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From: Rusty Russell <rusty@rustcorp.com.au>
To: Christoph Lameter <cl@linux-foundation.org>
Subject: Re: [my_cpu_ptr 1/5] Introduce my_cpu_ptr()
Date: Fri, 29 May 2009 10:57:15 +0930
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Cc: linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
       David Howells <dhowells@redhat.com>, Ingo Molnar <mingo@elte.hu>,
       Eric Dumazet <dada1@cosmosbay.com>, davem@davemloft.net
References: <20090527180635.008102701@gentwo.org> <200905281316.01923.rusty@rustcorp.com.au> <alpine.DEB.1.10.0905281153280.22354@gentwo.org>
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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@linux-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.