As part of my work on the Linux Kernel Janitors project, cleaning up on
  functions which call create_proc_*_entry and don't check for an error
  return, I would like to submit my patch to arch/mips64/sgi-ip27/ip27-rtc.c.

  This patch adds a printk() if misc_register fails (since that causes the
  driver to fail to load, it should be logged somewhere), and checks that
  create_proc_read_entry returned a valid handle. ENOENT seems to me like a
  good error code to return in this case, although EBUSY is a candidate too.