From: David Laight <David.Laight@ACULAB.COM>
To: 'Christophe Leroy' <christophe.leroy@csgroup.eu>,
Baoquan He <bhe@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"hch@infradead.org" <hch@infradead.org>,
"agordeev@linux.ibm.com" <agordeev@linux.ibm.com>,
"wangkefeng.wang@huawei.com" <wangkefeng.wang@huawei.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH v2 01/11] mm/ioremap: change the return value of io[re|un]map_allowed and rename
Date: Wed, 24 Aug 2022 08:16:54 +0000 [thread overview]
Message-ID: <b193efbff3a74343839c3dee1702f73c@AcuMS.aculab.com> (raw)
In-Reply-To: <429cb367-923f-bb3d-ccf0-57dce0c7f35b@csgroup.eu>
From: Christophe Leroy
> Sent: 23 August 2022 16:26
>
> Le 23/08/2022 à 17:14, Baoquan He a écrit :
> > On 08/23/22 at 05:24am, Christophe Leroy wrote:
> >>
> >>
> >> Le 23/08/2022 à 02:20, Baoquan He a écrit :
> >>> On 08/22/22 at 06:25am, Christophe Leroy wrote:
> >>>>
> >>>>
> >>>> Le 20/08/2022 à 02:31, Baoquan He a écrit :
> >>>>> In some architectures, there are ARCH specifici io address mapping
> >>>>> handling when calling ioremap() or ioremap_prot(), e.g, arc, ia64,
> >>>>> openrisc, s390, sh.
> >>>>>
> >>>>> In oder to convert them to take GENERIC_IOREMAP method, we need change
> >>>>> the return value of hook ioremap_allowed() and iounmap_allowed().
> >>>>> Meanwhile, rename them to arch_ioremap() and arch_iounmap() to reflect
> >>>>> their current behaviour.
> >>>
> >>> Thanks for reviewing.
> >>>
> >>>>
> >>>> Please don't just say you need to change the return value. Explain why.
> >>>
> >>> The 1st paragraph and the sentence 'In oder to convert them to take
> >>> GENERIC_IOREMAP method' tell the reason, no?
> >>
> >> What I would like to read is _why_ you need to change the return value
> >> in order to convert to GENERIC_IOREMAP
> >
> > I rephrase the log as below, it's OK to you? Or please help check and
> > tell what I need to improve to better explain the reason.
> >
> > ====
> > The current io[re|un]map_allowed() hooks are used to check if the
> > io[re|un]map() actions are qualified to proceed when taking
> > GENERIC_IOREMAP way to do ioremap()/iounmap(). Otherwise io[re|un]map()
> > will return NULL.
> >
> > On some architectures like arc, ia64, openris, s390, sh, there are
> > ARCH specific io address mapping to translate the passed in physical
> > address to io address when calling ioremap(). In order to convert
> > these architectures to take GENERIC_IOREMAP way to ioremap(), we need
> > change the return value of hook ioremap_allowed() and iounmap_allowed().
> > With the change, we can move the architecture specific io address
> > mapping into ioremap_allowed() hook, and give the mapped io address
> > out to let ioremap_prot() return it. While at it, rename the hooks to
> > arch_ioremap() and arch_iounmap() to reflect their new behaviour.
> > ====
> >
>
> That looks more in line with the type of explanation I foresee in the
> commit message, thanks.
I think you also need to summarise the change itself.
If the success/fail return actually changes then you really
need to change something so the compiler errors unchanged code.
