驱动程序函数不会在c中执行，但其他函数会在

Question

I'm making a device driver. I've added code that is most relevant to read and llseek. I can enter and use read perfectly fine. But for some reason, llseek can't be entered. I have it listed in the file operations as llseek and match it to the function I want, the arguments appear to be good?

In dmesg, i get "inside READ" but no "inside SEEK" and no errors. Also no errors in terminal, or during compilation. I don't know c too well either.

main

int file = open("/dev/simple_char_driver", O_RDWR);

//read example, this works fine
printf("Enter how many bytes you want to read: \n");
int len[10];
scanf("%d", len);
char *ptr = malloc(*len * sizeof(char));

read(file, ptr, *len);

//llseek example, doesn't enter
int offset [10];
int whence [10];
scanf("%d",offset);
printf("Enter a value for whence: \n");
scanf("%d",whence);

llseek(file, offset, whence); 

In my device driver:

loff_t simple_char_driver_seek (struct file *pfile, loff_t offset, int whence)
{
    printk(KERN_ALERT "Inside SEEK");
    return 0;
}

ssize_t simple_char_driver_read (struct file *pfile, char __user *buffer, size_t length, loff_t *offset)
{
    printk(KERN_ALERT "Inside READ");
    return 0;
}

struct file_operations simple_char_driver_file_operations = {

    .owner   = THIS_MODULE,
    .open    = simple_char_driver_open,
    .release = simple_char_driver_close,
    .read    = simple_char_driver_read,
    .write   = simple_char_driver_write,
    .llseek  = simple_char_driver_seek,
};

Answer 1

Regarding your second issue:
printk is line buffered. This means that the buffer will be flushed (contents will be sent to the logfile) upon encountering a newline character ( \\n ). Otherwise, it will be done only when the program exits.
So use '\\n' in your printk statements.