tree 37bccfd3f1c965f793bc8f039360e460d38f5a44
parent e91e52e42814b130c20d17bc1e2adf813c50db11
author Peter Hurley <peter@hurleysoftware.com> 1362577099 -0500
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1363648439 -0700

n_tty: Fix unsafe driver-side signals

An ldisc reference is insufficient guarantee the foreground process
group is not in the process of being signalled from a hangup.

1) Reads of tty->pgrp must be locked with ctrl_lock
2) The group pid must be referenced for the duration of signalling.
   Because the driver-side is not process-context, a pid reference
   must be acquired.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>