Re: [Patch] rcupdate: remove dead code

From: Paul E. McKenney
Date: Mon Jan 31 2011 - 02:59:09 EST


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@xxxxxxxxxx>
> Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
>
>
> ---
> 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;
> }
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