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 enum { 10 TTY_MUTEX_NORMAL, 11 TTY_MUTEX_NESTED, 12 }; 13 14 /* 15 * Getting the big tty mutex. 16 */ 17 18 static void __lockfunc tty_lock_nested(struct tty_struct *tty, 19 unsigned int subclass) 20 { 21 if (tty->magic != TTY_MAGIC) { 22 pr_err("L Bad %p\n", tty); 23 WARN_ON(1); 24 return; 25 } 26 tty_kref_get(tty); 27 mutex_lock_nested(&tty->legacy_mutex, subclass); 28 } 29 30 void __lockfunc tty_lock(struct tty_struct *tty) 31 { 32 return tty_lock_nested(tty, TTY_MUTEX_NORMAL); 33 } 34 EXPORT_SYMBOL(tty_lock); 35 36 void __lockfunc tty_unlock(struct tty_struct *tty) 37 { 38 if (tty->magic != TTY_MAGIC) { 39 pr_err("U Bad %p\n", tty); 40 WARN_ON(1); 41 return; 42 } 43 mutex_unlock(&tty->legacy_mutex); 44 tty_kref_put(tty); 45 } 46 EXPORT_SYMBOL(tty_unlock); 47 48 /* 49 * Getting the big tty mutex for a pair of ttys with lock ordering 50 * On a non pty/tty pair tty2 can be NULL which is just fine. 51 */ 52 void __lockfunc tty_lock_pair(struct tty_struct *tty, 53 struct tty_struct *tty2) 54 { 55 if (tty < tty2) { 56 tty_lock(tty); 57 tty_lock_nested(tty2, TTY_MUTEX_NESTED); 58 } else { 59 if (tty2 && tty2 != tty) 60 tty_lock(tty2); 61 tty_lock_nested(tty, TTY_MUTEX_NESTED); 62 } 63 } 64 EXPORT_SYMBOL(tty_lock_pair); 65 66 void __lockfunc tty_unlock_pair(struct tty_struct *tty, 67 struct tty_struct *tty2) 68 { 69 tty_unlock(tty); 70 if (tty2 && tty2 != tty) 71 tty_unlock(tty2); 72 } 73 EXPORT_SYMBOL(tty_unlock_pair); 74