/* * net/tipc/bcast.c: TIPC broadcast code * * Copyright (c) 2004-2006, 2014-2017, Ericsson AB * Copyright (c) 2004, Intel Corporation. * Copyright (c) 2005, 2010-2011, Wind River Systems * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the names of the copyright holders nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * Alternatively, this software may be distributed under the terms of the * GNU General Public License ("GPL") version 2 as published by the Free * Software Foundation. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include <linux/tipc_config.h> #include "socket.h" #include "msg.h" #include "bcast.h" #include "link.h" #include "name_table.h" #define BCLINK_WIN_DEFAULT 50 /* bcast link window size (default) */ #define BCLINK_WIN_MIN 32 /* bcast minimum link window size */ const char tipc_bclink_name[] = "broadcast-link"; /** * struct tipc_bc_base - base structure for keeping broadcast send state * @link: broadcast send link structure * @inputq: data input queue; will only carry SOCK_WAKEUP messages * @dests: array keeping number of reachable destinations per bearer * @primary_bearer: a bearer having links to all broadcast destinations, if any * @bcast_support: indicates if primary bearer, if any, supports broadcast * @force_bcast: forces broadcast for multicast traffic * @rcast_support: indicates if all peer nodes support replicast * @force_rcast: forces replicast for multicast traffic * @rc_ratio: dest count as percentage of cluster size where send method changes * @bc_threshold: calculated from rc_ratio; if dests > threshold use broadcast */ struct tipc_bc_base { struct tipc_link *link; struct sk_buff_head inputq; int dests[MAX_BEARERS]; int primary_bearer; bool bcast_support; bool force_bcast; bool rcast_support; bool force_rcast; int rc_ratio; int bc_threshold; }; static struct tipc_bc_base *tipc_bc_base(struct net *net) { return tipc_net(net)->bcbase; } /* tipc_bcast_get_mtu(): -get the MTU currently used by broadcast link * Note: the MTU is decremented to give room for a tunnel header, in * case the message needs to be sent as replicast */ int tipc_bcast_get_mtu(struct net *net) { return tipc_link_mss(tipc_bc_sndlink(net)); } void tipc_bcast_toggle_rcast(struct net *net, bool supp) { tipc_bc_base(net)->rcast_support = supp; } static void tipc_bcbase_calc_bc_threshold(struct net *net) { struct tipc_bc_base *bb = tipc_bc_base(net); int cluster_size = tipc_link_bc_peers(tipc_bc_sndlink(net)); bb->bc_threshold = 1 + (cluster_size * bb->rc_ratio / 100); } /* tipc_bcbase_select_primary(): find a bearer with links to all destinations, * if any, and make it primary bearer */ static void tipc_bcbase_select_primary(struct net *net) { struct tipc_bc_base *bb = tipc_bc_base(net); int all_dests = tipc_link_bc_peers(bb->link); int i, mtu, prim; bb->primary_bearer = INVALID_BEARER_ID; bb->bcast_support = true; if (!all_dests) return; for (i = 0; i < MAX_BEARERS; i++) { if (!bb->dests[i]) continue; mtu = tipc_bearer_mtu(net, i); if (mtu < tipc_link_mtu(bb->link)) tipc_link_set_mtu(bb->link, mtu); bb->bcast_support &= tipc_bearer_bcast_support(net, i); if (bb->dests[i] < all_dests) continue; bb->primary_bearer = i; /* Reduce risk that all nodes select same primary */ if ((i ^ tipc_own_addr(net)) & 1) break; } prim = bb->primary_bearer; if (prim != INVALID_BEARER_ID) bb->bcast_support = tipc_bearer_bcast_support(net, prim); } void tipc_bcast_inc_bearer_dst_cnt(struct net *net, int bearer_id) { struct tipc_bc_base *bb = tipc_bc_base(net); tipc_bcast_lock(net); bb->dests[bearer_id]++; tipc_bcbase_select_primary(net); tipc_bcast_unlock(net); } void tipc_bcast_dec_bearer_dst_cnt(struct net *net, int bearer_id) { struct tipc_bc_base *bb = tipc_bc_base(net); tipc_bcast_lock(net); bb->dests[bearer_id]--; tipc_bcbase_select_primary(net); tipc_bcast_unlock(net); } /* tipc_bcbase_xmit - broadcast a packet queue across one or more bearers * * Note that number of reachable destinations, as indicated in the dests[] * array, may transitionally differ from the number of destinations indicated * in each sent buffer. We can sustain this. Excess destination nodes will * drop and never acknowledge the unexpected packets, and missing destinations * will either require retransmission (if they are just about to be added to * the bearer), or be removed from the buffer's 'ackers' counter (if they * just went down) */ static void tipc_bcbase_xmit(struct net *net, struct sk_buff_head *xmitq) { int bearer_id; struct tipc_bc_base *bb = tipc_bc_base(net); struct sk_buff *skb, *_skb; struct sk_buff_head _xmitq; if (skb_queue_empty(xmitq)) return; /* The typical case: at least one bearer has links to all nodes */ bearer_id = bb->primary_bearer; if (bearer_id >= 0) { tipc_bearer_bc_xmit(net, bearer_id, xmitq); return; } /* We have to transmit across all bearers */ __skb_queue_head_init(&_xmitq); for (bearer_id = 0; bearer_id < MAX_BEARERS; bearer_id++) { if (!bb->dests[bearer_id]) continue; skb_queue_walk(xmitq, skb) { _skb = pskb_copy_for_clone(skb, GFP_ATOMIC); if (!_skb) break; __skb_queue_tail(&_xmitq, _skb); } tipc_bearer_bc_xmit(net, bearer_id, &_xmitq); } __skb_queue_purge(xmitq); __skb_queue_purge(&_xmitq); } static void tipc_bcast_select_xmit_method(struct net *net, int dests, struct tipc_mc_method *method) { struct tipc_bc_base *bb = tipc_bc_base(net); unsigned long exp = method->expires; /* Broadcast supported by used bearer/bearers? */ if (!bb->bcast_support) { method->rcast = true; return; } /* Any destinations which don't support replicast ? */ if (!bb->rcast_support) { method->rcast = false; return; } /* Can current method be changed ? */ method->expires = jiffies + TIPC_METHOD_EXPIRE; if (method->mandatory) return; if (!(tipc_net(net)->capabilities & TIPC_MCAST_RBCTL) && time_before(jiffies, exp)) return; /* Configuration as force 'broadcast' method */ if (bb->force_bcast) { method->rcast = false; return; } /* Configuration as force 'replicast' method */ if (bb->force_rcast) { method->rcast = true; return; } /* Configuration as 'autoselect' or default method */ /* Determine method to use now */ method->rcast = dests <= bb->bc_threshold; } /* tipc_bcast_xmit - broadcast the buffer chain to all external nodes * @net: the applicable net namespace * @pkts: chain of buffers containing message * @cong_link_cnt: set to 1 if broadcast link is congested, otherwise 0 * Consumes the buffer chain. * Returns 0 if success, otherwise errno: -EHOSTUNREACH,-EMSGSIZE */ static int tipc_bcast_xmit(struct net *net, struct sk_buff_head *pkts, u16 *cong_link_cnt) { struct tipc_link *l = tipc_bc_sndlink(net); struct sk_buff_head xmitq; int rc = 0; __skb_queue_head_init(&xmitq); tipc_bcast_lock(net); if (tipc_link_bc_peers(l)) rc = tipc_link_xmit(l, pkts, &xmitq); tipc_bcast_unlock(net); tipc_bcbase_xmit(net, &xmitq); __skb_queue_purge(pkts); if (rc == -ELINKCONG) { *cong_link_cnt = 1; rc = 0; } return rc; } /* tipc_rcast_xmit - replicate and send a message to given destination nodes * @net: the applicable net namespace * @pkts: chain of buffers containing message * @dests: list of destination nodes * @cong_link_cnt: returns number of congested links * @cong_links: returns identities of congested links * Returns 0 if success, otherwise errno */ static int tipc_rcast_xmit(struct net *net, struct sk_buff_head *pkts, struct tipc_nlist *dests, u16 *cong_link_cnt) { struct tipc_dest *dst, *tmp; struct sk_buff_head _pkts; u32 dnode, selector; selector = msg_link_selector(buf_msg(skb_peek(pkts))); __skb_queue_head_init(&_pkts); list_for_each_entry_safe(dst, tmp, &dests->list, list) { dnode = dst->node; if (!tipc_msg_pskb_copy(dnode, pkts, &_pkts)) return -ENOMEM; /* Any other return value than -ELINKCONG is ignored */ if (tipc_node_xmit(net, &_pkts, dnode, selector) == -ELINKCONG) (*cong_link_cnt)++; } return 0; } /* tipc_mcast_send_sync - deliver a dummy message with SYN bit * @net: the applicable net namespace * @skb: socket buffer to copy * @method: send method to be used * @dests: destination nodes for message. * Returns 0 if success, otherwise errno */ static int tipc_mcast_send_sync(struct net *net, struct sk_buff *skb, struct tipc_mc_method *method, struct tipc_nlist *dests) { struct tipc_msg *hdr, *_hdr; struct sk_buff_head tmpq; struct sk_buff *_skb; u16 cong_link_cnt; int rc = 0; /* Is a cluster supporting with new capabilities ? */ if (!(tipc_net(net)->capabilities & TIPC_MCAST_RBCTL)) return 0; hdr = buf_msg(skb); if (msg_user(hdr) == MSG_FRAGMENTER) hdr = msg_inner_hdr(hdr); if (msg_type(hdr) != TIPC_MCAST_MSG) return 0; /* Allocate dummy message */ _skb = tipc_buf_acquire(MCAST_H_SIZE, GFP_KERNEL); if (!_skb) return -ENOMEM; /* Preparing for 'synching' header */ msg_set_syn(hdr, 1); /* Copy skb's header into a dummy header */ skb_copy_to_linear_data(_skb, hdr, MCAST_H_SIZE); skb_orphan(_skb); /* Reverse method for dummy message */ _hdr = buf_msg(_skb); msg_set_size(_hdr, MCAST_H_SIZE); msg_set_is_rcast(_hdr, !msg_is_rcast(hdr)); msg_set_errcode(_hdr, TIPC_ERR_NO_PORT); __skb_queue_head_init(&tmpq); __skb_queue_tail(&tmpq, _skb); if (method->rcast) rc = tipc_bcast_xmit(net, &tmpq, &cong_link_cnt); else rc = tipc_rcast_xmit(net, &tmpq, dests, &cong_link_cnt); /* This queue should normally be empty by now */ __skb_queue_purge(&tmpq); return rc; } /* tipc_mcast_xmit - deliver message to indicated destination nodes * and to identified node local sockets * @net: the applicable net namespace * @pkts: chain of buffers containing message * @method: send method to be used * @dests: destination nodes for message. * @cong_link_cnt: returns number of encountered congested destination links * Consumes buffer chain. * Returns 0 if success, otherwise errno */ int tipc_mcast_xmit(struct net *net, struct sk_buff_head *pkts, struct tipc_mc_method *method, struct tipc_nlist *dests, u16 *cong_link_cnt) { struct sk_buff_head