/*
 * net/tipc/group.c: TIPC group messaging code
 *
 * Copyright (c) 2017, Ericsson AB
 * 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 "core.h"
#include "addr.h"
#include "group.h"
#include "bcast.h"
#include "topsrv.h"
#include "msg.h"
#include "socket.h"
#include "node.h"
#include "name_table.h"
#include "subscr.h"

#define ADV_UNIT (((MAX_MSG_SIZE + MAX_H_SIZE) / FLOWCTL_BLK_SZ) + 1)
#define ADV_IDLE ADV_UNIT
#define ADV_ACTIVE (ADV_UNIT * 12)

enum mbr_state {
        MBR_JOINING,
        MBR_PUBLISHED,
        MBR_JOINED,
        MBR_PENDING,
        MBR_ACTIVE,
        MBR_RECLAIMING,
        MBR_REMITTED,
        MBR_LEAVING
};

struct tipc_member {
        struct rb_node tree_node;
        struct list_head list;
        struct list_head small_win;
        struct sk_buff_head deferredq;
        struct tipc_group *group;
        u32 node;
        u32 port;
        u32 instance;
        enum mbr_state state;
        u16 advertised;
        u16 window;
        u16 bc_rcv_nxt;
        u16 bc_syncpt;
        u16 bc_acked;
};

struct tipc_group {
        struct rb_root members;
        struct list_head small_win;
        struct list_head pending;
        struct list_head active;
        struct tipc_nlist dests;
        struct net *net;
        int subid;
        u32 type;
        u32 instance;
        u32 scope;
        u32 portid;
        u16 member_cnt;
        u16 active_cnt;
        u16 max_active;
        u16 bc_snd_nxt;
        u16 bc_ackers;
        bool *open;
        bool loopback;
        bool events;
};

static void tipc_group_proto_xmit(struct tipc_group *grp, struct tipc_member *m,
                                  int mtyp, struct sk_buff_head *xmitq);

static void tipc_group_open(struct tipc_member *m, bool *wakeup)
{
        *wakeup = false;
        if (list_empty(&m->small_win))
                return;
        list_del_init(&m->small_win);
        *m->group->open = true;
        *wakeup = true;
}

static void tipc_group_decr_active(struct tipc_group *grp,
                                   struct tipc_member *m)
{
        if (m->state == MBR_ACTIVE || m->state == MBR_RECLAIMING ||
            m->state == MBR_REMITTED)
                grp->active_cnt--;
}

static int tipc_group_rcvbuf_limit(struct tipc_group *grp)
{
        int max_active, active_pool, idle_pool;
        int mcnt = grp->member_cnt + 1;

        /* Limit simultaneous reception from other members */
        max_active = min(mcnt / 8, 64);
        max_active = max(max_active, 16);
        grp->max_active = max_active;

        /* Reserve blocks for active and idle members */
        active_pool = max_active * ADV_ACTIVE;
        idle_pool = (mcnt - max_active) * ADV_IDLE;

        /* Scale to bytes, considering worst-case truesize/msgsize ratio */
        return (active_pool + idle_pool) * FLOWCTL_BLK_SZ * 4;
}

u16 tipc_group_bc_snd_nxt(struct tipc_group *grp)
{
        return grp->bc_snd_nxt;
}

static bool tipc_group_is_receiver(struct tipc_member *m)
{
        return m && m->state != MBR_JOINING && m->state != MBR_LEAVING;
}

static bool tipc_group_is_sender(struct tipc_member *m)
{
        return m && m->state != MBR_JOINING && m->state != MBR_PUBLISHED;
}

u32 tipc_group_exclude(struct tipc_group *grp)
{
        if (!grp->loopback)
                return grp->portid;
        return 0;
}

int tipc_group_size(struct tipc_group *grp)
{
        return grp->member_cnt;
}

struct tipc_group *tipc_group_create(struct net *net, u32 portid,
                                     struct tipc_group_req *mreq,
                                     bool *group_is_open)
{
        u32 filter = TIPC_SUB_PORTS | TIPC_SUB_NO_STATUS;
        bool global = mreq->scope != TIPC_NODE_SCOPE;
        struct tipc_group *grp;
        u32 type = mreq->type;

