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   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  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the names of the copyright holders nor the names of its
  18  *    contributors may be used to endorse or promote products derived from
  19  *    this software without specific prior written permission.
  20  *
  21  * Alternatively, this software may be distributed under the terms of the
  22  * GNU General Public License ("GPL") version 2 as published by the Free
  23  * Software Foundation.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  26  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  29  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  30  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  31  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  32  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  33  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  35  * POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 #include "core.h"
  39
  40 struct queue_item {
  41         struct list_head next_signal;
  42         void (*handler) (unsigned long);
  43         unsigned long data;
  44 };
  45
  46 static kmem_cache_t *tipc_queue_item_cache;
  47 static struct list_head signal_queue_head;
  48 static spinlock_t qitem_lock = SPIN_LOCK_UNLOCKED;
  49 static int handler_enabled = 0;
  50
  51 static void process_signal_queue(unsigned long dummy);
  52
  53 static DECLARE_TASKLET_DISABLED(tipc_tasklet, process_signal_queue, 0);
  54
  55
  56 unsigned int k_signal(Handler routine, unsigned long argument)
  57 {
  58         struct queue_item *item;
  59
  60         if (!handler_enabled) {
  61                 err("Signal request ignored by handler\n");
  62                 return -ENOPROTOOPT;
  63         }
  64
  65         spin_lock_bh(&qitem_lock);
  66         item = kmem_cache_alloc(tipc_queue_item_cache, GFP_ATOMIC);
  67         if (!item) {
  68                 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
  80 static 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
  97 int 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, 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
 111 void handler_stop(void)
 112 {
 113         struct list_head *l, *n;
 114         struct queue_item *item;
 115
 116         if (!handler_enabled)
 117                 return;
 118
 119         handler_enabled = 0;
 120         tasklet_disable(&tipc_tasklet);
 121         tasklet_kill(&tipc_tasklet);
 122
 123         spin_lock_bh(&qitem_lock);
 124         list_for_each_safe(l, n, &signal_queue_head) {
 125                 item = list_entry(l, struct queue_item, next_signal);
 126                 list_del(&item->next_signal);
 127                 kmem_cache_free(tipc_queue_item_cache, item);
 128         }
 129         spin_unlock_bh(&qitem_lock);
 130
 131         kmem_cache_destroy(tipc_queue_item_cache);
 132 }
 133