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46 lines
1.2 KiB
C
46 lines
1.2 KiB
C
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/* Function to determine if a thread group is single threaded or not
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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* - Derived from security/selinux/hooks.c
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <linux/sched.h>
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/**
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* is_single_threaded - Determine if a thread group is single-threaded or not
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* @p: A task in the thread group in question
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*
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* This returns true if the thread group to which a task belongs is single
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* threaded, false if it is not.
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*/
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bool is_single_threaded(struct task_struct *p)
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{
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struct task_struct *g, *t;
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struct mm_struct *mm = p->mm;
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if (atomic_read(&p->signal->count) != 1)
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goto no;
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if (atomic_read(&p->mm->mm_users) != 1) {
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read_lock(&tasklist_lock);
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do_each_thread(g, t) {
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if (t->mm == mm && t != p)
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goto no_unlock;
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} while_each_thread(g, t);
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read_unlock(&tasklist_lock);
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}
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return true;
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no_unlock:
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read_unlock(&tasklist_lock);
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no:
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return false;
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}
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