Subject: Re: [PATCH 7/8] percpu: add __percpu sparse annotations to hw_breakpoint

From: Tejun Heo <[email-masked]>
Date: Tue, 26 Jan 2010 10:19:04 +0900

Hello,

On 01/26/2010 10:02 AM, Frederic Weisbecker wrote:
> Well, sorry I must be missing something obvious, but is it impossible
> to make per_cpu(var, cpu) returning something cast in:
> 
> 	(typeof(var) __force)
> 
> Or I guess you did that already and it is not working with static
> arrays, or?

Yeap, the definition looks like

 #define SHIFT_PERCPU_PTR(__p, __offset)	({			\
	__verify_pcpu_ptr((__p));					\
	RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset)); \
 })

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

but it just ends up putting the __force at the wrong layer.  It seems
that (typeof(var) __kernel __force) tell sparse var is in the kernel
address space but not its members.

> Is there a patch that shows per_cpu() macro changes in the batch?

Sorry I forgot to write about this.  It's in the percpu tree.

  git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu.git for-next

The related commits are 545695fb41da117928ab946067a42d9e15fd009d and
e0fdb0e050eae331046385643618f12452aa7e73.

Thanks.

-- 
tejun