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Commit b87a173e authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

cls_cgroup: factor out classid retrieval 



Split out retrieving the cgroups net_cls classid retrieval into its
own function, so that it can be reused later on from other parts of
the traffic control subsystem. If there's no skb->sk, then the small
helper returns 0 as well, which in cls_cgroup terms means 'could not
classify'.

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Cc: Thomas Graf <tgraf@suug.ch>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d9382bda

include/net/cls_cgroup.h

+29 −0
Original line number Diff line number Diff line
@@ -49,9 +49,38 @@ static inline void sock_update_classid(struct sock *sk) 
	if (classid != sk->sk_classid)

		sk->sk_classid = classid;

}



static inline u32 task_get_classid(const struct sk_buff *skb)

{

	u32 classid = task_cls_state(current)->classid;



	/* Due to the nature of the classifier it is required to ignore all

	 * packets originating from softirq context as accessing `current'

	 * would lead to false results.

	 *

	 * This test assumes that all callers of dev_queue_xmit() explicitly

	 * disable bh. Knowing this, it is possible to detect softirq based

	 * calls by looking at the number of nested bh disable calls because

	 * softirqs always disables bh.

	 */

	if (in_serving_softirq()) {

		/* If there is an sk_classid we'll use that. */

		if (!skb->sk)

			return 0;



		classid = skb->sk->sk_classid;

	}



	return classid;

}

#else /* !CONFIG_CGROUP_NET_CLASSID */

static inline void sock_update_classid(struct sock *sk)

{

}



static inline u32 task_get_classid(const struct sk_buff *skb)

{

	return 0;

}

#endif /* CONFIG_CGROUP_NET_CLASSID */

#endif  /* _NET_CLS_CGROUP_H */

net/sched/cls_cgroup.c

+2 −21
Original line number Diff line number Diff line
@@ -30,35 +30,16 @@ static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp, 
			       struct tcf_result *res)

{

	struct cls_cgroup_head *head = rcu_dereference_bh(tp->root);

	u32 classid;



	classid = task_cls_state(current)->classid;



	/*

	 * Due to the nature of the classifier it is required to ignore all

	 * packets originating from softirq context as accessing `current'

	 * would lead to false results.

	 *

	 * This test assumes that all callers of dev_queue_xmit() explicitely

	 * disable bh. Knowing this, it is possible to detect softirq based

	 * calls by looking at the number of nested bh disable calls because

	 * softirqs always disables bh.

	 */

	if (in_serving_softirq()) {

		/* If there is an sk_classid we'll use that. */

		if (!skb->sk)

			return -1;

		classid = skb->sk->sk_classid;

	}

	u32 classid = task_get_classid(skb);



	if (!classid)

		return -1;



	if (!tcf_em_tree_match(skb, &head->ematches, NULL))

		return -1;



	res->classid = classid;

	res->class = 0;



	return tcf_exts_exec(skb, &head->exts, res);

}