        grp = kzalloc(sizeof(*grp), GFP_ATOMIC);
        if (!grp)
                return NULL;
        tipc_nlist_init(&grp->dests, tipc_own_addr(net));
        INIT_LIST_HEAD(&grp->small_win);
        INIT_LIST_HEAD(&grp->active);
        INIT_LIST_HEAD(&grp->pending);
        grp->members = RB_ROOT;
        grp->net = net;
        grp->portid = portid;
        grp->type = type;
        grp->instance = mreq->instance;
        grp->scope = mreq->scope;
        grp->loopback = mreq->flags & TIPC_GROUP_LOOPBACK;
        grp->events = mreq->flags & TIPC_GROUP_MEMBER_EVTS;
        grp->open = group_is_open;
        *grp->open = false;
        filter |= global ? TIPC_SUB_CLUSTER_SCOPE : TIPC_SUB_NODE_SCOPE;
        if (tipc_topsrv_kern_subscr(net, portid, type, 0, ~0,
                                    filter, &grp->subid))
                return grp;
        kfree(grp);
        return NULL;
}

void tipc_group_join(struct net *net, struct tipc_group *grp, int *sk_rcvbuf)
{
        struct rb_root *tree = &grp->members;
        struct tipc_member *m, *tmp;
        struct sk_buff_head xmitq;

        skb_queue_head_init(&xmitq);
        rbtree_postorder_for_each_entry_safe(m, tmp, tree, tree_node) {
                tipc_group_proto_xmit(grp, m, GRP_JOIN_MSG, &xmitq);
                tipc_group_update_member(m, 0);
        }
        tipc_node_distr_xmit(net, &xmitq);
        *sk_rcvbuf = tipc_group_rcvbuf_limit(grp);
}

void tipc_group_delete(struct net *net, struct tipc_group *grp)
{
        struct rb_root *tree = &grp->members;
        struct tipc_member *m, *tmp;
        struct sk_buff_head xmitq;

        __skb_queue_head_init(&xmitq);

        rbtree_postorder_for_each_entry_safe(m, tmp, tree, tree_node) {
                tipc_group_proto_xmit(grp, m, GRP_LEAVE_MSG, &xmitq);
                list_del(&m->list);
                kfree(m);
        }
        tipc_node_distr_xmit(net, &xmitq);
        tipc_nlist_purge(&grp->dests);
        tipc_topsrv_kern_unsubscr(net, grp->subid);
        kfree(grp);
}

struct tipc_member *tipc_group_find_member(struct tipc_group *grp,
                                           u32 node, u32 port)
{
        struct rb_node *n = grp->members.rb_node;
        u64 nkey, key = (u64)node << 32 | port;
        struct tipc_member *m;

        while (n) {
                m = container_of(n, struct tipc_member, tree_node);
                nkey = (u64)m->node << 32 | m->port;
                if (key < nkey)
                        n = n->rb_left;
                else if (key > nkey)
                        n = n->rb_right;
                else
                        return m;
        }
        return NULL;
}

static struct tipc_member *tipc_group_find_dest(struct tipc_group *grp,
                                                u32 node, u32 port)
{
        struct tipc_member *m;

        m = tipc_group_find_member(grp, node, port);
        if (m && tipc_group_is_receiver(m))
                return m;
        return NULL;
}

static struct tipc_member *tipc_group_find_node(struct tipc_group *grp,
                                                u32 node)
{
        struct tipc_member *m;
        struct rb_node *n;

        for (n = rb_first(&grp->members); n; n = rb_next(n)) {
                m = container_of(n, struct tipc_member, tree_node);
                if (m->node == node)
                        return m;
        }
        return NULL;
}

static void tipc_group_add_to_tree(struct tipc_group *grp,
                                   struct tipc_member *m)
{
        u64 nkey, key = (u64)m->node << 32 | m->port;
        struct rb_node **n, *parent = NULL;
        struct tipc_member *tmp;

        n = &grp->members.rb_node;
        while (*n) {
                tmp = container_of(*n, struct tipc_member, tree_node);
                parent = *n;
                tmp = container_of(parent, struct tipc_member, tree_node);
                nkey = (u64)tmp->node << 32 | tmp->port;
                if (key < nkey)
                        n = &(*n)->rb_left;
                else if (key > nkey)
                        n = &(*n)->rb_right;
                else
                        return;
        }
        rb_link_node(&m->tree_node, parent, n);
        rb_insert_color(&m->tree_node, &grp->members);
}

