blob: 133697540c738441d6b92f6e2ebf72b0622baae6 [file] [log] [blame]
Arnd Bergmannb07471f2010-08-06 21:40:30 +02001/*
2 * drivers/char/tty_lock.c
3 */
4#include <linux/tty.h>
5#include <linux/module.h>
6#include <linux/kallsyms.h>
7#include <linux/semaphore.h>
8#include <linux/sched.h>
9
10/*
11 * The 'big tty mutex'
12 *
13 * This mutex is taken and released by tty_lock() and tty_unlock(),
14 * replacing the older big kernel lock.
15 * It can no longer be taken recursively, and does not get
16 * released implicitly while sleeping.
17 *
18 * Don't use in new code.
19 */
20static DEFINE_MUTEX(big_tty_mutex);
21struct task_struct *__big_tty_mutex_owner;
22EXPORT_SYMBOL_GPL(__big_tty_mutex_owner);
23
24/*
25 * Getting the big tty mutex.
26 */
27void __lockfunc tty_lock(void)
28{
29 struct task_struct *task = current;
30
31 WARN_ON(__big_tty_mutex_owner == task);
32
33 mutex_lock(&big_tty_mutex);
34 __big_tty_mutex_owner = task;
35}
36EXPORT_SYMBOL(tty_lock);
37
38void __lockfunc tty_unlock(void)
39{
40 struct task_struct *task = current;
41
42 WARN_ON(__big_tty_mutex_owner != task);
43 __big_tty_mutex_owner = NULL;
44
45 mutex_unlock(&big_tty_mutex);
46}
47EXPORT_SYMBOL(tty_unlock);