From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Yury Norov <ynorov@caviumnetworks.com>
Cc: linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
arnd@arndb.de, pinskia@gmail.com,
Prasun.Kapoor@caviumnetworks.com, catalin.marinas@arm.com,
Nathan_Lynch@mentor.com, linux-kernel@vger.kernel.org,
agraf@suse.de, klimov.linux@gmail.com, broonie@kernel.org,
joseph@codesourcery.com, schwidefsky@de.ibm.com,
linux-arm-kernel@lists.infradead.org,
christoph.muellner@theobroma-systems.com
Subject: Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers
Date: Tue, 2 Feb 2016 20:54:34 +0100 [thread overview]
Message-ID: <20160202195434.GA3397@osiris> (raw)
In-Reply-To: <20160202160826.GF3990@osiris>
Hi Yury,
On Tue, Feb 02, 2016 at 05:08:26PM +0100, Heiko Carstens wrote:
> See e.g. 485d52768685 ("sys_personality: change sys_personality() to accept
> "unsigned int" instead of u_long") would have been a candidate which could
> silently break architectures which need compat wrappers.
Ok, this example is of course wrong. But now I can claim that also somebody
who should know better makes these mistakes.. :)
> > I don't know much about s390 specifics. Maybe because of that I do not
> > understand completely your worries. I'm OK with both 1st and 2nd
> > version, but I'd choose 2nd one because it allows inlines, and we
> > don't need the compat_wrapper.c.
>
> It would be only nicer if we can guarentee correctness all the time. That
> being said I'm about to revert my own commit :)
>
> So if you want to go without compat_wrapper.c then we should have a
> solution which will do the right thing all the time without that a system
> call author has to know about the sign and zero extension issue some
> architectures face. It _will_ go wrong.
So I think I can summarize my point to: if you can enforce correctness, why
shouldn't you do it if the performance impact is only a single instruction.
However I'll try to write an addon patch to your patch series. Maybe we can
still get rid of compat_wrapper.c in a way which makes both of us happy.
Also.. the idea with the alias names for compat wrappers does seem to have
the disadvantage that it will pollute /proc/kallsyms for example.
Anyway, I'm not sure if I will be able to come up with something this week
though.
WARNING: multiple messages have this Message-ID (diff)
From: heiko.carstens@de.ibm.com (Heiko Carstens)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers
Date: Tue, 2 Feb 2016 20:54:34 +0100 [thread overview]
Message-ID: <20160202195434.GA3397@osiris> (raw)
In-Reply-To: <20160202160826.GF3990@osiris>
Hi Yury,
On Tue, Feb 02, 2016 at 05:08:26PM +0100, Heiko Carstens wrote:
> See e.g. 485d52768685 ("sys_personality: change sys_personality() to accept
> "unsigned int" instead of u_long") would have been a candidate which could
> silently break architectures which need compat wrappers.
Ok, this example is of course wrong. But now I can claim that also somebody
who should know better makes these mistakes.. :)
> > I don't know much about s390 specifics. Maybe because of that I do not
> > understand completely your worries. I'm OK with both 1st and 2nd
> > version, but I'd choose 2nd one because it allows inlines, and we
> > don't need the compat_wrapper.c.
>
> It would be only nicer if we can guarentee correctness all the time. That
> being said I'm about to revert my own commit :)
>
> So if you want to go without compat_wrapper.c then we should have a
> solution which will do the right thing all the time without that a system
> call author has to know about the sign and zero extension issue some
> architectures face. It _will_ go wrong.
So I think I can summarize my point to: if you can enforce correctness, why
shouldn't you do it if the performance impact is only a single instruction.
However I'll try to write an addon patch to your patch series. Maybe we can
still get rid of compat_wrapper.c in a way which makes both of us happy.
Also.. the idea with the alias names for compat wrappers does seem to have
the disadvantage that it will pollute /proc/kallsyms for example.
Anyway, I'm not sure if I will be able to come up with something this week
though.
next prev parent reply other threads:[~2016-02-02 19:54 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-25 16:57 [PATCH 0/5] all: s390: make compat wrappers the generic solution Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 18:10 ` kbuild test robot
2016-01-25 18:10 ` kbuild test robot
2016-01-25 18:10 ` kbuild test robot
2016-01-25 18:10 ` kbuild test robot
2016-01-28 12:16 ` Heiko Carstens
2016-01-28 12:16 ` Heiko Carstens
2016-01-28 16:31 ` Yury Norov
2016-01-28 16:31 ` Yury Norov
2016-01-28 16:31 ` Yury Norov
2016-02-01 11:42 ` Yury Norov
2016-02-01 11:42 ` Yury Norov
2016-02-01 11:42 ` Yury Norov
2016-02-02 7:39 ` Heiko Carstens
2016-02-02 7:39 ` Heiko Carstens
2016-02-02 15:43 ` Yury Norov
2016-02-02 15:43 ` Yury Norov
2016-02-02 15:43 ` Yury Norov
2016-02-02 16:08 ` Heiko Carstens
2016-02-02 16:08 ` Heiko Carstens
2016-02-02 19:54 ` Heiko Carstens [this message]
2016-02-02 19:54 ` Heiko Carstens
2016-02-02 20:41 ` Yury Norov
2016-02-02 20:41 ` Yury Norov
2016-02-02 20:41 ` Yury Norov
2016-02-03 8:01 ` Heiko Carstens
2016-02-03 8:01 ` Heiko Carstens
2016-02-17 8:22 ` Heiko Carstens
2016-02-17 8:22 ` Heiko Carstens
2016-02-17 13:57 ` Yury Norov
2016-02-17 13:57 ` Yury Norov
2016-02-17 13:57 ` Yury Norov
2016-01-25 16:57 ` [PATCH 2/5] all: declare new wrappers Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` [PATCH 3/5] all: s390: redefine wrappers in generic code Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` [PATCH 4/5] all: wrap getdents64 syscall Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` [PATCH 5/5] all: introduce COMPAT_WRAPPER option and enable it for s390 Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
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