From 6cc88bc45ce8043171089c9592da223dfab91823 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 14 Nov 2008 10:39:21 +1100 Subject: CRED: Rename is_single_threaded() to is_wq_single_threaded() Rename is_single_threaded() to is_wq_single_threaded() so that a new is_single_threaded() can be created that refers to tasks rather than waitqueues. Signed-off-by: David Howells Reviewed-by: James Morris Signed-off-by: James Morris --- lib/is_single_threaded.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 lib/is_single_threaded.c (limited to 'lib/is_single_threaded.c') diff --git a/lib/is_single_threaded.c b/lib/is_single_threaded.c new file mode 100644 index 000000000000..f1ed2fe76c65 --- /dev/null +++ b/lib/is_single_threaded.c @@ -0,0 +1,45 @@ +/* Function to determine if a thread group is single threaded or not + * + * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * - Derived from security/selinux/hooks.c + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#include + +/** + * is_single_threaded - Determine if a thread group is single-threaded or not + * @p: A task in the thread group in question + * + * This returns true if the thread group to which a task belongs is single + * threaded, false if it is not. + */ +bool is_single_threaded(struct task_struct *p) +{ + struct task_struct *g, *t; + struct mm_struct *mm = p->mm; + + if (atomic_read(&p->signal->count) != 1) + goto no; + + if (atomic_read(&p->mm->mm_users) != 1) { + read_lock(&tasklist_lock); + do_each_thread(g, t) { + if (t->mm == mm && t != p) + goto no_unlock; + } while_each_thread(g, t); + read_unlock(&tasklist_lock); + } + + return true; + +no_unlock: + read_unlock(&tasklist_lock); +no: + return false; +} -- cgit v1.2.3