Commit df00b087 authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

mptcp: tag sequence_seq with socket state 



Paolo Abeni suggested to avoid re-syncing new subflows because
they inherit options from listener. In case options were set on
listener but are not set on mptcp-socket there is no need to
do any synchronisation for new subflows.

This change sets sockopt_seq of new mptcp sockets to the seq of
the mptcp listener sock.

Subflow sequence is set to the embedded tcp listener sk.
Add a comment explaing why sk_state is involved in sockopt_seq
generation.

Acked-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 78962489

net/mptcp/protocol.c

+9 −3
Original line number Diff line number Diff line
@@ -733,18 +733,23 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk) 
static bool mptcp_do_flush_join_list(struct mptcp_sock *msk)

{

	struct mptcp_subflow_context *subflow;

	bool ret = false;



	if (likely(list_empty(&msk->join_list)))

		return false;



	spin_lock_bh(&msk->join_list_lock);

	list_for_each_entry(subflow, &msk->join_list, node)

		mptcp_propagate_sndbuf((struct sock *)msk, mptcp_subflow_tcp_sock(subflow));

	list_for_each_entry(subflow, &msk->join_list, node) {

		u32 sseq = READ_ONCE(subflow->setsockopt_seq);



		mptcp_propagate_sndbuf((struct sock *)msk, mptcp_subflow_tcp_sock(subflow));

		if (READ_ONCE(msk->setsockopt_seq) != sseq)

			ret = true;

	}

	list_splice_tail_init(&msk->join_list, &msk->conn_list);

	spin_unlock_bh(&msk->join_list_lock);



	return true;

	return ret;

}



void __mptcp_flush_join_list(struct mptcp_sock *msk)
@@ -2718,6 +2723,7 @@ struct sock *mptcp_sk_clone(const struct sock *sk, 
	msk->snd_nxt = msk->write_seq;

	msk->snd_una = msk->write_seq;

	msk->wnd_end = msk->snd_nxt + req->rsk_rcv_wnd;

	msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;



	if (mp_opt->mp_capable) {

		msk->can_ack = true;

net/mptcp/protocol.h

+4 −0
Original line number Diff line number Diff line
@@ -256,6 +256,8 @@ struct mptcp_sock { 
		u64	time;	/* start time of measurement window */

		u64	rtt_us; /* last maximum rtt of subflows */

	} rcvq_space;



	u32 setsockopt_seq;

};



#define mptcp_lock_sock(___sk, cb) do {					\
@@ -414,6 +416,8 @@ struct mptcp_subflow_context { 
	long	delegated_status;

	struct	list_head delegated_node;   /* link into delegated_action, protected by local BH */



	u32 setsockopt_seq;



	struct	sock *tcp_sock;	    /* tcp sk backpointer */

	struct	sock *conn;	    /* parent mptcp_sock */

	const	struct inet_connection_sock_af_ops *icsk_af_ops;

net/mptcp/sockopt.c

+45 −2
Original line number Diff line number Diff line
@@ -24,6 +24,27 @@ static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk) 
	return msk->first;

}



static u32 sockopt_seq_reset(const struct sock *sk)

{

	sock_owned_by_me(sk);



	/* Highbits contain state.  Allows to distinguish sockopt_seq

	 * of listener and established:

	 * s0 = new_listener()

	 * sockopt(s0) - seq is 1

	 * s1 = accept(s0) - s1 inherits seq 1 if listener sk (s0)

	 * sockopt(s0) - seq increments to 2 on s0

	 * sockopt(s1) // seq increments to 2 on s1 (different option)

	 * new ssk completes join, inherits options from s0 // seq 2

	 * Needs sync from mptcp join logic, but ssk->seq == msk->seq

	 *

	 * Set High order bits to sk_state so ssk->seq == msk->seq test

	 * will fail.

	 */



	return (u32)sk->sk_state << 24u;

}



static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,

				       sockptr_t optval, unsigned int optlen)

{
@@ -350,22 +371,44 @@ int mptcp_getsockopt(struct sock *sk, int level, int optname, 
	return -EOPNOTSUPP;

}



static void __mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk)

{

}



void mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk)

{

	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);



	msk_owned_by_me(msk);



	if (READ_ONCE(subflow->setsockopt_seq) != msk->setsockopt_seq) {

		__mptcp_sockopt_sync(msk, ssk);



		subflow->setsockopt_seq = msk->setsockopt_seq;

	}

}



void mptcp_sockopt_sync_all(struct mptcp_sock *msk)

{

	struct mptcp_subflow_context *subflow;

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

	u32 seq;



	msk_owned_by_me(msk);

	seq = sockopt_seq_reset(sk);



	mptcp_for_each_subflow(msk, subflow) {

		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);

		u32 sseq = READ_ONCE(subflow->setsockopt_seq);



		mptcp_sockopt_sync(msk, ssk);

		if (sseq != msk->setsockopt_seq) {

			__mptcp_sockopt_sync(msk, ssk);

			WRITE_ONCE(subflow->setsockopt_seq, seq);

		} else if (sseq != seq) {

			WRITE_ONCE(subflow->setsockopt_seq, seq);

		}



		cond_resched();

	}



	msk->setsockopt_seq = seq;

}

net/mptcp/subflow.c

+4 −0
Original line number Diff line number Diff line
@@ -679,6 +679,9 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, 
			goto out;

		}



		/* ssk inherits options of listener sk */

		ctx->setsockopt_seq = listener->setsockopt_seq;



		if (ctx->mp_capable) {

			/* this can't race with mptcp_close(), as the msk is

			 * not yet exposted to user-space
@@ -694,6 +697,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, 
			 * created mptcp socket

			 */

			new_msk->sk_destruct = mptcp_sock_destruct;

			mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq;

			mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1);

			mptcp_token_accept(subflow_req, mptcp_sk(new_msk));

			ctx->conn = new_msk;