Re: [Patch] rcupdate: remove dead code

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Sun, Jan 30, 2011 at 06:23:08PM +0800, Amerigo Wang wrote:
> DEBUG_OBJECTS_RCU_HEAD depends on PREEMPT, so #ifndef CONFIG_PREEMPT
> is totally useless in kernel/rcupdate.c.

Queued, thank you, Amerigo!

I added a patch on top of this commenting why DEBUG_OBJECTS_RCU_HEAD
is disallowed if !PREEMPT, FYI.

							Thanx, Paul

> Signed-off-by: WANG Cong <amwang@redhat.com>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> 
> 
> ---
> diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
> index a23a57a..afd21d1 100644
> --- a/kernel/rcupdate.c
> +++ b/kernel/rcupdate.c
> @@ -215,10 +215,6 @@ static int rcuhead_fixup_free(void *addr, enum debug_obj_state state)
>  		 * If we detect that we are nested in a RCU read-side critical
>  		 * section, we should simply fail, otherwise we would deadlock.
>  		 */
> -#ifndef CONFIG_PREEMPT
> -		WARN_ON(1);
> -		return 0;
> -#else
>  		if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
>  		    irqs_disabled()) {
>  			WARN_ON(1);
> @@ -229,7 +225,6 @@ static int rcuhead_fixup_free(void *addr, enum debug_obj_state state)
>  		rcu_barrier_bh();
>  		debug_object_free(head, &rcuhead_debug_descr);
>  		return 1;
> -#endif
>  	default:
>  		return 0;
>  	}