static struct tipc_member *tipc_group_create_member(struct tipc_group *grp,
                                                    u32 node, u32 port,
                                                    u32 instance, int state)
{
        struct tipc_member *m;

        m = kzalloc(sizeof(*m), GFP_ATOMIC);
        if (!m)
                return NULL;
        INIT_LIST_HEAD(&m->list);
        INIT_LIST_HEAD(&m->small_win);
        __skb_queue_head_init(&m->deferredq);
        m->group = grp;
        m->node = node;
        m->port = port;
        m->instance = instance;
        m->bc_acked = grp->bc_snd_nxt - 1;
        grp->member_cnt++;
        tipc_group_add_to_tree(grp, m);
        tipc_nlist_add(&grp->dests, m->node);
        m->state = state;
        return m;
}

void tipc_group_add_member(struct tipc_group *grp, u32 node,
                           u32 port, u32 instance)
{
        tipc_group_create_member(grp, node, port, instance, MBR_PUBLISHED);
}

static void tipc_group_delete_member(struct tipc_group *grp,
                                     struct tipc_member *m)
{
        rb_erase(&m->tree_node, &grp->members);
        grp->member_cnt--;

        /* Check if we were waiting for replicast ack from this member */
        if (grp->bc_ackers && less(m->bc_acked, grp->bc_snd_nxt - 1))
                grp->bc_ackers--;

        list_del_init(&m->list);
        list_del_init(&m->small_win);
        tipc_group_decr_active(grp, m);

        /* If last member on a node, remove node from dest list */
        if (!tipc_group_find_node(grp, m->node))
                tipc_nlist_del(&grp->dests, m->node);

        kfree(m);
}

struct tipc_nlist *tipc_group_dests(struct tipc_group *grp)
{
        return &grp->dests;
}

void tipc_group_self(struct tipc_group *grp, struct tipc_name_seq *seq,
                     int *scope)
{
        seq->type = grp->type;
        seq->lower = grp->instance;
        seq->upper = grp->instance;
        *scope = grp->scope;
}

void tipc_group_update_member(struct tipc_member *m, int len)
{
        struct tipc_group *grp = m->group;
        struct tipc_member *_m, *tmp;

        if (!tipc_group_is_receiver(m))
                return;

        m->window -= len;

        if (m->window >= ADV_IDLE)
                return;

        list_del_init(&m->small_win);

        /* Sort member into small_window members' list */
        list_for_each_entry_safe(_m, tmp, &grp->small_win, small_win) {
                if (_m->window > m->window)
                        break;
        }
        list_add_tail(&m->small_win, &_m->small_win);
}

void tipc_group_update_bc_members(struct tipc_group *grp, int len, bool ack)
{
        u16 prev = grp->bc_snd_nxt - 1;
        struct tipc_member *m;
        struct rb_node *n;
        u16 ackers = 0;

        for (n = rb_first(&grp->members); n; n = rb_next(n)) {
                m = container_of(n, struct tipc_member, tree_node);
                if (tipc_group_is_receiver(m)) {
                        tipc_group_update_member(m, len);
                        m->bc_acked = prev;
                        ackers++;
                }
        }

        /* Mark number of acknowledges to expect, if any */
        if (ack)
                grp->bc_ackers = ackers;
        grp->bc_snd_nxt++;
}

bool tipc_group_cong(struct tipc_group *grp, u32 dnode, u32 dport,
                     int len, struct tipc_member **mbr)
{
        struct sk_buff_head xmitq;
        struct tipc_member *m;
        int adv, state;

        m = tipc_group_find_dest(grp, dnode, dport);
        if (!tipc_group_is_receiver(m)) {
                *mbr = NULL;
                return false;
        }
        *mbr = m;

        if (m->window >= len)
                return false;

        *grp->open = false;

