Re: [PATCH tip/core/rcu 03/15] rcu: Properly initialize->boost_tasks on CPU offline

[Josh Triplett]

On Thu, Aug 30, 2012 at 11:56:16AM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paul.mckenney@xxxxxxxxxx>
> 
> When rcu_preempt_offline_tasks() clears tasks from a leaf rcu_node
> structure, it does not NULL out the structure's ->boost_tasks field.
> This commit therefore fixes this issue.
> 
> Signed-off-by: Paul E. McKenney <paul.mckenney@xxxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>

Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>

> ---
>  kernel/rcutree_plugin.h |    7 ++++---
>  1 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
> index 7f3244c..b1b4851 100644
> --- a/kernel/rcutree_plugin.h
> +++ b/kernel/rcutree_plugin.h
> @@ -584,8 +584,11 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
>  		raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
>  	}
>  
> +	rnp->gp_tasks = NULL;
> +	rnp->exp_tasks = NULL;
>  #ifdef CONFIG_RCU_BOOST
> -	/* In case root is being boosted and leaf is not. */
> +	rnp->boost_tasks = NULL;
> +	/* In case root is being boosted and leaf was not. */
>  	raw_spin_lock(&rnp_root->lock); /* irqs already disabled */
>  	if (rnp_root->boost_tasks != NULL &&
>  	    rnp_root->boost_tasks != rnp_root->gp_tasks)
> @@ -593,8 +596,6 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
>  	raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
>  #endif /* #ifdef CONFIG_RCU_BOOST */
>  
> -	rnp->gp_tasks = NULL;
> -	rnp->exp_tasks = NULL;
>  	return retval;
>  }
>  
> -- 
> 1.7.8
> 
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