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df79d040dc
It is unnecessary to keep two structures, struct tipc_conn and struct
tipc_subscriber, with a one-to-one relationship and still with different
life cycles. The fact that the two often run in different contexts, and
still may access each other via direct pointers constitutes an additional
hazard, something we have experienced at several occasions, and still
see happening.
We have identified at least two remaining problems that are easier to
fix if we simplify the topology server data structure somewhat.
- When there is a race between a subscription up/down event and a
timeout event, it is fully possible that the former might be delivered
after the latter, leading to confusion for the receiver.
- The function tipc_subcrp_timeout() is executing in interrupt context,
while the following call chain is at least theoretically possible:
tipc_subscrp_timeout()
tipc_subscrp_send_event()
tipc_conn_sendmsg()
conn_put()
tipc_conn_kref_release()
sock_release(sock)
I.e., we end up calling a function that might try to sleep in
interrupt context. To eliminate this, we need to ensure that the
tipc_conn structure and the socket, as well as the subscription
instances, only are deleted in work queue context, i.e., after the
timeout event really has been sent out.
We now remove this unnecessary complexity, by merging data and
functionality of the subscriber structure into struct tipc_conn
and the associated file server.c. We thereafter add a spinlock and
a new 'inactive' state to the subscription structure. Using those,
both problems described above can be easily solved.
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
92 lines
3.7 KiB
C
92 lines
3.7 KiB
C
/*
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* net/tipc/subscr.h: Include file for TIPC network topology service
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*
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* Copyright (c) 2003-2006, Ericsson AB
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* Copyright (c) 2005-2007, 2012-2013, 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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#ifndef _TIPC_SUBSCR_H
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#define _TIPC_SUBSCR_H
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#include "server.h"
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#define TIPC_MAX_SUBSCRIPTIONS 65535
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#define TIPC_MAX_PUBLICATIONS 65535
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struct tipc_subscription;
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struct tipc_conn;
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/**
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* struct tipc_subscription - TIPC network topology subscription object
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* @subscriber: pointer to its subscriber
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* @seq: name sequence associated with subscription
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* @net: point to network namespace
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* @timer: timer governing subscription duration (optional)
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* @nameseq_list: adjacent subscriptions in name sequence's subscription list
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* @subscrp_list: adjacent subscriptions in subscriber's subscription list
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* @swap: indicates if subscriber uses opposite endianness in its messages
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* @evt: template for events generated by subscription
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*/
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struct tipc_subscription {
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struct kref kref;
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struct net *net;
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struct timer_list timer;
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struct list_head nameseq_list;
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struct list_head subscrp_list;
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struct tipc_event evt;
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int conid;
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bool swap;
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bool inactive;
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spinlock_t lock; /* serialize up/down and timer events */
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};
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struct tipc_subscription *tipc_subscrp_subscribe(struct net *net,
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struct tipc_subscr *s,
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int conid, bool swap,
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bool status);
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void tipc_sub_delete(struct tipc_subscription *sub);
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int tipc_subscrp_check_overlap(struct tipc_name_seq *seq, u32 found_lower,
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u32 found_upper);
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void tipc_subscrp_report_overlap(struct tipc_subscription *sub,
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u32 found_lower, u32 found_upper, u32 event,
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u32 port_ref, u32 node, u32 scope, int must);
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void tipc_subscrp_convert_seq(struct tipc_name_seq *in, int swap,
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struct tipc_name_seq *out);
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u32 tipc_subscrp_convert_seq_type(u32 type, int swap);
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int tipc_topsrv_start(struct net *net);
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void tipc_topsrv_stop(struct net *net);
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void tipc_subscrp_put(struct tipc_subscription *subscription);
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void tipc_subscrp_get(struct tipc_subscription *subscription);
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#endif
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