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handler.c
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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 
39 struct queue_item {
41  void (*handler) (unsigned long);
42  unsigned long data;
43 };
44 
45 static struct kmem_cache *tipc_queue_item_cache;
46 static struct list_head signal_queue_head;
47 static DEFINE_SPINLOCK(qitem_lock);
48 static int handler_enabled __read_mostly;
49 
50 static void process_signal_queue(unsigned long dummy);
51 
52 static DECLARE_TASKLET_DISABLED(tipc_tasklet, process_signal_queue, 0);
53 
54 
55 unsigned int tipc_k_signal(Handler routine, unsigned long argument)
56 {
57  struct queue_item *item;
58 
59  if (!handler_enabled) {
60  pr_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  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 
79 static 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 
97 {
98  tipc_queue_item_cache =
99  kmem_cache_create("tipc_queue_items", sizeof(struct queue_item),
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 
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_kill(&tipc_tasklet);
120 
121  spin_lock_bh(&qitem_lock);
122  list_for_each_safe(l, n, &signal_queue_head) {
123  item = list_entry(l, struct queue_item, next_signal);
124  list_del(&item->next_signal);
125  kmem_cache_free(tipc_queue_item_cache, item);
126  }
127  spin_unlock_bh(&qitem_lock);
128 
129  kmem_cache_destroy(tipc_queue_item_cache);
130 }