Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers

From	Heiko Carstens <heiko.carstens@de.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers
Date	2016-02-02 21:00 +0100
Message-ID	<qXPhg-7Yl-15@gated-at.bofh.it> (permalink)
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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.

Thread

Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-01-28 13:20 +0100
  Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Yury Norov <ynorov@caviumnetworks.com> - 2016-01-28 17:40 +0100
    Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Yury Norov <ynorov@caviumnetworks.com> - 2016-02-01 12:50 +0100
      Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-02-02 08:40 +0100
        Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Yury Norov <ynorov@caviumnetworks.com> - 2016-02-02 16:50 +0100
          Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-02-02 17:10 +0100
            Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-02-02 21:00 +0100
              Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Yury Norov <ynorov@caviumnetworks.com> - 2016-02-02 21:50 +0100
                Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-02-03 09:10 +0100

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