Question

我一直在使用超声波传感器进行障碍物检测。计划是比较用户空间的响应时间和可加载的内核模块。用户空间程序工作正常。但是当我插入LKM时，内核会冻结。我认为它是因为while循环但不知道如何处理它。有人能告诉我这个问题吗？

提前谢谢你。

#include<linux/module.h>
#include<linux/kernel.h>
#include<linux/time.h>
#include<linux/timer.h>
#include<linux/jiffies.h>
#include<linux/delay.h>
#include<linux/gpio.h>
#include<asm/div64.h>
# define LED 21
# define TRIG 11
# define ECHO 8

static int ultra_init(void){
    int ret=0,flag;
    unsigned long long delta, obj_time_start,distance ;
    unsigned long long speed=34;
    struct timeval start,end;
    //s64 delta;


    printk(KERN_ALERT "Module loaded");
    ret=gpio_request_one(TRIG,GPIOF_OUT_INIT_LOW,"write_pin");      

    if(ret)
    {
        printk(KERN_ALERT "Pin %d could not be assigned",ret);          //Priniting message in log file
        flag=1;
    }

    ret=gpio_request_one(LED,GPIOF_OUT_INIT_LOW,"write_pin");
    if(ret)
    {
        printk(KERN_ALERT "Pin %d could not be assigned",ret);          //Priniting message in log file
        flag=1;
    }

    ret=gpio_request_one(ECHO,GPIOF_IN,"read_pin");                                 //Defining GPIO 4 as an input
    if(ret)
        {
                printk(KERN_ALERT "Pin %d could not be assigned",ret);
        flag=1;
        }
    int i;
    for(i=1;i<5;i++){
            gpio_set_value(LED,0);
        gpio_set_value(TRIG,0);
        gpio_set_value(ECHO,0);
        udelay(200);
        gpio_set_value(TRIG,1);
        udelay(10) ;// us
        gpio_set_value(TRIG,0);
        printk(KERN_ALERT "measuring the distance......");
        printk(KERN_ALERT " ECHO STATE %d",gpio_get_value(ECHO)); 
        udelay(300);
        udelay(300);
        udelay(300);
        udelay(300);
        udelay(300);






        while(gpio_get_value(ECHO)==0){

        do_gettimeofday(&start);

        }   


        while(gpio_get_value(ECHO)==1){

        printk(KERN_ALERT "ECHO 1");
        do_gettimeofday(&end);}


    obj_time_start=ktime_to_ns(ktime_get()); // Response time
    //delta=ktime_to_ns(ktime_sub(end,start)); //ns

    delta=(end.tv_sec-start.tv_sec)*1000.0;

    delta+=(end.tv_usec-start.tv_usec)/1000.0;
    //long long num=delta*17;
    //printk(KERN_ALERT "Distance calculated is %llu cm \n ", delta);
    do_div(speed,2000000);
    printk(KERN_ALERT " %llu ",speed);

    //distance=delta*0.000017; //do_div((delta*17),1000000);
    //printk(KERN_ALERT "Distance calculated is %llu cm \n ", distance);




}





}
static void ultra_exit(void){
    printk(KERN_ALERT "Good byee");
    gpio_set_value(LED,0);
    gpio_free(LED);
}

MODULE_LICENSE("GPL");

module_init(ultra_init);

module_exit(ultra_exit);

插入模块时Linux内核崩溃

0 个答案: