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Commit fe2923af authored by Vlad Buslov's avatar Vlad Buslov Committed by David S. Miller
Browse files

net: sched: traverse classifiers in chain with tcf_get_next_proto() 



All users of chain->filters_chain rely on rtnl lock and assume that no new
classifier instances are added when traversing the list. Use
tcf_get_next_proto() to traverse filters list without relying on rtnl
mutex. This function iterates over classifiers by taking reference to
current iterator classifier only and doesn't assume external
synchronization of filters list.

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 4dbfa766

include/net/pkt_cls.h

+2 −0
Original line number Diff line number Diff line
@@ -46,6 +46,8 @@ struct tcf_chain *tcf_chain_get_by_act(struct tcf_block *block, 
void tcf_chain_put_by_act(struct tcf_chain *chain);

struct tcf_chain *tcf_get_next_chain(struct tcf_block *block,

				     struct tcf_chain *chain);

struct tcf_proto *tcf_get_next_proto(struct tcf_chain *chain,

				     struct tcf_proto *tp);

void tcf_block_netif_keep_dst(struct tcf_block *block);

int tcf_block_get(struct tcf_block **p_block,

		  struct tcf_proto __rcu **p_filter_chain, struct Qdisc *q,

net/sched/cls_api.c

+60 −10
Original line number Diff line number Diff line
@@ -980,6 +980,45 @@ tcf_get_next_chain(struct tcf_block *block, struct tcf_chain *chain) 
}

EXPORT_SYMBOL(tcf_get_next_chain);



static struct tcf_proto *

__tcf_get_next_proto(struct tcf_chain *chain, struct tcf_proto *tp)

{

	ASSERT_RTNL();

	mutex_lock(&chain->filter_chain_lock);



	if (!tp)

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

	else

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



	if (tp)

		tcf_proto_get(tp);



	mutex_unlock(&chain->filter_chain_lock);



	return tp;

}



/* Function to be used by all clients that want to iterate over all tp's on

 * chain. Users of this function must be tolerant to concurrent tp

 * insertion/deletion or ensure that no concurrent chain modification is

 * possible. Note that all netlink dump callbacks cannot guarantee to provide

 * consistent dump because rtnl lock is released each time skb is filled with

 * data and sent to user-space.

 */



struct tcf_proto *

tcf_get_next_proto(struct tcf_chain *chain, struct tcf_proto *tp)

{

	struct tcf_proto *tp_next = __tcf_get_next_proto(chain, tp);



	if (tp)

		tcf_proto_put(tp, NULL);



	return tp_next;

}

EXPORT_SYMBOL(tcf_get_next_proto);



static void tcf_block_flush_all_chains(struct tcf_block *block)

{

	struct tcf_chain *chain;
@@ -1352,7 +1391,7 @@ tcf_block_playback_offloads(struct tcf_block *block, tc_setup_cb_t *cb, 
			    struct netlink_ext_ack *extack)

{

	struct tcf_chain *chain, *chain_prev;

	struct tcf_proto *tp;

	struct tcf_proto *tp, *tp_prev;

	int err;



	for (chain = __tcf_get_next_chain(block, NULL);
@@ -1360,8 +1399,10 @@ tcf_block_playback_offloads(struct tcf_block *block, tc_setup_cb_t *cb, 
	     chain_prev = chain,

		     chain = __tcf_get_next_chain(block, chain),

		     tcf_chain_put(chain_prev)) {

		for (tp = rtnl_dereference(chain->filter_chain); tp;

		     tp = rtnl_dereference(tp->next)) {

		for (tp = __tcf_get_next_proto(chain, NULL); tp;

		     tp_prev = tp,

			     tp = __tcf_get_next_proto(chain, tp),

			     tcf_proto_put(tp_prev, NULL)) {

			if (tp->ops->reoffload) {

				err = tp->ops->reoffload(tp, add, cb, cb_priv,

							 extack);
@@ -1378,6 +1419,7 @@ tcf_block_playback_offloads(struct tcf_block *block, tc_setup_cb_t *cb, 
	return 0;



err_playback_remove:

	tcf_proto_put(tp, NULL);

	tcf_chain_put(chain);

	tcf_block_playback_offloads(block, cb, cb_priv, false, offload_in_use,

				    extack);
@@ -1677,8 +1719,8 @@ static void tfilter_notify_chain(struct net *net, struct sk_buff *oskb, 
{

	struct tcf_proto *tp;



	for (tp = rtnl_dereference(chain->filter_chain);

	     tp; tp = rtnl_dereference(tp->next))

	for (tp = tcf_get_next_proto(chain, NULL);

	     tp; tp = tcf_get_next_proto(chain, tp))

		tfilter_notify(net, oskb, n, tp, block,

			       q, parent, NULL, event, false);

}
@@ -2104,11 +2146,15 @@ static bool tcf_chain_dump(struct tcf_chain *chain, struct Qdisc *q, u32 parent, 
	struct net *net = sock_net(skb->sk);

	struct tcf_block *block = chain->block;

	struct tcmsg *tcm = nlmsg_data(cb->nlh);

	struct tcf_proto *tp, *tp_prev;

	struct tcf_dump_args arg;

	struct tcf_proto *tp;



	for (tp = rtnl_dereference(chain->filter_chain);

	     tp; tp = rtnl_dereference(tp->next), (*p_index)++) {

	for (tp = __tcf_get_next_proto(chain, NULL);

	     tp;

	     tp_prev = tp,

		     tp = __tcf_get_next_proto(chain, tp),

		     tcf_proto_put(tp_prev, NULL),

		     (*p_index)++) {

		if (*p_index < index_start)

			continue;

		if (TC_H_MAJ(tcm->tcm_info) &&
@@ -2125,7 +2171,7 @@ static bool tcf_chain_dump(struct tcf_chain *chain, struct Qdisc *q, u32 parent, 
					  NETLINK_CB(cb->skb).portid,

					  cb->nlh->nlmsg_seq, NLM_F_MULTI,

					  RTM_NEWTFILTER) <= 0)

				return false;

				goto errout;



			cb->args[1] = 1;

		}
@@ -2145,9 +2191,13 @@ static bool tcf_chain_dump(struct tcf_chain *chain, struct Qdisc *q, u32 parent, 
		cb->args[2] = arg.w.cookie;

		cb->args[1] = arg.w.count + 1;

		if (arg.w.stop)

			return false;

			goto errout;

	}

	return true;



errout:

	tcf_proto_put(tp, NULL);

	return false;

}



/* called with RTNL */

net/sched/sch_api.c

+2 −2
Original line number Diff line number Diff line
@@ -1914,8 +1914,8 @@ static void tc_bind_tclass(struct Qdisc *q, u32 portid, u32 clid, 
	     chain = tcf_get_next_chain(block, chain)) {

		struct tcf_proto *tp;



		for (tp = rtnl_dereference(chain->filter_chain);

		     tp; tp = rtnl_dereference(tp->next)) {

		for (tp = tcf_get_next_proto(chain, NULL);

		     tp; tp = tcf_get_next_proto(chain, tp)) {

			struct tcf_bind_args arg = {};



			arg.w.fn = tcf_node_bind;