Messages in this thread | | | Date | Tue, 2 Feb 2016 20:54:34 +0100 | From | Heiko Carstens <> | Subject | Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers |
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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.
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