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Commit 3af502b9 authored by Alan Cox's avatar Alan Cox Committed by Greg Kroah-Hartman
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tty_lock: undo the old tty_lock use on the ctty 



get_current_tty has its own consistent locking. That means a pile of the
tty lock cases are not needed. As get_current_tty also keeps a reference the
tty object lifetime means we can propogate the lock removal out.

Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 22886ee9

drivers/tty/tty_io.c

+7 −2
Original line number Diff line number Diff line
@@ -855,10 +855,11 @@ void disassociate_ctty(int on_exit) 
 */

void no_tty(void)

{

	/* FIXME: Review locking here. The tty_lock never covered any race

	   between a new association and proc_clear_tty but possible we need

	   to protect against this anyway */

	struct task_struct *tsk = current;

	tty_lock();

	disassociate_ctty(0);

	tty_unlock();

	proc_clear_tty(tsk);

}
@@ -1800,6 +1801,9 @@ int tty_release(struct inode *inode, struct file *filp) 
 *

 *	We cannot return driver and index like for the other nodes because

 *	devpts will not work then. It expects inodes to be from devpts FS.

 *

 *	We need to move to returning a refcounted object from all the lookup

 *	paths including this one.

 */

static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)

{
@@ -1816,6 +1820,7 @@ static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp) 
	/* noctty = 1; */

	tty_kref_put(tty);

	/* FIXME: we put a reference and return a TTY! */

	/* This is only safe because the caller holds tty_mutex */

	return tty;

}