err.no Git - linux-2.6/blob - net/tipc/handler.c

   1 /*
   2  * net/tipc/handler.c: TIPC signal handling
   3  *
   4  * Copyright (c) 2003-2005, Ericsson Research Canada
   5  * Copyright (c) 2005, Wind River Systems
   6  * Copyright (c) 2005-2006, Ericsson AB
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions are met:
  11  *
  12  * Redistributions of source code must retain the above copyright notice, this
  13  * list of conditions and the following disclaimer.
  14  * Redistributions in binary form must reproduce the above copyright notice,
  15  * this list of conditions and the following disclaimer in the documentation
  16  * and/or other materials provided with the distribution.
  17  * Neither the names of the copyright holders nor the names of its
  18  * contributors may be used to endorse or promote products derived from this
  19  * software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  22  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  25  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include "core.h"
  35
  36 struct queue_item {
  37         struct list_head next_signal;
  38         void (*handler) (unsigned long);
  39         unsigned long data;
  40 };
  41
  42 static kmem_cache_t *tipc_queue_item_cache;
  43 static struct list_head signal_queue_head;
  44 static spinlock_t qitem_lock = SPIN_LOCK_UNLOCKED;
  45 static int handler_enabled = 0;
  46
  47 static void process_signal_queue(unsigned long dummy);
  48
  49 static DECLARE_TASKLET_DISABLED(tipc_tasklet, process_signal_queue, 0);
  50
  51
  52 unsigned int k_signal(Handler routine, unsigned long argument)
  53 {
  54         struct queue_item *item;
  55
  56         if (!handler_enabled) {
  57                 err("Signal request ignored by handler\n");
  58                 return -ENOPROTOOPT;
  59         }
  60
  61         spin_lock_bh(&qitem_lock);
  62         item = kmem_cache_alloc(tipc_queue_item_cache, GFP_ATOMIC);
  63         if (!item) {
  64                 err("Signal queue out of memory\n");
  65                 spin_unlock_bh(&qitem_lock);
  66                 return -ENOMEM;
  67         }
  68         item->handler = routine;
  69         item->data = argument;
  70         list_add_tail(&item->next_signal, &signal_queue_head);
  71         spin_unlock_bh(&qitem_lock);
  72         tasklet_schedule(&tipc_tasklet);
  73         return 0;
  74 }
  75
  76 static void process_signal_queue(unsigned long dummy)
  77 {
  78         struct queue_item *__volatile__ item;
  79         struct list_head *l, *n;
  80
  81         spin_lock_bh(&qitem_lock);
  82         list_for_each_safe(l, n, &signal_queue_head) {
  83                 item = list_entry(l, struct queue_item, next_signal);
  84                 list_del(&item->next_signal);
  85                 spin_unlock_bh(&qitem_lock);
  86                 item->handler(item->data);
  87                 spin_lock_bh(&qitem_lock);
  88                 kmem_cache_free(tipc_queue_item_cache, item);
  89         }
  90         spin_unlock_bh(&qitem_lock);
  91 }
  92
  93 int handler_start(void)
  94 {
  95         tipc_queue_item_cache =
  96                 kmem_cache_create("tipc_queue_items", sizeof(struct queue_item),
  97                                   0, SLAB_HWCACHE_ALIGN, NULL, NULL);
  98         if (!tipc_queue_item_cache)
  99                 return -ENOMEM;
 100
 101         INIT_LIST_HEAD(&signal_queue_head);
 102         tasklet_enable(&tipc_tasklet);
 103         handler_enabled = 1;
 104         return 0;
 105 }
 106
 107 void handler_stop(void)
 108 {
 109         struct list_head *l, *n;
 110         struct queue_item *item;
 111
 112         if (!handler_enabled)
 113                 return;
 114
 115         handler_enabled = 0;
 116         tasklet_disable(&tipc_tasklet);
 117         tasklet_kill(&tipc_tasklet);
 118
 119         spin_lock_bh(&qitem_lock);
 120         list_for_each_safe(l, n, &signal_queue_head) {
 121                 item = list_entry(l, struct queue_item, next_signal);
 122                 list_del(&item->next_signal);
 123                 kmem_cache_free(tipc_queue_item_cache, item);
 124         }
 125         spin_unlock_bh(&qitem_lock);
 126
 127         kmem_cache_destroy(tipc_queue_item_cache);
 128 }
 129