1/*
  2 * net/tipc/handler.c: TIPC signal handling
  3 *
  4 * Copyright (c) 2000-2006, Ericsson AB
  5 * Copyright (c) 2005, Wind River Systems
  6 * All rights reserved.
  7 *
  8 * Redistribution and use in source and binary forms, with or without
  9 * modification, are permitted provided that the following conditions are met:
 10 *
 11 * 1. Redistributions of source code must retain the above copyright
 12 *    notice, this list of conditions and the following disclaimer.
 13 * 2. Redistributions in binary form must reproduce the above copyright
 14 *    notice, this list of conditions and the following disclaimer in the
 15 *    documentation and/or other materials provided with the distribution.
 16 * 3. Neither the names of the copyright holders nor the names of its
 17 *    contributors may be used to endorse or promote products derived from
 18 *    this software without specific prior written permission.
 19 *
 20 * Alternatively, this software may be distributed under the terms of the
 21 * GNU General Public License ("GPL") version 2 as published by the Free
 22 * Software Foundation.
 23 *
 24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 25 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 28 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 29 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 30 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 31 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 32 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 33 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 34 * POSSIBILITY OF SUCH DAMAGE.
 35 */
 36
 37#include "core.h"
 38
 39struct queue_item {
 40	struct list_head next_signal;
 41	void (*handler) (unsigned long);
 42	unsigned long data;
 43};
 44
 45static struct kmem_cache *tipc_queue_item_cache;
 46static struct list_head signal_queue_head;
 47static DEFINE_SPINLOCK(qitem_lock);
 48static int handler_enabled __read_mostly;
 49
 50static void process_signal_queue(unsigned long dummy);
 51
 52static DECLARE_TASKLET_DISABLED(tipc_tasklet, process_signal_queue, 0);
 53
 54
 55unsigned int tipc_k_signal(Handler routine, unsigned long argument)
 56{
 57	struct queue_item *item;
 58
 59	spin_lock_bh(&qitem_lock);
 60	if (!handler_enabled) {
 61		spin_unlock_bh(&qitem_lock);
 62		return -ENOPROTOOPT;
 63	}
 64
 65	item = kmem_cache_alloc(tipc_queue_item_cache, GFP_ATOMIC);
 66	if (!item) {
 67		pr_err("Signal queue out of memory\n");
 68		spin_unlock_bh(&qitem_lock);
 69		return -ENOMEM;
 70	}
 71	item->handler = routine;
 72	item->data = argument;
 73	list_add_tail(&item->next_signal, &signal_queue_head);
 74	spin_unlock_bh(&qitem_lock);
 75	tasklet_schedule(&tipc_tasklet);
 76	return 0;
 77}
 78
 79static void process_signal_queue(unsigned long dummy)
 80{
 81	struct queue_item *__volatile__ item;
 82	struct list_head *l, *n;
 83
 84	spin_lock_bh(&qitem_lock);
 85	list_for_each_safe(l, n, &signal_queue_head) {
 86		item = list_entry(l, struct queue_item, next_signal);
 87		list_del(&item->next_signal);
 88		spin_unlock_bh(&qitem_lock);
 89		item->handler(item->data);
 90		spin_lock_bh(&qitem_lock);
 91		kmem_cache_free(tipc_queue_item_cache, item);
 92	}
 93	spin_unlock_bh(&qitem_lock);
 94}
 95
 96int tipc_handler_start(void)
 97{
 98	tipc_queue_item_cache =
 99		kmem_cache_create("tipc_queue_items", sizeof(struct queue_item),
100				  0, SLAB_HWCACHE_ALIGN, NULL);
101	if (!tipc_queue_item_cache)
102		return -ENOMEM;
103
104	INIT_LIST_HEAD(&signal_queue_head);
105	tasklet_enable(&tipc_tasklet);
106	handler_enabled = 1;
107	return 0;
108}
109
110void tipc_handler_stop(void)
111{
112	struct list_head *l, *n;
113	struct queue_item *item;
114
115	spin_lock_bh(&qitem_lock);
116	if (!handler_enabled) {
117		spin_unlock_bh(&qitem_lock);
118		return;
119	}
120	handler_enabled = 0;
121	spin_unlock_bh(&qitem_lock);
122
123	tasklet_kill(&tipc_tasklet);
124
125	spin_lock_bh(&qitem_lock);
126	list_for_each_safe(l, n, &signal_queue_head) {
127		item = list_entry(l, struct queue_item, next_signal);
128		list_del(&item->next_signal);
129		kmem_cache_free(tipc_queue_item_cache, item);
130	}
131	spin_unlock_bh(&qitem_lock);
132
133	kmem_cache_destroy(tipc_queue_item_cache);
134}