = iovlen
+	};
+
+	for (;;) {
+		if (sendmsg(fd, &msg, 0) < 0) {
+			if (errno == EINTR)
+				continue;
+			die_perror("sendmsg");
+		}
+		break;
+	}
+}
+
+static void parse_rtattr_flags(struct rtattr *tb[], int max, struct rtattr *rta,
+			       int len, unsigned short flags)
+{
+	unsigned short type;
+
+	memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
+	while (RTA_OK(rta, len)) {
+		type = rta->rta_type & ~flags;
+		if (type <= max && !tb[type])
+			tb[type] = rta;
+		rta = RTA_NEXT(rta, len);
+	}
+}
+
+static void print_info_msg(struct mptcp_info *info)
+{
+	printf("Token & Flags\n");
+	printf("token:        %x\n", info->mptcpi_token);
+	printf("flags:        %x\n", info->mptcpi_flags);
+	printf("csum_enabled: %u\n", info->mptcpi_csum_enabled);
+
+	printf("\nBasic Info\n");
+	printf("subflows:              %u\n", info->mptcpi_subflows);
+	printf("subflows_max:          %u\n", info->mptcpi_subflows_max);
+	printf("subflows_total:        %u\n", info->mptcpi_subflows_total);
+	printf("local_addr_used:       %u\n", info->mptcpi_local_addr_used);
+	printf("local_addr_max:        %u\n", info->mptcpi_local_addr_max);
+	printf("add_addr_signal:       %u\n", info->mptcpi_add_addr_signal);
+	printf("add_addr_accepted:     %u\n", info->mptcpi_add_addr_accepted);
+	printf("add_addr_signal_max:   %u\n", info->mptcpi_add_addr_signal_max);
+	printf("add_addr_accepted_max: %u\n", info->mptcpi_add_addr_accepted_max);
+
+	printf("\nTransmission Info\n");
+	printf("write_seq:        %llu\n", info->mptcpi_write_seq);
+	printf("snd_una:          %llu\n", info->mptcpi_snd_una);
+	printf("rcv_nxt:          %llu\n", info->mptcpi_rcv_nxt);
+	printf("last_data_sent:   %u\n", info->mptcpi_last_data_sent);
+	printf("last_data_recv:   %u\n", info->mptcpi_last_data_recv);
+	printf("last_ack_recv:    %u\n", info->mptcpi_last_ack_recv);
+	printf("retransmits:      %u\n", info->mptcpi_retransmits);
+	printf("retransmit bytes: %llu\n", info->mptcpi_bytes_retrans);
+	printf("bytes_sent:       %llu\n", info->mptcpi_bytes_sent);
+	printf("bytes_received:   %llu\n", info->mptcpi_bytes_received);
+	printf("bytes_acked:      %llu\n", info->mptcpi_bytes_acked);
+}
+
+static void parse_nlmsg(struct nlmsghdr *nlh)
+{
+	struct inet_diag_msg *r = NLMSG_DATA(nlh);
+	struct rtattr *tb[INET_DIAG_MAX + 1];
+
+	parse_rtattr_flags(tb, INET_DIAG_MAX, (struct rtattr *)(r + 1),
+			   nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*r)),
+			   NLA_F_NESTED);
+
+	if (tb[INET_DIAG_INFO]) {
+		int len = RTA_PAYLOAD(tb[INET_DIAG_INFO]);
+		struct mptcp_info *info;
+
+		/* workaround fort older kernels with less fields */
+		if (len < sizeof(*info)) {
+			info = alloca(sizeof(*info));
+			memcpy(info, RTA_DATA(tb[INET_DIAG_INFO]), len);
+			memset((char *)info + len, 0, sizeof(*info) - len);
+		} else {
+			info = RTA_DATA(tb[INET_DIAG_INFO]);
+		}
+		print_info_msg(info);
+	}
+}
+
+static void recv_nlmsg(int fd, struct nlmsghdr *nlh)
+{
+	char rcv_buff[8192];
+	struct sockaddr_nl rcv_nladdr = {
+		.nl_family = AF_NETLINK
+	};
+	struct iovec rcv_iov = {
+		.iov_base = rcv_buff,
+		.iov_len = sizeof(rcv_buff)
+	};
+	struct msghdr rcv_msg = {
+		.msg_name = &rcv_nladdr,
+		.msg_namelen = sizeof(rcv_nladdr),
+		.msg_iov = &rcv_iov,
+		.msg_iovlen = 1
+	};
+	int len;
+
+	len = recvmsg(fd, &rcv_msg, 0);
+	nlh = (struct nlmsghdr *)rcv_buff;
+
+	while (NLMSG_OK(nlh, len)) {
+		if (nlh->nlmsg_type == NLMSG_DONE) {
+			printf("NLMSG_DONE\n");
+			break;
+		} else if (nlh->nlmsg_type == NLMSG_ERROR) {
+			struct nlmsgerr *err;
+
+			err = (struct nlmsgerr *)NLMSG_DATA(nlh);
+			printf("Error %d:%s\n",
+			       -(err->error), strerror(-(err->error)));
+			break;
+		}
+		parse_nlmsg(nlh);
+		nlh = NLMSG_NEXT(nlh, len);
+	}
+}
+
+static void get_mptcpinfo(__u32 token)
+{
+	struct nlmsghdr *nlh = NULL;
+	int fd;
+
+	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
+	if (fd < 0)
+		die_perror("Netlink socket");
+
+	send_query(fd, token);
+	recv_nlmsg(fd, nlh);
+
+	close(fd);
+}
+
+static void parse_opts(int argc, char **argv, __u32 *target_token)
+{
+	int c;
+
+	if (argc < 2)
+		die_usage(1);
+
+	while ((c = getopt(argc, argv, "ht:")) != -1) {
+		switch (c) {
+		case 'h':
+			die_usage(0);
+			break;
+		case 't':
+			sscanf(optarg, "%x", target_token);
+			break;
+		default:
+			die_usage(1);
+			break;
+		}
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	__u32 target_token;
+
+	parse_opts(argc, argv, &target_token);
+	get_mptcpinfo(target_token);
+
+	return 0;
+}
+

