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 * The 'big tty mutex' 9 * 10 * This mutex is taken and released by tty_lock() and tty_unlock(), 11 * replacing the older big kernel lock. 12 * It can no longer be taken recursively, and does not get 13 * released implicitly while sleeping. 14 * 15 * Don't use in new code. 16 */ 17 static DEFINE_MUTEX(big_tty_mutex); 18 struct task_struct *__big_tty_mutex_owner; 19 EXPORT_SYMBOL_GPL(__big_tty_mutex_owner); 20 21 /* 22 * Getting the big tty mutex. 23 */ 24 void __lockfunc tty_lock(void) 25 { 26 struct task_struct *task = current; 27 28 WARN_ON(__big_tty_mutex_owner == task); 29 30 mutex_lock(&big_tty_mutex); 31 __big_tty_mutex_owner = task; 32 } 33 EXPORT_SYMBOL(tty_lock); 34 35 void __lockfunc tty_unlock(void) 36 { 37 struct task_struct *task = current; 38 39 WARN_ON(__big_tty_mutex_owner != task); 40 __big_tty_mutex_owner = NULL; 41 42 mutex_unlock(&big_tty_mutex); 43 } 44 EXPORT_SYMBOL(tty_unlock); 45