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![Ying Xue](/assets/img/avatar_default.png)
Commit9faa89d4ed
("tipc: make function tipc_net_finalize() thread safe") tries to make it thread safe to set node address, so it uses node_list_lock lock to serialize the whole process of setting node address in tipc_net_finalize(). But it causes the following interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- rht_deferred_worker() rhashtable_rehash_table() lock(&(&ht->lock)->rlock) tipc_nl_compat_doit() tipc_net_finalize() local_irq_disable(); lock(&(&tn->node_list_lock)->rlock); tipc_sk_reinit() rhashtable_walk_enter() lock(&(&ht->lock)->rlock); <Interrupt> tipc_disc_rcv() tipc_node_check_dest() tipc_node_create() lock(&(&tn->node_list_lock)->rlock); *** DEADLOCK *** When rhashtable_rehash_table() holds ht->lock on CPU0, it doesn't disable BH. So if an interrupt happens after the lock, it can create an inverse lock ordering between ht->lock and tn->node_list_lock. As a consequence, deadlock might happen. The reason causing the inverse lock ordering scenario above is because the initial purpose of node_list_lock is not designed to do the serialization of node address setting. As cmpxchg() can guarantee CAS (compare-and-swap) process is atomic, we use it to replace node_list_lock to ensure setting node address can be atomically finished. It turns out the potential deadlock can be avoided as well. Fixes:9faa89d4ed
("tipc: make function tipc_net_finalize() thread safe") Signed-off-by: Ying Xue <ying.xue@windriver.com> Acked-by: Jon Maloy <maloy@donjonn.com> Signed-off-by: David S. Miller <davem@davemloft.net>
276 lines
8.7 KiB
C
276 lines
8.7 KiB
C
/*
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* net/tipc/net.c: TIPC network routing code
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*
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* Copyright (c) 1995-2006, 2014, Ericsson AB
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* Copyright (c) 2005, 2010-2011, Wind River Systems
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "core.h"
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#include "net.h"
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#include "name_distr.h"
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#include "subscr.h"
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#include "socket.h"
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#include "node.h"
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#include "bcast.h"
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#include "netlink.h"
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/*
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* The TIPC locking policy is designed to ensure a very fine locking
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* granularity, permitting complete parallel access to individual
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* port and node/link instances. The code consists of four major
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* locking domains, each protected with their own disjunct set of locks.
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*
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* 1: The bearer level.
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* RTNL lock is used to serialize the process of configuring bearer
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* on update side, and RCU lock is applied on read side to make
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* bearer instance valid on both paths of message transmission and
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* reception.
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*
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* 2: The node and link level.
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* All node instances are saved into two tipc_node_list and node_htable
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* lists. The two lists are protected by node_list_lock on write side,
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* and they are guarded with RCU lock on read side. Especially node
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* instance is destroyed only when TIPC module is removed, and we can
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* confirm that there has no any user who is accessing the node at the
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* moment. Therefore, Except for iterating the two lists within RCU
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* protection, it's no needed to hold RCU that we access node instance
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* in other places.
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*
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* In addition, all members in node structure including link instances
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* are protected by node spin lock.
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*
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* 3: The transport level of the protocol.
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* This consists of the structures port, (and its user level
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* representations, such as user_port and tipc_sock), reference and
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* tipc_user (port.c, reg.c, socket.c).
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*
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* This layer has four different locks:
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* - The tipc_port spin_lock. This is protecting each port instance
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* from parallel data access and removal. Since we can not place
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* this lock in the port itself, it has been placed in the
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* corresponding reference table entry, which has the same life
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* cycle as the module. This entry is difficult to access from
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* outside the TIPC core, however, so a pointer to the lock has
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* been added in the port instance, -to be used for unlocking
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* only.
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* - A read/write lock to protect the reference table itself (teg.c).
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* (Nobody is using read-only access to this, so it can just as
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* well be changed to a spin_lock)
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* - A spin lock to protect the registry of kernel/driver users (reg.c)
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* - A global spin_lock (tipc_port_lock), which only task is to ensure
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* consistency where more than one port is involved in an operation,
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* i.e., whe a port is part of a linked list of ports.
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* There are two such lists; 'port_list', which is used for management,
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* and 'wait_list', which is used to queue ports during congestion.
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*
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* 4: The name table (name_table.c, name_distr.c, subscription.c)
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* - There is one big read/write-lock (tipc_nametbl_lock) protecting the
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* overall name table structure. Nothing must be added/removed to
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* this structure without holding write access to it.
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* - There is one local spin_lock per sub_sequence, which can be seen
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* as a sub-domain to the tipc_nametbl_lock domain. It is used only
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* for translation operations, and is needed because a translation
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* steps the root of the 'publication' linked list between each lookup.
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* This is always used within the scope of a tipc_nametbl_lock(read).
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* - A local spin_lock protecting the queue of subscriber events.
