tty_io: fix remaining pid struct locking

This fixes the last couple of pid struct locking failures I know about.

[oleg@tv-sign.ru: clean up do_task_stat()]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/proc/array.c b/fs/proc/array.c
index b07a71002f2f..c135cbdd9127 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -429,7 +429,9 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
                 struct signal_struct *sig = task->signal;
 
                 if (sig->tty) {
-                        tty_pgrp = pid_nr_ns(sig->tty->pgrp, ns);
+                        struct pid *pgrp = tty_get_pgrp(sig->tty);
+                        tty_pgrp = pid_nr_ns(pgrp, ns);
+                        put_pid(pgrp);
                         tty_nr = new_encode_dev(tty_devnum(sig->tty));
                 }