Commit 680a9671 authored Feb 12, 2007 by Eric W. Biederman Committed by Linus Torvalds Feb 12, 2007

[PATCH] tty: clarify disassociate_ctty



The code to look at tty_old_pgrp and send SIGHUP and SIGCONT when it is
present only executes when disassociate_ctty is called from do_exit.  Make
this clear by adding an explict on_exit check, and explicitly setting
tty_old_pgrp to 0.

In addition fix the locking by reading tty_old_pgrp under the siglock.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent cdc62330

drivers/char/tty_io.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -1508,8 +1508,12 @@ void disassociate_ctty(int on_exit)
		/* XXX: here we race, there is nothing protecting tty */
		if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
		tty_vhangup(tty);
		} else {
		pid_t old_pgrp = current->signal->tty_old_pgrp;
		} else if (on_exit) {
		pid_t old_pgrp;
		spin_lock_irq(&current->sighand->siglock);
		old_pgrp = current->signal->tty_old_pgrp;
		current->signal->tty_old_pgrp = 0;
		spin_unlock_irq(&current->sighand->siglock);
		if (old_pgrp) {
		kill_pg(old_pgrp, SIGHUP, on_exit);
		kill_pg(old_pgrp, SIGCONT, on_exit);