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
   8 /* Legacy tty mutex glue */
   9
  10 /*
  11  * Getting the big tty mutex.
  12  */
  13
  14 void tty_lock(struct tty_struct *tty)
  15 {
  16         if (WARN(tty->magic != TTY_MAGIC, "L Bad %p\n", tty))
  17                 return;
  18         tty_kref_get(tty);
  19         mutex_lock(&tty->legacy_mutex);
  20 }
  21 EXPORT_SYMBOL(tty_lock);
  22
  23 int tty_lock_interruptible(struct tty_struct *tty)
  24 {
  25         int ret;
  26
  27         if (WARN(tty->magic != TTY_MAGIC, "L Bad %p\n", tty))
  28                 return -EIO;
  29         tty_kref_get(tty);
  30         ret = mutex_lock_interruptible(&tty->legacy_mutex);
  31         if (ret)
  32                 tty_kref_put(tty);
  33         return ret;
  34 }
  35
  36 void tty_unlock(struct tty_struct *tty)
  37 {
  38         if (WARN(tty->magic != TTY_MAGIC, "U Bad %p\n", tty))
  39                 return;
  40         mutex_unlock(&tty->legacy_mutex);
  41         tty_kref_put(tty);
  42 }
  43 EXPORT_SYMBOL(tty_unlock);
  44
  45 void tty_lock_slave(struct tty_struct *tty)
  46 {
  47         if (tty && tty != tty->link)
  48                 tty_lock(tty);
  49 }
  50
  51 void tty_unlock_slave(struct tty_struct *tty)
  52 {
  53         if (tty && tty != tty->link)
  54                 tty_unlock(tty);
  55 }
  56
  57 void tty_set_lock_subclass(struct tty_struct *tty)
  58 {
  59         lockdep_set_subclass(&tty->legacy_mutex, TTY_LOCK_SLAVE);
  60 }