LXR linux/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
  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;
  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        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
  79static 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
  96int 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
 110void 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
 133