Re: [GIT RFC] percpu: use dynamic percpu allocator as the defaultpercpu allocator

[Tejun Heo]

Hello, Martin.

Sorry about the delay.

Martin Schwidefsky wrote:
> We do have a problem with #2, the dynamic percpu patches currently
> breaks s390. But the nice thing is that we can now get rid of the GOTENT
> relocation for the percpu symbols. If the code is changed to use
> RELOC_HIDE for the SHIFT_PERCPU_PTR define, everything works just fine.
> Patch attached. Nice works guys.
> 
> Subject: [PATCH] s390: percpu access.
> 
> From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
> 
> With the dynamic percpu allocator there is no need anymore to play
> tricks with the GOTENT relocation for the access to the percpu
> symbols. A simple RELOC_HIDE gets the job done.

Hmm... I don't quite get it.  The GOTENT was to work around large
offsets for modules, right?  Can you please explain what changed by
the dynamic percpu allocator?

> +#define SHIFT_PERCPU_PTR(var, offset) RELOC_HIDE(&per_cpu_var(var), (offset))

Hmm... @var already has per_cpu__ prefix when the above macro is
invoked, so doing per_cpu_var() on it again wouldn't work.  If simple
RELOC_HIDE works, you should be able to simply drop the above
definition.  The generic percpu.h will define it.

Thanks.

-- 
tejun
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