Messages in this thread | | | Date | Sun, 25 Mar 2012 22:09:07 +0100 | From | Alan Cox <> | Subject | Re: TTY: tty_port questions |
| |
On Sun, 25 Mar 2012 18:20:18 +0100 Al Viro <viro@ZenIV.linux.org.uk> wrote:
> On Sun, Mar 25, 2012 at 05:14:37PM +0200, Richard Weinberger wrote: > > >> FWIW, uml console in default config is basically "start xterm for each VC". > > >> What do you suggest to do on vhangup() on one of those? > > > > > > What posix says must happen. Which is that the running processes get a > > > hangup. So a vhangup() would ensure there were no old apps on the UML > > > guess talking to the xterm (eg stealing login credentials, or abusing > > > TIOCSTI etc). > > IIRC, vhangup(2) is Linux-specific, so I would be surprised if POSIX had > anything on it...
vhangup causes a carrier drop event equivalent. The rest of the behavior is POSIX/SUSv3.
> login(1) from util-linux does vhangup(); login(1) from shadow doesn't.
Shadow assumes the getty cleans the channel I believe.
> The thing is, we don't want to do that when port is in use. And we definitely > don't want somebody to open the damn thing when it's halfway through getting > set up. I don't see any natural way to do that exclusion with tty_port - > port->{count,block_open} is protected only by a spinlock and port setup > we need to do is blocking...
How does this differ from a hardware hotplug ?
Alan
| |