Message-ID: <4B5E3F2C.2010702@zytor.com>
Date: Mon, 25 Jan 2010 17:02:36 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Frederic Weisbecker <fweisbec@gmail.com>
CC: Tejun Heo <tj@kernel.org>, linux-kernel@vger.kernel.org, axboe@kernel.dk,
       rusty@rustcorp.com.au, akpm@linux-foundation.org, ebiederm@xmission.com,
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       lenb@kernel.org, neilb@suse.de, cl@linux-foundation.org
Subject: Re: [PATCH 7/8] percpu: add __percpu sparse annotations to	hw_breakpoint
References: <1264432935-10453-1-git-send-email-tj@kernel.org> <1264432935-10453-8-git-send-email-tj@kernel.org> <20100126001901.GI5087@nowhere>
In-Reply-To: <20100126001901.GI5087@nowhere>
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On 01/25/2010 04:19 PM, Frederic Weisbecker wrote:
> On Tue, Jan 26, 2010 at 12:22:14AM +0900, Tejun Heo wrote:
>> Add __percpu sparse annotations to hw_breakpoint.
>>
>> These annotations are to make sparse consider percpu variables to be
>> in a different address space and warn if accessed without going
>> through percpu accessors.  This patch doesn't affect normal builds.
>>
>> per_cpu(nr_task_bp_pinned, cpu) is replaced with
>> &per_cpu(nr_task_bp_pinned[0], cpu).  This is the same to the compiler
>> but allows per_cpu() macro to correctly drop __percpu designation for
>> the returned pointer.
> 
> Ouch... It's unpleasant to see such workaround that messes up the
> code just to make sparse happy.
> 
> I guess __percpu is an address_space attribute? Is there no
> way to force the address space change directly from the
> per_cpu() macro?
> 

A cast (using __typeof__) combined with an address space override?

	-hpa
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