From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Date: Fri, 29 Sep 2006 09:00:41 +0000 (-0700)
Subject: [PATCH] tty: stop the tty vanishing under procfs access
X-Git-Tag: v2.6.19-rc1~734
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3cfd0885fac78c130a119ed576d18b5948fa2a5a;p=linux-2.6

[PATCH] tty: stop the tty vanishing under procfs access

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 0b615d62a1..c0e554971d 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -347,6 +347,8 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole)
 	sigemptyset(&sigign);
 	sigemptyset(&sigcatch);
 	cutime = cstime = utime = stime = cputime_zero;
+
+	mutex_lock(&tty_mutex);
 	read_lock(&tasklist_lock);
 	if (task->sighand) {
 		spin_lock_irq(&task->sighand->siglock);
@@ -388,6 +390,7 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole)
 	}
 	ppid = pid_alive(task) ? task->group_leader->real_parent->tgid : 0;
 	read_unlock(&tasklist_lock);
+	mutex_unlock(&tty_mutex);
 
 	if (!whole || num_threads<2)
 		wchan = get_wchan(task);