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54 lines
1.2 KiB
54 lines
1.2 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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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 ([email protected]) |
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* - Derived from security/selinux/hooks.c |
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*/ |
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#include <linux/sched/signal.h> |
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#include <linux/sched/task.h> |
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#include <linux/sched/mm.h> |
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/* |
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* Returns true if the task does not share ->mm with another thread/process. |
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*/ |
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bool current_is_single_threaded(void) |
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{ |
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struct task_struct *task = current; |
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struct mm_struct *mm = task->mm; |
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struct task_struct *p, *t; |
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bool ret; |
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if (atomic_read(&task->signal->live) != 1) |
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return false; |
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if (atomic_read(&mm->mm_users) == 1) |
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return true; |
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ret = false; |
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rcu_read_lock(); |
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for_each_process(p) { |
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if (unlikely(p->flags & PF_KTHREAD)) |
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continue; |
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if (unlikely(p == task->group_leader)) |
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continue; |
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for_each_thread(p, t) { |
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if (unlikely(t->mm == mm)) |
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goto found; |
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if (likely(t->mm)) |
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break; |
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/* |
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* t->mm == NULL. Make sure next_thread/next_task |
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* will see other CLONE_VM tasks which might be |
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* forked before exiting. |
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*/ |
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smp_rmb(); |
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} |
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} |
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ret = true; |
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found: |
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rcu_read_unlock(); |
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return ret; |
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}
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