linux-kernel - Re: [PATCH 1/2] taskstats: factor out reply assembling

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Date:	Thu, 02 Nov 2006 10:43:25 +0530
From:	Balbir Singh <balbir@...ibm.com>
To:	Oleg Nesterov <oleg@...sign.ru>
CC:	Andrew Morton <akpm@...l.org>, Thomas Graf <tgraf@...g.ch>,
	Shailabh Nagar <nagar@...son.ibm.com>, Jay Lan <jlan@....com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] taskstats: factor out reply assembling

Oleg Nesterov wrote:
> Introduce mk_reply() helper which does all nla_put()s on reply.
> 
> Saves 453 bytes and a preparation for the next patch.
> 
> Signed-off-by: Oleg Nesterov <oleg@...sign.ru>
> 
>  taskstats.c |   55 ++++++++++++++++++++++++++++---------------------------
>  1 files changed, 28 insertions(+), 27 deletions(-)
> 
> --- STATS/kernel/taskstats.c~5_factor	2006-10-31 16:33:56.000000000 +0300
> +++ STATS/kernel/taskstats.c	2006-11-01 14:00:03.000000000 +0300
> @@ -348,6 +348,25 @@ static int parse(struct nlattr *na, cpum
>  	return ret;
>  }
>  
> +static int mk_reply(struct sk_buff *skb, int type, u32 pid, struct taskstats *stats)
> +{
> +	struct nlattr *na;
> +	int aggr;
> +
> +	aggr = TASKSTATS_TYPE_AGGR_TGID;
> +	if (type == TASKSTATS_TYPE_PID)
> +		aggr = TASKSTATS_TYPE_AGGR_PID;
> +
> +	na = nla_nest_start(skb, aggr);
> +	NLA_PUT_U32(skb, type, pid);
> +	NLA_PUT_TYPE(skb, struct taskstats, TASKSTATS_TYPE_STATS, *stats);
> +	nla_nest_end(skb, na);
> +
> +	return 0;
> +nla_put_failure:
> +	return -1;
> +}
> +

How about using

aggr = (type == TASKSTATS_TYPE_PID) ? TASKSTATS_TYPE_AGGR_PID  :
				TASKSTATS_TYPE_AGGR_TGID;



>  static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
>  {
>  	int rc = 0;
> @@ -355,7 +374,6 @@ static int taskstats_user_cmd(struct sk_
>  	struct taskstats stats;
>  	void *reply;
>  	size_t size;
> -	struct nlattr *na;
>  	cpumask_t mask;
>  
>  	rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], &mask);
> @@ -387,27 +405,21 @@ static int taskstats_user_cmd(struct sk_
>  		if (rc < 0)
>  			goto err;
>  
> -		na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
> -		NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, pid);
> -		NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
> -				stats);
> +		if (mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid, &stats))
> +			goto nla_put_failure;
>  	} else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
>  		u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
>  		rc = fill_tgid(tgid, NULL, &stats);
>  		if (rc < 0)
>  			goto err;
>  
> -		na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
> -		NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, tgid);
> -		NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
> -				stats);
> +		if (mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid, &stats))
> +			goto nla_put_failure;
>  	} else {
>  		rc = -EINVAL;
>  		goto err;
>  	}
>  
> -	nla_nest_end(rep_skb, na);
> -
>  	return send_reply(rep_skb, info->snd_pid);
>  
>  nla_put_failure:
> @@ -451,7 +463,6 @@ void taskstats_exit(struct task_struct *
>  	void *reply;
>  	size_t size;
>  	int is_thread_group;
> -	struct nlattr *na;
>  
>  	if (!family_registered)
>  		return;
> @@ -486,27 +497,17 @@ void taskstats_exit(struct task_struct *
>  	if (rc < 0)
>  		goto err_skb;
>  
> -	na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
> -	NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, (u32)tsk->pid);
> -	NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
> -			*tidstats);
> -	nla_nest_end(rep_skb, na);
> -
> -	if (!is_thread_group)
> -		goto send;
> +	if (mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid, tidstats))
> +		goto nla_put_failure;
>  
>  	/*
>  	 * Doesn't matter if tsk is the leader or the last group member leaving
>  	 */
> -	if (!group_dead)
> +	if (!is_thread_group || !group_dead)
>  		goto send;
>  
> -	na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
> -	NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, (u32)tsk->tgid);
> -	/* No locking needed for tsk->signal->stats since group is dead */
> -	NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
> -			*tsk->signal->stats);
> -	nla_nest_end(rep_skb, na);
> +	if (mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid, tsk->signal->stats))
> +		goto nla_put_failure;
>  
>  send:
>  	send_cpu_listeners(rep_skb, listeners);
> 

Looks good!

Acked-by: Balbir Singh <balbir@...ibm.com>

-- 

	Balbir Singh,
	Linux Technology Center,
	IBM Software Labs
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