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*/
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int tipc_net_init(struct net *net, u8 *node_id, u32 addr)
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{
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if (tipc_own_id(net)) {
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pr_info("Cannot configure node identity twice\n");
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return -1;
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}
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pr_info("Started in network mode\n");
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if (node_id)
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tipc_set_node_id(net, node_id);
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if (addr)
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tipc_net_finalize(net, addr);
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return 0;
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}
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void tipc_net_finalize(struct net *net, u32 addr)
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{
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struct tipc_net *tn = tipc_net(net);
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if (!cmpxchg(&tn->node_addr, 0, addr)) {
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tipc_set_node_addr(net, addr);
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tipc_named_reinit(net);
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tipc_sk_reinit(net);
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tipc_nametbl_publish(net, TIPC_CFG_SRV, addr, addr,
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TIPC_CLUSTER_SCOPE, 0, addr);
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}
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}
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void tipc_net_stop(struct net *net)
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{
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u32 self = tipc_own_addr(net);
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if (!self)
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return;
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tipc_nametbl_withdraw(net, TIPC_CFG_SRV, self, self, self);
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rtnl_lock();
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tipc_bearer_stop(net);
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tipc_node_stop(net);
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rtnl_unlock();
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pr_info("Left network mode\n");
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}
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static int __tipc_nl_add_net(struct net *net, struct tipc_nl_msg *msg)
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{
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struct tipc_net *tn = net_generic(net, tipc_net_id);
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u64 *w0 = (u64 *)&tn->node_id[0];
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u64 *w1 = (u64 *)&tn->node_id[8];
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struct nlattr *attrs;
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void *hdr;
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hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
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NLM_F_MULTI, TIPC_NL_NET_GET);
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if (!hdr)
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return -EMSGSIZE;
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attrs = nla_nest_start(msg->skb, TIPC_NLA_NET);
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if (!attrs)
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goto msg_full;
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if (nla_put_u32(msg->skb, TIPC_NLA_NET_ID, tn->net_id))
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goto attr_msg_full;
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if (nla_put_u64_64bit(msg->skb, TIPC_NLA_NET_NODEID, *w0, 0))
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goto attr_msg_full;
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if (nla_put_u64_64bit(msg->skb, TIPC_NLA_NET_NODEID_W1, *w1, 0))
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goto attr_msg_full;
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nla_nest_end(msg->skb, attrs);
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genlmsg_end(msg->skb, hdr);
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return 0;
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attr_msg_full:
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nla_nest_cancel(msg->skb, attrs);
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msg_full:
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genlmsg_cancel(msg->skb, hdr);
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return -EMSGSIZE;
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}
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int tipc_nl_net_dump(struct sk_buff *skb, struct netlink_callback *cb)
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{
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struct net *net = sock_net(skb->sk);
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int err;
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int done = cb->args[0];
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struct tipc_nl_msg msg;
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if (done)
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return 0;
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msg.skb = skb;
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msg.portid = NETLINK_CB(cb->skb).portid;
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msg.seq = cb->nlh->nlmsg_seq;
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err = __tipc_nl_add_net(net, &msg);
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if (err)
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goto out;
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done = 1;
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out:
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cb->args[0] = done;
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return skb->len;
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}
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int __tipc_nl_net_set(struct sk_buff *skb, struct genl_info *info)
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{
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struct nlattr *attrs[TIPC_NLA_NET_MAX + 1];
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struct net *net = sock_net(skb->sk);
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struct tipc_net *tn = tipc_net(net);
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int err;
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if (!info->attrs[TIPC_NLA_NET])
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return -EINVAL;
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err = nla_parse_nested(attrs, TIPC_NLA_NET_MAX,
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info->attrs[TIPC_NLA_NET], tipc_nl_net_policy,
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info->extack);
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if (err)
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return err;
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/* Can't change net id once TIPC has joined a network */
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if (tipc_own_addr(net))
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return -EPERM;
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if (attrs[TIPC_NLA_NET_ID]) {
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u32 val;
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val = nla_get_u32(attrs[TIPC_NLA_NET_ID]);
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if (val < 1 || val > 9999)
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return -EINVAL;
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tn->net_id = val;
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}
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if (attrs[TIPC_NLA_NET_ADDR]) {
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u32 addr;
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addr = nla_get_u32(attrs[TIPC_NLA_NET_ADDR]);
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if (!addr)
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return -EINVAL;
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tn->legacy_addr_format = true;
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tipc_net_init(net, NULL, addr);
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}
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if (attrs[TIPC_NLA_NET_NODEID]) {
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u8 node_id[NODE_ID_LEN];
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u64 *w0 = (u64 *)&node_id[0];
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u64 *w1 = (u64 *)&node_id[8];
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if (!attrs[TIPC_NLA_NET_NODEID_W1])
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return -EINVAL;
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*w0 = nla_get_u64(attrs[TIPC_NLA_NET_NODEID]);
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*w1 = nla_get_u64(attrs[TIPC_NLA_NET_NODEID_W1]);
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tipc_net_init(net, node_id, 0);
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}
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return 0;
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}
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int tipc_nl_net_set(struct sk_buff *skb, struct genl_info *info)
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{
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int err;
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rtnl_lock();
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err = __tipc_nl_net_set(skb, info);
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rtnl_unlock();
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return err;
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}
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