Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) // SPDX-License-Identifier: GPL-2.0-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) /* Function to determine if a thread group is single threaded or not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4)  * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5)  * Written by David Howells (dhowells@redhat.com)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6)  * - Derived from security/selinux/hooks.c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) #include <linux/sched/signal.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) #include <linux/sched/task.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <linux/sched/mm.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13)  * Returns true if the task does not share ->mm with another thread/process.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) bool current_is_single_threaded(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 	struct task_struct *task = current;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 	struct mm_struct *mm = task->mm;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 	struct task_struct *p, *t;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 	bool ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 	if (atomic_read(&task->signal->live) != 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 		return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 	if (atomic_read(&mm->mm_users) == 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 		return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 	ret = false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 	rcu_read_lock();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 	for_each_process(p) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 		if (unlikely(p->flags & PF_KTHREAD))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 			continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 		if (unlikely(p == task->group_leader))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 			continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 		for_each_thread(p, t) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 			if (unlikely(t->mm == mm))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 				goto found;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 			if (likely(t->mm))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 				break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 			/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 			 * t->mm == NULL. Make sure next_thread/next_task
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 			 * will see other CLONE_VM tasks which might be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 			 * forked before exiting.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 			 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 			smp_rmb();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	ret = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) found:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 	rcu_read_unlock();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 	return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) }