handler.c
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/*
* 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 __read_mostly;
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;
spin_lock_bh(&qitem_lock);
if (!handler_enabled) {
spin_unlock_bh(&qitem_lock);
return -ENOPROTOOPT;
}
item = kmem_cache_alloc(tipc_queue_item_cache, GFP_ATOMIC);
if (!item) {
pr_err("Signal queue out of memory\n");
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;
spin_lock_bh(&qitem_lock);
if (!handler_enabled) {
spin_unlock_bh(&qitem_lock);
return;
}
handler_enabled = 0;
spin_unlock_bh(&qitem_lock);
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);
}