Otherwise it is a complete recipe for disaster.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2022-08-24 8:17 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-20 0:31 [PATCH v2 00/11] mm: ioremap: Convert architectures to take GENERIC_IOREMAP way Baoquan He
2022-08-20 0:31 ` [PATCH v2 01/11] mm/ioremap: change the return value of io[re|un]map_allowed and rename Baoquan He
2022-08-21 6:53 ` Christoph Hellwig
2022-08-22 23:55 ` Baoquan He
2022-08-22 6:25 ` Christophe Leroy
2022-08-23 0:20 ` Baoquan He
2022-08-23 5:24 ` Christophe Leroy
2022-08-23 15:14 ` Baoquan He
2022-08-23 15:26 ` Christophe Leroy
2022-08-24 8:16 ` David Laight [this message]
2022-08-28 14:44 ` Baoquan He
2022-08-28 8:36 ` Alexander Gordeev
2022-08-28 9:55 ` Baoquan He
2022-08-20 0:31 ` [PATCH v2 02/11] mm: ioremap: fixup the physical address and page prot Baoquan He
2022-08-21 6:54 ` Christoph Hellwig
2022-08-23 1:13 ` Baoquan He
2022-08-22 6:30 ` Christophe Leroy
2022-08-23 1:19 ` Baoquan He
2022-08-23 5:33 ` Christophe Leroy
2022-08-23 12:32 ` Baoquan He
2022-08-23 19:03 ` Christophe Leroy
2022-08-28 11:10 ` Baoquan He
2022-09-12 2:55 ` Baoquan He
2022-09-12 7:10 ` Christophe Leroy
2022-09-13 15:11 ` Baoquan He
2022-09-21 16:40 ` Christophe Leroy
2022-09-22 13:23 ` Baoquan He
2022-08-20 0:31 ` [PATCH v2 03/11] mm: ioremap: allow ARCH to have its own ioremap definition Baoquan He
2022-08-21 6:57 ` Christoph Hellwig
2022-08-23 2:42 ` Baoquan He
2022-08-20 0:31 ` [PATCH v2 04/11] arc: mm: Convert to GENERIC_IOREMAP Baoquan He
2022-08-20 0:31 ` [PATCH v2 05/11] hexagon: " Baoquan He
2022-08-20 1:23 ` Brian Cain
2022-08-21 7:00 ` Christoph Hellwig
2022-08-28 15:08 ` Baoquan He
2022-08-22 6:38 ` Christophe Leroy
2022-08-28 15:12 ` Baoquan He
2022-08-20 0:31 ` [PATCH v2 06/11] ia64: " Baoquan He
2022-08-21 7:02 ` Christoph Hellwig
2022-08-28 15:12 ` Baoquan He
2022-08-20 0:31 ` [PATCH v2 07/11] openrisc: " Baoquan He
2022-08-21 7:03 ` Christoph Hellwig
2022-08-29 1:40 ` Baoquan He
2022-08-29 6:42 ` Stafford Horne
2022-08-29 8:18 ` Baoquan He
2022-08-30 6:05 ` Christophe Leroy
2022-08-29 6:32 ` Stafford Horne
2022-08-29 8:19 ` Baoquan He
2022-08-20 0:31 ` [PATCH v2 08/11] parisc: " Baoquan He
2022-08-20 4:03 ` kernel test robot
2022-08-21 10:26 ` Baoquan He
2022-08-21 14:18 ` Helge Deller
2022-08-30 13:00 ` Baoquan He
2022-08-20 0:31 ` [PATCH v2 09/11] s390: " Baoquan He
2022-08-21 7:05 ` Christoph Hellwig
2022-08-22 15:08 ` Niklas Schnelle
2022-08-31 8:59 ` Baoquan He
2022-08-22 15:19 ` Niklas Schnelle
2022-08-31 8:58 ` Baoquan He
2022-08-23 12:30 ` Niklas Schnelle
2022-08-31 8:50 ` Baoquan He
2022-08-20 0:31 ` [PATCH v2 10/11] sh: " Baoquan He
2022-08-20 3:41 ` kernel test robot
2022-09-01 10:39 ` Baoquan He
2022-09-01 12:11 ` [kbuild-all] " Chen, Rong A
2022-09-01 12:31 ` Baoquan He
2022-09-02 9:48 ` Baoquan He
2022-08-21 7:06 ` Christoph Hellwig
2022-09-01 7:36 ` Baoquan He
2022-08-20 0:31 ` [PATCH v2 11/11] xtensa: " Baoquan He
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