FAILED: patch "[PATCH] mptcp: consolidate fallback and non fallback state machine" failed to apply to 5.15-stable tree

PATCH In review [email protected] 2 participants 3 messages Jun 23, 2023 – Jun 28, 2023

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Networking Stable branch Networking MPTCP

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[email protected]

author maintainer

2023-06-23 09:31 UTC #0 lore raw

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 81c1d029016001f994ce1c46849c5e9900d8eab8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023062315-example-anger-442b@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 81c1d029016001f994ce1c46849c5e9900d8eab8 Mon Sep 17 00:00:00 2001
From: Paolo Abeni <[email protected]>
Date: Tue, 20 Jun 2023 18:24:21 +0200
Subject: [PATCH] mptcp: consolidate fallback and non fallback state machine

An orphaned msk releases the used resources via the worker, when the latter first see the msk in CLOSED status.

If the msk status transitions to TCP_CLOSE in the release callback invoked by the worker's final release_sock(), such instance of the workqueue will not take any action.

Additionally the MPTCP code prevents scheduling the worker once the socket reaches the CLOSE status: such msk resources will be leaked.

The only code path that can trigger the above scenario is the __mptcp_check_send_data_fin() in fallback mode.

Address the issue removing the special handling of fallback socket in __mptcp_check_send_data_fin(), consolidating the state machine for fallback and non fallback socket.

Since non-fallback sockets do not send and do not receive data_fin, the mptcp code can update the msk internal status to match the next step in the SM every time data fin (ack) should be generated or received.

As a consequence we can remove a bunch of checks for fallback from the fastpath.

Fixes 6e628cd3a8f7 ("mptcp: use mptcp release_cb for delayed tasks")

Cc [email protected]

Signed-off-by Paolo Abeni <[email protected]>

Reviewed-by Mat Martineau <[email protected]>

Signed-off-by Matthieu Baerts <[email protected]>

Signed-off-by Jakub Kicinski <[email protected]>

net/mptcp/protocol.c +15 ~~-26~~

index 9a40dae31cec..27d206f7af62 100644
@@ -44,7 +44,7 @@ enum {
 static struct percpu_counter mptcp_sockets_allocated ____cacheline_aligned_in_smp;
 
 static void __mptcp_destroy_sock(struct sock *sk);
-static void __mptcp_check_send_data_fin(struct sock *sk);
+static void mptcp_check_send_data_fin(struct sock *sk);
 
 DEFINE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions);
 static struct net_device mptcp_napi_dev;

@@ -424,8 +424,7 @@ static bool mptcp_pending_data_fin_ack(struct sock *sk)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
-	return !__mptcp_check_fallback(msk) &&
-	       ((1 << sk->sk_state) &
+	return ((1 << sk->sk_state) &
 		(TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK)) &&
 	       msk->write_seq == READ_ONCE(msk->snd_una);
 }

@@ -583,9 +582,6 @@ static bool mptcp_check_data_fin(struct sock *sk)
 	u64 rcv_data_fin_seq;
 	bool ret = false;
 
-	if (__mptcp_check_fallback(msk))
-		return ret;
-
 	/* Need to ack a DATA_FIN received from a peer while this side
 	 * of the connection is in ESTABLISHED, FIN_WAIT1, or FIN_WAIT2.
 	 * msk->rcv_data_fin was set when parsing the incoming options

@@ -623,7 +619,8 @@ static bool mptcp_check_data_fin(struct sock *sk)
 		}
 
 		ret = true;
-		mptcp_send_ack(msk);
+		if (!__mptcp_check_fallback(msk))
+			mptcp_send_ack(msk);
 		mptcp_close_wake_up(sk);
 	}
 	return ret;

@@ -1609,7 +1606,7 @@ out:
 	if (!mptcp_timer_pending(sk))
 		mptcp_reset_timer(sk);
 	if (do_check_data_fin)
-		__mptcp_check_send_data_fin(sk);
+		mptcp_check_send_data_fin(sk);
 }
 
 static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk, bool first)

@@ -2680,8 +2677,6 @@ static void mptcp_worker(struct work_struct *work)
 	if (unlikely((1 << state) & (TCPF_CLOSE | TCPF_LISTEN)))
 		goto unlock;
 
-	mptcp_check_data_fin_ack(sk);
-
 	mptcp_check_fastclose(msk);
 
 	mptcp_pm_nl_work(msk);

@@ -2689,7 +2684,8 @@ static void mptcp_worker(struct work_struct *work)
 	if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags))
 		mptcp_check_for_eof(msk);
 
-	__mptcp_check_send_data_fin(sk);
+	mptcp_check_send_data_fin(sk);
+	mptcp_check_data_fin_ack(sk);
 	mptcp_check_data_fin(sk);
 
 	if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))

