Root/net/tipc/handler.c

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);
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
133

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