        /* If not fully advertised, do it now to prevent mutual blocking */
        adv = m->advertised;
        state = m->state;
        if (state == MBR_JOINED && adv == ADV_IDLE)
                return true;
        if (state == MBR_ACTIVE && adv == ADV_ACTIVE)
                return true;
        if (state == MBR_PENDING && adv == ADV_IDLE)
                return true;
        skb_queue_head_init(&xmitq);
        tipc_group_proto_xmit(grp, m, GRP_ADV_MSG, &xmitq);
        tipc_node_distr_xmit(grp->net, &xmitq);
        return true;
}

bool tipc_group_bc_cong(struct tipc_group *grp, int len)
{
        struct tipc_member *m = NULL;

        /* If prev bcast was replicast, reject until all receivers have acked */
        if (grp->bc_ackers) {
                *grp->open = false;
                return true;
        }
        if (list_empty(&grp->small_win))
                return false;

        m = list_first_entry(&grp->small_win, struct tipc_member, small_win);
        if (m->window >= len)
                return false;

        return tipc_group_cong(grp, m->node, m->port, len, &m);
}

/* tipc_group_sort_msg() - sort msg into queue by bcast sequence number
 */
static void tipc_group_sort_msg(struct sk_buff *skb, struct sk_buff_head *defq)
{
        struct tipc_msg *_hdr, *hdr = buf_msg(skb);
        u16 bc_seqno = msg_grp_bc_seqno(hdr);
        struct sk_buff *_skb, *tmp;
        int mtyp = msg_type(hdr);

        /* Bcast/mcast may be bypassed by ucast or other bcast, - sort it in */
        if (mtyp == TIPC_GRP_BCAST_MSG || mtyp == TIPC_GRP_MCAST_MSG) {
                skb_queue_walk_safe(defq, _skb, tmp) {
                        _hdr = buf_msg(_skb);
                        if (!less(bc_seqno, msg_grp_bc_seqno(_hdr)))
                                continue;
                        __skb_queue_before(defq, _skb, skb);
                        return;
                }
                /* Bcast was not bypassed, - add to tail */
        }
        /* Unicasts are never bypassed, - always add to tail */
        __skb_queue_tail(defq, skb);
}

/* tipc_group_filter_msg() - determine if we should accept arriving message
 */
void tipc_group_filter_msg(struct tipc_group *grp, struct sk_buff_head *inputq,
                           struct sk_buff_head *xmitq)
{
        struct sk_buff *skb = __skb_dequeue(inputq);
        bool ack, deliver, update, leave = false;
        struct sk_buff_head *defq;
        struct tipc_member *m;
        struct tipc_msg *hdr;
        u32 node, port;
        int mtyp, blks;

        if (!skb)
                return;

        hdr = buf_msg(skb);
        node =  msg_orignode(hdr);
        port = msg_origport(hdr);

        if (!msg_in_group(hdr))
                goto drop;

        m = tipc_group_find_member(grp, node, port);
        if (!tipc_group_is_sender(m))
                goto drop;

        if (less(msg_grp_bc_seqno(hdr), m->bc_rcv_nxt))
                goto drop;

        TIPC_SKB_CB(skb)->orig_member = m->instance;
        defq = &m->deferredq;
        tipc_group_sort_msg(skb, defq);

        while ((skb = skb_peek(defq))) {
                hdr = buf_msg(skb);
                mtyp = msg_type(hdr);
                blks = msg_blocks(hdr);
                deliver = true;
                ack = false;
                update = false;

                if (more(msg_grp_bc_seqno(hdr), m->bc_rcv_nxt))
                        break;

                /* Decide what to do with message */
                switch (mtyp) {
                case TIPC_GRP_MCAST_MSG:
                        if (msg_nameinst(hdr) != grp->instance) {
                                update = true;
                                deliver = false;
                        }
                        /* Fall thru */
                case TIPC_GRP_BCAST_MSG:
                        m->bc_rcv_nxt++;
                        ack = msg_grp_bc_ack_req(hdr);
                        break;
                case TIPC_GRP_UCAST_MSG:
                        break;
                case TIPC_GRP_MEMBER_EVT:
                        if (m->state == MBR_LEAVING)
                                leave = true;
                        if (!grp->events)
                                deliver = false;
                        break;
                default:
                        break;
                }

