本节介绍下kernel thread简单使用的例子实验.
我的系统：
joseph:/usr/src/linux-2.6.23/joseph# uname -a
Linux joseph 2.6.23 #1 SMP PREEMPT Fri May 6 18:02:45 CST 2011 i686 GNU/Linux
文件：
├── hello.c
└── Makefile
1. hello.c
#include <linux/init.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kthread.h>
MODULE_LICENSE("Dual BSD/GPL");
//static DECLARE_WAIT_QUEUE_HEAD(myevent_waitqueue);
//rwlock_t myevent_lock;
static int mykthread(void* unused)
{
daemonize("josephThread");
// reuest delivery of SIGKILL
allow_signal(SIGKILL);
for(;;) {
//relinquish the processor until the event occurs
set_current_state(TASK_INTERRUPTIBLE);
schedule();//allow other parts of the kernel to run
//Die if I receive SIGKILL
if (signal_pending(current)) break;
}
printk("josephThread out <------<<<<< /n");
set_current_state(TASK_RUNNING);
return 0;
}
static int hello_init(void)
{
printk("Hello, I am a test module/n");
//create my kernel thread
printk("Create mythread<---------<<<<<<<</n");
kernel_thread(mykthread, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND | SIGCHLD);
return 0;
}
static void hello_exit(void)
{
printk("Bye, my dear!/n Cruel world/n");
}
2. Makefile
obj-m := hello.o
3. 编译
#make -C /usr/src/linux-2.6.23 M=`pwd` modules
// /usr/src/linux-2.6.23 是我的源码路径
会生成 hello.ko
4. 清除记录的信息
#
echo "" > /var/log/messages
5. 插入模块
# insmod hello.ko
6. 查看信息
# cat /var/log/messages
May 7 20:24:10 joseph kernel: [ 4281.427586] Hello, I am a test module
May 7 20:24:10 joseph kernel: [ 4281.427758] Create mythread<---------<<<<<<<<
查看我们的内核线程
#ps -ef
...
root 4030 2 0 20:24 ? 00:00:00 [josephThread]
...
7. 结束内核线程
#kill -s 9 4030
查看信息
# cat /var/log/messages
May 7 20:24:10 joseph kernel: [ 4281.427586] Hello, I am a test module
May 7 20:24:10 joseph kernel: [ 4281.427758] Create mythread<---------<<<<<<<<
May 7 20:27:22 joseph kernel: [ 4472.245694] josephThread out <------<<<<<
8. 卸载模块
#rmmod hello
查看信息
#cat /var/log/messages
May 7 20:24:10 joseph kernel: [ 4281.427586] Hello, I am a test module
May 7 20:24:10 joseph kernel: [ 4281.427758] Create mythread<---------<<<<<<<<
May 7 20:27:22 joseph kernel: [ 4472.245694] josephThread out <------<<<<<
May 7 20:28:43 joseph kernel: [ 4553.589958] Bye, my dear!
May 7 20:28:43 joseph kernel: [ 4553.589960] Cruel world
另一个例子：
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
MODULE_AUTHOR("T-bagwell_CU");
MODULE_LICENSE("GPL");
static DECLARE_WAIT_QUEUE_HEAD(myevent_waitqueue);
extern unsigned int myevent_id;
static int example_kernel_thread(void *unused)
{
DECLARE_WAITQUEUE(wait, current);
daemonize("create_by_T-bag");
allow_signal(SIGKILL);
add_wait_queue(&myevent_waitqueue, &wait);
while(1){
set_current_state(TASK_INTERRUPTIBLE);
schedule();
if(signal_pending(current)){
break;
}
}
set_current_state(TASK_RUNNING);
remove_wait_queue(&myevent_waitqueue, &wait);
printk(KERN_WARNING "This is in example_kernel_thread\n");
return 0;
}
static __init int init_hello_kernel_thread(void)
{
int ret;
ret=kernel_thread(example_kernel_thread, NULL,
CLONE_FS | CLONE_FILES | CLONE_SIGHAND | SIGCHLD );
if(unlikely(ret<0)){
printk(KERN_WARNING "kernel_thread create failed \n");
}
else{
printk(KERN_WARNING "kernel_thread create success \n");
}
return 0;
}
static __exit void cleanup_hello_kernel_thread(void)
{
printk(KERN_WARNING "kernel_thread exit \n");
return ;
}
module_init(init_hello_kernel_thread);
module_exit(cleanup_hello_kernel_thread);
写一个Makefile来编译这个module
KERNELDIR = /usr/src/kernels/2.6.27.5-117.fc10.i686
PWD := $(shell pwd)
obj-m := kernel_thread.o
modules:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
rm -rf *.o *.ko test_chrdev Module.* module* *.mod.c
