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tty_lock: undo the old tty_lock use on the ctty

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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: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Cox 2012-05-03 22:21:53 +01:00 committed by Greg Kroah-Hartman
parent 22886ee968
commit 3af502b966
1 changed files with 7 additions and 2 deletions
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9
drivers/tty/tty_io.c
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@ -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;
}