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Commit 0911261d authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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tty: Don't take tty_mutex for tty count changes 



Holding tty_mutex is no longer required to serialize changes to
the tty_count or to prevent concurrent opens of closing ttys;
tty_lock() is sufficient.

Reviewed-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 04980706

drivers/tty/tty_io.c

+0 −6
Original line number Diff line number Diff line
@@ -1804,10 +1804,6 @@ int tty_release(struct inode *inode, struct file *filp) 
	 * each iteration we avoid any problems.

	 */

	while (1) {

		/* Guard against races with tty->count changes elsewhere and

		   opens on /dev/tty */



		mutex_lock(&tty_mutex);

		tty_lock_pair(tty, o_tty);

		tty_closing = tty->count <= 1;

		o_tty_closing = o_tty &&
@@ -1840,7 +1836,6 @@ int tty_release(struct inode *inode, struct file *filp) 
		printk(KERN_WARNING "%s: %s: read/write wait queue active!\n",

				__func__, tty_name(tty, buf));

		tty_unlock_pair(tty, o_tty);

		mutex_unlock(&tty_mutex);

		schedule();

	}
@@ -1891,7 +1886,6 @@ int tty_release(struct inode *inode, struct file *filp) 
		read_unlock(&tasklist_lock);

	}



	mutex_unlock(&tty_mutex);

	tty_unlock_pair(tty, o_tty);

	/* At this point, the tty->count == 0 should ensure a dead tty

	   cannot be re-opened by a racing opener */