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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); |
55eb9a6c | 19 | static DECLARE_COMPLETION(busymod_work_started); |
a2818ee4 JL |
20 | |
21 | static void busymod_work_func(struct work_struct *work) | |
22 | { | |
547840bd | 23 | pr_info("%s enter\n", __func__); |
55eb9a6c | 24 | complete(&busymod_work_started); |
547840bd JL |
25 | |
26 | while (READ_ONCE(block_transition)) { | |
27 | /* | |
28 | * Busy-wait until the sysfs writer has acknowledged a | |
29 | * blocked transition and clears the flag. | |
30 | */ | |
31 | msleep(20); | |
32 | } | |
33 | ||
a2818ee4 JL |
34 | pr_info("%s exit\n", __func__); |
35 | } | |
36 | ||
37 | static int test_klp_callbacks_busy_init(void) | |
38 | { | |
39 | pr_info("%s\n", __func__); | |
547840bd JL |
40 | schedule_work(&work); |
41 | ||
55eb9a6c JL |
42 | /* |
43 | * To synchronize kernel messages, hold the init function from | |
44 | * exiting until the work function's entry message has printed. | |
45 | */ | |
46 | wait_for_completion(&busymod_work_started); | |
47 | ||
547840bd JL |
48 | if (!block_transition) { |
49 | /* | |
50 | * Serialize output: print all messages from the work | |
51 | * function before returning from init(). | |
52 | */ | |
53 | flush_work(&work); | |
54 | } | |
55 | ||
a2818ee4 JL |
56 | return 0; |
57 | } | |
58 | ||
59 | static void test_klp_callbacks_busy_exit(void) | |
60 | { | |
547840bd JL |
61 | WRITE_ONCE(block_transition, false); |
62 | flush_work(&work); | |
a2818ee4 JL |
63 | pr_info("%s\n", __func__); |
64 | } | |
65 | ||
66 | module_init(test_klp_callbacks_busy_init); | |
67 | module_exit(test_klp_callbacks_busy_exit); | |
68 | MODULE_LICENSE("GPL"); | |
69 | MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>"); | |
70 | MODULE_DESCRIPTION("Livepatch test: busy target module"); |