@@ -2828,6 +2824,12 @@ void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
 			pr_debug("Fallback");
 			ssk->sk_shutdown |= how;
 			tcp_shutdown(ssk, how);
+
+			/* simulate the data_fin ack reception to let the state
+			 * machine move forward
+			 */
+			WRITE_ONCE(mptcp_sk(sk)->snd_una, mptcp_sk(sk)->snd_nxt);
+			mptcp_schedule_work(sk);
 		} else {
 			pr_debug("Sending DATA_FIN on subflow %p", ssk);
 			tcp_send_ack(ssk);

@@ -2867,7 +2869,7 @@ static int mptcp_close_state(struct sock *sk)
 	return next & TCP_ACTION_FIN;
 }
 
-static void __mptcp_check_send_data_fin(struct sock *sk)
+static void mptcp_check_send_data_fin(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow;
 	struct mptcp_sock *msk = mptcp_sk(sk);

@@ -2885,19 +2887,6 @@ static void __mptcp_check_send_data_fin(struct sock *sk)
 
 	WRITE_ONCE(msk->snd_nxt, msk->write_seq);
 
-	/* fallback socket will not get data_fin/ack, can move to the next
-	 * state now
-	 */
-	if (__mptcp_check_fallback(msk)) {
-		WRITE_ONCE(msk->snd_una, msk->write_seq);
-		if ((1 << sk->sk_state) & (TCPF_CLOSING | TCPF_LAST_ACK)) {
-			inet_sk_state_store(sk, TCP_CLOSE);
-			mptcp_close_wake_up(sk);
-		} else if (sk->sk_state == TCP_FIN_WAIT1) {
-			inet_sk_state_store(sk, TCP_FIN_WAIT2);
-		}
-	}
-
 	mptcp_for_each_subflow(msk, subflow) {
 		struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);

@@ -2917,7 +2906,7 @@ static void __mptcp_wr_shutdown(struct sock *sk)
 	WRITE_ONCE(msk->write_seq, msk->write_seq + 1);
 	WRITE_ONCE(msk->snd_data_fin_enable, 1);
 
-	__mptcp_check_send_data_fin(sk);
+	mptcp_check_send_data_fin(sk);
 }
 
 static void __mptcp_destroy_sock(struct sock *sk)

net/mptcp/subflow.c +10 -7

index 4688daa6b38b..d9c8b21c6076 100644
@@ -1749,14 +1749,16 @@ static void subflow_state_change(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 	struct sock *parent = subflow->conn;
+	struct mptcp_sock *msk;
 
 	__subflow_state_change(sk);
 
+	msk = mptcp_sk(parent);
 	if (subflow_simultaneous_connect(sk)) {
 		mptcp_propagate_sndbuf(parent, sk);
 		mptcp_do_fallback(sk);
-		mptcp_rcv_space_init(mptcp_sk(parent), sk);
-		pr_fallback(mptcp_sk(parent));
+		mptcp_rcv_space_init(msk, sk);
+		pr_fallback(msk);
 		subflow->conn_finished = 1;
 		mptcp_set_connected(parent);
 	}

@@ -1772,11 +1774,12 @@ static void subflow_state_change(struct sock *sk)
 
 	subflow_sched_work_if_closed(mptcp_sk(parent), sk);
 
-	if (__mptcp_check_fallback(mptcp_sk(parent)) &&
-	    !subflow->rx_eof && subflow_is_done(sk)) {
-		subflow->rx_eof = 1;
-		mptcp_subflow_eof(parent);
-	}
+	/* when the fallback subflow closes the rx side, trigger a 'dummy'
+	 * ingress data fin, so that the msk state will follow along
+	 */
+	if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
+	    mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true))
+		mptcp_schedule_work(parent);
 }
 
 void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)

Matthieu Baerts

2023-06-27 13:26 UTC #1 lore raw

PATCH 1/1 mptcp: consolidate fallback and non fallback state machine

From: Paolo Abeni <[email protected]>

commit 81c1d029016001f994ce1c46849c5e9900d8eab8 upstream.

An orphaned msk releases the used resources via the worker, when the latter first see the msk in CLOSED status.

If the msk status transitions to TCP_CLOSE in the release callback invoked by the worker's final release_sock(), such instance of the workqueue will not take any action.

Additionally the MPTCP code prevents scheduling the worker once the socket reaches the CLOSE status: such msk resources will be leaked.

The only code path that can trigger the above scenario is the __mptcp_check_send_data_fin() in fallback mode.

Address the issue removing the special handling of fallback socket in __mptcp_check_send_data_fin(), consolidating the state machine for fallback and non fallback socket.

As a consequence we can remove a bunch of checks for fallback from the fastpath.

