[PATCH net-next 0/2] mptcp: add last time fields in mptcp_info

[PATCH net-next 0/2] mptcp: add last time fields in mptcp_info

[Matthieu Baerts (NGI0)]

These patches from Geliang add support for the "last time" field in
MPTCP Info, and verify that the counters look valid.

Patch 1 adds these counters: last_data_sent, last_data_recv and
last_ack_recv. They are available in the MPTCP Info, so exposed via
getsockopt(MPTCP_INFO) and the Netlink Diag interface.

Patch 2 adds a test in diag.sh MPTCP selftest, to check that the
counters have moved by at least 250ms, after having waited twice that
time.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Geliang Tang (2):
      mptcp: add last time fields in mptcp_info
      selftests: mptcp: test last time mptcp_info

 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                       |  4 +++
 tools/testing/selftests/net/mptcp/diag.sh | 53 +++++++++++++++++++++++++++++++
 6 files changed, 72 insertions(+)
---
base-commit: d76c740b2eaaddc5fc3a8b21eaec5b6b11e8c3f5
change-id: 20240405-upstream-net-next-20240405-mptcp-last-time-info-9b03618e08f1

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

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

[Matthieu Baerts (NGI0)]

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.

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>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 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        | 4 ++++
 5 files changed, 19 insertions(+)

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 7e74b812e366..6c1af0155bb0 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 73fdf423de44..2ec2fdf9f4af 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -896,6 +896,7 @@ static int mptcp_getsockopt_first_sf_only(struct mptcp_sock *msk, int level, int
 void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
 {
 	struct sock *sk = (struct sock *)msk;
+	u32 now = tcp_jiffies32;
 	u32 flags = 0;
 	bool slow;
 
@@ -930,6 +931,7 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
 	info->mptcpi_snd_una = msk->snd_una;
 	info->mptcpi_rcv_nxt = msk->ack_seq;
 	info->mptcpi_bytes_acked = msk->bytes_acked;
+	info->mptcpi_last_ack_recv = jiffies_to_msecs(now - msk->last_ack_recv);
 	mptcp_data_unlock(sk);
 
 	slow = lock_sock_fast(sk);
@@ -942,6 +944,8 @@ 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);
+	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);
 }
 EXPORT_SYMBOL_GPL(mptcp_diag_fill_info);

-- 
2.43.0

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

[Eric Dumazet]

On Fri, Apr 5, 2024 at 3:06 PM Matthieu Baerts (NGI0)
<matttbe@kernel.org> wrote:
>
> 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.
>
> 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>
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
> ---
>  include/uapi/linux/mptcp.h | 4 ++++


> diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
> index 73fdf423de44..2ec2fdf9f4af 100644
> --- a/net/mptcp/sockopt.c
> +++ b/net/mptcp/sockopt.c
> @@ -896,6 +896,7 @@ static int mptcp_getsockopt_first_sf_only(struct mptcp_sock *msk, int level, int
>  void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
>  {
>         struct sock *sk = (struct sock *)msk;
> +       u32 now = tcp_jiffies32;
>         u32 flags = 0;
>         bool slow;
>
> @@ -930,6 +931,7 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
>         info->mptcpi_snd_una = msk->snd_una;
>         info->mptcpi_rcv_nxt = msk->ack_seq;
>         info->mptcpi_bytes_acked = msk->bytes_acked;
> +       info->mptcpi_last_ack_recv = jiffies_to_msecs(now - msk->last_ack_recv);
>         mptcp_data_unlock(sk);
>
>         slow = lock_sock_fast(sk);

 lock_sock_fast(sk) can sleep and be quite slow...

I suggest you reload now = jiffies32;


> @@ -942,6 +944,8 @@ 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);
> +       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);
>  }
>  EXPORT_SYMBOL_GPL(mptcp_diag_fill_info);
>
> --
> 2.43.0
>

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

[Matthieu Baerts]

Hi Eric,

Thank you for the review!