-- 
2.47.1

[PATCH net-next 2/5] selftests: mptcp: add a test for mptcp_diag_dump_one

[Matthieu Baerts (NGI0)]

From: Gang Yan <yangang@kylinos.cn>

This patch introduces a new 'chk_diag' test in diag.sh. It retrieves
the token for a specified MPTCP socket (msk) using the 'ss' command and
then accesses the 'mptcp_diag_dump_one' in kernel via ./mptcp_diag
to verify if the correct token is returned.

Link: https://github.com/multipath-tcp/mptcp_net-next/issues/524
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/mptcp/diag.sh | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
index 2bd0c1eb70c5b69b4ab364eec3f4017898ff7f03..4f55477ffe087721ad13774e82a5e2b1e6cec7c4 100755
--- a/tools/testing/selftests/net/mptcp/diag.sh
+++ b/tools/testing/selftests/net/mptcp/diag.sh
@@ -200,6 +200,32 @@ chk_msk_cestab()
 		 "${expected}" "${msg}" ""
 }
 
+chk_dump_one()
+{
+	local ss_token
+	local token
+	local msg
+
+	ss_token="$(ss -inmHMN $ns | grep 'token:' |\
+		    head -n 1 |\
+		    sed 's/.*token:\([0-9a-f]*\).*/\1/')"
+
+	token="$(ip netns exec $ns ./mptcp_diag -t $ss_token |\
+		 awk -F':[ \t]+' '/^token/ {print $2}')"
+
+	msg="....chk dump_one"
+
+	mptcp_lib_print_title "$msg"
+	if [ -n "$ss_token" ] && [ "$ss_token" = "$token" ]; then
+		mptcp_lib_pr_ok
+		mptcp_lib_result_pass "${msg}"
+	else
+		mptcp_lib_pr_fail "expected $ss_token found $token"
+		mptcp_lib_result_fail "${msg}"
+		ret=${KSFT_FAIL}
+	fi
+}
+
 msk_info_get_value()
 {
 	local port="${1}"
@@ -290,6 +316,7 @@ chk_msk_remote_key_nr 2 "....chk remote_key"
 chk_msk_fallback_nr 0 "....chk no fallback"
 chk_msk_inuse 2
 chk_msk_cestab 2
+chk_dump_one
 flush_pids
 
 chk_msk_inuse 0 "2->0"

-- 
2.47.1

[PATCH net-next 3/5] mptcp: pm: in-kernel: avoid access entry without lock

[Matthieu Baerts (NGI0)]

From: Geliang Tang <tanggeliang@kylinos.cn>

In mptcp_pm_nl_set_flags(), "entry" is copied to "local" when pernet->lock
is held to avoid direct access to entry without pernet->lock.

Therefore, "local->flags" should be passed to mptcp_nl_set_flags instead
of "entry->flags" when pernet->lock is not held, so as to avoid access to
entry.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Fixes: 145dc6cc4abd ("mptcp: pm: change to fullmesh only for 'subflow'")
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/pm_netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index d4328443d844dbe52d2b0cc0018dcac1e4245320..fb83eba041f17c09923a8ed1a033983692962c5a 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1983,7 +1983,7 @@ int mptcp_pm_nl_set_flags(struct mptcp_pm_addr_entry *local,
 	*local = *entry;
 	spin_unlock_bh(&pernet->lock);
 
-	mptcp_nl_set_flags(net, &local->addr, entry->flags, changed);
+	mptcp_nl_set_flags(net, &local->addr, local->flags, changed);
 	return 0;
 }
 

-- 
2.47.1

[PATCH net-next 4/5] mptcp: pm: in-kernel: reduce parameters of set_flags

[Matthieu Baerts (NGI0)]

From: Geliang Tang <tanggeliang@kylinos.cn>

The number of parameters in mptcp_nl_set_flags() can be reduced.
Only need to pass a "local" parameter to it instead of "local->addr"
and "local->flags".

