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a2818ee4 JL |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | // Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com> | |
3 | ||
4 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
5 | ||
6 | #include <linux/module.h> | |
7 | #include <linux/kernel.h> | |
547840bd | 8 | #include <linux/sched.h> |
a2818ee4 JL |
9 | #include <linux/workqueue.h> |
10 | #include <linux/delay.h> | |
11 | ||
547840bd JL |
12 | /* load/run-time control from sysfs writer */ |
13 | static bool block_transition; | |
14 | module_param(block_transition, bool, 0644); | |
15 | MODULE_PARM_DESC(block_transition, "block_transition (default=false)"); | |
a2818ee4 JL |
16 | |
17 | static void busymod_work_func(struct work_struct *work); | |
547840bd | 18 | static DECLARE_WORK(work, busymod_work_func); |
a2818ee4 JL |
19 | |
20 | static void busymod_work_func(struct work_struct *work) | |
21 | { | |
547840bd JL |
22 | pr_info("%s enter\n", __func__); |
23 | ||
24 | while (READ_ONCE(block_transition)) { | |
25 | /* | |
26 | * Busy-wait until the sysfs writer has acknowledged a | |
27 | * blocked transition and clears the flag. | |
28 | */ | |
29 | msleep(20); | |
30 | } | |
31 | ||
a2818ee4 JL |
32 | pr_info("%s exit\n", __func__); |
33 | } | |
34 | ||
35 | static int test_klp_callbacks_busy_init(void) | |
36 | { | |
37 | pr_info("%s\n", __func__); | |
547840bd JL |
38 | schedule_work(&work); |
39 | ||
40 | if (!block_transition) { | |
41 | /* | |
42 | * Serialize output: print all messages from the work | |
43 | * function before returning from init(). | |
44 | */ | |
45 | flush_work(&work); | |
46 | } | |
47 | ||
a2818ee4 JL |
48 | return 0; |
49 | } | |
50 | ||
51 | static void test_klp_callbacks_busy_exit(void) | |
52 | { | |
547840bd JL |
53 | WRITE_ONCE(block_transition, false); |
54 | flush_work(&work); | |
a2818ee4 JL |
55 | pr_info("%s\n", __func__); |
56 | } | |
57 | ||
58 | module_init(test_klp_callbacks_busy_init); | |
59 | module_exit(test_klp_callbacks_busy_exit); | |
60 | MODULE_LICENSE("GPL"); | |
61 | MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>"); | |
62 | MODULE_DESCRIPTION("Livepatch test: busy target module"); |