Re: [PATCH 31/40] trace syscalls: Convert various generic compat syscalls

Re: [PATCH 31/40] trace syscalls: Convert various generic compat syscalls

[Andi Kleen]

, Ian Munsie wrote:
> From: Ian Munsie<imunsie@au1.ibm.com>
>
> This patch converts numerous trivial compat syscalls through the generic
> kernel code to use the COMPAT_SYSCALL_DEFINE family of macros.

Why? This just makes the code look uglier and the functions harder
to grep for.

-Andi

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Re: [PATCH 31/40] trace syscalls: Convert various generic compat syscalls

[Frederic Weisbecker]

On Wed, Jun 23, 2010 at 12:19:38PM +0200, Andi Kleen wrote:
> , Ian Munsie wrote:
>> From: Ian Munsie<imunsie@au1.ibm.com>
>>
>> This patch converts numerous trivial compat syscalls through the generic
>> kernel code to use the COMPAT_SYSCALL_DEFINE family of macros.
>
> Why? This just makes the code look uglier and the functions harder
> to grep for.


Because it makes them usable with syscall tracing.


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Re: [PATCH 31/40] trace syscalls: Convert various generic compat syscalls

[KOSAKI Motohiro]

> , Ian Munsie wrote:
> > From: Ian Munsie<imunsie@au1.ibm.com>
> >
> > This patch converts numerous trivial compat syscalls through the generic
> > kernel code to use the COMPAT_SYSCALL_DEFINE family of macros.
> 
> Why? This just makes the code look uglier and the functions harder
> to grep for.

I guess trace-syscall feature need to override COMPAT_SYSCALL_DEFINE. but
It's only guess...



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Re: [PATCH 31/40] trace syscalls: Convert various generic compat syscalls

[Andi Kleen]

, Frederic Weisbecker wrote:
> On Wed, Jun 23, 2010 at 12:19:38PM +0200, Andi Kleen wrote:
>> , Ian Munsie wrote:
>>> From: Ian Munsie<imunsie@au1.ibm.com>
>>>
>>> This patch converts numerous trivial compat syscalls through the generic
>>> kernel code to use the COMPAT_SYSCALL_DEFINE family of macros.
>>
>> Why? This just makes the code look uglier and the functions harder
>> to grep for.
>
>
> Because it makes them usable with syscall tracing.

Ok that information is missing in the changelog then.

Also I hope the uglification<->usefullness factor is really worth it.
The patch is certainly no slouch on the uglification side.

It also has maintenance costs, e.g. I doubt ctags and cscope
will be able to deal with these kinds of macros, so it has a
high cost for everyone using these tools. For those
it would be actually better if you used separate annotation
that does not confuse standard C parsers.

-Andi

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Re: [PATCH 31/40] trace syscalls: Convert various generic compat syscalls

[Frederic Weisbecker]

On Wed, Jun 23, 2010 at 12:37:44PM +0200, Andi Kleen wrote:
> , Frederic Weisbecker wrote:
>> On Wed, Jun 23, 2010 at 12:19:38PM +0200, Andi Kleen wrote:
>>> , Ian Munsie wrote:
>>>> From: Ian Munsie<imunsie@au1.ibm.com>
>>>>
>>>> This patch converts numerous trivial compat syscalls through the generic
>>>> kernel code to use the COMPAT_SYSCALL_DEFINE family of macros.
>>>
>>> Why? This just makes the code look uglier and the functions harder
>>> to grep for.
>>
>>
>> Because it makes them usable with syscall tracing.
>
> Ok that information is missing in the changelog then.


Agreed, the changelog lacks the purpose of what it does.



> Also I hope the uglification<->usefullness factor is really worth it.
> The patch is certainly no slouch on the uglification side.


It's worth because the kernel's syscall tracing is not complete, we lack all
the compat part.

These wrappers let us create TRACE_EVENT() for every syscalls automatically.
If we had to create them manually, the uglification would be way much more worse.

Most syscalls use the syscall wrappers already, so the uglification
is there mostly. We just forgot to uglify a bunch of them :)


> It also has maintenance costs, e.g. I doubt ctags and cscope
> will be able to deal with these kinds of macros, so it has a
> high cost for everyone using these tools. For those
> it would be actually better if you used separate annotation
> that does not confuse standard C parsers.


I haven't heard any complains about existing syscalls wrappers.

What kind of annotations could solve that?


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Re: [PATCH 31/40] trace syscalls: Convert various generic compat syscalls

[Andi Kleen]

>
> I haven't heard any complains about existing syscalls wrappers.

At least for me they always interrupt my grepping.

>
> What kind of annotations could solve that?

If you put the annotation in a separate macro and leave the original
prototype alone. Then C parsers could still parse it.

-Andi

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Re: [PATCH 31/40] trace syscalls: Convert various generic compat syscalls

[Christoph Hellwig]

On Wed, Jun 23, 2010 at 02:35:38PM +0200, Andi Kleen wrote:
> >I haven't heard any complains about existing syscalls wrappers.
> 
> At least for me they always interrupt my grepping.
> 
> >
> >What kind of annotations could solve that?
> 
> If you put the annotation in a separate macro and leave the original
> prototype alone. Then C parsers could still parse it.

I personally hate the way SYSCALL_DEFINE works with passion, mostly
for the grep reason, but also because it looks horribly ugly.

But there is no reason not to be consistent here.  We already use
the wrappers for all native system calls, so leaving the compat
calls out doesn't make any sense.  And I'd cheer for anyone who
comes up with a better scheme for the native and compat wrappers.


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Re: [PATCH 31/40] trace syscalls: Convert various generic compat syscalls

[H. Peter Anvin]

On 06/23/2010 04:38 AM, Frederic Weisbecker wrote:
> 
> I haven't heard any complains about existing syscalls wrappers.
> 

Then you truly haven't been listening.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.


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