inputq, localq; bool rcast = method->rcast; struct tipc_msg *hdr; struct sk_buff *skb; int rc = 0; skb_queue_head_init(&inputq); __skb_queue_head_init(&localq); /* Clone packets before they are consumed by next call */ if (dests->local && !tipc_msg_reassemble(pkts, &localq)) { rc = -ENOMEM; goto exit; } /* Send according to determined transmit method */ if (dests->remote) { tipc_bcast_select_xmit_method(net, dests->remote, method); skb = skb_peek(pkts); hdr = buf_msg(skb); if (msg_user(hdr) == MSG_FRAGMENTER) hdr = msg_inner_hdr(hdr); msg_set_is_rcast(hdr, method->rcast); /* Switch method ? */ if (rcast != method->rcast) { rc = tipc_mcast_send_sync(net, skb, method, dests); if (unlikely(rc)) { pr_err("Unable to send SYN: method %d, rc %d\n", rcast, rc); goto exit; } } if (method->rcast) rc = tipc_rcast_xmit(net, pkts, dests, cong_link_cnt); else rc = tipc_bcast_xmit(net, pkts, cong_link_cnt); } if (dests->local) { tipc_loopback_trace(net, &localq); tipc_sk_mcast_rcv(net, &localq, &inputq); } exit: /* This queue should normally be empty by now */ __skb_queue_purge(pkts); return rc; } /* tipc_bcast_rcv - receive a broadcast packet, and deliver to rcv link * * RCU is locked, no other locks set */ int tipc_bcast_rcv(struct net *net, struct tipc_link *l, struct sk_buff *skb) { struct tipc_msg *hdr = buf_msg(skb); struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq; struct sk_buff_head xmitq; int rc; __skb_queue_head_init(&xmitq); if (msg_mc_netid(hdr) != tipc_netid(net) || !tipc_link_is_up(l)) { kfree_skb(skb); return 0; } tipc_bcast_lock(net); if (msg_user(hdr) == BCAST_PROTOCOL) rc = tipc_link_bc_nack_rcv(l, skb, &xmitq); else rc = tipc_link_rcv(l, skb, NULL); tipc_bcast_unlock(net); tipc_bcbase_xmit(net, &xmitq); /* Any socket wakeup messages ? */ if (!skb_queue_empty(inputq)) tipc_sk_rcv(net, inputq); return rc; } /* tipc_bcast_ack_rcv - receive and handle a broadcast acknowledge * * RCU is locked, no other locks set */ void tipc_bcast_ack_rcv(struct net *net, struct tipc_link *l, struct tipc_msg *hdr) { struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq; u16 acked = msg_bcast_ack(hdr); struct sk_buff_head xmitq; /* Ignore bc acks sent by peer before bcast synch point was received */ if (msg_bc_ack_invalid(hdr)) return; __skb_queue_head_init(&xmitq); tipc_bcast_lock(net); tipc_link_bc_ack_rcv(l, acked, &xmitq); tipc_bcast_unlock(net); tipc_bcbase_xmit(net, &xmitq); /* Any socket wakeup messages ? */ if (!skb_queue_empty(inputq)) tipc_sk_rcv(net, inputq); } /* tipc_bcast_synch_rcv - check and update rcv link with peer's send state * * RCU is locked, no other locks set */ int tipc_bcast_sync_rcv(struct net *net, struct tipc_link *l, struct tipc_msg *hdr) { struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq; struct sk_buff_head xmitq; int rc = 0; __skb_queue_head_init(&xmitq); tipc_bcast_lock(net); if (msg_type(hdr) != STATE_MSG) { tipc_link_bc_init_rcv(l, hdr); } else if (!msg_bc_ack_invalid(hdr)) { tipc_link_bc_ack_rcv(l, msg_bcast_ack(hdr), &xmitq); rc = tipc_link_bc_sync_rcv(l, hdr, &xmitq); } tipc_bcast_unlock(net); tipc_bcbase_xmit(net, &xmitq); /* Any socket wakeup messages ? */ if (!skb_queue_empty(inputq)) tipc_sk_rcv(net, inputq); return rc; } /* tipc_bcast_add_peer - add a peer node to broadcast link and bearer * * RCU is locked, node lock is set */ void tipc_bcast_add_peer(struct net *net, struct tipc_link *uc_l, struct sk_buff_head *xmitq) { struct tipc_link *snd_l = tipc_bc_sndlink(net); tipc_bcast_lock(net); tipc_link_add_bc_peer(snd_l, uc_l, xmitq); tipc_bcbase_select_primary(net); tipc_bcbase_calc_bc_threshold(net); tipc_bcast_unlock(net); } /* tipc_bcast_remove_peer - remove a peer node from broadcast link and bearer * * RCU is locked, node lock is set */ void tipc_bcast_remove_peer(struct net *net, struct tipc_link *rcv_l) { struct tipc_link *snd_l = tipc_bc_sndlink(net); struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq; struct sk_buff_head xmitq; __skb_queue_head_init(&xmitq); tipc_bcast_lock(net); tipc_link_remove_bc_peer(snd_l, rcv_l, &xmitq); tipc_bcbase_select_primary(net); tipc_bcbase_calc_bc_threshold(net); tipc_bcast_unlock(net); tipc_bcbase_xmit(net, &xmitq); /* Any socket wakeup messages ? */ if (!skb_queue_empty(inputq)) tipc_sk_rcv(net, inputq); } int tipc_bclink_reset_stats(struct net *net) { struct tipc_link *l = tipc_bc_sndlink(net); if (!l) return -ENOPROTOOPT; tipc_bcast_lock(net); tipc_link_reset_stats(l); tipc_bcast_unlock(net); return 0; } static int tipc_bc_link_set_queue_limits(struct net *net, u32 max_win) { struct tipc_link *l = tipc_bc_sndlink(net); if (!l) return -ENOPROTOOPT; if (max_win < BCLINK_WIN_MIN) max_win = BCLINK_WIN_MIN; if (max_win > TIPC_MAX_LINK_WIN) return -EINVAL; tipc_bcast_lock(net); tipc_link_set_queue_limits(l, BCLINK_WIN_MIN, max_win); tipc_bcast_unlock(net); return 0; } static int tipc_bc_link_set_broadcast_mode(struct net *net, u32 bc_mode) { struct tipc_bc_base *bb = tipc_bc_base(net); switch (bc_mode) { case BCLINK_MODE_BCAST: if (!bb->bcast_support) return -ENOPROTOOPT; bb->force_bcast = true; bb->force_rcast = false; break; case BCLINK_MODE_RCAST: if (!bb->rcast_support) return -ENOPROTOOPT; bb->force_bcast = false; bb->force_rcast = true; break; case BCLINK_MODE_SEL: if (!bb->bcast_support || !bb->rcast_support) return -ENOPROTOOPT; bb->force_bcast = false; bb->force_rcast = false; break; default: return -EINVAL; } return 0; } static int tipc_bc_link_set_broadcast_ratio(struct net *net, u32 bc_ratio) { struct tipc_bc_base *bb = tipc_bc_base(net); if (!bb->bcast_support || !bb->rcast_support) return -ENOPROTOOPT; if (bc_ratio > 100 || bc_ratio <= 0) return -EINVAL; bb->rc_ratio = bc_ratio; tipc_bcast_lock(net); tipc_bcbase_calc_bc_threshold(net); tipc_bcast_unlock(net); return 0; } int tipc_nl_bc_link_set(struct net *net, struct nlattr *attrs[]) { int err; u32 win; u32 bc_mode; u32 bc_ratio; struct nlattr *props[TIPC_NLA_PROP_MAX + 1]; if (!attrs[TIPC_NLA_LINK_PROP]) return -EINVAL; err = tipc_nl_parse_link_prop(attrs[TIPC_NLA_LINK_PROP], props); if (err) return err; if (!props[TIPC_NLA_PROP_WIN] && !props[TIPC_NLA_PROP_BROADCAST] && !props[TIPC_NLA_PROP_BROADCAST_RATIO]) { return -EOPNOTSUPP; } if (props[TIPC_NLA_PROP_BROADCAST]) { bc_mode = nla_get_u32(props[TIPC_NLA_PROP_BROADCAST]); err = tipc_bc_link_set_broadcast_mode(net, bc_mode); } if (!err && props[TIPC_NLA_PROP_BROADCAST_RATIO]) { bc_ratio = nla_get_u32(props[TIPC_NLA_PROP_BROADCAST_RATIO]); err = tipc_bc_link_set_broadcast_ratio(net, bc_ratio); } if (!err && props[TIPC_NLA_PROP_WIN]) { win = nla_get_u32(props[TIPC_NLA_PROP_WIN]); err = tipc_bc_link_set_queue_limits(net, win); } return err; } int tipc_bcast_init(struct net *net) { struct tipc_net *tn = tipc_net(net); struct tipc_bc_base *bb = NULL; struct tipc_link *l = NULL; bb = kzalloc(sizeof(*bb), GFP_KERNEL); if (!bb) goto enomem; tn->bcbase = bb; spin_lock_init(&tipc_net(net)->bclock); if (!tipc_link_bc_create(net, 0, 0, FB_MTU, BCLINK_WIN_DEFAULT, BCLINK_WIN_DEFAULT, 0, &bb->inputq, NULL, NULL, &l)) goto enomem; bb->link = l; tn->bcl = l; bb->rc_ratio = 10; bb->rcast_support = true; return 0; enomem: kfree(bb); kfree(l); return -ENOMEM; } void tipc_bcast_stop(struct net *net) { struct tipc_net *tn = net_generic(net, tipc_net_id); synchronize_net(); kfree(tn->bcbase); kfree(tn->bcl); } void tipc_nlist_init(struct tipc_nlist *nl, u32 self) { memset(nl, 0, sizeof(*nl)); INIT_LIST_HEAD(&nl->list); nl->self = self; } void tipc_nlist_add(struct tipc_nlist *nl, u32 node) { if (node == nl->self) nl->local = true; else if (tipc_dest_push(&nl->list, node, 0)) nl->remote++; } void tipc_nlist_del(struct tipc_nlist *nl, u32 node) { if (node == nl->self) nl->local = false; else if (tipc_dest_del(&nl->list, node, 0)) nl->remote--; } void tipc_nlist_purge(struct tipc_nlist *nl) { tipc_dest_list_purge(&nl->list); nl->remote = 0; nl->local = false; } u32 tipc_bcast_get_broadcast_mode(struct net *net) { struct tipc_bc_base *bb = tipc_bc_base(net); if (bb->force_bcast) return BCLINK_MODE_BCAST; if (bb->force_rcast) return BCLINK_MODE_RCAST; if (bb->bcast_support && bb->rcast_support) return BCLINK_MODE_SEL; return 0; } u32 tipc_bcast_get_broadcast_ratio(struct net *net) { struct tipc_bc_base *bb = tipc_bc_base(net); return bb->rc_ratio; } void tipc_mcast_filter_msg(struct net *net, struct sk_buff_head *defq, struct sk_buff_head *inputq) { struct sk_buff *skb, *_skb, *tmp; struct tipc_msg *hdr, *_hdr; bool match = false; u32 node, port; skb = skb_peek(inputq); if (!skb) return; hdr = buf_msg(skb); if (likely(!msg_is_syn(hdr) && skb_queue_empty(defq))) return; node = msg_orignode(hdr); if (node == tipc_own_addr(net)) return; port = msg_origport(hdr); /* Has the twin SYN message already arrived ? */ skb_queue_walk(defq, _skb) { _hdr = buf_msg(_skb); if (msg_orignode(_hdr) != node) continue; if (msg_origport(_hdr) != port) continue; match = true; break; } if (!match) { if (!msg_is_syn(hdr)) return; __skb_dequeue(inputq); __skb_queue_tail(defq, skb); return; } /* Deliver non-SYN message from other link, otherwise queue it */ if (!msg_is_syn(hdr)) { if (msg_is_rcast(hdr) != msg_is_rcast(_hdr)) return; __skb_dequeue(inputq); __skb_queue_tail(defq, skb); return; } /* Queue non-SYN/SYN message from same link */ if (msg_is_rcast(hdr) == msg_is_rcast(_hdr)) { __skb_dequeue(inputq); __skb_queue_tail(defq, skb); return; } /* Matching SYN messages => return the one with data, if any */ __skb_unlink(_skb, defq); if (msg_data_sz(hdr)) { kfree_skb(_skb); } else { __skb_dequeue(inputq); kfree_skb(skb); __skb_queue_tail(inputq, _skb); } /* Deliver subsequent non-SYN messages from same peer */ skb_queue_walk_safe(defq, _skb, tmp) { _hdr = buf_msg(_skb); if (msg_orignode(_hdr) != node) continue; if (msg_origport(_hdr) != port) continue; if (msg_is_syn(_hdr)) break; __skb_unlink(_skb, defq); __skb_queue_tail(inputq, _skb); } }