On 05/04/2024 15:29, Eric Dumazet wrote:
> On Fri, Apr 5, 2024 at 3:06 PM Matthieu Baerts (NGI0)
> <matttbe@kernel.org> wrote:
>>
>> 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.
>>
>> 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>
>> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
>> ---
>>  include/uapi/linux/mptcp.h | 4 ++++
> 
> 
>> diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
>> index 73fdf423de44..2ec2fdf9f4af 100644
>> --- a/net/mptcp/sockopt.c
>> +++ b/net/mptcp/sockopt.c
>> @@ -896,6 +896,7 @@ static int mptcp_getsockopt_first_sf_only(struct mptcp_sock *msk, int level, int
>>  void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
>>  {
>>         struct sock *sk = (struct sock *)msk;
>> +       u32 now = tcp_jiffies32;
>>         u32 flags = 0;
>>         bool slow;
>>
>> @@ -930,6 +931,7 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
>>         info->mptcpi_snd_una = msk->snd_una;
>>         info->mptcpi_rcv_nxt = msk->ack_seq;
>>         info->mptcpi_bytes_acked = msk->bytes_acked;
>> +       info->mptcpi_last_ack_recv = jiffies_to_msecs(now - msk->last_ack_recv);
>>         mptcp_data_unlock(sk);
>>
>>         slow = lock_sock_fast(sk);
> 
>  lock_sock_fast(sk) can sleep and be quite slow...
> 
> I suggest you reload now = jiffies32;

Good point, it would make more sense to reload it after this lock!

(or defining "now" only here, under this lock_sock_fast(), and move the
block here above that is under the data spin lock, after, so all the
"time" counter are "in sync"?)

pw-bot: changes-requested

> 
> 
>> @@ -942,6 +944,8 @@ 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);
>> +       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);
>>  }
>>  EXPORT_SYMBOL_GPL(mptcp_diag_fill_info);
>>
>> --
>> 2.43.0
>>
> 

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.

[PATCH net-next 2/2] selftests: mptcp: test last time mptcp_info

[Matthieu Baerts (NGI0)]

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch adds a new helper chk_msk_info() to show the counters in
mptcp_info of the given info, and check that the timestamps move
forward. Use it to show newly added last_data_sent, last_data_recv
and last_ack_recv in mptcp_info in chk_last_time_info().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/mptcp/diag.sh | 53 +++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
index bc97ab33a00e..776d43a6922d 100755
--- a/tools/testing/selftests/net/mptcp/diag.sh
+++ b/tools/testing/selftests/net/mptcp/diag.sh
@@ -200,6 +200,58 @@ chk_msk_cestab()
 		 "${expected}" "${msg}" ""
 }
 
+msk_info_get_value()
+{
+	local port="${1}"
+	local info="${2}"
+
+	ss -N "${ns}" -inHM dport "${port}" | \
+		mptcp_lib_get_info_value "${info}" "${info}"
+}
+
+chk_msk_info()
+{
+	local port="${1}"
+	local info="${2}"
+	local cnt="${3}"
+	local msg="....chk ${info}"
+	local delta_ms=250  # half what we waited before, just to be sure
+	local now
+
+	now=$(msk_info_get_value "${port}" "${info}")
+
+	mptcp_lib_print_title "${msg}"
+	if { [ -z "${cnt}" ] || [ -z "${now}" ]; } &&
+	   ! mptcp_lib_expect_all_features; then
+		mptcp_lib_pr_skip "Feature probably not supported"
+		mptcp_lib_result_skip "${msg}"
+	elif [ "$((cnt + delta_ms))" -lt "${now}" ]; then
+		mptcp_lib_pr_ok
+		mptcp_lib_result_pass "${msg}"
+	else
+		mptcp_lib_pr_fail "value of ${info} changed by $((now - cnt))ms," \
+				  "expected at least ${delta_ms}ms"
+		mptcp_lib_result_fail "${msg}"
+		ret=${KSFT_FAIL}
+	fi
+}
+
+chk_last_time_info()
+{
+	local port="${1}"
+	local data_sent data_recv ack_recv
+
+	data_sent=$(msk_info_get_value "${port}" "last_data_sent")
+	data_recv=$(msk_info_get_value "${port}" "last_data_recv")
+	ack_recv=$(msk_info_get_value "${port}" "last_ack_recv")
+
+	sleep 0.5  # wait to check after if the timestamps difference
+
+	chk_msk_info "${port}" "last_data_sent" "${data_sent}"
+	chk_msk_info "${port}" "last_data_recv" "${data_recv}"
+	chk_msk_info "${port}" "last_ack_recv" "${ack_recv}"
+}
+
 wait_connected()
 {
 	local listener_ns="${1}"
@@ -233,6 +285,7 @@ echo "b" | \
 				127.0.0.1 >/dev/null &
 wait_connected $ns 10000
 chk_msk_nr 2 "after MPC handshake "
+chk_last_time_info 10000
 chk_msk_remote_key_nr 2 "....chk remote_key"
 chk_msk_fallback_nr 0 "....chk no fallback"
 chk_msk_inuse 2

-- 
2.43.0