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Commit 2cbfab07 authored by Vlad Buslov's avatar Vlad Buslov Committed by David S. Miller
Browse files

net: sched: refactor tc_ctl_chain() to use block->lock 



In order to remove dependency on rtnl lock, modify chain API to use
block->lock to protect chain from concurrent modification. Rearrange
tc_ctl_chain() code to call tcf_chain_hold() while holding block->lock to
prevent concurrent chain removal.

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 91052fa1

net/sched/cls_api.c

+25 −11
Original line number Diff line number Diff line
@@ -2255,6 +2255,8 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n, 
		err = -EINVAL;

		goto errout_block;

	}



	mutex_lock(&block->lock);

	chain = tcf_chain_lookup(block, chain_index);

	if (n->nlmsg_type == RTM_NEWCHAIN) {

		if (chain) {
@@ -2266,41 +2268,49 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n, 
			} else {

				NL_SET_ERR_MSG(extack, "Filter chain already exists");

				err = -EEXIST;

				goto errout_block;

				goto errout_block_locked;

			}

		} else {

			if (!(n->nlmsg_flags & NLM_F_CREATE)) {

				NL_SET_ERR_MSG(extack, "Need both RTM_NEWCHAIN and NLM_F_CREATE to create a new chain");

				err = -ENOENT;

				goto errout_block;

				goto errout_block_locked;

			}

			chain = tcf_chain_create(block, chain_index);

			if (!chain) {

				NL_SET_ERR_MSG(extack, "Failed to create filter chain");

				err = -ENOMEM;

				goto errout_block;

				goto errout_block_locked;

			}

		}

	} else {

		if (!chain || tcf_chain_held_by_acts_only(chain)) {

			NL_SET_ERR_MSG(extack, "Cannot find specified filter chain");

			err = -EINVAL;

			goto errout_block;

			goto errout_block_locked;

		}

		tcf_chain_hold(chain);

	}



	if (n->nlmsg_type == RTM_NEWCHAIN) {

		/* Modifying chain requires holding parent block lock. In case

		 * the chain was successfully added, take a reference to the

		 * chain. This ensures that an empty chain does not disappear at

		 * the end of this function.

		 */

		tcf_chain_hold(chain);

		chain->explicitly_created = true;

	}

	mutex_unlock(&block->lock);



	switch (n->nlmsg_type) {

	case RTM_NEWCHAIN:

		err = tc_chain_tmplt_add(chain, net, tca, extack);

		if (err)

		if (err) {

			tcf_chain_put_explicitly_created(chain);

			goto errout;

		/* In case the chain was successfully added, take a reference

		 * to the chain. This ensures that an empty chain

		 * does not disappear at the end of this function.

		 */

		tcf_chain_hold(chain);

		chain->explicitly_created = true;

		}



		tc_chain_notify(chain, NULL, 0, NLM_F_CREATE | NLM_F_EXCL,

				RTM_NEWCHAIN, false);

		break;
@@ -2334,6 +2344,10 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n, 
		/* Replay the request. */

		goto replay;

	return err;



errout_block_locked:

	mutex_unlock(&block->lock);

	goto errout_block;

}



/* called with RTNL */