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Commit 37167485 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

[PATCH] taskstats: cleanup reply assembling 



Thomas Graf wrote:
>
> nla_nest_start() may return NULL, either rely on prepare_reply() to be
> correct and BUG() on failure or do proper error handling for all
> functions.

nla_put() in taskstat.c can fail only if the 'size' argument of alloc_skb()
was not right. This is a kernel bug, we should not hide it. So add 'BUG()'
on error path and check for 'na == NULL'.

> genlmsg_cancel() is only required in error paths for dumping
> procedures.

So we can remove 'genlmsg_cancel()' calls and 'void *reply' (saves 227 bytes).

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Jay Lan <jlan@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 51de4d90

kernel/taskstats.c

+16 −22
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ enum actions { 
};



static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,

			void **replyp, size_t size)

				size_t size)

{

	struct sk_buff *skb;

	void *reply;
@@ -94,7 +94,6 @@ static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp, 
	}



	*skbp = skb;

	*replyp = reply;

	return 0;

}
@@ -351,11 +350,13 @@ static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid) 
	struct nlattr *na, *ret;

	int aggr;



	aggr = TASKSTATS_TYPE_AGGR_TGID;

	if (type == TASKSTATS_TYPE_PID)

		aggr = TASKSTATS_TYPE_AGGR_PID;

	aggr = (type == TASKSTATS_TYPE_PID)

			? TASKSTATS_TYPE_AGGR_PID

			: TASKSTATS_TYPE_AGGR_TGID;



	na = nla_nest_start(skb, aggr);

	if (!na)

		goto err;

	if (nla_put(skb, type, sizeof(pid), &pid) < 0)

		goto err;

	ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
@@ -373,7 +374,6 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info) 
	int rc = 0;

	struct sk_buff *rep_skb;

	struct taskstats *stats;

	void *reply;

	size_t size;

	cpumask_t mask;
@@ -395,7 +395,7 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info) 
	size = nla_total_size(sizeof(u32)) +

		nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);



	rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);

	rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);

	if (rc < 0)

		return rc;
@@ -404,27 +404,24 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info) 
		u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);

		stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);

		if (!stats)

			goto nla_err;

			goto err;



		rc = fill_pid(pid, NULL, stats);

		if (rc < 0)

			goto nla_err;

			goto err;

	} else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {

		u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);

		stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);

		if (!stats)

			goto nla_err;

			goto err;



		rc = fill_tgid(tgid, NULL, stats);

		if (rc < 0)

			goto nla_err;

			goto err;

	} else

		goto err;



	return send_reply(rep_skb, info->snd_pid);



nla_err:

	genlmsg_cancel(rep_skb, reply);

err:

	nlmsg_free(rep_skb);

	return rc;
@@ -461,7 +458,6 @@ void taskstats_exit(struct task_struct *tsk, int group_dead) 
	struct listener_list *listeners;

	struct taskstats *stats;

	struct sk_buff *rep_skb;

	void *reply;

	size_t size;

	int is_thread_group;
@@ -486,17 +482,17 @@ void taskstats_exit(struct task_struct *tsk, int group_dead) 
	if (list_empty(&listeners->list))

		return;



	rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);

	rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);

	if (rc < 0)

		return;



	stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);

	if (!stats)

		goto nla_err;

		goto err;



	rc = fill_pid(tsk->pid, tsk, stats);

	if (rc < 0)

		goto nla_err;

		goto err;



	/*

	 * Doesn't matter if tsk is the leader or the last group member leaving
@@ -506,16 +502,14 @@ void taskstats_exit(struct task_struct *tsk, int group_dead) 


	stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);

	if (!stats)

		goto nla_err;

		goto err;



	memcpy(stats, tsk->signal->stats, sizeof(*stats));



send:

	send_cpu_listeners(rep_skb, listeners);

	return;



nla_err:

	genlmsg_cancel(rep_skb, reply);

err:

	nlmsg_free(rep_skb);

}