Hi Ilya,
On Wed, 2012-12-19 at 23:00 +0400, Ilya Zykov wrote:
> When we are opening ptmx, we have closed pts, by description.
> Now only if we open and after close all pts' descriptions, pty_close() sets
> this bit correctly
>
> Signed-off-by: Ilya Zykov <i...@ilyx.ru>
> ---
> drivers/tty/pty.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
> index 1ce1362..7b69307 100644
> --- a/drivers/tty/pty.c
> +++ b/drivers/tty/pty.c
> @@ -659,6 +659,7 @@ static int ptmx_open(struct inode *inode, struct file
> *filp)
> retval = ptm_driver->ops->open(tty, filp);
> if (retval)
> goto err_release;
> + set_bit(TTY_OTHER_CLOSED, &tty->flags); /* THE SLAVE STILL CLOSED */
I'm not sure this is a good idea.
Ideally, if you were only trying to make the logic "more correct", this
change would be here, instead:
mutex_unlock(&tty_mutex);
set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
+ set_bit(TTY_OTHER_CLOSED, &tty->flags); /* THE SLAVE STILL CLOSED */
tty->driver_data = inode;
tty_add_file(tty, filp);
Of course, that would be a bad idea because then the master pty_open()
would fail because of the test in pty_open().
Setting TTY_OTHER_CLOSED after the open() -- as you've done -- appears
to leave a race open when this bit is not set but while a slave open()
may still be attempted.
But as far as I can tell, this change doesn't actually affect any code
branches -- that is, doesn't actually do anything -- so no such race
exists. Is that correct?
Regards,
Peter Hurley
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