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         if (!handler_enabled) {
  60                 pr_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                 pr_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
  79 static 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
  96 int 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
 110 void 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_kill(&tipc_tasklet);
 120
 121         spin_lock_bh(&qitem_lock);
 122         list_for_each_safe(l, n, &signal_queue_head) {
 123                 item = list_entry(l, struct queue_item, next_signal);
 124                 list_del(&item->next_signal);
 125                 kmem_cache_free(tipc_queue_item_cache, item);
 126         }
 127         spin_unlock_bh(&qitem_lock);
 128
 129         kmem_cache_destroy(tipc_queue_item_cache);
 130 }