                /* Execute decisions */
                __skb_dequeue(defq);
                if (deliver)
                        __skb_queue_tail(inputq, skb);
                else
                        kfree_skb(skb);

                if (ack)
                        tipc_group_proto_xmit(grp, m, GRP_ACK_MSG, xmitq);

                if (leave) {
                        __skb_queue_purge(defq);
                        tipc_group_delete_member(grp, m);
                        break;
                }
                if (!update)
                        continue;

                tipc_group_update_rcv_win(grp, blks, node, port, xmitq);
        }
        return;
drop:
        kfree_skb(skb);
}

void tipc_group_update_rcv_win(struct tipc_group *grp, int blks, u32 node,
                               u32 port, struct sk_buff_head *xmitq)
{
        struct list_head *active = &grp->active;
        int max_active = grp->max_active;
        int reclaim_limit = max_active * 3 / 4;
        int active_cnt = grp->active_cnt;
        struct tipc_member *m, *rm, *pm;

        m = tipc_group_find_member(grp, node, port);
        if (!m)
                return;

        m->advertised -= blks;

        switch (m->state) {
        case MBR_JOINED:
                /* First, decide if member can go active */
                if (active_cnt <= max_active) {
                        m->state = MBR_ACTIVE;
                        list_add_tail(&m->list, active);
                        grp->active_cnt++;
                        tipc_group_proto_xmit(grp, m, GRP_ADV_MSG, xmitq);
                } else {
                        m->state = MBR_PENDING;
                        list_add_tail(&m->list, &grp->pending);
                }

                if (active_cnt < reclaim_limit)
                        break;

                /* Reclaim from oldest active member, if possible */
                if (!list_empty(active)) {
                        rm = list_first_entry(active, struct tipc_member, list);
                        rm->state = MBR_RECLAIMING;
                        list_del_init(&rm->list);
                        tipc_group_proto_xmit(grp, rm, GRP_RECLAIM_MSG, xmitq);
                        break;
                }
                /* Nobody to reclaim from; - revert oldest pending to JOINED */
                pm = list_first_entry(&grp->pending, struct tipc_member, list);
                list_del_init(&pm->list);
                pm->state = MBR_JOINED;
                tipc_group_proto_xmit(grp, pm, GRP_ADV_MSG, xmitq);
                break;
        case MBR_ACTIVE:
                if (!list_is_last(&m->list, &grp->active))
                        list_move_tail(&m->list, &grp->active);
                if (m->advertised > (ADV_ACTIVE * 3 / 4))
                        break;
                tipc_group_proto_xmit(grp, m, GRP_ADV_MSG, xmitq);
                break;
        case MBR_REMITTED:
                if (m->advertised > ADV_IDLE)
                        break;
                m->state = MBR_JOINED;
                grp->active_cnt--;
                if (m->advertised < ADV_IDLE) {
                        pr_warn_ratelimited("Rcv unexpected msg after REMIT\n");
                        tipc_group_proto_xmit(grp, m, GRP_ADV_MSG, xmitq);
                }

                if (list_empty(&grp->pending))
                        return;

                /* Set oldest pending member to active and advertise */
                pm = list_first_entry(&grp->pending, struct tipc_member, list);
                pm->state = MBR_ACTIVE;
                list_move_tail(&pm->list, &grp->active);
                grp->active_cnt++;
                tipc_group_proto_xmit(grp, pm, GRP_ADV_MSG, xmitq);
                break;
        case MBR_RECLAIMING:
        case MBR_JOINING:
        case MBR_LEAVING:
        default:
                break;
        }
}

static void tipc_group_create_event(struct tipc_group *grp,
                                    struct tipc_member *m,
                                    u32 event, u16 seqno,
                                    struct sk_buff_head *inputq)
{       u32 dnode = tipc_own_addr(grp->net);
        struct tipc_event evt;
        struct sk_buff *skb;
        struct tipc_msg *hdr;

        evt.event = event;
        evt.found_lower = m->instance;
        evt.found_upper = m->instance;
        evt.port.ref = m->port;
        evt.port.node = m->node;
        evt.s.seq.type = grp->type;
        evt.s.seq.lower = m->instance;
        evt.s.seq.upper = m->instance;

        skb = tipc_msg_create(TIPC_CRITICAL_IMPORTANCE, TIPC_GRP_MEMBER_EVT,
                              GROUP_H_SIZE, sizeof(evt), dnode, m->node,
                              grp->portid, m->port, 0);
        if (!skb)
                return;

