linux-kernel - Re: [my_cpu_ptr 1/5] Introduce my_cpu

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Date:	Fri, 29 May 2009 10:57:15 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Christoph Lameter <cl@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>,
	David Howells <dhowells@...hat.com>,
	Ingo Molnar <mingo@...e.hu>,
	Eric Dumazet <dada1@...mosbay.com>, davem@...emloft.net
Subject: Re: [my_cpu_ptr 1/5] Introduce my_cpu_ptr()

On Fri, 29 May 2009 01:29:31 am Christoph Lameter wrote:
> On Thu, 28 May 2009, Rusty Russell wrote:
> > On Thu, 28 May 2009 03:16:59 am cl@...ux-foundation.org wrote:
> > > my_cpu_ptr(xx) = per_cpu_ptr(xx, smp_processor_id).
> >
> > I had this implemented earlier as as get_cpu_ptr()/__get_cpu_ptr(), to
> > match get_cpu_var() / __get_cpu_var().
>
> Have not seen it but it would be a bit confusing since
> we already have get_cpu* which must be paired with put_cpu*
> because of the refcount taking (get_cpu_var and get_cpu).
> get_cpu_ptr() would not have to be paired.

To clarify, get_cpu_ptr() would be paired with put_cpu_ptr().  __get_cpu_ptr() 
would be the "raw" one:

#define get_cpu_ptr(xx) per_cpu_ptr(xx, get_cpu())
#define __get_cpu_ptr(xx) per_cpu_ptr(xx, smp_processor_id())

> Better use a different name.
>
> 	my_cpu_ptr came from my_cpu_offset:

Yep, but that's not as widely exposed as get_cpu & get_cpu_var.

Cheers,
Rusty.
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