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linux/net/tipc/bcast.h
Hoang Huu Le cad2929dc4 tipc: update a binding service via broadcast 
Currently, updating binding table (add service binding to
name table/withdraw a service binding) is being sent over replicast.
However, if we are scaling up clusters to > 100 nodes/containers this
method is less affection because of looping through nodes in a cluster one
by one.

It is worth to use broadcast to update a binding service. This way, the
binding table can be updated on all peer nodes in one shot.

Broadcast is used when all peer nodes, as indicated by a new capability
flag TIPC_NAMED_BCAST, support reception of this message type.

Four problems need to be considered when introducing this feature.
1) When establishing a link to a new peer node we still update this by a
unicast 'bulk' update. This may lead to race conditions, where a later
broadcast publication/withdrawal bypass the 'bulk', resulting in
disordered publications, or even that a withdrawal may arrive before the
corresponding publication. We solve this by adding an 'is_last_bulk' bit
in the last bulk messages so that it can be distinguished from all other
messages. Only when this message has arrived do we open up for reception
of broadcast publications/withdrawals.

2) When a first legacy node is added to the cluster all distribution
will switch over to use the legacy 'replicast' method, while the
opposite happens when the last legacy node leaves the cluster. This
entails another risk of message disordering that has to be handled. We
solve this by adding a sequence number to the broadcast/replicast
messages, so that disordering can be discovered and corrected. Note
however that we don't need to consider potential message loss or
duplication at this protocol level.

3) Bulk messages don't contain any sequence numbers, and will always
arrive in order. Hence we must exempt those from the sequence number
control and deliver them unconditionally. We solve this by adding a new
'is_bulk' bit in those messages so that they can be recognized.

4) Legacy messages, which don't contain any new bits or sequence
numbers, but neither can arrive out of order, also need to be exempt
from the initial synchronization and sequence number check, and
delivered unconditionally. Therefore, we add another 'is_not_legacy' bit
to all new messages so that those can be distinguished from legacy
messages and the latter delivered directly.

v1->v2:
 - fix warning issue reported by kbuild test robot <lkp@intel.com>
 - add santiy check to drop the publication message with a sequence
number that is lower than the agreed synch point

Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Hoang Huu Le <hoang.h.le@dektech.com.au>
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-06-17 08:53:34 -07:00

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/*
* net/tipc/bcast.h: Include file for TIPC broadcast code
*
* Copyright (c) 2003-2006, 2014-2015, Ericsson AB
* 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.
*/
#ifndef _TIPC_BCAST_H
#define _TIPC_BCAST_H
#include "core.h"
struct tipc_node;
struct tipc_msg;
struct tipc_nl_msg;
struct tipc_nlist;
struct tipc_nitem;
extern const char tipc_bclink_name[];
extern unsigned long sysctl_tipc_bc_retruni;
#define TIPC_METHOD_EXPIRE msecs_to_jiffies(5000)
#define BCLINK_MODE_BCAST 0x1
#define BCLINK_MODE_RCAST 0x2
#define BCLINK_MODE_SEL 0x4
struct tipc_nlist {
struct list_head list;
u32 self;
u16 remote;
bool local;
};
void tipc_nlist_init(struct tipc_nlist *nl, u32 self);
void tipc_nlist_purge(struct tipc_nlist *nl);
void tipc_nlist_add(struct tipc_nlist *nl, u32 node);
void tipc_nlist_del(struct tipc_nlist *nl, u32 node);
/* Cookie to be used between socket and broadcast layer
* @rcast: replicast (instead of broadcast) was used at previous xmit
* @mandatory: broadcast/replicast indication was set by user
* @deferredq: defer queue to make message in order
* @expires: re-evaluate non-mandatory transmit method if we are past this
*/
struct tipc_mc_method {
bool rcast;
bool mandatory;
struct sk_buff_head deferredq;
unsigned long expires;
};
int tipc_bcast_init(struct net *net);
void tipc_bcast_stop(struct net *net);
void tipc_bcast_add_peer(struct net *net, struct tipc_link *l,
struct sk_buff_head *xmitq);
void tipc_bcast_remove_peer(struct net *net, struct tipc_link *rcv_bcl);
void tipc_bcast_inc_bearer_dst_cnt(struct net *net, int bearer_id);
void tipc_bcast_dec_bearer_dst_cnt(struct net *net, int bearer_id);
int tipc_bcast_get_mtu(struct net *net);
void tipc_bcast_toggle_rcast(struct net *net, bool supp);
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);
int tipc_bcast_xmit(struct net *net, struct sk_buff_head *pkts,
u16 *cong_link_cnt);
int tipc_bcast_rcv(struct net *net, struct tipc_link *l, struct sk_buff *skb);
void tipc_bcast_ack_rcv(struct net *net, struct tipc_link *l,
struct tipc_msg *hdr);
int tipc_bcast_sync_rcv(struct net *net, struct tipc_link *l,
struct tipc_msg *hdr,
struct sk_buff_head *retrq);
int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg,
struct tipc_link *bcl);
int tipc_nl_bc_link_set(struct net *net, struct nlattr *attrs[]);
int tipc_bclink_reset_stats(struct net *net, struct tipc_link *l);
u32 tipc_bcast_get_mode(struct net *net);
u32 tipc_bcast_get_broadcast_ratio(struct net *net);
void tipc_mcast_filter_msg(struct net *net, struct sk_buff_head *defq,
struct sk_buff_head *inputq);
static inline void tipc_bcast_lock(struct net *net)
{
spin_lock_bh(&tipc_net(net)->bclock);
}
static inline void tipc_bcast_unlock(struct net *net)
{
spin_unlock_bh(&tipc_net(net)->bclock);
}
static inline struct tipc_link *tipc_bc_sndlink(struct net *net)
{
return tipc_net(net)->bcl;
}
#endif
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