drivers/tty/tty_mutex.c

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