From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 3/3] lglock: add DEFINE_STATIC_LGLOCK()
Date: Tue, 9 Oct 2012 14:48:42 -0700
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Cc: linux-kernel@vger.kernel.org,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Andi Kleen <ak@linux.intel.com>, linux-fsdevel@vger.kernel.org
To: Lai Jiangshan <laijs@cn.fujitsu.com>
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On Tue, 9 Oct 2012 11:46:40 +0800
Lai Jiangshan <laijs@cn.fujitsu.com> wrote:

> When if the lglock don't to be exported,
> we can use DEFINE_STATIC_LGLOCK().
> 
> --- a/include/linux/lglock.h
> +++ b/include/linux/lglock.h
> @@ -32,7 +32,8 @@
>  #define br_write_lock(name)	lg_global_lock(name)
>  #define br_write_unlock(name)	lg_global_unlock(name)
>  
> -#define DEFINE_BRLOCK(name)	DEFINE_LGLOCK(name)
> +#define DEFINE_BRLOCK(name)		DEFINE_LGLOCK(name)
> +#define DEFINE_STATIC_BRLOCK(name)	DEFINE_STATIC_LGLOCK(name)
>  
>  #ifdef CONFIG_DEBUG_LOCK_ALLOC
>  #define LOCKDEP_INIT_MAP lockdep_init_map
> @@ -53,6 +54,11 @@ struct lglock {
>  	= __ARCH_SPIN_LOCK_UNLOCKED;					\
>  	struct lglock name = { .lock = &name ## _lock }
>  
> +#define DEFINE_STATIC_LGLOCK(name)					\
> +	static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock)		\
> +	= __ARCH_SPIN_LOCK_UNLOCKED;					\
> +	static struct lglock name = { .lock = &name ## _lock }
> +
>  void lg_lock_init(struct lglock *lg, char *name);
>  void lg_local_lock(struct lglock *lg);
>  void lg_local_unlock(struct lglock *lg);

hm, this is a bit sad.  It would be better if we could do

static DEFINE_LGLOCK(foo);

but I don't immediately see a way in which we can rework
DEFINE_LGLOCK() to permit that.