Commit 6f8a612a authored by Florian Westphal's avatar Florian Westphal Committed by Jakub Kicinski
Browse files

mptcp: keep track of advertised windows right edge 



Before sending 'x' new bytes also check that the new snd_una would
be within the permitted receive window.

For every ACK that also contains a DSS ack, check whether its tcp-level
receive window would advance the current mptcp window right edge and
update it if so.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Co-developed-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 8edf0864

net/mptcp/options.c

+20 −4
Original line number Diff line number Diff line
@@ -809,11 +809,14 @@ static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit) 
	return cur_ack;

}



static void update_una(struct mptcp_sock *msk,

static void ack_update_msk(struct mptcp_sock *msk,

			   const struct sock *ssk,

			   struct mptcp_options_received *mp_opt)

{

	u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);

	u64 new_wnd_end, wnd_end, old_wnd_end = atomic64_read(&msk->wnd_end);

	u64 snd_nxt = READ_ONCE(msk->snd_nxt);

	struct sock *sk = (struct sock *)msk;



	/* avoid ack expansion on update conflict, to reduce the risk of

	 * wrongly expanding to a future ack sequence number, which is way
@@ -825,12 +828,25 @@ static void update_una(struct mptcp_sock *msk, 
	if (after64(new_snd_una, snd_nxt))

		new_snd_una = old_snd_una;



	new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;



	while (after64(new_wnd_end, old_wnd_end)) {

		wnd_end = old_wnd_end;

		old_wnd_end = atomic64_cmpxchg(&msk->wnd_end, wnd_end,

					       new_wnd_end);

		if (old_wnd_end == wnd_end) {

			if (mptcp_send_head(sk))

				mptcp_schedule_work(sk);

			break;

		}

	}



	while (after64(new_snd_una, old_snd_una)) {

		snd_una = old_snd_una;

		old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,

					       new_snd_una);

		if (old_snd_una == snd_una) {

			mptcp_data_acked((struct sock *)msk);

			mptcp_data_acked(sk);

			break;

		}

	}
@@ -930,7 +946,7 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 
	 * monodirectional flows will stuck

	 */

	if (mp_opt.use_ack)

		update_una(msk, &mp_opt);

		ack_update_msk(msk, sk, &mp_opt);



	/* Zero-data-length packets are dropped by the caller and not

	 * propagated to the MPTCP layer, so the skb extension does not

net/mptcp/protocol.c

+48 −1
Original line number Diff line number Diff line
@@ -57,6 +57,12 @@ static struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk) 
	return msk->subflow;

}



/* Returns end sequence number of the receiver's advertised window */

static u64 mptcp_wnd_end(const struct mptcp_sock *msk)

{

	return atomic64_read(&msk->wnd_end);

}



static bool mptcp_is_tcpsk(struct sock *sk)

{

	struct socket *sock = sk->sk_socket;
@@ -174,6 +180,7 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb) 
	if (after64(seq, max_seq)) {

		/* out of window */

		mptcp_drop(sk, skb);

		pr_debug("oow by %ld", (unsigned long)seq - (unsigned long)max_seq);

		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_NODSSWINDOW);

		return;

	}
@@ -847,6 +854,7 @@ static void mptcp_clean_una(struct sock *sk) 
	 */

	if (__mptcp_check_fallback(msk))

		atomic64_set(&msk->snd_una, msk->snd_nxt);



	snd_una = atomic64_read(&msk->snd_una);



	list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) {
@@ -944,12 +952,30 @@ struct mptcp_sendmsg_info { 
	unsigned int flags;

};



static int mptcp_check_allowed_size(struct mptcp_sock *msk, u64 data_seq,

				    int avail_size)

{

	u64 window_end = mptcp_wnd_end(msk);



	if (__mptcp_check_fallback(msk))

		return avail_size;



	if (!before64(data_seq + avail_size, window_end)) {

		u64 allowed_size = window_end - data_seq;



		return min_t(unsigned int, allowed_size, avail_size);

	}



	return avail_size;

}



static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,

			      struct mptcp_data_frag *dfrag,

			      struct mptcp_sendmsg_info *info)

{

	u64 data_seq = dfrag->data_seq + info->sent;

	struct mptcp_sock *msk = mptcp_sk(sk);

	bool zero_window_probe = false;

	struct mptcp_ext *mpext = NULL;

	struct sk_buff *skb, *tail;

	bool can_collapse = false;
@@ -979,6 +1005,16 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, 
			avail_size = info->size_goal - skb->len;

	}



	/* Zero window and all data acked? Probe. */

	avail_size = mptcp_check_allowed_size(msk, data_seq, avail_size);

	if (avail_size == 0) {

		if (skb || atomic64_read(&msk->snd_una) != msk->snd_nxt)

			return 0;

		zero_window_probe = true;

		data_seq = atomic64_read(&msk->snd_una) - 1;

		avail_size = 1;

	}



	if (WARN_ON_ONCE(info->sent > info->limit ||

			 info->limit > dfrag->data_len))

		return 0;
@@ -996,6 +1032,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, 
	if (skb == tail) {

		WARN_ON_ONCE(!can_collapse);

		mpext->data_len += ret;

		WARN_ON_ONCE(zero_window_probe);

		goto out;

	}
@@ -1013,6 +1050,12 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, 
		 mpext->data_seq, mpext->subflow_seq, mpext->data_len,

		 mpext->dsn64);



	if (zero_window_probe) {

		mptcp_subflow_ctx(ssk)->rel_write_seq += ret;

		mpext->frozen = 1;

		ret = 0;

		tcp_push_pending_frames(ssk);

	}

out:

	mptcp_subflow_ctx(ssk)->rel_write_seq += ret;

	return ret;
@@ -1866,7 +1909,7 @@ static void mptcp_worker(struct work_struct *work) 
	info.limit = dfrag->already_sent;

	while (info.sent < dfrag->already_sent) {

		ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);

		if (ret < 0)

		if (ret <= 0)

			break;



		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RETRANSSEGS);
@@ -2226,6 +2269,8 @@ struct sock *mptcp_sk_clone(const struct sock *sk, 
	msk->write_seq = subflow_req->idsn + 1;

	msk->snd_nxt = msk->write_seq;

	atomic64_set(&msk->snd_una, msk->write_seq);

	atomic64_set(&msk->wnd_end, msk->snd_nxt + req->rsk_rcv_wnd);



	if (mp_opt->mp_capable) {

		msk->can_ack = true;

		msk->remote_key = mp_opt->sndr_key;
@@ -2258,6 +2303,8 @@ void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk) 
				      TCP_INIT_CWND * tp->advmss);

	if (msk->rcvq_space.space == 0)

		msk->rcvq_space.space = TCP_INIT_CWND * TCP_MSS_DEFAULT;



	atomic64_set(&msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);

}



static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,

net/mptcp/protocol.h

+1 −0
Original line number Diff line number Diff line
@@ -215,6 +215,7 @@ struct mptcp_sock { 
	struct sock	*last_snd;

	int		snd_burst;

	atomic64_t	snd_una;

	atomic64_t	wnd_end;

	unsigned long	timer_ival;

	u32		token;

	unsigned long	flags;

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