+ tty-clarify-disassociate_ctty.patch added to -mm tree

+ tty-clarify-disassociate_ctty.patch added to -mm tree

[akpm]

The patch titled
     tty: clarify disassociate_ctty
has been added to the -mm tree.  Its filename is
     tty-clarify-disassociate_ctty.patch

See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this

------------------------------------------------------
Subject: tty: clarify disassociate_ctty
From: Eric W. Biederman <ebiederm@xmission.com>

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@osdl.org>
---

 drivers/char/tty_io.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff -puN drivers/char/tty_io.c~tty-clarify-disassociate_ctty drivers/char/tty_io.c
--- a/drivers/char/tty_io.c~tty-clarify-disassociate_ctty
+++ a/drivers/char/tty_io.c
@@ -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);
_

Patches currently in -mm which might be from ebiederm@xmission.com are

origin.patch
revert-identifier-to-nsproxy.patch
vt-fix-comments-to-not-refer-to-kill_proc.patch
n_r3964-use-struct-pid-to-track-user-space-clients.patch
smbfs-make-conn_pid-a-struct-pid.patch
ncpfs-use-struct-pid-to-track-the-userspace-watchdog-process.patch
ncpfs-ensure-we-free-wdog_pid-on-parse_option-or-fill_inode-failure.patch
usbatm-update-to-use-the-kthread-api.patch
genapic-optimize-fix-apic-mode-setup-2.patch
genapic-always-use-physical-delivery-mode-on-8-cpus.patch
genapic-remove-es7000-workaround.patch
genapic-remove-clustered-apic-mode.patch
genapic-default-to-physical-mode-on-hotplug-cpu-kernels.patch
vt-refactor-console-sak-processing.patch
sysctl_ms_jiffies-fix-oldlen-semantics.patch
9p-use-kthread_stop-instead-of-sending-a-sigkill.patch
tty-make-__proc_set_tty-static.patch
tty-clarify-disassociate_ctty.patch
tty-fix-the-locking-for-signal-session-in-disassociate_ctty.patch
signal-use-kill_pgrp-not-kill_pg-in-the-sunos-compatibility-code.patch
signal-rewrite-kill_something_info-so-it-uses-newer-helpers.patch
pid-make-session_of_pgrp-use-struct-pid-instead-of-pid_t.patch
pid-use-struct-pid-for-talking-about-process-groups-in-exitc.patch
pid-replace-is_orphaned_pgrp-with-is_current_pgrp_orphaned.patch
tty-update-the-tty-layer-to-work-with-struct-pid.patch
pid-replace-do-while_each_task_pid-with-do-while_each_pid_task.patch
pid-remove-now-unused-do_each_task_pid-and-while_each_task_pid.patch
pid-remove-the-now-unused-kill_pg-kill_pg_info-and-__kill_pg_info.patch
sched2-sched-domain-sysctl-use-ctl_unnumbered.patch
mm-implement-swap-prefetching-use-ctl_unnumbered.patch
readahead-sysctl-parameters-use-ctl_unnumbered.patch
updated-i386-cleanup-apic-code.patch
updated-i386-rework-local-apic-calibration.patch
updated-dynticks-fix-nmi-watchdog.patch
clockevents-core-check-for-clock-event-device-handler-being-non-null-before-calling-it.patch
pidhash-temporary-debug-checks.patch
vdso-print-fatal-signals-use-ctl_unnumbered.patch