From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Krzysztof Kozlowski <krzk@kernel.org>,
Rich Felker <dalias@libc.org>, Jiri Slaby <jirislaby@gmail.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
David Airlie <airlied@linux.ie>, Jason Wang <jasowang@redhat.com>,
DRI Development <dri-devel@lists.freedesktop.org>,
virtualization@lists.linux-foundation.org,
"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
netdev <netdev@vger.kernel.org>,
Paul Mackerras <paulus@samba.org>,
Linux-Arch <linux-arch@vger.kernel.org>,
Dave Jiang <dave.jiang@intel.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Helge Deller <deller@gmx.de>,
Linux-sh list <linux-sh@vger.kernel.org>,
Alexey Brodkin <abrodkin@synopsys.com>,
Ben Skeggs <bskeggs@redhat.com>,
nouveau@lists.freedesktop.org, Dave Airlie <airlied@redhat.com>,
Matt Turner <mattst88@gmail.com>,
arcml <linux-snps-arc@lists.infradead.org>,
Nick Kossifidis <mickflemm@gmail.com>,
Allen Hubbe <allenbh@gmail.com>, Arnd Bergmann <arnd@arndb.de>,
alpha <linux-alpha@vger.kernel.org>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Thomas Gleixner <tglx@linutronix.de>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Kalle Valo <kvalo@codeaurora.org>,
Richard Henderson <rth@twiddle.net>,
Parisc List <linux-parisc@vger.kernel.org>,
Vineet Gupta <vgupta@synopsys.com>,
linux-wireless <linux-wireless@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Luis Chamberlain <mcgrof@kernel.org>,
Daniel Vetter <daniel@ffwll.ch>, Jon Mason <jdmason@kudzu.us>,
linux-ntb@googlegroups.com,
Andrew Morton <akpm@linux-foundation.org>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [RFT 00/13] iomap: Constify ioreadX() iomem argument
Date: Wed, 8 Jan 2020 09:43:04 +0100 [thread overview]
Message-ID: <CAMuHMdV=-m-eN4rOa=XQhk2oBDZZwgXXMU6RMVQRVsc6ALyeoA@mail.gmail.com> (raw)
In-Reply-To: <2355489c-a207-1927-54cf-85c04b62f18f@c-s.fr>
Hi Christophe,
On Wed, Jan 8, 2020 at 9:35 AM Christophe Leroy <christophe.leroy@c-s.fr> wrote:
> Le 08/01/2020 à 09:18, Krzysztof Kozlowski a écrit :
> > On Wed, 8 Jan 2020 at 09:13, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> >> On Wed, Jan 8, 2020 at 9:07 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> >>> On Tue, Jan 7, 2020 at 5:53 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>>> The ioread8/16/32() and others have inconsistent interface among the
> >>>> architectures: some taking address as const, some not.
> >>>>
> >>>> It seems there is nothing really stopping all of them to take
> >>>> pointer to const.
> >>>
> >>> Shouldn't all of them take const volatile __iomem pointers?
> >>> It seems the "volatile" is missing from all but the implementations in
> >>> include/asm-generic/io.h.
> >>
> >> As my "volatile" comment applies to iowrite*(), too, probably that should be
> >> done in a separate patch.
> >>
> >> Hence with patches 1-5 squashed, and for patches 11-13:
> >> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> >
> > I'll add to this one also changes to ioreadX_rep() and add another
> > patch for volatile for reads and writes. I guess your review will be
> > appreciated once more because of ioreadX_rep()
>
> volatile should really only be used where deemed necessary:
>
> https://www.kernel.org/doc/html/latest/process/volatile-considered-harmful.html
>
> It is said: " ... accessor functions might use volatile on
> architectures where direct I/O memory access does work. Essentially,
> each accessor call becomes a little critical section on its own and
> ensures that the access happens as expected by the programmer."
That is exactly the use case here: all above are accessor functions.
Why would ioreadX() not need volatile, while readY() does?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2020-01-08 8:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-07 16:52 [RFT 00/13] iomap: Constify ioreadX() iomem argument Krzysztof Kozlowski
2020-01-07 16:52 ` [RFT 01/13] iomap: Constify ioreadX() iomem argument (as in generic implementation) Krzysztof Kozlowski
2020-01-07 16:52 ` [RFT 02/13] alpha: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 02/13] sh: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 03/13] alpha: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 03/13] sh: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 04/13] parisc: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 05/13] powerpc: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 06/13] arc: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 07/13] drm/mgag200: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 08/13] drm/nouveau: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 09/13] media: fsl-viu: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 10/13] net: wireless: ath5k: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 11/13] net: wireless: rtl818x: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 12/13] ntb: intel: " Krzysztof Kozlowski
2020-01-07 16:53 ` [RFT 13/13] virtio: pci: " Krzysztof Kozlowski
[not found] ` <CAMuHMdW4ek0OYQDrrbcpZjNUTTP04nSbwkmiZvBmKcU=PQM9qA@mail.gmail.com>
[not found] ` <CAMuHMdUBmYtJKtSYzS_5u67hVZOqcKSgFY1rDGme6gLNRBJ_gA@mail.gmail.com>
[not found] ` <CAJKOXPfq9vS4kSyx1jOPHBvi9_HjviRv0LU2A8ZwdmqgUuebHQ@mail.gmail.com>
2020-01-08 8:35 ` [RFT 00/13] iomap: Constify ioreadX() iomem argument Christophe Leroy
2020-01-08 8:43 ` Geert Uytterhoeven [this message]
2020-01-08 8:48 ` Christophe Leroy
2020-01-08 8:44 ` Arnd Bergmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAMuHMdV=-m-eN4rOa=XQhk2oBDZZwgXXMU6RMVQRVsc6ALyeoA@mail.gmail.com' \
--to=geert@linux-m68k.org \
--cc=James.Bottomley@hansenpartnership.com \
--cc=abrodkin@synopsys.com \
--cc=airlied@linux.ie \
--cc=airlied@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=allenbh@gmail.com \
--cc=arnd@arndb.de \
--cc=bskeggs@redhat.com \
--cc=christophe.leroy@c-s.fr \
--cc=dalias@libc.org \
--cc=daniel@ffwll.ch \
--cc=dave.jiang@intel.com \
--cc=davem@davemloft.net \
--cc=deller@gmx.de \
--cc=dri-devel@lists.freedesktop.org \
--cc=ink@jurassic.park.msu.ru \
--cc=jasowang@redhat.com \
--cc=jdmason@kudzu.us \
--cc=jirislaby@gmail.com \
--cc=krzk@kernel.org \
--cc=kvalo@codeaurora.org \
--cc=linux-alpha@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=linux-ntb@googlegroups.com \
--cc=linux-parisc@vger.kernel.org \
--cc=linux-sh@vger.kernel.org \
--cc=linux-snps-arc@lists.infradead.org \
--cc=linux-wireless@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mattst88@gmail.com \
--cc=mcgrof@kernel.org \
--cc=mchehab@kernel.org \
--cc=mickflemm@gmail.com \
--cc=mst@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=nouveau@lists.freedesktop.org \
--cc=paulus@samba.org \
--cc=rth@twiddle.net \
--cc=tglx@linutronix.de \
--cc=vgupta@synopsys.com \
--cc=virtualization@lists.linux-foundation.org \
--cc=ysato@users.sourceforge.jp \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).