Commit 5ab54e57 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'mptcp-Optimize-received-options-handling' 



Mat Martineau says:

====================
mptcp: Optimize received options handling

These patches optimize received MPTCP option handling in terms of both
storage and fewer conditionals to evaluate in common cases, and also add
a couple of cleanup patches.

Patches 1 and 5 do some cleanup in checksum option parsing and
clarification of lock handling.

Patches 2 and 3 rearrange struct mptcp_options_received to shrink it
slightly and consolidate frequently used fields in the same cache line.

Patch 4 optimizes incoming MPTCP option parsing to skip many extra
comparisons in the common case where only a DSS option is present.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 3aa7857f 9758f40e

net/mptcp/options.c

+63 −78
Original line number Diff line number Diff line
@@ -81,12 +81,11 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
		 * is if both hosts in their SYNs set A=0."

		 */

		if (flags & MPTCP_CAP_CHECKSUM_REQD)

			mp_opt->csum_reqd = 1;

			mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;



		if (flags & MPTCP_CAP_DENY_JOIN_ID0)

			mp_opt->deny_join_id0 = 1;

		mp_opt->deny_join_id0 = !!(flags & MPTCP_CAP_DENY_JOIN_ID0);



		mp_opt->mp_capable = 1;

		mp_opt->suboptions |= OPTIONS_MPTCP_MPC;

		if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {

			mp_opt->sndr_key = get_unaligned_be64(ptr);

			ptr += 8;
@@ -101,7 +100,7 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
			 * equivalent to those in a DSS option and can be used

			 * interchangeably."

			 */

			mp_opt->dss = 1;

			mp_opt->suboptions |= OPTION_MPTCP_DSS;

			mp_opt->use_map = 1;

			mp_opt->mpc_map = 1;

			mp_opt->data_len = get_unaligned_be16(ptr);
@@ -109,7 +108,7 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
		}

		if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) {

			mp_opt->csum = (__force __sum16)get_unaligned_be16(ptr);

			mp_opt->csum_reqd = 1;

			mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;

			ptr += 2;

		}

		pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u",
@@ -118,7 +117,7 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
		break;



	case MPTCPOPT_MP_JOIN:

		mp_opt->mp_join = 1;

		mp_opt->suboptions |= OPTIONS_MPTCP_MPJ;

		if (opsize == TCPOLEN_MPTCP_MPJ_SYN) {

			mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;

			mp_opt->join_id = *ptr++;
@@ -144,7 +143,7 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
			memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN);

			pr_debug("MP_JOIN hmac");

		} else {

			mp_opt->mp_join = 0;

			mp_opt->suboptions &= ~OPTIONS_MPTCP_MPJ;

		}

		break;
@@ -192,8 +191,7 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
		    opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)

			break;



		mp_opt->dss = 1;



		mp_opt->suboptions |= OPTION_MPTCP_DSS;

		if (mp_opt->use_ack) {

			if (mp_opt->ack64) {

				mp_opt->data_ack = get_unaligned_be64(ptr);
@@ -222,14 +220,15 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
			ptr += 2;



			if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) {

				mp_opt->csum_reqd = 1;

				mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;

				mp_opt->csum = (__force __sum16)get_unaligned_be16(ptr);

				ptr += 2;

			}



			pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",

				 mp_opt->data_seq, mp_opt->subflow_seq,

				 mp_opt->data_len, mp_opt->csum_reqd, mp_opt->csum);

				 mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD),

				 mp_opt->csum);

		}



		break;
@@ -260,8 +259,10 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
				break;

