Re: [patch 0/3] Re: tty contention resulting from tty_open_by_device export

From: Greg Kroah-Hartman
Date: Sun Jul 09 2017 - 07:58:43 EST

On Sun, Jul 09, 2017 at 12:41:53PM +0100, Okash Khawaja wrote:
> On Sat, Jul 08, 2017 at 10:38:03AM +0200, Greg Kroah-Hartman wrote:
> > Overall, the idea looks sane to me. Keeping userspace from opening a
> > tty that the kernel has opened internally makes sense, hopefully
> > userspace doesn't get too confused when that happens. I don't think we
> > normally return -EBUSY from an open call, have you seen what happens
> > with apps when you do this (like minicom?)
> >
> I tested this wil minincom, picocom and commands like "echo foo >
> /dev/ttyS0". They all correctly report "Device or resource busy".
> I have addressed all the comments you made. I have also split the patch
> into three. Following is summary of each.
> Patch 1: introduces the tty_kopen function and checks for TTY_KOPENED
> Patch 2: updates speakup code to use tty_kopen instead of
> tty_open_by_driver
> Patch 3: reverses the export of tty_open_by_driver

Looks great, only one tiny comment about the return value from me, and
really, it's not a big deal at all, you can send a patch 4/3 to change
that up if you want. No one really runs without the tty layer enabled :)

If there are no other objections, I'll queue this up after 4.13-rc1 is
out, nice job.

greg k-h