Linux驱动调试笔记

#include <linux/module.h> 
#include <linux/init.h> 
#include <linux/slab.h> 
#include <linux/miscdevice.h> 
#include <linux/gpio/consumer.h> 
#include <asm-generic/gpio.h> 
#include <linux/gpio/consumer.h> 
 
static int __init my_gpio_init(void){ 
    int ret = 0; 
    char *p = NULL; 
    printk(KERN_ERR"==sfl: enter my_gpio_init==\n"); 
    p = kcalloc(0xff, 0, GFP_KERNEL); 
    if (!p) { 
        printk(KERN_ERR"==sfl: p==NULL==\n"); 
    } else { 
        printk(KERN_ERR"==sfl: p==%p\n", p); 
        p[0] = 5; 
        printk(KERN_ERR"==sfl: p[0]==%d\n", p[0]); 
    } 
 
    kfree(p); 
     
    return 0; 
} 
 
static void __exit my_gpio_exit(void){ 
    printk(KERN_ERR"==enter my_gpio_exit==\n"); 
} 
 
module_init(my_gpio_init); 
module_exit(my_gpio_exit); 
MODULE_LICENSE("GPL");

root@ggs:/mytest# insmod test.ko  
[ 1040.877617] ==sfl: enter my_gpio_init== 
[ 1040.881570] ==sfl: p==0000000000000010 
[ 1040.885381] Unable to handle kernel NULL pointer dereference at virtual address 00000010