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More simple kthread experiments, failed wait queue experiment

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Ciro Santilli
2017-05-25 08:18:03 +01:00
parent 3eaac95c0f
commit 36f48aa9c7
5 changed files with 161 additions and 2 deletions
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2
README.md
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@@ -231,5 +231,7 @@ ARM TODOs:
1. [workqueue](kernel_module/workqueue.c)
1. [sleep](kernel_module/sleep.c)
1. [kthread](kernel_module/kthread.c)
1. [kthreads](kernel_module/kthreads.c)
1. [kthread_uninterruptible](kernel_module/kthread_uninterruptible.c)
1. [timer](kernel_module/timer.c)
1. [work_from_work](kernel_module/work_from_work.c)

38
kernel_module/kthread_uninterruptible.c Normal file
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@@ -0,0 +1,38 @@
/*
Let's block the entire kernel! Yay!
Also try after dmesg -n 1 to become convinced of the full blockage.
*/
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
MODULE_LICENSE("GPL");
static struct task_struct *kthread;
static int work_func(void *data)
{
set_current_state(TASK_UNINTERRUPTIBLE);
int i = 0;
while (!kthread_should_stop()) {
printk(KERN_INFO "%d\n", i);
i++;
if (i == 10)
i = 0;
}
return 0;
}
int init_module(void)
{
kthread = kthread_create(work_func, NULL, "mykthread");
wake_up_process(kthread);
return 0;
}
void cleanup_module(void)
{
kthread_stop(kthread);
}

53
kernel_module/kthreads.c Normal file
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@@ -0,0 +1,53 @@
/*
2 kthreads!!! Will they interleave??? Yup.
*/
#include <linux/delay.h> /* usleep_range */
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
MODULE_LICENSE("GPL");
static struct task_struct *kthread1, *kthread2;
static int work_func1(void *data)
{
int i = 0;
while (!kthread_should_stop()) {
printk(KERN_INFO "1 %d\n", i);
usleep_range(1000000, 1000001);
i++;
if (i == 10)
i = 0;
}
return 0;
}
static int work_func2(void *data)
{
int i = 0;
while (!kthread_should_stop()) {
printk(KERN_INFO "2 %d\n", i);
usleep_range(1000000, 1000001);
i++;
if (i == 10)
i = 0;
}
return 0;
}
int init_module(void)
{
kthread1 = kthread_create(work_func1, NULL, "mykthread1");
kthread2 = kthread_create(work_func2, NULL, "mykthread2");
wake_up_process(kthread1);
wake_up_process(kthread2);
return 0;
}
void cleanup_module(void)
{
kthread_stop(kthread1);
kthread_stop(kthread2);
}

5
kernel_module/poll.c
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@@ -1,9 +1,9 @@
/*
TODO now yet waiting for anything!
Basic poll file_operation example.
Waits for a second, give jiffies to user, wait for a second...
usleep_range
*/
#include <asm/uaccess.h> /* copy_from_user, copy_to_user */
@@ -17,6 +17,7 @@ usleep_range
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/printk.h> /* printk */
#include <linux/wait.h> /* wait_queue_head_t, wait_event_interruptible, wake_up_interruptible */
MODULE_LICENSE("GPL");

65
kernel_module/wait_queue.c Normal file
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@@ -0,0 +1,65 @@
/*
TODO get working. Thread 2 only wakes up once! Wake thread 2 up every 2 seconds from thread 1.
*/
#include <linux/delay.h> /* usleep_range */
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/wait.h> /* wait_queue_head_t, wait_event_interruptible, wake_up_interruptible */
MODULE_LICENSE("GPL");
static struct task_struct *kthread1, *kthread2;
static wait_queue_head_t queue;
static int awake = 0;
static int kthread_func1(void *data)
{
int i = 0;
while (!kthread_should_stop()) {
awake = !awake;
pr_info("1 %d\n", i);
wake_up_interruptible(&queue);
schedule();
usleep_range(1000000, 1000001);
i++;
if (i == 10)
i = 0;
}
i = !i;
wake_up_interruptible(&queue);
return 0;
}
static int kthread_func2(void *data)
{
set_current_state(TASK_INTERRUPTIBLE);
int i = 0;
while (!kthread_should_stop()) {
wait_event(queue, awake);
pr_info("2 %d\n", i);
set_current_state(TASK_INTERRUPTIBLE);
schedule();
i++;
if (i == 10)
i = 0;
}
return 0;
}
int init_module(void)
{
init_waitqueue_head(&queue);
kthread1 = kthread_create(kthread_func1, NULL, "mykthread1");
kthread2 = kthread_create(kthread_func2, NULL, "mykthread2");
wake_up_process(kthread1);
wake_up_process(kthread2);
return 0;
}
void cleanup_module(void)
{
kthread_stop(kthread1);
kthread_stop(kthread2);
}