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Date: Tue, 26 Jan 2010 03:35:43 +0100
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org, axboe@kernel.dk, rusty@rustcorp.com.au,
       akpm@linux-foundation.org, ebiederm@xmission.com, tytso@mit.edu,
       Trond.Myklebust@netapp.com, aelder@sgi.com, hch@infradead.org,
       viro@zeniv.linux.org.uk, davem@davemloft.net, netdev@vger.kernel.org,
       x86@kernel.org, mingo@redhat.com, dan.j.williams@intel.com,
       borislav.petkov@amd.com, ying.huang@intel.com, lenb@kernel.org,
       neilb@suse.de, cl@linux-foundation.org
Subject: Re: [PATCH 7/8] percpu: add __percpu sparse annotations to
	hw_breakpoint
Message-ID: <20100126023542.GQ5087@nowhere>
References: <1264432935-10453-8-git-send-email-tj@kernel.org> <20100126001901.GI5087@nowhere> <4B5E3BED.6030705@kernel.org> <20100126010239.GK5087@nowhere> <4B5E4308.8020105@kernel.org> <20100126020113.GM5087@nowhere> <4B5E4FE7.30700@kernel.org> <20100126021846.GO5087@nowhere> <20100126022211.GP5087@nowhere> <4B5E54C0.2040709@kernel.org>
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On Tue, Jan 26, 2010 at 11:34:40AM +0900, Tejun Heo wrote:
> On 01/26/2010 11:22 AM, Frederic Weisbecker wrote:
> >> What about this? It doesn't use direct cast to scalar but should
> >> create a pointer type to kernel space datas:
> >>
> >>
> >> #define kernel_space_t(var)	\
> >> 	(typeof(var)	__kernel __force)
> > 
> > 
> > Should be typeof(*var)
> > 
> >>
> >> #define SHIFT_PERCPU_PTR(__p, __offset) ({                              \
> >>         __verify_pcpu_ptr((__p));                                       \
> >>         RELOC_HIDE((typeof(*(kernel_space_t(var)) __kernel __force *)(__p), (__offset)); \
> >> })
> 
> Can you balance ()'s here too?


#define kernel_space_t(var)        \
    (typeof(*(var))    __kernel __force)


/* Weird cast keeps both GCC and sparse happy. */
#define SHIFT_PERCPU_PTR(__p, __offset) ({                              \
        __verify_pcpu_ptr((__p));                                       \
        RELOC_HIDE((typeof(*(kernel_space_t(__p))) __kernel __force *)(__p), (__offset)); \
})

#define per_cpu(var, cpu) \
        (*SHIFT_PERCPU_PTR(&(var), per_cpu_offset(cpu)));


No guarantee that will build. I should pull your tree and install
sparse (yeah, shame on me, I've never installed it).

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