/* * drivers/char/tty_lock.c */ #include <linux/tty.h> #include <linux/module.h> #include <linux/kallsyms.h> #include <linux/semaphore.h> #include <linux/sched.h> /* * The 'big tty mutex' * * This mutex is taken and released by tty_lock() and tty_unlock(), * replacing the older big kernel lock. * It can no longer be taken recursively, and does not get * released implicitly while sleeping. * * Don't use in new code. */ static DEFINE_MUTEX(big_tty_mutex); struct task_struct *__big_tty_mutex_owner; EXPORT_SYMBOL_GPL(__big_tty_mutex_owner); /* * Getting the big tty mutex. */ void __lockfunc tty_lock(void) { struct task_struct *task = current; WARN_ON(__big_tty_mutex_owner == task); mutex_lock(&big_tty_mutex); __big_tty_mutex_owner = task; } EXPORT_SYMBOL(tty_lock); void __lockfunc tty_unlock(void) { struct task_struct *task = current; WARN_ON(__big_tty_mutex_owner != task); __big_tty_mutex_owner = NULL; mutex_unlock(&big_tty_mutex); } EXPORT_SYMBOL(tty_unlock);