[linux.git] / drivers / tty / tty_mutex.c

/*
 * 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);
Commit	Line	Data
b07471fa AB	1	/*
	2	* drivers/char/tty_lock.c
	3	*/
	4	#include <linux/tty.h>
	5	#include <linux/module.h>
	6	#include <linux/kallsyms.h>
	7	#include <linux/semaphore.h>
	8	#include <linux/sched.h>
	9
	10	/*
	11	* The 'big tty mutex'
	12	*
	13	* This mutex is taken and released by tty_lock() and tty_unlock(),
	14	* replacing the older big kernel lock.
	15	* It can no longer be taken recursively, and does not get
	16	* released implicitly while sleeping.
	17	*
	18	* Don't use in new code.
	19	*/
	20	static DEFINE_MUTEX(big_tty_mutex);
	21	struct task_struct *__big_tty_mutex_owner;
	22	EXPORT_SYMBOL_GPL(__big_tty_mutex_owner);
	23
	24	/*
	25	* Getting the big tty mutex.
	26	*/
	27	void __lockfunc tty_lock(void)
	28	{
	29	struct task_struct *task = current;
	30
	31	WARN_ON(__big_tty_mutex_owner == task);
	32
	33	mutex_lock(&big_tty_mutex);
	34	__big_tty_mutex_owner = task;
	35	}
	36	EXPORT_SYMBOL(tty_lock);
	37
	38	void __lockfunc tty_unlock(void)
	39	{
	40	struct task_struct *task = current;
	41
	42	WARN_ON(__big_tty_mutex_owner != task);
	43	__big_tty_mutex_owner = NULL;
	44
	45	mutex_unlock(&big_tty_mutex);
	46	}
	47	EXPORT_SYMBOL(tty_unlock);