		}



		mp_opt->add_addr = 1;

		mp_opt->suboptions |= OPTION_MPTCP_ADD_ADDR;

		mp_opt->addr.id = *ptr++;

		mp_opt->addr.port = 0;

		mp_opt->ahmac = 0;

		if (mp_opt->addr.family == AF_INET) {

			memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4);

			ptr += 4;
@@ -298,7 +299,7 @@ static void mptcp_parse_option(const struct sk_buff *skb, 


		ptr++;



		mp_opt->rm_addr = 1;

		mp_opt->suboptions |= OPTION_MPTCP_RM_ADDR;

		mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE;

		for (i = 0; i < mp_opt->rm_list.nr; i++)

			mp_opt->rm_list.ids[i] = *ptr++;
@@ -309,7 +310,7 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
		if (opsize != TCPOLEN_MPTCP_PRIO)

			break;



		mp_opt->mp_prio = 1;

		mp_opt->suboptions |= OPTION_MPTCP_PRIO;

		mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP;

		pr_debug("MP_PRIO: prio=%d", mp_opt->backup);

		break;
@@ -321,7 +322,7 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
		ptr += 2;

		mp_opt->rcvr_key = get_unaligned_be64(ptr);

		ptr += 8;

		mp_opt->fastclose = 1;

		mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE;

		break;



	case MPTCPOPT_RST:
@@ -330,7 +331,8 @@ static void mptcp_parse_option(const struct sk_buff *skb, 


		if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))

			break;

		mp_opt->reset = 1;



		mp_opt->suboptions |= OPTION_MPTCP_RST;

		flags = *ptr++;

		mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT;

		mp_opt->reset_reason = *ptr;
@@ -341,7 +343,7 @@ static void mptcp_parse_option(const struct sk_buff *skb, 
			break;



		ptr += 2;

		mp_opt->mp_fail = 1;

		mp_opt->suboptions |= OPTION_MPTCP_FAIL;

		mp_opt->fail_seq = get_unaligned_be64(ptr);

		pr_debug("MP_FAIL: data_seq=%llu", mp_opt->fail_seq);

		break;
@@ -355,26 +357,12 @@ void mptcp_get_options(const struct sock *sk, 
		       const struct sk_buff *skb,

		       struct mptcp_options_received *mp_opt)

{

	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);

	struct mptcp_sock *msk = mptcp_sk(subflow->conn);

	const struct tcphdr *th = tcp_hdr(skb);

	const unsigned char *ptr;

	int length;



	/* initialize option status */

	mp_opt->mp_capable = 0;

	mp_opt->mp_join = 0;

	mp_opt->add_addr = 0;

	mp_opt->ahmac = 0;

	mp_opt->fastclose = 0;

	mp_opt->addr.port = 0;

	mp_opt->rm_addr = 0;

	mp_opt->dss = 0;

	mp_opt->mp_prio = 0;

	mp_opt->reset = 0;

	mp_opt->csum_reqd = READ_ONCE(msk->csum_enabled);

	mp_opt->deny_join_id0 = 0;

	mp_opt->mp_fail = 0;

	mp_opt->suboptions = 0;



	length = (th->doff * 4) - sizeof(struct tcphdr);

	ptr = (const unsigned char *)(th + 1);
@@ -928,7 +916,7 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk, 
		 */

		if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&

		    TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&

		    subflow->mp_join && mp_opt->mp_join &&

		    subflow->mp_join && (mp_opt->suboptions & OPTIONS_MPTCP_MPJ) &&

		    READ_ONCE(msk->pm.server_side))

			tcp_send_ack(ssk);

		goto fully_established;
@@ -945,8 +933,8 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk, 
		return subflow->mp_capable;

	}



	if ((mp_opt->dss && mp_opt->use_ack) ||

	    (mp_opt->add_addr && !mp_opt->echo)) {

	if (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) ||

	    ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && !mp_opt->echo)) {

		/* subflows are fully established as soon as we get any

		 * additional ack, including ADD_ADDR.

		 */
@@ -959,7 +947,7 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk, 
	 * then fallback to TCP. Fallback scenarios requires a reset for

	 * MP_JOIN subflows.

