Re: [PATCH] io: Fix return type of _inb and _inl

[John Garry]

On 27/07/2020 09:04, Arnd Bergmann wrote:> On Sun, Jul 26, 2020 at 2:53 
PM Stafford Horne <shorne@xxxxxxxxx> wrote:
> > On Sun, Jul 26, 2020 at 12:00:37PM +0300, Andy Shevchenko wrote:
> > > On Sun, Jul 26, 2020 at 6:14 AM Stafford Horne <shorne@xxxxxxxxx> wrote:
> > > > The return type of functions _inb, _inw and _inl are all u16 which looks
> > > > wrong.  This patch makes them u8, u16 and u32 respectively.
> > > >
> > > > The original commit text for these does not indicate that these should
> > > > be all forced to u16.
> > >
> > > Is it in alight with all architectures? that support this interface natively?
> > >
> > > (Return value is arch-dependent AFAIU, so it might actually return
> > > 16-bit for byte read, but I agree that this is weird for 32-bit value.
> > > I think you have elaborate more in the commit message)
> >
> > Well, this is the generic io code,  at least these api's appear to not be different
> > for each architecture.  The output read by the architecture dependant code i.e.
> > __raw_readb() below is getting is placed into a u8.  So I think the output of
> > the function will be u8.
> >
> > static inline u8 _inb(unsigned long addr)
> > {
> >          u8 val;
> >
> >          __io_pbr();
> >          val = __raw_readb(PCI_IOBASE + addr);
> >          __io_par(val);
> >          return val;
> > }
> >
> > I can expand the commit text, but I would like to get some comments from the
> > original author to confirm if this is an issue.
>
> I think your original version is fine, this was clearly just a typo and I've
> applied your fix now and will forward it to Linus in the next few days,
> giving John the chance to add his Ack or further comments.
>
> Thanks a lot for spotting it and sending a fix.

Thanks Arnd.

Yeah, these looks like copy+paste errors on my part:

Reviewed-by: John Garry <john.garry@xxxxxxxxxx>

I'll give this patch a spin, but not expecting any differences (since 
original seems ok).

Note that kbuild robot also reported this:
https://lore.kernel.org/lkml/202007140549.J7X9BVPT%25lkp@xxxxxxxxx/

Extract:

include/asm-generic/io.h:521:22: sparse: sparse: incorrect type in 
argument 1 (different base types) @@     expected unsigned int 
[usertype] value @@     got restricted __le32 [usertype] @@
   include/asm-generic/io.h:521:22: sparse:     expected unsigned int 
[usertype] value
   include/asm-generic/io.h:521:22: sparse:     got restricted __le32 
[usertype]

But they look like issues which were in the existing code. I tried to 
recreate to verify any change, but trying to manually upgrade glibc 
busted my machine :(

Thanks,
John