Re: [PATCH] net: remove disc_data_lock in ppp line discipline

From: Jakub Kicinski
Date: Wed Dec 16 2020 - 19:49:21 EST


On Tue, 15 Dec 2020 23:00:54 +0800 Gao Yan wrote:
> tty layer provide tty->ldisc_sem lock to protect tty->disc_data;
> For examlpe, when cpu A is running ppp_synctty_ioctl that
> hold the tty->ldisc_sem, so if cpu B calls ppp_synctty_close,
> it will wait until cpu A release tty->ldisc_sem. So I think it is
> unnecessary to have the disc_data_lock;
>
> cpu A cpu B
> tty_ioctl tty_reopen
> ->hold tty->ldisc_sem ->hold tty->ldisc_sem(write), failed
> ->ld->ops->ioctl ->wait...
> ->release tty->ldisc_sem ->wait...OK,hold tty->ldisc_sem
> ->tty_ldisc_reinit
> ->tty_ldisc_close
> ->ld->ops->close
>
> Signed-off-by: Gao Yan <gao.yanB@xxxxxxx>

# Form letter - net-next is closed

We have already sent the networking pull request for 5.11 and therefore
net-next is closed for new drivers, features, code refactoring and
optimizations. We are currently accepting bug fixes only.

Please repost when net-next reopens after 5.11-rc1 is cut.

Look out for the announcement on the mailing list or check:
http://vger.kernel.org/~davem/net-next.html

RFC patches sent for review only are obviously welcome at any time.