10:20 p.m.
On Thu, Nov 12, 2020 at 09:27:15AM +0100, Miquel Raynal wrote:
Hi Sergey,
Serge Semin <Sergey.Semin(a)baikalelectronics.ru> wrote on Wed, 11 Nov
2020 22:22:59 +0300:
> On Tue, Nov 10, 2020 at 04:35:56PM +0100, Miquel Raynal wrote:
> > Hi Serge,
> >
> > Serge Semin <Sergey.Semin(a)baikalelectronics.ru> wrote on Tue, 10 Nov
> > 2020 14:38:27 +0300:
> >
> > > Hello Miquel,
> > >
> > > A situation noted by the warning below won't cause any problem
because
> > > the casting is done to a non-dereferenced variable. It is utilized
> > > as a pointer bias later in that function. Shall we just ignore the
> > > warning or still fix it somehow?
> >
>
> > Do you think the cast to a !__iomem value is mandatory
here?
>
> It's not mandatory to have the casting with no __iomem, but wouldn't
> doing like this:
> + shift = (ssize_t __iomem)src & 0x3;
> be looking weird? Really, is there a good way to somehow extract the first
> two bits of a __iomem pointer without getting the sparse warning?
I asked around me, what about trying uintptr_t?
Hm, that's weird. sparse gets happy if a casting to an unsigned type
is used here. That's why the similar statement defined in
bt1_rom_map_read() doesn't cause the sparse warning, while the
statement with ssize_t does.
Can people around explain whether that is just an internal sparse
feature or there is a particular reason of having the unsigned types
casting ignored by sparse in this case? I don't really understand why
removing the __iomem attribute with casting to a signed type cause the
warning, while casting to an unsigned type doesn't...
Anyway I'll send a patch with the fix of using the uintptr_t casting
here. Thanks for suggesting the solution.
-Sergey
>
> Thanks,
> Miquèl