linux/net/tipc/subscr.h
Ying Xue 7efea60dcf tipc: adjust the policy of holding subscription kref
When a new subscription object is inserted into name_seq->subscriptions
list, it's under name_seq->lock protection; when a subscription is
deleted from the list, it's also under the same lock protection;
similarly, when accessing a subscription by going through subscriptions
list, the entire process is also protected by the name_seq->lock.

Therefore, if subscription refcount is increased before it's inserted
into subscriptions list, and its refcount is decreased after it's
deleted from the list, it will be unnecessary to hold refcount at all
before accessing subscription object which is obtained by going through
subscriptions list under name_seq->lock protection.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-28 18:03:33 -07:00

85 lines
3.4 KiB
C

/*
* net/tipc/subscr.h: Include file for TIPC network topology service
*
* Copyright (c) 2003-2006, Ericsson AB
* Copyright (c) 2005-2007, 2012-2013, 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_SUBSCR_H
#define _TIPC_SUBSCR_H
#include "server.h"
#define TIPC_MAX_SUBSCRIPTIONS 65535
#define TIPC_MAX_PUBLICATIONS 65535
struct tipc_subscription;
struct tipc_subscriber;
/**
* struct tipc_subscription - TIPC network topology subscription object
* @subscriber: pointer to its subscriber
* @seq: name sequence associated with subscription
* @net: point to network namespace
* @timer: timer governing subscription duration (optional)
* @nameseq_list: adjacent subscriptions in name sequence's subscription list
* @subscrp_list: adjacent subscriptions in subscriber's subscription list
* @swap: indicates if subscriber uses opposite endianness in its messages
* @evt: template for events generated by subscription
*/
struct tipc_subscription {
struct kref kref;
struct tipc_subscriber *subscriber;
struct net *net;
struct timer_list timer;
struct list_head nameseq_list;
struct list_head subscrp_list;
int swap;
struct tipc_event evt;
};
int tipc_subscrp_check_overlap(struct tipc_name_seq *seq, u32 found_lower,
u32 found_upper);
void tipc_subscrp_report_overlap(struct tipc_subscription *sub,
u32 found_lower, u32 found_upper, u32 event,
u32 port_ref, u32 node, int must);
void tipc_subscrp_convert_seq(struct tipc_name_seq *in, int swap,
struct tipc_name_seq *out);
u32 tipc_subscrp_convert_seq_type(u32 type, int swap);
int tipc_topsrv_start(struct net *net);
void tipc_topsrv_stop(struct net *net);
void tipc_subscrp_put(struct tipc_subscription *subscription);
void tipc_subscrp_get(struct tipc_subscription *subscription);
#endif