[RFC 30/32] /dev/port: don't compile file operations without CONFIG_DEVPORT

[Arnd Bergmann]

On Wed, Dec 29, 2021 at 5:38 AM Greg Kroah-Hartman
<gregkh at linuxfoundation.org> wrote:
> > > > -static const struct file_operations __maybe_unused port_fops = {
> > > > +#ifdef CONFIG_DEVPORT
> > > > +static const struct file_operations port_fops = {
> > > >   .llseek         = memory_lseek,
> > > >   .read           = read_port,
> > > >   .write          = write_port,
> > > >   .open           = open_port,
> > > >  };
> > > > +#endif
> > >
> > > Why is this #ifdef needed if it is already __maybe_unused?
> >
> > Because read_port() calls inb() and write_port() calls outb() they
> > wouldn't compile once these are no longer defined. Then however the
> > read_port/write_port symbols in the struct initialization above
> > couldn't be resolved.
> >
> > >
> > > In looking closer, this change could be taken now as the use of this
> > > variable already is behind this same #ifdef statement, right?
> >
> > Yes
>
> Great, feel free to send this individually, not as a RFC patch, and I
> will be glad to queue it up.

I think this patch should contain the 'depends on HAS_IOPORT' that
is currently added in a different patch (char: impi, tpm: depend on
HAS_IOPORT).

However, we can't merge that version until HAS_IOPORT is actually
added to the kernel.

      Arnd