tty: disassociate_ctty() sends the extra SIGCONT

commit 03e1261778cca782d41a3d8e3945ca88cf93e01e upstream.

Starting from v3.10 (probably commit f91e2590410b: "tty: Signal
foreground group processes in hangup") disassociate_ctty() sends SIGCONT
if tty && on_exit.  This breaks LSB test-suite, in particular test8 in
_exit.c and test40 in sigcon5.c.

Put the "!on_exit" check back to restore the old behaviour.

Review by Peter Hurley:
 "Yes, this regression was introduced by me in that commit.  The effect
  of the regression is that ptys will receive a SIGCONT when, in similar
  circumstances, ttys would not.

  The fact that two test vectors accidentally tripped over this
  regression suggests that some other apps may as well.

  Thanks for catching this"

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Karel Srot <ksrot@redhat.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 4476682139006400fe86990b8436f835d73fd373..59d26ef538d864e4396e8f76bd560b68908e8b13 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -850,7 +850,8 @@ void disassociate_ctty(int on_exit)
                        struct pid *tty_pgrp = tty_get_pgrp(tty);
                        if (tty_pgrp) {
                                kill_pgrp(tty_pgrp, SIGHUP, on_exit);
-                               kill_pgrp(tty_pgrp, SIGCONT, on_exit);
+                               if (!on_exit)
+                                       kill_pgrp(tty_pgrp, SIGCONT, on_exit);
                                put_pid(tty_pgrp);
                        }
                }