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