Commit | Line | Data |
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b07471fa AB |
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 | ||
2aff5e2b PH |
7 | /* |
8 | * Nested tty locks are necessary for releasing pty pairs. | |
9 | * The stable lock order is master pty first, then slave pty. | |
10 | */ | |
11 | ||
89c8d91e AC |
12 | /* Legacy tty mutex glue */ |
13 | ||
14 | enum { | |
15 | TTY_MUTEX_NORMAL, | |
16 | TTY_MUTEX_NESTED, | |
17 | }; | |
fde86d31 | 18 | |
b07471fa AB |
19 | /* |
20 | * Getting the big tty mutex. | |
21 | */ | |
89c8d91e AC |
22 | |
23 | static void __lockfunc tty_lock_nested(struct tty_struct *tty, | |
24 | unsigned int subclass) | |
b07471fa | 25 | { |
89c8d91e | 26 | if (tty->magic != TTY_MAGIC) { |
7a0c4eda | 27 | pr_err("L Bad %p\n", tty); |
89c8d91e AC |
28 | WARN_ON(1); |
29 | return; | |
30 | } | |
31 | tty_kref_get(tty); | |
32 | mutex_lock_nested(&tty->legacy_mutex, subclass); | |
33 | } | |
34 | ||
35 | void __lockfunc tty_lock(struct tty_struct *tty) | |
36 | { | |
37 | return tty_lock_nested(tty, TTY_MUTEX_NORMAL); | |
b07471fa AB |
38 | } |
39 | EXPORT_SYMBOL(tty_lock); | |
40 | ||
89c8d91e | 41 | void __lockfunc tty_unlock(struct tty_struct *tty) |
b07471fa | 42 | { |
89c8d91e | 43 | if (tty->magic != TTY_MAGIC) { |
7a0c4eda | 44 | pr_err("U Bad %p\n", tty); |
89c8d91e AC |
45 | WARN_ON(1); |
46 | return; | |
47 | } | |
48 | mutex_unlock(&tty->legacy_mutex); | |
49 | tty_kref_put(tty); | |
b07471fa AB |
50 | } |
51 | EXPORT_SYMBOL(tty_unlock); | |
89c8d91e | 52 | |
2aff5e2b | 53 | void __lockfunc tty_lock_slave(struct tty_struct *tty) |
89c8d91e | 54 | { |
2aff5e2b PH |
55 | if (tty && tty != tty->link) { |
56 | WARN_ON(!mutex_is_locked(&tty->link->legacy_mutex) || | |
57 | !tty->driver->type == TTY_DRIVER_TYPE_PTY || | |
58 | !tty->driver->type == PTY_TYPE_SLAVE); | |
89c8d91e AC |
59 | tty_lock_nested(tty, TTY_MUTEX_NESTED); |
60 | } | |
61 | } | |
89c8d91e | 62 | |
2aff5e2b | 63 | void __lockfunc tty_unlock_slave(struct tty_struct *tty) |
89c8d91e | 64 | { |
2aff5e2b PH |
65 | if (tty && tty != tty->link) |
66 | tty_unlock(tty); | |
89c8d91e | 67 | } |