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Commit 4dbfa766 authored by Vlad Buslov's avatar Vlad Buslov Committed by David S. Miller
Browse files

net: sched: introduce reference counting for tcf_proto 



In order to remove dependency on rtnl lock and allow concurrent tcf_proto
modification, extend tcf_proto with reference counter. Implement helper
get/put functions for tcf proto and use them to modify cls API to always
take reference to tcf_proto while using it. Only release reference to
parent chain after releasing last reference to tp.

Signed-off-by: default avatarVlad Buslov <vladbu@mellanox.com>
Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ed76f5ed

include/net/sch_generic.h

+1 −0
Original line number Diff line number Diff line
@@ -322,6 +322,7 @@ struct tcf_proto { 
	void			*data;

	const struct tcf_proto_ops	*ops;

	struct tcf_chain	*chain;

	refcount_t		refcnt;

	struct rcu_head		rcu;

};

net/sched/cls_api.c

+43 −10
Original line number Diff line number Diff line
@@ -180,6 +180,7 @@ static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol, 
	tp->protocol = protocol;

	tp->prio = prio;

	tp->chain = chain;

	refcount_set(&tp->refcnt, 1);



	err = tp->ops->init(tp);

	if (err) {
@@ -193,14 +194,29 @@ static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol, 
	return ERR_PTR(err);

}



static void tcf_proto_get(struct tcf_proto *tp)

{

	refcount_inc(&tp->refcnt);

}



static void tcf_chain_put(struct tcf_chain *chain);



static void tcf_proto_destroy(struct tcf_proto *tp,

			      struct netlink_ext_ack *extack)

{

	tp->ops->destroy(tp, extack);

	tcf_chain_put(tp->chain);

	module_put(tp->ops->owner);

	kfree_rcu(tp, rcu);

}



static void tcf_proto_put(struct tcf_proto *tp,

			  struct netlink_ext_ack *extack)

{

	if (refcount_dec_and_test(&tp->refcnt))

		tcf_proto_destroy(tp, extack);

}



#define ASSERT_BLOCK_LOCKED(block)					\

	lockdep_assert_held(&(block)->lock)
@@ -445,18 +461,18 @@ static void tcf_chain_put_explicitly_created(struct tcf_chain *chain) 


static void tcf_chain_flush(struct tcf_chain *chain)

{

	struct tcf_proto *tp;

	struct tcf_proto *tp, *tp_next;



	mutex_lock(&chain->filter_chain_lock);

	tp = tcf_chain_dereference(chain->filter_chain, chain);

	RCU_INIT_POINTER(chain->filter_chain, NULL);

	tcf_chain0_head_change(chain, NULL);

	mutex_unlock(&chain->filter_chain_lock);



	while (tp) {

		RCU_INIT_POINTER(chain->filter_chain, tp->next);

		tcf_proto_destroy(tp, NULL);

		tp = rtnl_dereference(chain->filter_chain);

		tcf_chain_put(chain);

		tp_next = rcu_dereference_protected(tp->next, 1);

		tcf_proto_put(tp, NULL);

		tp = tp_next;

	}

}
@@ -1500,9 +1516,9 @@ static void tcf_chain_tp_insert(struct tcf_chain *chain, 
{

	if (*chain_info->pprev == chain->filter_chain)

		tcf_chain0_head_change(chain, tp);

	tcf_proto_get(tp);

	RCU_INIT_POINTER(tp->next, tcf_chain_tp_prev(chain, chain_info));

	rcu_assign_pointer(*chain_info->pprev, tp);

	tcf_chain_hold(chain);

}



static void tcf_chain_tp_remove(struct tcf_chain *chain,
@@ -1514,7 +1530,6 @@ static void tcf_chain_tp_remove(struct tcf_chain *chain, 
	if (tp == chain->filter_chain)

		tcf_chain0_head_change(chain, next);

	RCU_INIT_POINTER(*chain_info->pprev, next);

	tcf_chain_put(chain);

}



static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain,
@@ -1541,7 +1556,12 @@ static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain, 
		}

	}

	chain_info->pprev = pprev;

	chain_info->next = tp ? tp->next : NULL;

	if (tp) {

		chain_info->next = tp->next;

		tcf_proto_get(tp);

	} else {

		chain_info->next = NULL;

	}

	return tp;

}
@@ -1699,6 +1719,7 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n, 
	prio = TC_H_MAJ(t->tcm_info);

	prio_allocate = false;

	parent = t->tcm_parent;

	tp = NULL;

	cl = 0;



	if (prio == 0) {
@@ -1816,6 +1837,12 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n, 
errout:

	if (chain)

		tcf_chain_put(chain);

	if (chain) {

		if (tp && !IS_ERR(tp))

			tcf_proto_put(tp, NULL);

		if (!tp_created)

			tcf_chain_put(chain);

	}

	tcf_block_release(q, block);

	if (err == -EAGAIN)

		/* Replay the request. */
@@ -1946,8 +1973,11 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n, 
	}



errout:

	if (chain)

	if (chain) {

		if (tp && !IS_ERR(tp))

			tcf_proto_put(tp, NULL);

		tcf_chain_put(chain);

	}

	tcf_block_release(q, block);

	return err;
@@ -2038,8 +2068,11 @@ static int tc_get_tfilter(struct sk_buff *skb, struct nlmsghdr *n, 
	}



errout:

	if (chain)

	if (chain) {

		if (tp && !IS_ERR(tp))

			tcf_proto_put(tp, NULL);

		tcf_chain_put(chain);

	}

	tcf_block_release(q, block);

	return err;

}