Re: [akpm-mm:mm-unstable 93/173] drivers/clk/clk-fixed-mmio.c:33:2: error: call to undeclared function 'iounmap'; ISO C99 and later do not support implicit function declarations

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 14 Jul 2023 07:59:14 +0800 Baoquan He <bhe@redhat.com> wrote:

> > > All errors (new ones prefixed by >>):
> > > 
> > >    In file included from drivers/clk/clk-fixed-mmio.c:13:
> > >    In file included from include/linux/io.h:13:
> > >    In file included from arch/s390/include/asm/io.h:78:
> > >    include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
> > >      547 |         val = __raw_readb(PCI_IOBASE + addr);
> > >          |                           ~~~~~~~~~~ ^
> > 
> > Thanks.  When I tried that config I got
> 
> These two kinds of errors have been reported many times.
> 
> This PCI_IOBASE warning will be fixed by Niklas's patch at below:
> 
> https://lore.kernel.org/20230522105049.1467313-1-schnelle@linux.ibm.com/
> 
> 
> Nathan told this when he reviewed by patch at this sub-thread:
> https://lore.kernel.org/all/20230612160237.GA199007@dev-arch.thelio-3990X/T/#u
> 
> Quote his words here:
> ===
> I believe that this series [1] by Niklas Schnelle should take care of
> the PCI_IOBASE warnings (which are not Hexagon specific), so there is no
> need to worry about them when they show up in build reports.
> 
> [1]: https://lore.kernel.org/20230522105049.1467313-1-schnelle@linux.ibm.com/

OK, I'll restore the series "mm: ioremap: Convert architectures to take
GENERIC_IOREMAP way", v8.

This kind of already-was-there warning causes quite some trouble. 
Attempts to fix such fallout are appreciated.