	 */

	if (!mp_opt->mp_capable) {

	if (!(mp_opt->suboptions & OPTIONS_MPTCP_MPC)) {

		if (subflow->mp_join)

			goto reset;

		subflow->mp_capable = 0;
@@ -1123,13 +1111,15 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 
	if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))

		return sk->sk_state != TCP_CLOSE;



	if (mp_opt.fastclose &&

	if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) {

		if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) &&

		    msk->local_key == mp_opt.rcvr_key) {

			WRITE_ONCE(msk->rcv_fastclose, true);

			mptcp_schedule_work((struct sock *)msk);

		}



	if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {

		if ((mp_opt.suboptions & OPTION_MPTCP_ADD_ADDR) &&

		    add_addr_hmac_valid(msk, &mp_opt)) {

			if (!mp_opt.echo) {

				mptcp_pm_add_addr_received(msk, &mp_opt.addr);

				MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
@@ -1141,35 +1131,30 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 


			if (mp_opt.addr.port)

				MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD);



		mp_opt.add_addr = 0;

		}



	if (mp_opt.rm_addr) {

		if (mp_opt.suboptions & OPTION_MPTCP_RM_ADDR)

			mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list);

		mp_opt.rm_addr = 0;

	}



	if (mp_opt.mp_prio) {

		if (mp_opt.suboptions & OPTION_MPTCP_PRIO) {

			mptcp_pm_mp_prio_received(sk, mp_opt.backup);

			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX);

		mp_opt.mp_prio = 0;

		}



	if (mp_opt.mp_fail) {

		if (mp_opt.suboptions & OPTION_MPTCP_FAIL) {

			mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq);

			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX);

		mp_opt.mp_fail = 0;

		}



	if (mp_opt.reset) {

		if (mp_opt.suboptions & OPTION_MPTCP_RST) {

			subflow->reset_seen = 1;

			subflow->reset_reason = mp_opt.reset_reason;

			subflow->reset_transient = mp_opt.reset_transient;

		}



	if (!mp_opt.dss)

		if (!(mp_opt.suboptions & OPTION_MPTCP_DSS))

			return true;

	}



	/* we can't wait for recvmsg() to update the ack_seq, otherwise

	 * monodirectional flows will stuck
@@ -1197,7 +1182,7 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 


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



	if (mp_opt.use_map) {

	if (likely(mp_opt.use_map)) {

		if (mp_opt.mpc_map) {

			/* this is an MP_CAPABLE carrying MPTCP data

			 * we know this map the first chunk of data
@@ -1217,7 +1202,7 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 
		}

		mpext->data_len = mp_opt.data_len;

		mpext->use_map = 1;

		mpext->csum_reqd = mp_opt.csum_reqd;

		mpext->csum_reqd = !!(mp_opt.suboptions & OPTION_MPTCP_CSUMREQD);



		if (mpext->csum_reqd)

			mpext->csum = mp_opt.csum;

net/mptcp/protocol.c

+9 −5
Original line number Diff line number Diff line
@@ -1515,15 +1515,19 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags) 
			mptcp_flush_join_list(msk);

			ssk = mptcp_subflow_get_send(msk);



			/* try to keep the subflow socket lock across

			 * consecutive xmit on the same socket

			/* First check. If the ssk has changed since

			 * the last round, release prev_ssk

			 */

			if (ssk != prev_ssk && prev_ssk)

				mptcp_push_release(sk, prev_ssk, &info);

			if (!ssk)

				goto out;



			if (ssk != prev_ssk || !prev_ssk)

			/* Need to lock the new subflow only if different

			 * from the previous one, otherwise we are still

			 * helding the relevant lock

			 */

			if (ssk != prev_ssk)

				lock_sock(ssk);



			/* keep it simple and always provide a new skb for the
@@ -2832,7 +2836,7 @@ struct sock *mptcp_sk_clone(const struct sock *sk, 
	msk->token = subflow_req->token;

	msk->subflow = NULL;

	WRITE_ONCE(msk->fully_established, false);

	if (mp_opt->csum_reqd)

	if (mp_opt->suboptions & OPTION_MPTCP_CSUMREQD)

