drivers/tty/tty_mutex.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/tty.h>
   3 #include <linux/module.h>
   4 #include <linux/kallsyms.h>
   5 #include <linux/semaphore.h>
   6 #include <linux/sched.h>
   7 #include "tty.h"
   8
   9 /* Legacy tty mutex glue */
  10
  11 /*
  12  * Getting the big tty mutex.
  13  */
  14
  15 void tty_lock(struct tty_struct *tty)
  16 {
  17         tty_kref_get(tty);
  18         mutex_lock(&tty->legacy_mutex);
  19 }
  20 EXPORT_SYMBOL(tty_lock);
  21
  22 int tty_lock_interruptible(struct tty_struct *tty)
  23 {
  24         int ret;
  25
  26         tty_kref_get(tty);
  27         ret = mutex_lock_interruptible(&tty->legacy_mutex);
  28         if (ret)
  29                 tty_kref_put(tty);
  30         return ret;
  31 }
  32
  33 void tty_unlock(struct tty_struct *tty)
  34 {
  35         mutex_unlock(&tty->legacy_mutex);
  36         tty_kref_put(tty);
  37 }
  38 EXPORT_SYMBOL(tty_unlock);
  39
  40 void tty_lock_slave(struct tty_struct *tty)
  41 {
  42         if (tty && tty != tty->link)
  43                 tty_lock(tty);
  44 }
  45
  46 void tty_unlock_slave(struct tty_struct *tty)
  47 {
  48         if (tty && tty != tty->link)
  49                 tty_unlock(tty);
  50 }
  51
  52 void tty_set_lock_subclass(struct tty_struct *tty)
  53 {
  54         lockdep_set_subclass(&tty->legacy_mutex, TTY_LOCK_SLAVE);
  55 }