[linux-block.git] / lib / livepatch / test_klp_callbacks_busy.c

// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/workqueue.h>
#include <linux/delay.h>

/* load/run-time control from sysfs writer  */
static bool block_transition;
module_param(block_transition, bool, 0644);
MODULE_PARM_DESC(block_transition, "block_transition (default=false)");

static void busymod_work_func(struct work_struct *work);
static DECLARE_WORK(work, busymod_work_func);
static DECLARE_COMPLETION(busymod_work_started);

static void busymod_work_func(struct work_struct *work)
{
	pr_info("%s enter\n", __func__);
	complete(&busymod_work_started);

	while (READ_ONCE(block_transition)) {
		/*
		 * Busy-wait until the sysfs writer has acknowledged a
		 * blocked transition and clears the flag.
		 */
		msleep(20);
	}

	pr_info("%s exit\n", __func__);
}

static int test_klp_callbacks_busy_init(void)
{
	pr_info("%s\n", __func__);
	schedule_work(&work);

	/*
	 * To synchronize kernel messages, hold the init function from
	 * exiting until the work function's entry message has printed.
	 */
	wait_for_completion(&busymod_work_started);

	if (!block_transition) {
		/*
		 * Serialize output: print all messages from the work
		 * function before returning from init().
		 */
		flush_work(&work);
	}

	return 0;
}

static void test_klp_callbacks_busy_exit(void)
{
	WRITE_ONCE(block_transition, false);
	flush_work(&work);
	pr_info("%s\n", __func__);
}

module_init(test_klp_callbacks_busy_init);
module_exit(test_klp_callbacks_busy_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
MODULE_DESCRIPTION("Livepatch test: busy target module");
Commit	Line	Data
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
a2818ee4 JL	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);
547840bd JL	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);
547840bd JL	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");