From: Kefeng Wang <wangkefeng.wang@huawei.com> To: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>, "Christoph Hellwig" <hch@infradead.org>, Anshuman Khandual <anshuman.khandual@arm.com> Subject: Re: [PATCH v3 4/6] mm: ioremap: Add arch_ioremap/iounmap() Date: Tue, 24 May 2022 22:53:54 +0800 [thread overview] Message-ID: <f9bbfe38-ce1d-b4c4-6acf-4b81e6587e2d@huawei.com> (raw) In-Reply-To: <CAK8P3a19S8CFxJKQo_8UXSKA0L8J40DsjL+u649oDhqUPHSW7A@mail.gmail.com> 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 > > .
WARNING: multiple messages have this Message-ID (diff)
From: Kefeng Wang <wangkefeng.wang@huawei.com> To: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>, "Christoph Hellwig" <hch@infradead.org>, Anshuman Khandual <anshuman.khandual@arm.com> Subject: Re: [PATCH v3 4/6] mm: ioremap: Add arch_ioremap/iounmap() Date: Tue, 24 May 2022 22:53:54 +0800 [thread overview] Message-ID: <f9bbfe38-ce1d-b4c4-6acf-4b81e6587e2d@huawei.com> (raw) In-Reply-To: <CAK8P3a19S8CFxJKQo_8UXSKA0L8J40DsjL+u649oDhqUPHSW7A@mail.gmail.com> 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 > > . _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-05-24 14:54 UTC|newest] Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-19 8:25 [PATCH v3 0/6] arm64: Cleanup ioremap() and support ioremap_prot() Kefeng Wang 2022-05-19 8:25 ` Kefeng Wang 2022-05-19 8:25 ` [PATCH v3 1/6] ARM: mm: kill unused runtime hook arch_iounmap() Kefeng Wang 2022-05-19 8:25 ` Kefeng Wang 2022-05-19 8:51 ` Anshuman Khandual 2022-05-19 8:51 ` Anshuman Khandual 2022-05-20 15:28 ` Catalin Marinas 2022-05-20 15:28 ` Catalin Marinas 2022-05-24 2:03 ` Kefeng Wang 2022-05-24 2:03 ` Kefeng Wang 2022-05-21 20:30 ` Arnd Bergmann 2022-05-21 20:30 ` Arnd Bergmann 2022-05-19 8:25 ` [PATCH v3 2/6] mm: ioremap: Use more sensibly name in ioremap_prot() Kefeng Wang 2022-05-19 8:25 ` Kefeng Wang 2022-05-19 8:25 ` [PATCH v3 3/6] mm: ioremap: Setup phys_addr of struct vm_struct Kefeng Wang 2022-05-19 8:25 ` Kefeng Wang 2022-05-19 8:25 ` [PATCH v3 4/6] mm: ioremap: Add arch_ioremap/iounmap() Kefeng Wang 2022-05-19 8:25 ` Kefeng Wang 2022-05-19 18:52 ` Andrew Morton 2022-05-19 18:52 ` Andrew Morton 2022-05-20 1:22 ` Kefeng Wang 2022-05-20 1:22 ` Kefeng Wang 2022-05-23 3:57 ` Anshuman Khandual 2022-05-23 3:57 ` Anshuman Khandual 2022-05-23 22:17 ` kernel test robot 2022-05-23 22:17 ` kernel test robot 2022-05-24 9:48 ` Kefeng Wang 2022-05-24 9:48 ` Kefeng Wang 2022-05-24 9:48 ` Kefeng Wang 2022-05-24 12:35 ` Arnd Bergmann 2022-05-24 12:35 ` Arnd Bergmann 2022-05-24 12:35 ` Arnd Bergmann 2022-05-24 14:31 ` Kefeng Wang 2022-05-24 14:31 ` Kefeng Wang 2022-05-24 14:31 ` Kefeng Wang 2022-05-24 12:37 ` Arnd Bergmann 2022-05-24 12:37 ` Arnd Bergmann 2022-05-24 14:32 ` Kefeng Wang 2022-05-24 14:32 ` Kefeng Wang 2022-05-24 14:47 ` Arnd Bergmann 2022-05-24 14:47 ` Arnd Bergmann 2022-05-24 14:53 ` Kefeng Wang [this message] 2022-05-24 14:53 ` Kefeng Wang 2022-05-31 6:13 ` Christoph Hellwig 2022-05-31 6:13 ` Christoph Hellwig 2022-06-01 1:05 ` Kefeng Wang 2022-06-01 1:05 ` Kefeng Wang 2022-05-19 8:25 ` [PATCH v3 5/6] arm64: mm: Convert to GENERIC_IOREMAP Kefeng Wang 2022-05-19 8:25 ` Kefeng Wang 2022-05-19 8:25 ` [PATCH v3 6/6] arm64: Add HAVE_IOREMAP_PROT support Kefeng Wang 2022-05-19 8:25 ` Kefeng Wang
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