netdev - [PATCH net-next v3 01/15] mptcp: add mptcpi_subflows

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Date: Wed, 15 Nov 2023 16:31:29 -0800
From: Mat Martineau <martineau@...nel.org>
To: Matthieu Baerts <matttbe@...nel.org>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, mptcp@...ts.linux.dev, 
 Mat Martineau <martineau@...nel.org>, Geliang Tang <geliang.tang@...e.com>
Subject: [PATCH net-next v3 01/15] mptcp: add mptcpi_subflows_total counter

From: Geliang Tang <geliang.tang@...e.com>

If the initial subflow has been removed, we cannot know without checking
other counters, e.g. ss -ti <filter> | grep -c tcp-ulp-mptcp or
getsockopt(SOL_MPTCP, MPTCP_FULL_INFO, ...) (or others except MPTCP_INFO
of course) and then check mptcp_subflow_data->num_subflows to get the
total amount of subflows.

This patch adds a new counter mptcpi_subflows_total in mptcpi_flags to
store the total amount of subflows, including the initial one. A new
helper __mptcp_has_initial_subflow() is added to check whether the
initial subflow has been removed or not. With this helper, we can then
compute the total amount of subflows from mptcp_info by doing something
like:

    mptcpi_subflows_total = mptcpi_subflows +
            __mptcp_has_initial_subflow(msk).

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/428
Reviewed-by: Matthieu Baerts <matttbe@...nel.org>
Signed-off-by: Geliang Tang <geliang.tang@...e.com>
Signed-off-by: Mat Martineau <martineau@...nel.org>
---
 include/uapi/linux/mptcp.h | 1 +
 net/mptcp/protocol.h       | 9 +++++++++
 net/mptcp/sockopt.c        | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
index a6451561f3f8..74cfe496891e 100644
--- a/include/uapi/linux/mptcp.h
+++ b/include/uapi/linux/mptcp.h
@@ -57,6 +57,7 @@ struct mptcp_info {
 	__u64	mptcpi_bytes_sent;
 	__u64	mptcpi_bytes_received;
 	__u64	mptcpi_bytes_acked;
+	__u8	mptcpi_subflows_total;
 };

 /* MPTCP Reset reason codes, rfc8684 */
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index fe6f2d399ee8..458a2d7bb0dd 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -1072,6 +1072,15 @@ static inline void __mptcp_do_fallback(struct mptcp_sock *msk)
 	set_bit(MPTCP_FALLBACK_DONE, &msk->flags);
 }

+static inline bool __mptcp_has_initial_subflow(const struct mptcp_sock *msk)
+{
+	struct sock *ssk = READ_ONCE(msk->first);
+
+	return ssk && ((1 << inet_sk_state_load(ssk)) &
+		       (TCPF_ESTABLISHED | TCPF_SYN_SENT |
+			TCPF_SYN_RECV | TCPF_LISTEN));
+}
+
 static inline void mptcp_do_fallback(struct sock *ssk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 77f5e8932abf..8d485c40585a 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -935,6 +935,8 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
 	info->mptcpi_bytes_sent = msk->bytes_sent;
 	info->mptcpi_bytes_received = msk->bytes_received;
 	info->mptcpi_bytes_retrans = msk->bytes_retrans;
+	info->mptcpi_subflows_total = info->mptcpi_subflows +
+		__mptcp_has_initial_subflow(msk);
 	unlock_sock_fast(sk, slow);
 }
 EXPORT_SYMBOL_GPL(mptcp_diag_fill_info);

-- 
2.41.0