How to call a function from another kernel module in a kernel module?

Question

I've written three kernel modules. A, B, C. B needs some functions from A and C also. How to achieve this. Please be code specific. Any help is appreciated.

Answer 1

Below the function implementation in A, export it:

#include "moduleA_header.h"

int foo(void)
{
    printk(KERN_NOTICE "Hi there!\n");
}
EXPORT_SYMBOL(foo);

Make sure that the prototype of your function is declared in a header file that you can include in module B. Also, make sure module A gets loaded before module B.

Just make sure that your include has the path right to the moduleA_header.h file.