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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - lib/is_single_threaded.c
1 /* Function to determine if a thread group is single threaded or not
3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 * - Derived from security/selinux/hooks.c
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public Licence
9 * as published by the Free Software Foundation; either version
10 * 2 of the Licence, or (at your option) any later version.
13 #include <linux/sched.h>
16 * Returns true if the task does not share ->mm with another thread/process.
18 bool is_single_threaded(struct task_struct
*task
)
20 struct mm_struct
*mm
= task
->mm
;
21 struct task_struct
*p
, *t
;
26 if (atomic_read(&task
->signal
->live
) != 1)
29 if (atomic_read(&mm
->mm_users
) == 1)
33 down_write(&mm
->mmap_sem
);
36 if (unlikely(p
->flags
& PF_KTHREAD
))
38 if (unlikely(p
== task
->group_leader
))
43 if (unlikely(t
->mm
== mm
))
47 } while_each_thread(p
, t
);
52 up_write(&mm
->mmap_sem
);