how to find if unregister_chrdev() call was successful

Question

unregister_chrdev() call from [linux\\fs.h] used to return 0 if successful and <0 other wise. But now, in newer kernel versions, the return value of the function has been

Answer 1

The return of void was done by changeset: e53252d97e670a38b1d2e9723b48077bba11ffffda

commit e53252d97e670a38b1d2e9723b48077bba11ffffda
Author: Akinobu Mita 
Date:   Thu Jul 19 01:47:51 2007 -0700

    unregister_chrdev() return void

    unregister_chrdev() does not return meaningful value.  This patch makes it
    return void like most unregister_* functions.

In fact if you look at the code before (from 2.6.12-rc2 onwards) you can see it always returned 0 so this is a function that is always expected to succeed.