		WRITE_ONCE(msk->csum_enabled, true);



	msk->write_seq = subflow_req->idsn + 1;
@@ -2841,7 +2845,7 @@ struct sock *mptcp_sk_clone(const struct sock *sk, 
	msk->wnd_end = msk->snd_nxt + req->rsk_rcv_wnd;

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



	if (mp_opt->mp_capable) {

	if (mp_opt->suboptions & OPTIONS_MPTCP_MPC) {

		msk->can_ack = true;

		msk->remote_key = mp_opt->sndr_key;

		mptcp_crypto_key_sha(msk->remote_key, NULL, &ack_seq);

net/mptcp/protocol.h

+17 −19
Original line number Diff line number Diff line
@@ -29,6 +29,13 @@ 
#define OPTION_MPTCP_DSS	BIT(11)

#define OPTION_MPTCP_FAIL	BIT(12)



#define OPTION_MPTCP_CSUMREQD	BIT(13)



#define OPTIONS_MPTCP_MPC	(OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK | \

				 OPTION_MPTCP_MPC_ACK)

#define OPTIONS_MPTCP_MPJ	(OPTION_MPTCP_MPJ_SYN | OPTION_MPTCP_MPJ_SYNACK | \

				 OPTION_MPTCP_MPJ_SYNACK)



/* MPTCP option subtypes */

#define MPTCPOPT_MP_CAPABLE	0

#define MPTCPOPT_MP_JOIN	1
@@ -132,36 +139,27 @@ struct mptcp_options_received { 
	u32	subflow_seq;

	u16	data_len;

	__sum16	csum;

	u16	mp_capable : 1,

		mp_join : 1,

		fastclose : 1,

		reset : 1,

		dss : 1,

		add_addr : 1,

		rm_addr : 1,

		mp_prio : 1,

		mp_fail : 1,

		echo : 1,

		csum_reqd : 1,

		backup : 1,

		deny_join_id0 : 1;

	u16	suboptions;

	u32	token;

	u32	nonce;

	u64	thmac;

	u8	hmac[MPTCPOPT_HMAC_LEN];

	u8	join_id;

	u8	use_map:1,

	u16	use_map:1,

		dsn64:1,

		data_fin:1,

		use_ack:1,

		ack64:1,

		mpc_map:1,

		reset_reason:4,

		reset_transient:1,

		echo:1,

		backup:1,

		deny_join_id0:1,

		__unused:2;

	u8	join_id;

	u64	thmac;

	u8	hmac[MPTCPOPT_HMAC_LEN];

	struct mptcp_addr_info addr;

	struct mptcp_rm_list rm_list;

	u64	ahmac;

	u8	reset_reason:4;

	u8	reset_transient:1;

	u64	fail_seq;

};

net/mptcp/subflow.c

+23 −17
Original line number Diff line number Diff line
@@ -141,6 +141,7 @@ static int subflow_check_req(struct request_sock *req, 
	struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);

	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);

	struct mptcp_options_received mp_opt;

	bool opt_mp_capable, opt_mp_join;



	pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
@@ -154,16 +155,18 @@ static int subflow_check_req(struct request_sock *req, 


	mptcp_get_options(sk_listener, skb, &mp_opt);



	if (mp_opt.mp_capable) {

	opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);

	opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);

	if (opt_mp_capable) {

		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);



		if (mp_opt.mp_join)

		if (opt_mp_join)

			return 0;

	} else if (mp_opt.mp_join) {

	} else if (opt_mp_join) {

		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);

	}



	if (mp_opt.mp_capable && listener->request_mptcp) {

	if (opt_mp_capable && listener->request_mptcp) {

		int err, retries = MPTCP_TOKEN_MAX_RETRIES;



		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
@@ -194,7 +197,7 @@ static int subflow_check_req(struct request_sock *req, 
		else

			SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);



	} else if (mp_opt.mp_join && listener->request_mptcp) {

	} else if (opt_mp_join && listener->request_mptcp) {

		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;

		subflow_req->mp_join = 1;

		subflow_req->backup = mp_opt.backup;
@@ -243,15 +246,18 @@ int mptcp_subflow_init_cookie_req(struct request_sock *req, 
	struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);

	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);

	struct mptcp_options_received mp_opt;

	bool opt_mp_capable, opt_mp_join;

	int err;



	subflow_init_req(req, sk_listener);

	mptcp_get_options(sk_listener, skb, &mp_opt);



	if (mp_opt.mp_capable && mp_opt.mp_join)

	opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);

	opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);

	if (opt_mp_capable && opt_mp_join)

		return -EINVAL;



	if (mp_opt.mp_capable && listener->request_mptcp) {

	if (opt_mp_capable && listener->request_mptcp) {

		if (mp_opt.sndr_key == 0)

			return -EINVAL;
@@ -262,7 +268,7 @@ int mptcp_subflow_init_cookie_req(struct request_sock *req, 


		subflow_req->mp_capable = 1;

		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;

	} else if (mp_opt.mp_join && listener->request_mptcp) {

	} else if (opt_mp_join && listener->request_mptcp) {

		if (!mptcp_token_join_cookie_init_state(subflow_req, skb))

			return -EINVAL;
@@ -394,7 +400,6 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) 


	subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);





	/* be sure no special action on any packet other than syn-ack */

	if (subflow->conn_finished)

		return;
@@ -407,7 +412,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) 


	mptcp_get_options(sk, skb, &mp_opt);

	if (subflow->request_mptcp) {

		if (!mp_opt.mp_capable) {

		if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {

			MPTCP_INC_STATS(sock_net(sk),

					MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);

			mptcp_do_fallback(sk);
@@ -415,7 +420,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) 
			goto fallback;

		}



		if (mp_opt.csum_reqd)

		if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)

			WRITE_ONCE(mptcp_sk(parent)->csum_enabled, true);

		if (mp_opt.deny_join_id0)

			WRITE_ONCE(mptcp_sk(parent)->pm.remote_deny_join_id0, true);
@@ -430,7 +435,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) 
	} else if (subflow->request_join) {

		u8 hmac[SHA256_DIGEST_SIZE];



		if (!mp_opt.mp_join) {

		if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) {

			subflow->reset_reason = MPTCP_RST_EMPTCP;

			goto do_reset;

		}
@@ -636,10 +641,10 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, 


	pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);



	/* After child creation we must look for 'mp_capable' even when options

	/* After child creation we must look for MPC even when options

	 * are not parsed

	 */

	mp_opt.mp_capable = 0;

	mp_opt.suboptions = 0;



	/* hopefully temporary handling for MP_JOIN+syncookie */

	subflow_req = mptcp_subflow_rsk(req);
@@ -659,7 +664,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, 
		 * options.

		 */

		mptcp_get_options(sk, skb, &mp_opt);

		if (!mp_opt.mp_capable) {

		if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {

			fallback = true;

			goto create_child;

		}
@@ -669,7 +674,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, 
			fallback = true;

	} else if (subflow_req->mp_join) {

		mptcp_get_options(sk, skb, &mp_opt);

		if (!mp_opt.mp_join || !subflow_hmac_valid(req, &mp_opt) ||

		if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ) ||

		    !subflow_hmac_valid(req, &mp_opt) ||

		    !mptcp_can_accept_new_subflow(subflow_req->msk)) {

			SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);

			fallback = true;
@@ -726,7 +732,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, 
			/* with OoO packets we can reach here without ingress

			 * mpc option

			 */

			if (mp_opt.mp_capable)

			if (mp_opt.suboptions & OPTIONS_MPTCP_MPC)

				mptcp_subflow_fully_established(ctx, &mp_opt);

		} else if (ctx->mp_join) {

			struct mptcp_sock *owner;