1
 2#include <linux/user-return-notifier.h>
 3#include <linux/percpu.h>
 4#include <linux/sched.h>
 5#include <linux/export.h>
 6
 7static DEFINE_PER_CPU(struct hlist_head, return_notifier_list);
 8
 9/*
10 * Request a notification when the current cpu returns to userspace.  Must be
11 * called in atomic context.  The notifier will also be called in atomic
12 * context.
13 */
14void user_return_notifier_register(struct user_return_notifier *urn)
15{
16	set_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY);
17	hlist_add_head(&urn->link, this_cpu_ptr(&return_notifier_list));
18}
19EXPORT_SYMBOL_GPL(user_return_notifier_register);
20
21/*
22 * Removes a registered user return notifier.  Must be called from atomic
23 * context, and from the same cpu registration occurred in.
24 */
25void user_return_notifier_unregister(struct user_return_notifier *urn)
26{
27	hlist_del(&urn->link);
28	if (hlist_empty(this_cpu_ptr(&return_notifier_list)))
29		clear_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY);
30}
31EXPORT_SYMBOL_GPL(user_return_notifier_unregister);
32
33/* Calls registered user return notifiers */
34void fire_user_return_notifiers(void)
35{
36	struct user_return_notifier *urn;
37	struct hlist_node *tmp2;
38	struct hlist_head *head;
39
40	head = &get_cpu_var(return_notifier_list);
41	hlist_for_each_entry_safe(urn, tmp2, head, link)
42		urn->on_user_return(urn);
43	put_cpu_var(return_notifier_list);
44}

 1// SPDX-License-Identifier: GPL-2.0-only
 2
 3#include <linux/user-return-notifier.h>
 4#include <linux/percpu.h>
 5#include <linux/sched.h>
 6#include <linux/export.h>
 7
 8static DEFINE_PER_CPU(struct hlist_head, return_notifier_list);
 9
10/*
11 * Request a notification when the current cpu returns to userspace.  Must be
12 * called in atomic context.  The notifier will also be called in atomic
13 * context.
14 */
15void user_return_notifier_register(struct user_return_notifier *urn)
16{
17	set_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY);
18	hlist_add_head(&urn->link, this_cpu_ptr(&return_notifier_list));
19}
20EXPORT_SYMBOL_GPL(user_return_notifier_register);
21
22/*
23 * Removes a registered user return notifier.  Must be called from atomic
24 * context, and from the same cpu registration occurred in.
25 */
26void user_return_notifier_unregister(struct user_return_notifier *urn)
27{
28	hlist_del(&urn->link);
29	if (hlist_empty(this_cpu_ptr(&return_notifier_list)))
30		clear_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY);
31}
32EXPORT_SYMBOL_GPL(user_return_notifier_unregister);
33
34/* Calls registered user return notifiers */
35void fire_user_return_notifiers(void)
36{
37	struct user_return_notifier *urn;
38	struct hlist_node *tmp2;
39	struct hlist_head *head;
40
41	head = &get_cpu_var(return_notifier_list);
42	hlist_for_each_entry_safe(urn, tmp2, head, link)
43		urn->on_user_return(urn);
44	put_cpu_var(return_notifier_list);
45}