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Commit ddcd9fb6 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Greg Kroah-Hartman
Browse files

tty: remove tty_lock_nested 



This changes all remaining users of tty_lock_nested
to be non-recursive, which lets us kill this function.
As a consequence, we won't need to keep the lock count
any more, which allows more simplifications later.

Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 20365219

drivers/char/pty.c

+1 −1
Original line number Diff line number Diff line
@@ -62,7 +62,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp) 
		if (tty->driver == ptm_driver)

			devpts_pty_kill(tty->link);

#endif

		tty_vhangup(tty->link);

		tty_vhangup_locked(tty->link);

	}

}

drivers/char/selection.c

+2 −2
Original line number Diff line number Diff line
@@ -313,7 +313,8 @@ int paste_selection(struct tty_struct *tty) 
	struct  tty_ldisc *ld;

	DECLARE_WAITQUEUE(wait, current);



	tty_lock_nested(); /* always called with BTM from vt_ioctl */

	/* always called with BTM from vt_ioctl */

	WARN_ON(!tty_locked());



	acquire_console_sem();

	poke_blanked_console();
@@ -343,6 +344,5 @@ int paste_selection(struct tty_struct *tty) 
	__set_current_state(TASK_RUNNING);



	tty_ldisc_deref(ld);

	tty_unlock();

	return 0;

}

drivers/char/tty_io.c

+20 −21
Original line number Diff line number Diff line
@@ -492,10 +492,8 @@ EXPORT_SYMBOL_GPL(tty_wakeup); 
 *		  tasklist_lock to walk task list for hangup event

 *		    ->siglock to protect ->signal/->sighand

 */

static void do_tty_hangup(struct work_struct *work)

void tty_vhangup_locked(struct tty_struct *tty)

{

	struct tty_struct *tty =

		container_of(work, struct tty_struct, hangup_work);

	struct file *cons_filp = NULL;

	struct file *filp, *f = NULL;

	struct task_struct *p;
@@ -517,8 +515,6 @@ static void do_tty_hangup(struct work_struct *work) 
	/* inuse_filps is protected by the single tty lock,

	   this really needs to change if we want to flush the

	   workqueue with the lock held */

	tty_lock_nested(); /* called with BTM held from pty_close and

				others */

	check_tty_count(tty, "do_tty_hangup");



	file_list_lock();
@@ -598,11 +594,20 @@ static void do_tty_hangup(struct work_struct *work) 
	 */

	set_bit(TTY_HUPPED, &tty->flags);

	tty_ldisc_enable(tty);

	tty_unlock();

	if (f)

		fput(f);

}



static void do_tty_hangup(struct work_struct *work)

{

	struct tty_struct *tty =

		container_of(work, struct tty_struct, hangup_work);



	tty_lock();

	tty_vhangup_locked(tty);

	tty_unlock();

}



/**

 *	tty_hangup		-	trigger a hangup event

 *	@tty: tty to hangup
@@ -638,7 +643,9 @@ void tty_vhangup(struct tty_struct *tty) 


	printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));

#endif

	do_tty_hangup(&tty->hangup_work);

	tty_lock();

	tty_vhangup_locked(tty);

	tty_unlock();

}



EXPORT_SYMBOL(tty_vhangup);
@@ -719,10 +726,12 @@ void disassociate_ctty(int on_exit) 
	tty = get_current_tty();

	if (tty) {

		tty_pgrp = get_pid(tty->pgrp);

		tty_lock_nested(); /* see above */

		if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)

			tty_vhangup(tty);

		if (on_exit) {

			tty_lock();

			if (tty->driver->type != TTY_DRIVER_TYPE_PTY)

				tty_vhangup_locked(tty);

			tty_unlock();

		}

		tty_kref_put(tty);

	} else if (on_exit) {

		struct pid *old_pgrp;
@@ -1213,18 +1222,14 @@ static int tty_driver_install_tty(struct tty_driver *driver, 
	int ret;



	if (driver->ops->install) {

		tty_lock_nested(); /* already called with BTM held */

		ret = driver->ops->install(driver, tty);

		tty_unlock();

		return ret;

	}



	if (tty_init_termios(tty) == 0) {

		tty_lock_nested();

		tty_driver_kref_get(driver);

		tty->count++;

		driver->ttys[idx] = tty;

		tty_unlock();

		return 0;

	}

	return -ENOMEM;
@@ -1317,15 +1322,11 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx, 
	struct tty_struct *tty;

	int retval;



	tty_lock_nested(); /* always called with tty lock held already */



	/* Check if pty master is being opened multiple times */

	if (driver->subtype == PTY_TYPE_MASTER &&

		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {

		tty_unlock();

		return ERR_PTR(-EIO);

	}

	tty_unlock();



	/*

	 * First time open is complex, especially for PTY devices.
@@ -1369,9 +1370,7 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx, 
	if (printk_ratelimit())

		printk(KERN_INFO "tty_init_dev: ldisc open failed, "

				 "clearing slot %d\n", idx);

	tty_lock_nested();

	release_tty(tty, idx);

	tty_unlock();

	return ERR_PTR(retval);

}

drivers/char/tty_ldisc.c

+1 −2
Original line number Diff line number Diff line
@@ -450,9 +450,8 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) 
	if (ld->ops->open) {

		int ret;

                /* BTM here locks versus a hangup event */

		tty_lock_nested(); /* always held here already */

		WARN_ON(!tty_locked());

		ret = ld->ops->open(tty);

		tty_unlock();

		return ret;

	}

	return 0;

include/linux/tty.h

+1 −15
Original line number Diff line number Diff line
@@ -417,6 +417,7 @@ extern int is_ignored(int sig); 
extern int tty_signal(int sig, struct tty_struct *tty);

extern void tty_hangup(struct tty_struct *tty);

extern void tty_vhangup(struct tty_struct *tty);

extern void tty_vhangup_locked(struct tty_struct *tty);

extern void tty_vhangup_self(void);

extern void tty_unhangup(struct file *filp);

extern int tty_hung_up_p(struct file *filp);
@@ -578,21 +579,6 @@ extern long vt_compat_ioctl(struct tty_struct *tty, struct file * file, 
		     unsigned int cmd, unsigned long arg);



/* functions for preparation of BKL removal */



/*

 * tty_lock_nested get the tty_lock while potentially holding it

 *

 * The Big TTY Mutex is a recursive lock, meaning you can take it

 * from a thread that is already holding it.

 * This is bad for a number of reasons, so tty_lock_nested should

 * really be used as rarely as possible. If a code location can

 * be shown to never get called with this held already, it should

 * use tty_lock() instead.

 */

static inline void __lockfunc tty_lock_nested(void) __acquires(kernel_lock)

{

	lock_kernel();

}

static inline void tty_lock(void) __acquires(kernel_lock)

{

#ifdef CONFIG_LOCK_KERNEL