Fixes 6e628cd3a8f7 ("mptcp: use mptcp release_cb for delayed tasks")

Cc [email protected]

Signed-off-by Paolo Abeni <[email protected]>

Reviewed-by Mat Martineau <[email protected]>

Signed-off-by Matthieu Baerts <[email protected]>

Signed-off-by Jakub Kicinski <[email protected]>

Signed-off-by Matthieu Baerts <[email protected]>

---
Conflicting with:
- 0522b424c4c2 ("mptcp: add do_check_data_fin to replace copied")
- 3e5014909b56 ("mptcp: cleanup MPJ subflow list handling")

I took the new modifications but leaving the old variable name for "copied" instead of "do_check_data_fin" and the calls to __mptcp_flush_join_list()

Applied on top of d2efde0d1c2e ("Linux 5.15.119-rc1").

Signed-off-by Matthieu Baerts <[email protected]>

---
 net/mptcp/protocol.c | 39 +++++++++++++++------------------------
 net/mptcp/subflow.c  | 17 ++++++++++-------
 2 files changed, 25 insertions(+), 31 deletions(-)

net/mptcp/protocol.c +15 ~~-24~~

index f2977201f8fa..82b1583f709d 100644
@@ -51,7 +51,7 @@ enum {
 static struct percpu_counter mptcp_sockets_allocated;
 
 static void __mptcp_destroy_sock(struct sock *sk);
-static void __mptcp_check_send_data_fin(struct sock *sk);
+static void mptcp_check_send_data_fin(struct sock *sk);
 
 DEFINE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions);
 static struct net_device mptcp_napi_dev;

@@ -355,8 +355,7 @@ static bool mptcp_pending_data_fin_ack(struct sock *sk)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
-	return !__mptcp_check_fallback(msk) &&
-	       ((1 << sk->sk_state) &
+	return ((1 << sk->sk_state) &
 		(TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK)) &&
 	       msk->write_seq == READ_ONCE(msk->snd_una);
 }

@@ -509,9 +508,6 @@ static bool mptcp_check_data_fin(struct sock *sk)
 	u64 rcv_data_fin_seq;
 	bool ret = false;
 
-	if (__mptcp_check_fallback(msk))
-		return ret;
-
 	/* Need to ack a DATA_FIN received from a peer while this side
 	 * of the connection is in ESTABLISHED, FIN_WAIT1, or FIN_WAIT2.
 	 * msk->rcv_data_fin was set when parsing the incoming options

@@ -549,7 +545,8 @@ static bool mptcp_check_data_fin(struct sock *sk)
 		}
 
 		ret = true;
-		mptcp_send_ack(msk);
+		if (!__mptcp_check_fallback(msk))
+			mptcp_send_ack(msk);
 		mptcp_close_wake_up(sk);
 	}
 	return ret;

@@ -1612,7 +1609,7 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 	if (!mptcp_timer_pending(sk))
 		mptcp_reset_timer(sk);
 	if (copied)
-		__mptcp_check_send_data_fin(sk);
+		mptcp_check_send_data_fin(sk);
 }
 
 static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)

@@ -2451,7 +2448,6 @@ static void mptcp_worker(struct work_struct *work)
 	if (unlikely((1 << state) & (TCPF_CLOSE | TCPF_LISTEN)))
 		goto unlock;
 
-	mptcp_check_data_fin_ack(sk);
 	mptcp_flush_join_list(msk);
 
 	mptcp_check_fastclose(msk);

@@ -2462,7 +2458,8 @@ static void mptcp_worker(struct work_struct *work)
 	if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags))
 		mptcp_check_for_eof(msk);
 
-	__mptcp_check_send_data_fin(sk);
+	mptcp_check_send_data_fin(sk);
+	mptcp_check_data_fin_ack(sk);
 	mptcp_check_data_fin(sk);
 
 	/* There is no point in keeping around an orphaned sk timedout or

@@ -2591,6 +2588,12 @@ void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
 			pr_debug("Fallback");
 			ssk->sk_shutdown |= how;
 			tcp_shutdown(ssk, how);
+
+			/* simulate the data_fin ack reception to let the state
+			 * machine move forward
+			 */
+			WRITE_ONCE(mptcp_sk(sk)->snd_una, mptcp_sk(sk)->snd_nxt);
+			mptcp_schedule_work(sk);
 		} else {
 			pr_debug("Sending DATA_FIN on subflow %p", ssk);
 			tcp_send_ack(ssk);

@@ -2630,7 +2633,7 @@ static int mptcp_close_state(struct sock *sk)
 	return next & TCP_ACTION_FIN;
 }
 
-static void __mptcp_check_send_data_fin(struct sock *sk)
+static void mptcp_check_send_data_fin(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow;
 	struct mptcp_sock *msk = mptcp_sk(sk);

@@ -2648,18 +2651,6 @@ static void __mptcp_check_send_data_fin(struct sock *sk)
 
 	WRITE_ONCE(msk->snd_nxt, msk->write_seq);
 
