linux-kernel - Re: [PATCH v10 00/11] uapi: export all headers under uapi directories

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Message-ID: <CAK7LNAQJWNCRjWoKMH_Br1bwqtq+mQG-6yaWu5fwhC6sJ1fV8Q@mail.gmail.com>
Date:   Mon, 27 Mar 2017 14:26:51 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Michal Marek <mmarek@...e.com>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch@...r.kernel.org, David Airlie <airlied@...ux.ie>,
        "David S. Miller" <davem@...emloft.net>,
        Russell King <linux@...linux.org.uk>, bp@...en8.de,
        slash.tmp@...e.fr, Daniel Vetter <daniel.vetter@...ll.ch>,
        rmk+kernel@...linux.org.uk, msalter@...hat.com, jengelh@...i.de,
        hch@...radead.org, Tobias Klauser <tklauser@...tanz.ch>,
        mpe@...erman.id.au, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Dmitry V. Levin" <ldv@...linux.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        linux-rdma@...r.kernel.org
Subject: Re: [PATCH v10 00/11] uapi: export all headers under uapi directories

Hi Nocolas,


2017-03-24 18:03 GMT+09:00 Nicolas Dichtel <nicolas.dichtel@...nd.com>:
> Le 24/03/2017 à 09:42, Masahiro Yamada a écrit :
>> Hi Nicolas,
>>
>>
>> 2017-03-24 17:32 GMT+09:00 Nicolas Dichtel <nicolas.dichtel@...nd.com>:
>>> Le 14/03/2017 à 13:54, Nicolas Dichtel a écrit :
>>>> Patches #1 and #2 are just cleanup: some exported headers were still under
>>>> a non-uapi directory. Patch #3 is a fix to avoid exporting a file that was
>>>> not under an uapi directory.
>>>> After these three patches, all exported headers are under an uapi directory:
>>>> path #4 stops searching files in non uapi directories.
>>>> The patch #5 was spotted by code review: there is no in-tree user of this
>>>> functionality.
>>>> Patch #6 fixes some warnings/errors reported by 0-day tests.
>>>> Patch #7 to #9 fix some errors when the corresponding files are included by
>>>> userland.
>>>> Patches #10 and #11 remove the need to list explicitly headers. Now all files
>>>> under an uapi directory are exported.
>>>>
>>>> This series has been tested with a 'make headers_install' on x86 and a
>>>> 'make headers_install_all'. I've checked the result of both commands.
>>>>
>>>> This patch is built on top of masahiroy/linux-kbuild.git#for-next (v4.11-rc1).
>>>> I didn't find any conflict with v4.11-rc2.
>>> Masahiro, is this series under review or do you expect something else on my side?
>>>
>>
>> Under review.
>> Please give me time to take a closer look.
>> Sorry for the delay.
> No problem, take your time. I just wanted to be sure to not miss something ;-)
>
>


As a whole, this series is amazing.  Thanks for your great work!


I added some comments, but they are trivial.




I wanted to leave comments/questions on 10/11,
but I could not find 10/11 in my mailbox.  I do not know why.


I am leaving comments on the cover-letter,
the following are related to 10/11.



[1]

>mandatory-y += $(foreach hdr,$(opt-header), \
>              $(if \
>                $(wildcard \
>                        $(srctree)/arch/$(SRCARCH)/include/uapi/asm/$(hdr) \
>                        $(srctree)/arch/$(SRCARCH)/include/asm/$(hdr) \
>                ), \
>                $(hdr) \
>                ))

What is this actually checking?

If ARCH has its own (uapi/)asm/{kvm.h,kvm_para.h,a.out.h},
they are added to mandatory-y, then they are checked if they exist.
But, we know they exist.


This check reminds us only when we added asm/*.h
but forgot to add uapi/asm/*.h

$(srctree)/arch/$(SRCARCH)/include/uapi/asm/$(hdr) seems unneeded at least.
(perhaps, the whole hunk might be unneeded.)



[2]

>ifeq ($(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/a.out.h \
>                 $(srctree)/arch/$(SRCARCH)/include/asm/a.out.h),)
>header-n += a.out.h
>endif
>
>ifeq ($(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/kvm.h \
>                 $(srctree)/arch/$(SRCARCH)/include/asm/kvm.h),)
>header-n += kvm.h
>endif
>
>ifeq ($(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/kvm_para.h \
>                 $(srctree)/arch/$(SRCARCH)/include/asm/kvm_para.h),)
>header-n += kvm_para.h
>endif

This series intends all headers are exported from uapi/, correct?
Do we still need to check $(srctree)/arch/$(SRCARCH)/include/asm/*.h ?
(related to [1])



[3]

>--- 7.1 header-n
>
>header-n is essentially used by include/uapi/linux/Kbuild to avoid
>exporting specific headers (e.g. kvm.h) on architectures that do not
>support it. It should be avoided as much as possible.


Going forward, header-y will be never used
because uapi/ is exported by default.

So, I wonder if we could rename this into something clearer.

Kbuild supports "no-clean-files".
(Please see ./Kbuild for its usage)
I guess this notation seems clearer
when we want to negate the default behavior.

Can you consider "no-export", "no-export-files", "no-export-headers"
or whatever you like?




Thanks!



-- 
Best Regards
Masahiro Yamada