/*
   * net/tipc/handler.c: TIPC signal handling

   *

   * Copyright (c) 2000-2006, Ericsson AB

   * Copyright (c) 2005, Wind River Systems

   * All rights reserved.
   *

   * Redistribution and use in source and binary forms, with or without

   * modification, are permitted provided that the following conditions are met:
   *

   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the names of the copyright holders nor the names of its
   *    contributors may be used to endorse or promote products derived from
   *    this software without specific prior written permission.

   *

   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "core.h"
  
  struct queue_item {
  	struct list_head next_signal;
  	void (*handler) (unsigned long);
  	unsigned long data;
  };

  static struct kmem_cache *tipc_queue_item_cache;

  static struct list_head signal_queue_head;

  static DEFINE_SPINLOCK(qitem_lock);

  static int handler_enabled;

  
  static void process_signal_queue(unsigned long dummy);
  
  static DECLARE_TASKLET_DISABLED(tipc_tasklet, process_signal_queue, 0);

  unsigned int tipc_k_signal(Handler routine, unsigned long argument)

  {
  	struct queue_item *item;
  
  	if (!handler_enabled) {
  		err("Signal request ignored by handler
  ");
  		return -ENOPROTOOPT;
  	}
  
  	spin_lock_bh(&qitem_lock);
  	item = kmem_cache_alloc(tipc_queue_item_cache, GFP_ATOMIC);
  	if (!item) {
  		err("Signal queue out of memory
  ");
  		spin_unlock_bh(&qitem_lock);
  		return -ENOMEM;
  	}
  	item->handler = routine;
  	item->data = argument;
  	list_add_tail(&item->next_signal, &signal_queue_head);
  	spin_unlock_bh(&qitem_lock);
  	tasklet_schedule(&tipc_tasklet);
  	return 0;
  }
  
  static void process_signal_queue(unsigned long dummy)
  {
  	struct queue_item *__volatile__ item;
  	struct list_head *l, *n;
  
  	spin_lock_bh(&qitem_lock);
  	list_for_each_safe(l, n, &signal_queue_head) {
  		item = list_entry(l, struct queue_item, next_signal);
  		list_del(&item->next_signal);
  		spin_unlock_bh(&qitem_lock);
  		item->handler(item->data);
  		spin_lock_bh(&qitem_lock);
  		kmem_cache_free(tipc_queue_item_cache, item);
  	}
  	spin_unlock_bh(&qitem_lock);
  }

  int tipc_handler_start(void)

  {

  	tipc_queue_item_cache =

  		kmem_cache_create("tipc_queue_items", sizeof(struct queue_item),

  				  0, SLAB_HWCACHE_ALIGN, NULL);

  	if (!tipc_queue_item_cache)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&signal_queue_head);
  	tasklet_enable(&tipc_tasklet);
  	handler_enabled = 1;
  	return 0;
  }

  void tipc_handler_stop(void)

  {
  	struct list_head *l, *n;

  	struct queue_item *item;

  
  	if (!handler_enabled)
  		return;
  
  	handler_enabled = 0;
  	tasklet_disable(&tipc_tasklet);
  	tasklet_kill(&tipc_tasklet);
  
  	spin_lock_bh(&qitem_lock);
  	list_for_each_safe(l, n, &signal_queue_head) {
  		item = list_entry(l, struct queue_item, next_signal);
  		list_del(&item->next_signal);
  		kmem_cache_free(tipc_queue_item_cache, item);
  	}
  	spin_unlock_bh(&qitem_lock);
  
  	kmem_cache_destroy(tipc_queue_item_cache);
  }