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 = 0;
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	if (!handler_enabled) {
60		err("Signal request ignored by handler\n");
61		return -ENOPROTOOPT;
62	}
63
64	spin_lock_bh(&qitem_lock);
65	item = kmem_cache_alloc(tipc_queue_item_cache, GFP_ATOMIC);
66	if (!item) {
67		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, 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	if (!handler_enabled)
116		return;
117
118	handler_enabled = 0;
119	tasklet_disable(&tipc_tasklet);
120	tasklet_kill(&tipc_tasklet);
121
122	spin_lock_bh(&qitem_lock);
123	list_for_each_safe(l, n, &signal_queue_head) {
124		item = list_entry(l, struct queue_item, next_signal);
125		list_del(&item->next_signal);
126		kmem_cache_free(tipc_queue_item_cache, item);
127	}
128	spin_unlock_bh(&qitem_lock);
129
130	kmem_cache_destroy(tipc_queue_item_cache);
131}
132