tty_mutex.c (6d31a88cb2e01d46c0cb74aa5da529e1f92ae3db) tty_mutex.c (89c8d91e31f267703e365593f6bfebb9f6d2ad01)
1#include <linux/tty.h>
2#include <linux/module.h>
3#include <linux/kallsyms.h>
4#include <linux/semaphore.h>
5#include <linux/sched.h>
6
1#include <linux/tty.h>
2#include <linux/module.h>
3#include <linux/kallsyms.h>
4#include <linux/semaphore.h>
5#include <linux/sched.h>
6
7/*
8 * The 'big tty mutex'
9 *
10 * This mutex is taken and released by tty_lock() and tty_unlock(),
11 * replacing the older big kernel lock.
12 * It can no longer be taken recursively, and does not get
13 * released implicitly while sleeping.
14 *
15 * Don't use in new code.
16 */
17static DEFINE_MUTEX(big_tty_mutex);
7/* Legacy tty mutex glue */
18
8
9enum {
10 TTY_MUTEX_NORMAL,
11 TTY_MUTEX_NESTED,
12};
13
19/*
20 * Getting the big tty mutex.
21 */
14/*
15 * Getting the big tty mutex.
16 */
22void __lockfunc tty_lock(void)
17
18static void __lockfunc tty_lock_nested(struct tty_struct *tty,
19 unsigned int subclass)
23{
20{
24 mutex_lock(&big_tty_mutex);
21 if (tty->magic != TTY_MAGIC) {
22 printk(KERN_ERR "L Bad %p\n", tty);
23 WARN_ON(1);
24 return;
25 }
26 tty_kref_get(tty);
27 mutex_lock_nested(&tty->legacy_mutex, subclass);
25}
28}
29
30void __lockfunc tty_lock(struct tty_struct *tty)
31{
32 return tty_lock_nested(tty, TTY_MUTEX_NORMAL);
33}
26EXPORT_SYMBOL(tty_lock);
27
34EXPORT_SYMBOL(tty_lock);
35
28void __lockfunc tty_unlock(void)
36void __lockfunc tty_unlock(struct tty_struct *tty)
29{
37{
30 mutex_unlock(&big_tty_mutex);
38 if (tty->magic != TTY_MAGIC) {
39 printk(KERN_ERR "U Bad %p\n", tty);
40 WARN_ON(1);
41 return;
42 }
43 mutex_unlock(&tty->legacy_mutex);
44 tty_kref_put(tty);
31}
32EXPORT_SYMBOL(tty_unlock);
45}
46EXPORT_SYMBOL(tty_unlock);
47
48/*
49 * Getting the big tty mutex for a pair of ttys with lock ordering
50 * On a non pty/tty pair tty2 can be NULL which is just fine.
51 */
52void __lockfunc tty_lock_pair(struct tty_struct *tty,
53 struct tty_struct *tty2)
54{
55 if (tty < tty2) {
56 tty_lock(tty);
57 tty_lock_nested(tty2, TTY_MUTEX_NESTED);
58 } else {
59 if (tty2 && tty2 != tty)
60 tty_lock(tty2);
61 tty_lock_nested(tty, TTY_MUTEX_NESTED);
62 }
63}
64EXPORT_SYMBOL(tty_lock_pair);
65
66void __lockfunc tty_unlock_pair(struct tty_struct *tty,
67 struct tty_struct *tty2)
68{
69 tty_unlock(tty);
70 if (tty2 && tty2 != tty)
71 tty_unlock(tty2);
72}
73EXPORT_SYMBOL(tty_unlock_pair);