Re: [PATCH] rcu: make rcu_*_data variables static

[josh@joshtriplett.org]

On Tue, May 05, 2015 at 09:57:06PM +0800, Nicolas Iooss wrote:
> rcu_bh_data, rcu_sched_data and rcu_preempt_data are never used outside
> kernel/rcu/tree.c and thus can be made static.
> 
> Doing so fixes a section mismatch warning reported by clang when
> building LLVMLinux with -Wsection, because these variables were declared
> in .data..percpu and defined in .data..percpu..shared_aligned since
> commit 11bbb235c26f ("rcu: Use DEFINE_PER_CPU_SHARED_ALIGNED for
> rcu_data").
> 
> Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>

Reviewed-by: Josh Triplett <josh@joshtriplett.org>

Nice improvement.

Minor nit: since these are only one line each now, they don't really
need a blank line between them, but *shrug*.

> ---
>  kernel/rcu/tree.c | 2 +-
>  kernel/rcu/tree.h | 3 ---
>  2 files changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 233165da782f..e4a607fc5ad0 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -91,7 +91,7 @@ static const char *tp_##sname##_varname __used __tracepoint_string = sname##_var
>  
>  #define RCU_STATE_INITIALIZER(sname, sabbr, cr) \
>  DEFINE_RCU_TPS(sname) \
> -DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, sname##_data); \
> +static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, sname##_data); \
>  struct rcu_state sname##_state = { \
>  	.level = { &sname##_state.node[0] }, \
>  	.rda = &sname##_data, \
> diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
> index a69d3dab2ec4..0c32f730d033 100644
> --- a/kernel/rcu/tree.h
> +++ b/kernel/rcu/tree.h
> @@ -519,14 +519,11 @@ extern struct list_head rcu_struct_flavors;
>   * RCU implementation internal declarations:
>   */
>  extern struct rcu_state rcu_sched_state;
> -DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
>  
>  extern struct rcu_state rcu_bh_state;
> -DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
>  
>  #ifdef CONFIG_PREEMPT_RCU
>  extern struct rcu_state rcu_preempt_state;
> -DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
>  #endif /* #ifdef CONFIG_PREEMPT_RCU */
>  
>  #ifdef CONFIG_RCU_BOOST
> -- 
> 2.3.6
>