| 1 | |
| 2 | |
| 3 | *
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| 4 | * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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| 5 | * Written by David Howells ([email protected])
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| 6 | * - Derived from security/selinux/hooks.c
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| 7 |
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| 8 | #include <linux/sched/signal.h>
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| 9 | #include <linux/sched/task.h>
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| 10 | #include <linux/sched/mm.h>
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| 11 |
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| 12 | |
| 13 | * Returns true if the task does not share ->mm with another thread/process.
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| 14 |
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| 15 | bool current_is_single_threaded(void)
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| 16 | {
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| 17 | struct task_struct *task = current;
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| 18 | struct mm_struct *mm = task->mm;
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| 19 | struct task_struct *p, *t;
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| 20 | bool ret;
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| 21 |
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| 22 | if (atomic_read(&task->signal->live) != 1)
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| 23 | return false;
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| 24 |
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| 25 | if (atomic_read(&mm->mm_users) == 1)
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| 26 | return true;
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| 27 |
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| 28 | ret = false;
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| 29 | rcu_read_lock();
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| 30 | for_each_process(p) {
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| 31 | if (unlikely(p->flags & PF_KTHREAD))
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| 32 | continue;
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| 33 | if (unlikely(p == task->group_leader))
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| 34 | continue;
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| 35 |
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| 36 | for_each_thread(p, t) {
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| 37 | if (unlikely(t->mm == mm))
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| 38 | goto found;
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| 39 | if (likely(t->mm))
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| 40 | break;
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| 41 | |
| 42 | * t->mm == NULL. Make sure next_thread/next_task
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| 43 | * will see other CLONE_VM tasks which might be
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| 44 | * forked before exiting.
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| 45 |
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| 46 | smp_rmb();
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| 47 | }
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| 48 | }
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| 49 | ret = true;
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| 50 | found:
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| 51 | rcu_read_unlock();
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| 52 |
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| 53 | return ret;
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| 54 | }
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