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linux/net/tipc/core.h
Ying Xue c5fa7b3cf3 tipc: introduce new TIPC server infrastructure 
TIPC has two internal servers, one providing a subscription
service for topology events, and another providing the
configuration interface. These servers have previously been running
in BH context, accessing the TIPC-port (aka native) API directly.
Apart from these servers, even the TIPC socket implementation is
partially built on this API.

As this API may simultaneously be called via different paths and in
different contexts, a complex and costly lock policiy is required
in order to protect TIPC internal resources.

To eliminate the need for this complex lock policiy, we introduce
a new, generic service API that uses kernel sockets for message
passing instead of the native API. Once the toplogy and configuration
servers are converted to use this new service, all code pertaining
to the native API can be removed. This entails a significant
reduction in code amount and complexity, and opens up for a complete
rework of the locking policy in TIPC.

The new service also solves another problem:

As the current topology server works in BH context, it cannot easily
be blocked when sending of events fails due to congestion. In such
cases events may have to be silently dropped, something that is
unacceptable. Therefore, the new service keeps a dedicated outbound
queue receiving messages from BH context. Once messages are
inserted into this queue, we will immediately schedule a work from a
special workqueue. This way, messages/events from the topology server
are in reality sent in process context, and the server can block
if necessary.

Analogously, there is a new workqueue for receiving messages. Once a
notification about an arriving message is received in BH context, we
schedule a work from the receive workqueue to do the job of
receiving the message in process context.

As both sending and receive messages are now finished in processes,
subscribed events cannot be dropped any more.

As of this commit, this new server infrastructure is built, but
not actually yet called by the existing TIPC code, but since the
conversion changes required in order to use it are significant,
the addition is kept here as a separate commit.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-06-17 15:53:00 -07:00

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/*
* net/tipc/core.h: Include file for TIPC global declarations
*
* Copyright (c) 2005-2006, 2013 Ericsson AB
* Copyright (c) 2005-2007, 2010-2013, 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_CORE_H
#define _TIPC_CORE_H
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/tipc.h>
#include <linux/tipc_config.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <asm/uaccess.h>
#include <linux/interrupt.h>
#include <linux/atomic.h>
#include <asm/hardirq.h>
#include <linux/netdevice.h>
#include <linux/in.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#define TIPC_MOD_VER "2.0.0"
#define ULTRA_STRING_MAX_LEN 32768
#define TIPC_MAX_SUBSCRIPTIONS 65535
#define TIPC_MAX_PUBLICATIONS 65535
struct tipc_msg; /* msg.h */
int tipc_snprintf(char *buf, int len, const char *fmt, ...);
/*
* TIPC-specific error codes
*/
#define ELINKCONG EAGAIN /* link congestion <=> resource unavailable */
/*
* Global configuration variables
*/
extern u32 tipc_own_addr __read_mostly;
extern int tipc_max_ports __read_mostly;
extern int tipc_net_id __read_mostly;
extern int tipc_remote_management __read_mostly;
extern int sysctl_tipc_rmem[3] __read_mostly;
/*
* Other global variables
*/
extern int tipc_random __read_mostly;
/*
* Routines available to privileged subsystems
*/
extern int tipc_core_start_net(unsigned long);
extern int tipc_handler_start(void);
extern void tipc_handler_stop(void);
extern int tipc_netlink_start(void);
extern void tipc_netlink_stop(void);
extern int tipc_socket_init(void);
extern void tipc_socket_stop(void);
extern int tipc_sock_create_local(int type, struct socket **res);
extern void tipc_sock_release_local(struct socket *sock);
extern int tipc_sock_accept_local(struct socket *sock,
struct socket **newsock, int flags);
#ifdef CONFIG_SYSCTL
extern int tipc_register_sysctl(void);
extern void tipc_unregister_sysctl(void);
#else
#define tipc_register_sysctl() 0
#define tipc_unregister_sysctl()
#endif
/*
* TIPC timer and signal code
*/
typedef void (*Handler) (unsigned long);
u32 tipc_k_signal(Handler routine, unsigned long argument);
/**
* k_init_timer - initialize a timer
* @timer: pointer to timer structure
* @routine: pointer to routine to invoke when timer expires
* @argument: value to pass to routine when timer expires
*
* Timer must be initialized before use (and terminated when no longer needed).
*/
static inline void k_init_timer(struct timer_list *timer, Handler routine,
unsigned long argument)
{
setup_timer(timer, routine, argument);
}
/**
* k_start_timer - start a timer
* @timer: pointer to timer structure
* @msec: time to delay (in ms)
*
* Schedules a previously initialized timer for later execution.
* If timer is already running, the new timeout overrides the previous request.
*
* To ensure the timer doesn't expire before the specified delay elapses,
* the amount of delay is rounded up when converting to the jiffies
* then an additional jiffy is added to account for the fact that
* the starting time may be in the middle of the current jiffy.
*/
static inline void k_start_timer(struct timer_list *timer, unsigned long msec)
{
mod_timer(timer, jiffies + msecs_to_jiffies(msec) + 1);
}
/**
* k_cancel_timer - cancel a timer
* @timer: pointer to timer structure
*
* Cancels a previously initialized timer.
* Can be called safely even if the timer is already inactive.
*
* WARNING: Must not be called when holding locks required by the timer's
* timeout routine, otherwise deadlock can occur on SMP systems!
*/
static inline void k_cancel_timer(struct timer_list *timer)
{
del_timer_sync(timer);
}
/**
* k_term_timer - terminate a timer
* @timer: pointer to timer structure
*
* Prevents further use of a previously initialized timer.
*
* WARNING: Caller must ensure timer isn't currently running.
*
* (Do not "enhance" this routine to automatically cancel an active timer,
* otherwise deadlock can arise when a timeout routine calls k_term_timer.)
*/
static inline void k_term_timer(struct timer_list *timer)
{
}
/*
* TIPC message buffer code
*
* TIPC message buffer headroom reserves space for the worst-case
* link-level device header (in case the message is sent off-node).
*
* Note: Headroom should be a multiple of 4 to ensure the TIPC header fields
* are word aligned for quicker access
*/
#define BUF_HEADROOM LL_MAX_HEADER
struct tipc_skb_cb {
void *handle;
};
#define TIPC_SKB_CB(__skb) ((struct tipc_skb_cb *)&((__skb)->cb[0]))
static inline struct tipc_msg *buf_msg(struct sk_buff *skb)
{
return (struct tipc_msg *)skb->data;
}
extern struct sk_buff *tipc_buf_acquire(u32 size);
#endif
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