-	/* fallback socket will not get data_fin/ack, can move to the next
-	 * state now
-	 */
-	if (__mptcp_check_fallback(msk)) {
-		if ((1 << sk->sk_state) & (TCPF_CLOSING | TCPF_LAST_ACK)) {
-			inet_sk_state_store(sk, TCP_CLOSE);
-			mptcp_close_wake_up(sk);
-		} else if (sk->sk_state == TCP_FIN_WAIT1) {
-			inet_sk_state_store(sk, TCP_FIN_WAIT2);
-		}
-	}
-
 	mptcp_flush_join_list(msk);
 	mptcp_for_each_subflow(msk, subflow) {
 		struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);

@@ -2680,7 +2671,7 @@ static void __mptcp_wr_shutdown(struct sock *sk)
 	WRITE_ONCE(msk->write_seq, msk->write_seq + 1);
 	WRITE_ONCE(msk->snd_data_fin_enable, 1);
 
-	__mptcp_check_send_data_fin(sk);
+	mptcp_check_send_data_fin(sk);
 }
 
 static void __mptcp_destroy_sock(struct sock *sk)

net/mptcp/subflow.c +10 -7

index 9b89999062c9..666f6720db76 100644
@@ -1653,14 +1653,16 @@ static void subflow_state_change(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 	struct sock *parent = subflow->conn;
+	struct mptcp_sock *msk;
 
 	__subflow_state_change(sk);
 
+	msk = mptcp_sk(parent);
 	if (subflow_simultaneous_connect(sk)) {
 		mptcp_propagate_sndbuf(parent, sk);
 		mptcp_do_fallback(sk);
-		mptcp_rcv_space_init(mptcp_sk(parent), sk);
-		pr_fallback(mptcp_sk(parent));
+		mptcp_rcv_space_init(msk, sk);
+		pr_fallback(msk);
 		subflow->conn_finished = 1;
 		mptcp_set_connected(parent);
 	}

@@ -1676,11 +1678,12 @@ static void subflow_state_change(struct sock *sk)
 
 	subflow_sched_work_if_closed(mptcp_sk(parent), sk);
 
-	if (__mptcp_check_fallback(mptcp_sk(parent)) &&
-	    !subflow->rx_eof && subflow_is_done(sk)) {
-		subflow->rx_eof = 1;
-		mptcp_subflow_eof(parent);
-	}
+	/* when the fallback subflow closes the rx side, trigger a 'dummy'
+	 * ingress data fin, so that the msk state will follow along
+	 */
+	if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
+	    mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true))
+		mptcp_schedule_work(parent);
 }
 
 static int subflow_ulp_init(struct sock *sk)

Signature · 1 line

2.40.1

Greg KH

author maintainer

2023-06-28 18:20 UTC #2 lore raw

Re: [PATCH 5.15.y] mptcp: consolidate fallback and non fallback state machine

Quoted 41 lines · Matthieu Baerts

From: Paolo Abeni <[email protected]>
commit 81c1d029016001f994ce1c46849c5e9900d8eab8 upstream.
An orphaned msk releases the used resources via the worker, when the latter first see the msk in CLOSED status.
If the msk status transitions to TCP_CLOSE in the release callback invoked by the worker's final release_sock(), such instance of the workqueue will not take any action.
Additionally the MPTCP code prevents scheduling the worker once the socket reaches the CLOSE status: such msk resources will be leaked.
The only code path that can trigger the above scenario is the __mptcp_check_send_data_fin() in fallback mode.
Address the issue removing the special handling of fallback socket in __mptcp_check_send_data_fin(), consolidating the state machine for fallback and non fallback socket.
Since non-fallback sockets do not send and do not receive data_fin, the mptcp code can update the msk internal status to match the next step in the SM every time data fin (ack) should be generated or received.
As a consequence we can remove a bunch of checks for fallback from the fastpath.
Fixes 6e628cd3a8f7 ("mptcp: use mptcp release_cb for delayed tasks")
Cc [email protected]
Signed-off-by Paolo Abeni <[email protected]>
Reviewed-by Mat Martineau <[email protected]>
Signed-off-by Matthieu Baerts <[email protected]>
Signed-off-by Jakub Kicinski <[email protected]>
Signed-off-by Matthieu Baerts <[email protected]>
---
Conflicting with:
- 0522b424c4c2 ("mptcp: add do_check_data_fin to replace copied")
- 3e5014909b56 ("mptcp: cleanup MPJ subflow list handling")

Quoted 7 lines

I took the new modifications but leaving the old variable name for "copied" instead of "do_check_data_fin" and the calls to __mptcp_flush_join_list()
Applied on top of d2efde0d1c2e ("Linux 5.15.119-rc1").
Signed-off-by Matthieu Baerts <[email protected]>

All backports now queued up, thanks.

greg k-h