projects/linux·blob master · refs

45 lines · 1.3 KiB

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}