[PATCH net-next v2 1/2] mptcp: add last time fields in mptcp_info

Matthieu Baerts (NGI0)
2024-04-10T09:48:34Z

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch adds "last time" fields last_data_sent, last_data_recv and
last_ack_recv in struct mptcp_sock to record the last time data_sent,
data_recv and ack_recv happened. They all are initialized as
tcp_jiffies32 in __mptcp_init_sock(), and updated as tcp_jiffies32 too
when data is sent in __subflow_push_pending(), data is received in
__mptcp_move_skbs_from_subflow(), and ack is received in ack_update_msk().

Similar to tcpi_last_data_sent, tcpi_last_data_recv and tcpi_last_ack_recv
exposed with TCP, this patch exposes the last time "an action happened" for
MPTCP in mptcp_info, named mptcpi_last_data_sent, mptcpi_last_data_recv and
mptcpi_last_ack_recv, calculated in mptcp_diag_fill_info() as the time
deltas between now and the newly added last time fields in mptcp_sock.

Since msk->last_ack_recv needs to be protected by mptcp_data_lock/unlock,
and lock_sock_fast can sleep and be quite slow, move the entire
mptcp_data_lock/unlock block after the lock/unlock_sock_fast block.
Then mptcpi_last_data_sent and mptcpi_last_data_recv are set in
lock/unlock_sock_fast block, while mptcpi_last_ack_recv is set in
mptcp_data_lock/unlock block, which is protected by a spinlock and
should not block for too long.

Also add three reserved bytes in struct mptcp_info not to have holes in
this structure exposed to userspace.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/446
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
v2:
- Set 'now = jiffies32' inside '(un)lock_sock_fast' block (Eric).
- Move 'mptcp_data_(un)lock' block after '(un)lock_sock_fast', not to
reload 'now', and have all counters synced (Matthieu / Mat).
---
include/uapi/linux/mptcp.h | 4 ++++
net/mptcp/options.c | 1 +
net/mptcp/protocol.c | 7 +++++++
net/mptcp/protocol.h | 3 +++
net/mptcp/sockopt.c | 16 +++++++++++-----
5 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
index 74cfe496891e..67d015df8893 100644
--- a/include/uapi/linux/mptcp.h
+++ b/include/uapi/linux/mptcp.h
@@ -58,6 +58,10 @@ struct mptcp_info {
__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;
};

/* MPTCP Reset reason codes, rfc8684 */
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 27ca42c77b02..8e8dcfbc2993 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -1068,6 +1068,7 @@ static void ack_update_msk(struct mptcp_sock *msk,
__mptcp_snd_una_update(msk, new_snd_una);
__mptcp_data_acked(sk);
}
+ msk->last_ack_recv = tcp_jiffies32;
mptcp_data_unlock(sk);

trace_ack_update_msk(mp_opt->data_ack,
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 995b53cd021c..f8bc34f0d973 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -706,6 +706,8 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
}
} while (more_data_avail);

+ if (moved > 0)
+ msk->last_data_recv = tcp_jiffies32;
*bytes += moved;
return done;
}
@@ -1556,6 +1558,8 @@ static int __subflow_push_pending(struct sock *sk, struct sock *ssk,
err = copied;

out:
+ if (err > 0)
+ msk->last_data_sent = tcp_jiffies32;
return err;
}

@@ -2793,6 +2797,9 @@ static void __mptcp_init_sock(struct sock *sk)
WRITE_ONCE(msk->allow_infinite_fallback, true);
msk->recovery = false;
msk->subflow_id = 1;
+ msk->last_data_sent = tcp_jiffies32;
+ msk->last_data_recv = tcp_jiffies32;
+ msk->last_ack_recv = tcp_jiffies32;

mptcp_pm_data_init(msk);

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 46f4655b7123..fdfa843e2d88 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -282,6 +282,9 @@ struct mptcp_sock {
u64 bytes_acked;
u64 snd_una;
u64 wnd_end;
+ u32 last_data_sent;
+ u32 last_data_recv;
+ u32 last_ack_recv;
unsigned long timer_ival;
u32 token;
int rmem_released;
diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 9d5d42a77bcc..1fea43f5b6f3 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -898,6 +898,7 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
struct sock *sk = (struct sock *)msk;
u32 flags = 0;
bool slow;
+ u32 now;

memset(info, 0, sizeof(*info));

@@ -926,11 +927,6 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
if (READ_ONCE(msk->can_ack))
flags |= MPTCP_INFO_FLAG_REMOTE_KEY_RECEIVED;
info->mptcpi_flags = flags;
- mptcp_data_lock(sk);
- info->mptcpi_snd_una = msk->snd_una;
- info->mptcpi_rcv_nxt = msk->ack_seq;
- info->mptcpi_bytes_acked = msk->bytes_acked;
- mptcp_data_unlock(sk);

slow = lock_sock_fast(sk);
info->mptcpi_csum_enabled = READ_ONCE(msk->csum_enabled);
@@ -942,7 +938,17 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
info->mptcpi_bytes_retrans = msk->bytes_retrans;
info->mptcpi_subflows_total = info->mptcpi_subflows +
__mptcp_has_initial_subflow(msk);
+ now = tcp_jiffies32;
+ info->mptcpi_last_data_sent = jiffies_to_msecs(now - msk->last_data_sent);
+ info->mptcpi_last_data_recv = jiffies_to_msecs(now - msk->last_data_recv);
unlock_sock_fast(sk, slow);
+
+ mptcp_data_lock(sk);
+ info->mptcpi_last_ack_recv = jiffies_to_msecs(now - msk->last_ack_recv);
+ info->mptcpi_snd_una = msk->snd_una;
+ info->mptcpi_rcv_nxt = msk->ack_seq;
+ info->mptcpi_bytes_acked = msk->bytes_acked;
+ mptcp_data_unlock(sk);
}
EXPORT_SYMBOL_GPL(mptcp_diag_fill_info);

--
2.43.0