        hdr = buf_msg(skb);
        msg_set_nametype(hdr, grp->type);
        msg_set_grp_evt(hdr, event);
        msg_set_dest_droppable(hdr, true);
        msg_set_grp_bc_seqno(hdr, seqno);
        memcpy(msg_data(hdr), &evt, sizeof(evt));
        TIPC_SKB_CB(skb)->orig_member = m->instance;
        __skb_queue_tail(inputq, skb);
}

static void tipc_group_proto_xmit(struct tipc_group *grp, struct tipc_member *m,
                                  int mtyp, struct sk_buff_head *xmitq)
{
        struct tipc_msg *hdr;
        struct sk_buff *skb;
        int adv = 0;

        skb = tipc_msg_create(GROUP_PROTOCOL, mtyp, INT_H_SIZE, 0,
                              m->node, tipc_own_addr(grp->net),
                              m->port, grp->portid, 0);
        if (!skb)
                return;

        if (m->state == MBR_ACTIVE)
                adv = ADV_ACTIVE - m->advertised;
        else if (m->state == MBR_JOINED || m->state == MBR_PENDING)
                adv = ADV_IDLE - m->advertised;

        hdr = buf_msg(skb);

        if (mtyp == GRP_JOIN_MSG) {
                msg_set_grp_bc_syncpt(hdr, grp->bc_snd_nxt);
                msg_set_adv_win(hdr, adv);
                m->advertised += adv;
        } else if (mtyp == GRP_LEAVE_MSG) {
                msg_set_grp_bc_syncpt(hdr, grp->bc_snd_nxt);
        } else if (mtyp == GRP_ADV_MSG) {
                msg_set_adv_win(hdr, adv);
                m->advertised += adv;
        } else if (mtyp == GRP_ACK_MSG) {
                msg_set_grp_bc_acked(hdr, m->bc_rcv_nxt);
        } else if (mtyp == GRP_REMIT_MSG) {
                msg_set_grp_remitted(hdr, m->window);
        }
        msg_set_dest_droppable(hdr, true);
        __skb_queue_tail(xmitq, skb);
}

void tipc_group_proto_rcv(struct tipc_group *grp, bool *usr_wakeup,
                          struct tipc_msg *hdr, struct sk_buff_head *inputq,
                          struct sk_buff_head *xmitq)
{
        u32 node = msg_orignode(hdr);
        u32 port = msg_origport(hdr);
        struct tipc_member *m, *pm;
        u16 remitted, in_flight;

        if (!grp)
                return;

        if (grp->scope == TIPC_NODE_SCOPE && node != tipc_own_addr(grp->net))
                return;

        m = tipc_group_find_member(grp, node, port);

        switch (msg_type(hdr)) {
        case GRP_JOIN_MSG:
                if (!m)
                        m = tipc_group_create_member(grp, node, port,
                                                     0, MBR_JOINING);
                if (!m)
                        return;
                m->bc_syncpt = msg_grp_bc_syncpt(hdr);
                m->bc_rcv_nxt = m->bc_syncpt;
                m->window += msg_adv_win(hdr);

                /* Wait until PUBLISH event is received if necessary */
                if (m->state != MBR_PUBLISHED)
                        return;

                /* Member can be taken into service */
                m->state = MBR_JOINED;
                tipc_group_open(m, usr_wakeup);
                tipc_group_update_member(m, 0);
                tipc_group_proto_xmit(grp, m, GRP_ADV_MSG, xmitq);
                tipc_group_create_event(grp, m, TIPC_PUBLISHED,
                                        m->bc_syncpt, inputq);
                return;
        case GRP_LEAVE_MSG:
                if (!m)
                        return;
                m->bc_syncpt = msg_grp_bc_syncpt(hdr);
                list_del_init(&m->list);
                tipc_group_open(m, usr_wakeup);
                tipc_group_decr_active(grp, m);
                m->state = MBR_LEAVING;
                tipc_group_create_event(grp, m, TIPC_WITHDRAWN,
                                        m->bc_syncpt, inputq);
                return;
        case GRP_ADV_MSG:
                if (!m)
                        return;
                m->window += msg_adv_win(hdr);
                tipc_group_open(m, usr_wakeup);
                return;
        case GRP_ACK_MSG:
                if (!m)
                        return;
                m->bc_acked = msg_grp_bc_acked(hdr);
                if (--grp->bc_ackers)
                        return;
                list_del_init(&m->small_win);
                *m->group->open = true;
                *usr_wakeup = true;
                tipc_group_update_member(m, 0);
                return;
        case GRP_RECLAIM_MSG:
                if (!m)
                        return;
                tipc_group_proto_xmit(grp, m, GRP_REMIT_MSG, xmitq);
                m->window = ADV_IDLE;
                tipc_group_open(m, usr_wakeup);
                return;
        case GRP_REMIT_MSG:
                if (!m || m->state != MBR_RECLAIMING)
                        return;

