Messages in this thread | | | Date | Thu, 12 Nov 2020 18:27:39 +0300 | From | Serge Semin <> | Subject | Re: drivers/mtd/maps/physmap-bt1-rom.c:78:18: sparse: sparse: cast removes address space '__iomem' of expression |
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Hello Vignesh
On Thu, Nov 12, 2020 at 08:30:42PM +0530, Vignesh Raghavendra wrote: > > > On 11/12/20 1:57 PM, Miquel Raynal wrote: > > Hi Sergey, > > > > Serge Semin <Sergey.Semin@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@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? > > >
> One more way is to use __force to tell sparse that this casting is > intentional: > > shift = (__force ssize_t)src & 0x3;
Oh, great! That solution is actually much better than using some currently unexplained sparse peculiarity! I was thinking about applying some other attribute, but __force just didn't come to my mind. Thank you very much for the suggestion. I'll post the fix with the solution suggested by you.
-Sergey
> > > > Thanks, > > Miquèl > > > > ______________________________________________________ > > Linux MTD discussion mailing list > > http://lists.infradead.org/mailman/listinfo/linux-mtd/ > >
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