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 __lockfunc tty_lock(struct tty_struct *tty)
  14 {
  15         if (tty->magic != TTY_MAGIC) {
  16                 printk(KERN_ERR "L Bad %p\n", tty);
  17                 WARN_ON(1);
  18                 return;
  19         }
  20         tty_kref_get(tty);
  21         mutex_lock(&tty->legacy_mutex);
  22 }
  23 EXPORT_SYMBOL(tty_lock);
  24
  25 void __lockfunc tty_unlock(struct tty_struct *tty)
  26 {
  27         if (tty->magic != TTY_MAGIC) {
  28                 printk(KERN_ERR "U Bad %p\n", tty);
  29                 WARN_ON(1);
  30                 return;
  31         }
  32         mutex_unlock(&tty->legacy_mutex);
  33         tty_kref_put(tty);
  34 }
  35 EXPORT_SYMBOL(tty_unlock);
  36
  37 /*
  38  * Getting the big tty mutex for a pair of ttys with lock ordering
  39  * On a non pty/tty pair tty2 can be NULL which is just fine.
  40  */
  41 void __lockfunc tty_lock_pair(struct tty_struct *tty,
  42                                         struct tty_struct *tty2)
  43 {
  44         if (tty < tty2) {
  45                 tty_lock(tty);
  46                 tty_lock(tty2);
  47         } else {
  48                 if (tty2 && tty2 != tty)
  49                         tty_lock(tty2);
  50                 tty_lock(tty);
  51         }
  52 }
  53 EXPORT_SYMBOL(tty_lock_pair);
  54
  55 void __lockfunc tty_unlock_pair(struct tty_struct *tty,
  56                                                 struct tty_struct *tty2)
  57 {
  58         tty_unlock(tty);
  59         if (tty2 && tty2 != tty)
  60                 tty_unlock(tty2);
  61 }
  62 EXPORT_SYMBOL(tty_unlock_pair);