Messages in this thread | | | Date | Tue, 24 May 2022 22:53:54 +0800 | Subject | Re: [PATCH v3 4/6] mm: ioremap: Add arch_ioremap/iounmap() | From | Kefeng Wang <> |
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On 2022/5/24 22:47, Arnd Bergmann wrote: > On Tue, May 24, 2022 at 4:32 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote: >> On 2022/5/24 20:37, Arnd Bergmann wrote: >>> On Thu, May 19, 2022 at 10:25 AM Kefeng Wang <wangkefeng.wang@huawei.com> wrote: >>>> Add special hook for architecture to verify or setup addr, size >>>> or prot when ioremap() or iounmap(), which will make the generic >>>> ioremap more useful. >>>> >>>> arch_ioremap() return a pointer, >>>> - IS_ERR means return an error >>>> - NULL means continue to remap >>>> - a non-NULL, non-IS_ERR pointer is directly returned >>>> arch_iounmap() return a int value, >>>> - 0 means continue to vunmap >>>> - error code means skip vunmap and return directly >>>> >>>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> >>> I don't really like interfaces that mix error pointers and NULL pointer >>> returns. >>> >>> Would it be possible to have a special error code other than NULL >>> for the fallback case? >> I don't find a good error code, maybe ENOTSUPP, any better suggestion? > I had another look at the resulting arm64 function, and it appears that > you never actually return a non-error pointer here. If I didn't miss anything, > I think the best way would be to change the return type to just indicate > success or an error code, and drop the case of returning the actual result, > and changing the function name accordingly. > > Would that work, or do you actually require returning an __iomem > token from somewhere else?
Christoph suggested in the first version,
https://lore.kernel.org/linux-arm-kernel/Ymq2uX%2FY15HlIpo7@infradead.org/
> Arnd > > .
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