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cdevice-driverkernel-module

Error compiling kernel module for simple device driver

I've got such a function:

void cleanup_module(void)
{
    /* 
     * Unregister the device 
     */
    if(unregister_chrdev(Major, DEVICE_NAME)<0) 
        printk(KERN_ALERT "Error in unregister_chrdev:\n");
}

and error:

/home/student/kernel/hello.c: In function ‘cleanup_module’:
/home/student/kernel/hello.c:39:2: error: void value not ignored as it ought to be

This line is the one with if statement. Do you know what I'm doing wrong?

Solution

  • This means that unregister_chrdev doesn't have a return value (it's void), but you have put it in an if. That is, you are using a void value which should have been ignored. Hence the error message.

    Check out this question which asks why the return value was changed to void.