test_klp_callbacks_busy.c (1510B)
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> 8#include <linux/sched.h> 9#include <linux/workqueue.h> 10#include <linux/delay.h> 11 12/* load/run-time control from sysfs writer */ 13static bool block_transition; 14module_param(block_transition, bool, 0644); 15MODULE_PARM_DESC(block_transition, "block_transition (default=false)"); 16 17static void busymod_work_func(struct work_struct *work); 18static DECLARE_WORK(work, busymod_work_func); 19 20static void busymod_work_func(struct work_struct *work) 21{ 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 32 pr_info("%s exit\n", __func__); 33} 34 35static int test_klp_callbacks_busy_init(void) 36{ 37 pr_info("%s\n", __func__); 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 48 return 0; 49} 50 51static void test_klp_callbacks_busy_exit(void) 52{ 53 WRITE_ONCE(block_transition, false); 54 flush_work(&work); 55 pr_info("%s\n", __func__); 56} 57 58module_init(test_klp_callbacks_busy_init); 59module_exit(test_klp_callbacks_busy_exit); 60MODULE_LICENSE("GPL"); 61MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>"); 62MODULE_DESCRIPTION("Livepatch test: busy target module");