[PATCH] pid: replace is_orphaned_pgrp with is_current_pgrp_orphaned

Every call to is_orphaned_pgrp passed in process_group(current) which is racy
with respect to another thread changing our process group.  It didn't bite us
because we were dealing with integers and the worse we would get would be a
stale answer.

In switching the checks to use struct pid to be a little more efficient and
prepare the way for pid namespaces this race became apparent.

So I simplified the calls to the more specialized is_current_pgrp_orphaned so
I didn't have to worry about making logic changes to avoid the race.

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>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index 2bdb0144a22e..c035c2f1f462 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -1188,7 +1188,7 @@ static int job_control(struct tty_struct *tty, struct file *file)
                         printk("read_chan: tty->pgrp <= 0!\n");
                 else if (process_group(current) != tty->pgrp) {
                         if (is_ignored(SIGTTIN) ||
-                            is_orphaned_pgrp(process_group(current)))
+                            is_current_pgrp_orphaned())
                                 return -EIO;
                         kill_pg(process_group(current), SIGTTIN, 1);
                         return -ERESTARTSYS;