Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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 pr_err("Signal request ignored by handler\n");
62 spin_unlock_bh(&qitem_lock);
63 return -ENOPROTOOPT;
64 }
65
66 item = kmem_cache_alloc(tipc_queue_item_cache, GFP_ATOMIC);
67 if (!item) {
68 pr_err("Signal queue out of memory\n");
69 spin_unlock_bh(&qitem_lock);
70 return -ENOMEM;
71 }
72 item->handler = routine;
73 item->data = argument;
74 list_add_tail(&item->next_signal, &signal_queue_head);
75 spin_unlock_bh(&qitem_lock);
76 tasklet_schedule(&tipc_tasklet);
77 return 0;
78}
79
80static void process_signal_queue(unsigned long dummy)
81{
82 struct queue_item *__volatile__ item;
83 struct list_head *l, *n;
84
85 spin_lock_bh(&qitem_lock);
86 list_for_each_safe(l, n, &signal_queue_head) {
87 item = list_entry(l, struct queue_item, next_signal);
88 list_del(&item->next_signal);
89 spin_unlock_bh(&qitem_lock);
90 item->handler(item->data);
91 spin_lock_bh(&qitem_lock);
92 kmem_cache_free(tipc_queue_item_cache, item);
93 }
94 spin_unlock_bh(&qitem_lock);
95}
96
97int tipc_handler_start(void)
98{
99 tipc_queue_item_cache =
100 kmem_cache_create("tipc_queue_items", sizeof(struct queue_item),
101 0, SLAB_HWCACHE_ALIGN, NULL);
102 if (!tipc_queue_item_cache)
103 return -ENOMEM;
104
105 INIT_LIST_HEAD(&signal_queue_head);
106 tasklet_enable(&tipc_tasklet);
107 handler_enabled = 1;
108 return 0;
109}
110
111void tipc_handler_stop(void)
112{
113 struct list_head *l, *n;
114 struct queue_item *item;
115
116 spin_lock_bh(&qitem_lock);
117 if (!handler_enabled) {
118 spin_unlock_bh(&qitem_lock);
119 return;
120 }
121 handler_enabled = 0;
122 spin_unlock_bh(&qitem_lock);
123
124 tasklet_kill(&tipc_tasklet);
125
126 spin_lock_bh(&qitem_lock);
127 list_for_each_safe(l, n, &signal_queue_head) {
128 item = list_entry(l, struct queue_item, next_signal);
129 list_del(&item->next_signal);
130 kmem_cache_free(tipc_queue_item_cache, item);
131 }
132 spin_unlock_bh(&qitem_lock);
133
134 kmem_cache_destroy(tipc_queue_item_cache);
135}