tipc: Minor optimization to rejection of connection-based messages
[linux-2.6.git] / 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
39 struct queue_item {
40         struct list_head next_signal;
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;
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                 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
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
96 int 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
110 void 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