                remitted = msg_grp_remitted(hdr);

                /* Messages preceding the REMIT still in receive queue */
                if (m->advertised > remitted) {
                        m->state = MBR_REMITTED;
                        in_flight = m->advertised - remitted;
                        m->advertised = ADV_IDLE + in_flight;
                        return;
                }
                /* This should never happen */
                if (m->advertised < remitted)
                        pr_warn_ratelimited("Unexpected REMIT msg\n");

                /* All messages preceding the REMIT have been read */
                m->state = MBR_JOINED;
                grp->active_cnt--;
                m->advertised = ADV_IDLE;

                /* Set oldest pending member to active and advertise */
                if (list_empty(&grp->pending))
                        return;
                pm = list_first_entry(&grp->pending, struct tipc_member, list);
                pm->state = MBR_ACTIVE;
                list_move_tail(&pm->list, &grp->active);
                grp->active_cnt++;
                if (pm->advertised <= (ADV_ACTIVE * 3 / 4))
                        tipc_group_proto_xmit(grp, pm, GRP_ADV_MSG, xmitq);
                return;
        default:
                pr_warn("Received unknown GROUP_PROTO message\n");
        }
}

/* tipc_group_member_evt() - receive and handle a member up/down event
 */
void tipc_group_member_evt(struct tipc_group *grp,
                           bool *usr_wakeup,
                           int *sk_rcvbuf,
                           struct tipc_msg *hdr,
                           struct sk_buff_head *inputq,
                           struct sk_buff_head *xmitq)
{
        struct tipc_event *evt = (void *)msg_data(hdr);
        u32 instance = evt->found_lower;
        u32 node = evt->port.node;
        u32 port = evt->port.ref;
        int event = evt->event;
        struct tipc_member *m;
        struct net *net;
        u32 self;

        if (!grp)
                return;

        net = grp->net;
        self = tipc_own_addr(net);
        if (!grp->loopback && node == self && port == grp->portid)
                return;

        m = tipc_group_find_member(grp, node, port);

        switch (event) {
        case TIPC_PUBLISHED:
                /* Send and wait for arrival of JOIN message if necessary */
                if (!m) {
                        m = tipc_group_create_member(grp, node, port, instance,
                                                     MBR_PUBLISHED);
                        if (!m)
                                break;
                        tipc_group_update_member(m, 0);
                        tipc_group_proto_xmit(grp, m, GRP_JOIN_MSG, xmitq);
                        break;
                }

                if (m->state != MBR_JOINING)
                        break;

                /* Member can be taken into service */
                m->instance = instance;
                m->state = MBR_JOINED;
                tipc_group_open(m, usr_wakeup);
                tipc_group_update_member(m, 0);
                tipc_group_proto_xmit(grp, m, GRP_JOIN_MSG, xmitq);
                tipc_group_create_event(grp, m, TIPC_PUBLISHED,
                                        m->bc_syncpt, inputq);
                break;
        case TIPC_WITHDRAWN:
                if (!m)
                        break;

                tipc_group_decr_active(grp, m);
                m->state = MBR_LEAVING;
                list_del_init(&m->list);
                tipc_group_open(m, usr_wakeup);

                /* Only send event if no LEAVE message can be expected */
                if (!tipc_node_is_up(net, node))
                        tipc_group_create_event(grp, m, TIPC_WITHDRAWN,
                                                m->bc_rcv_nxt, inputq);
                break;
        default:
                break;
        }
        *sk_rcvbuf = tipc_group_rcvbuf_limit(grp);
}