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/pm_netlink.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index fb83eba041f17c09923a8ed1a033983692962c5a..4bebc4963c42d481f041999ef8976a58889919d5 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1907,11 +1907,12 @@ static void mptcp_pm_nl_fullmesh(struct mptcp_sock *msk,
 	spin_unlock_bh(&msk->pm.lock);
 }
 
-static void mptcp_nl_set_flags(struct net *net, struct mptcp_addr_info *addr,
-			       u8 flags, u8 changed)
+static void mptcp_nl_set_flags(struct net *net,
+			       struct mptcp_pm_addr_entry *local,
+			       u8 changed)
 {
-	u8 is_subflow = !!(flags & MPTCP_PM_ADDR_FLAG_SUBFLOW);
-	u8 bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
+	u8 is_subflow = !!(local->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW);
+	u8 bkup = !!(local->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
 	long s_slot = 0, s_num = 0;
 	struct mptcp_sock *msk;
 
@@ -1926,10 +1927,10 @@ static void mptcp_nl_set_flags(struct net *net, struct mptcp_addr_info *addr,
 
 		lock_sock(sk);
 		if (changed & MPTCP_PM_ADDR_FLAG_BACKUP)
-			mptcp_pm_nl_mp_prio_send_ack(msk, addr, NULL, bkup);
+			mptcp_pm_nl_mp_prio_send_ack(msk, &local->addr, NULL, bkup);
 		/* Subflows will only be recreated if the SUBFLOW flag is set */
 		if (is_subflow && (changed & MPTCP_PM_ADDR_FLAG_FULLMESH))
-			mptcp_pm_nl_fullmesh(msk, addr);
+			mptcp_pm_nl_fullmesh(msk, &local->addr);
 		release_sock(sk);
 
 next:
@@ -1983,7 +1984,7 @@ int mptcp_pm_nl_set_flags(struct mptcp_pm_addr_entry *local,
 	*local = *entry;
 	spin_unlock_bh(&pernet->lock);
 
-	mptcp_nl_set_flags(net, &local->addr, local->flags, changed);
+	mptcp_nl_set_flags(net, local, changed);
 	return 0;
 }
 

-- 
2.47.1

[PATCH net-next 5/5] mptcp: pm: exit early with ADD_ADDR echo if possible

[Matthieu Baerts (NGI0)]

When the userspace PM is used, or when the in-kernel limits are reached,
there will be no need to schedule the PM worker to signal new addresses.
That corresponds to pm->work_pending set to 0.

In this case, an early exit can be done in mptcp_pm_add_addr_echoed()
not to hold the PM lock, and iterate over the announced addresses list,
not to schedule the worker anyway in this case. This is similar to what
is done when a connection or a subflow has been established.

Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/pm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 16cacce6c10fe86467aa7ef8e588f9f535b586fb..6c8cadf84f31f4c7dcc38b787beda048d5362dc8 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -251,6 +251,9 @@ void mptcp_pm_add_addr_echoed(struct mptcp_sock *msk,
 
 	pr_debug("msk=%p\n", msk);
 
+	if (!READ_ONCE(pm->work_pending))
+		return;
+
 	spin_lock_bh(&pm->lock);
 
 	if (mptcp_lookup_anno_list_by_saddr(msk, addr) && READ_ONCE(pm->work_pending))

-- 
2.47.1

Re: [PATCH net-next 0/5] mptcp: improve code coverage and small optimisations

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Fri, 28 Feb 2025 15:38:34 +0100 you wrote:
> This small series have various unrelated patches:
> 
> - Patch 1 and 2: improve code coverage by validating mptcp_diag_dump_one
>   thanks to a new tool displaying MPTCP info for a specific token.
> 
> - Patch 3: a fix for a commit which is only in net-next.
> 
> [...]

Here is the summary with links:
  - [net-next,1/5] selftests: mptcp: Add a tool to get specific msk_info
    https://git.kernel.org/netdev/net-next/c/00f5e338cf7e
  - [net-next,2/5] selftests: mptcp: add a test for mptcp_diag_dump_one
    https://git.kernel.org/netdev/net-next/c/ba2400166570
  - [net-next,3/5] mptcp: pm: in-kernel: avoid access entry without lock
    https://git.kernel.org/netdev/net-next/c/e85d33b35508
  - [net-next,4/5] mptcp: pm: in-kernel: reduce parameters of set_flags
    https://git.kernel.org/netdev/net-next/c/70c575d5a94f
  - [net-next,5/5] mptcp: pm: exit early with ADD_ADDR echo if possible
    https://git.kernel.org/netdev/net-next/c/f0de92479a09

You are awesome, thank you!
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