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Commit 0eae4686 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
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Revert "tty: pty: Fix race condition between release_one_tty and pty_write" 



This reverts commit b9ca5f85 as 0-day
shows it has a circular locking dependency.

Fixes: b9ca5f85 ("tty: pty: Fix race condition between release_one_tty and pty_write")
Reported-by: default avatarkernel test robot <lkp@intel.com>
Cc: Sahara <keun-o.park@darkmatter.ae>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4b0a2c5f

drivers/tty/pty.c

+0 −7
Original line number Diff line number Diff line
@@ -116,12 +116,6 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c) 
	if (tty->stopped)

		return 0;



	mutex_lock(&tty_mutex);

	if (to->magic != TTY_MAGIC) {

		mutex_unlock(&tty_mutex);

		return -EIO;

	}



	if (c > 0) {

		spin_lock_irqsave(&to->port->lock, flags);

		/* Stuff the data into the input queue of the other end */
@@ -131,7 +125,6 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c) 
			tty_flip_buffer_push(to->port);

		spin_unlock_irqrestore(&to->port->lock, flags);

	}

	mutex_unlock(&tty_mutex);

	return c;

}

drivers/tty/tty_io.c

+0 −3
Original line number Diff line number Diff line
@@ -1448,13 +1448,10 @@ static void release_one_tty(struct work_struct *work) 
	struct tty_driver *driver = tty->driver;

	struct module *owner = driver->owner;



	mutex_lock(&tty_mutex);

	if (tty->ops->cleanup)

		tty->ops->cleanup(tty);



	tty->magic = 0;

	mutex_unlock(&tty_mutex);



	tty_driver_kref_put(driver);

	module_put(owner);