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 __read_mostly;
  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         spin_lock_bh(&qitem_lock);
  60         if (!handler_enabled) {
  61                 pr_err("Signal request ignored by handler\n");
  62                 spin_unlock_bh(&qitem_lock);
  63                 return -ENOPROTOOPT;
  64         }
  65
  66         item = kmem_cache_alloc(tipc_queue_item_cache, GFP_ATOMIC);
  67         if (!item) {
  68                 pr_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 tipc_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);
 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 tipc_handler_stop(void)
 112 {
 113         struct list_head *l, *n;
 114         struct queue_item *item;
 115
 116         spin_lock_bh(&qitem_lock);
 117         if (!handler_enabled) {
 118                 spin_unlock_bh(&qitem_lock);
 119                 return;
 120         }
 121         handler_enabled = 0;
 122         spin_unlock_bh(&qitem_lock);
 123
 124         tasklet_kill(&tipc_tasklet);
 125
 126         spin_lock_bh(&qitem_lock);
 127         list_for_each_safe(l, n, &signal_queue_head) {
 128                 item = list_entry(l, struct queue_item, next_signal);
 129                 list_del(&item->next_signal);
 130                 kmem_cache_free(tipc_queue_item_cache, item);
 131         }
 132         spin_unlock_bh(&qitem_lock);
 133
 134         kmem_cache_destroy(tipc_queue_item_cache);
 135 }