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linux-next/net/tipc/node.h
Ying Xue 8a0f6ebe84 tipc: involve reference counter for node structure 
TIPC node hash node table is protected with rcu lock on read side.
tipc_node_find() is used to look for a node object with node address
through iterating the hash node table. As the entire process of what
tipc_node_find() traverses the table is guarded with rcu read lock,
it's safe for us. However, when callers use the node object returned
by tipc_node_find(), there is no rcu read lock applied. Therefore,
this is absolutely unsafe for callers of tipc_node_find().

Now we introduce a reference counter for node structure. Before
tipc_node_find() returns node object to its caller, it first increases
the reference counter. Accordingly, after its caller used it up,
it decreases the counter again. This can prevent a node being used by
one thread from being freed by another thread.

Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Jon Maloy <jon.maloy@ericson.com>
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-29 12:40:28 -07:00

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/*
* net/tipc/node.h: Include file for TIPC node management routines
*
* Copyright (c) 2000-2006, 2014-2015, Ericsson AB
* Copyright (c) 2005, 2010-2014, 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_NODE_H
#define _TIPC_NODE_H
#include "addr.h"
#include "net.h"
#include "bearer.h"
#include "msg.h"
/* Out-of-range value for node signature */
#define INVALID_NODE_SIG 0x10000
#define NODE_HTABLE_SIZE 512
/* Flags used to take different actions according to flag type
* TIPC_WAIT_PEER_LINKS_DOWN: wait to see that peer's links are down
* TIPC_WAIT_OWN_LINKS_DOWN: wait until peer node is declared down
* TIPC_NOTIFY_NODE_DOWN: notify node is down
* TIPC_NOTIFY_NODE_UP: notify node is up
* TIPC_DISTRIBUTE_NAME: publish or withdraw link state name type
*/
enum {
TIPC_MSG_EVT = 1,
TIPC_WAIT_PEER_LINKS_DOWN = (1 << 1),
TIPC_WAIT_OWN_LINKS_DOWN = (1 << 2),
TIPC_NOTIFY_NODE_DOWN = (1 << 3),
TIPC_NOTIFY_NODE_UP = (1 << 4),
TIPC_WAKEUP_BCAST_USERS = (1 << 5),
TIPC_NOTIFY_LINK_UP = (1 << 6),
TIPC_NOTIFY_LINK_DOWN = (1 << 7),
TIPC_NAMED_MSG_EVT = (1 << 8),
TIPC_BCAST_MSG_EVT = (1 << 9),
TIPC_BCAST_RESET = (1 << 10)
};
/**
* struct tipc_node_bclink - TIPC node bclink structure
* @acked: sequence # of last outbound b'cast message acknowledged by node
* @last_in: sequence # of last in-sequence b'cast message received from node
* @last_sent: sequence # of last b'cast message sent by node
* @oos_state: state tracker for handling OOS b'cast messages
* @deferred_queue: deferred queue saved OOS b'cast message received from node
* @reasm_buf: broadcast reassembly queue head from node
* @inputq_map: bitmap indicating which inqueues should be kicked
* @recv_permitted: true if node is allowed to receive b'cast messages
*/
struct tipc_node_bclink {
u32 acked;
u32 last_in;
u32 last_sent;
u32 oos_state;
u32 deferred_size;
struct sk_buff_head deferdq;
struct sk_buff *reasm_buf;
int inputq_map;
bool recv_permitted;
};
/**
* struct tipc_node - TIPC node structure
* @addr: network address of node
* @ref: reference counter to node object
* @lock: spinlock governing access to structure
* @net: the applicable net namespace
* @hash: links to adjacent nodes in unsorted hash chain
* @inputq: pointer to input queue containing messages for msg event
* @namedq: pointer to name table input queue with name table messages
* @curr_link: the link holding the node lock, if any
* @active_links: pointers to active links to node
* @links: pointers to all links to node
* @action_flags: bit mask of different types of node actions
* @bclink: broadcast-related info
* @list: links to adjacent nodes in sorted list of cluster's nodes
* @working_links: number of working links to node (both active and standby)
* @link_cnt: number of links to node
* @capabilities: bitmap, indicating peer node's functional capabilities
* @signature: node instance identifier
* @link_id: local and remote bearer ids of changing link, if any
* @publ_list: list of publications
* @rcu: rcu struct for tipc_node
*/
struct tipc_node {
u32 addr;
struct kref kref;
spinlock_t lock;
struct net *net;
struct hlist_node hash;
struct sk_buff_head *inputq;
struct sk_buff_head *namedq;
struct tipc_link *active_links[2];
u32 act_mtus[2];
struct tipc_link *links[MAX_BEARERS];
int action_flags;
struct tipc_node_bclink bclink;
struct list_head list;
int link_cnt;
u16 working_links;
u16 capabilities;
u32 signature;
u32 link_id;
struct list_head publ_list;
struct list_head conn_sks;
struct rcu_head rcu;
};
struct tipc_node *tipc_node_find(struct net *net, u32 addr);
void tipc_node_put(struct tipc_node *node);
struct tipc_node *tipc_node_create(struct net *net, u32 addr);
void tipc_node_stop(struct net *net);
void tipc_node_attach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
void tipc_node_detach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
void tipc_node_link_down(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
void tipc_node_link_up(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
int tipc_node_active_links(struct tipc_node *n_ptr);
int tipc_node_is_up(struct tipc_node *n_ptr);
int tipc_node_get_linkname(struct net *net, u32 bearer_id, u32 node,
char *linkname, size_t len);
void tipc_node_unlock(struct tipc_node *node);
int tipc_node_add_conn(struct net *net, u32 dnode, u32 port, u32 peer_port);
void tipc_node_remove_conn(struct net *net, u32 dnode, u32 port);
int tipc_nl_node_dump(struct sk_buff *skb, struct netlink_callback *cb);
static inline void tipc_node_lock(struct tipc_node *node)
{
spin_lock_bh(&node->lock);
}
static inline bool tipc_node_blocked(struct tipc_node *node)
{
return (node->action_flags & (TIPC_WAIT_PEER_LINKS_DOWN |
TIPC_NOTIFY_NODE_DOWN | TIPC_WAIT_OWN_LINKS_DOWN));
}
static inline uint tipc_node_get_mtu(struct net *net, u32 addr, u32 selector)
{
struct tipc_node *node;
u32 mtu;
node = tipc_node_find(net, addr);
if (likely(node)) {
mtu = node->act_mtus[selector & 1];
tipc_node_put(node);
} else {
mtu = MAX_MSG_SIZE;
}
return mtu;
}
#endif
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