Commit ace4a267 authored by Vlad Buslov's avatar Vlad Buslov Committed by David S. Miller
Browse files

net: sched: don't release block->lock when dumping chains 



Function tc_dump_chain() obtains and releases block->lock on each iteration
of its inner loop that dumps all chains on block. Outputting chain template
info is fast operation so locking/unlocking mutex multiple times is an
overhead when lock is highly contested. Modify tc_dump_chain() to only
obtain block->lock once and dump all chains without releasing it.

Signed-off-by: default avatarVlad Buslov <vladbu@mellanox.com>
Suggested-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6676d5e4

net/sched/cls_api.c

+7 −9
Original line number Diff line number Diff line
@@ -2912,12 +2912,12 @@ errout_block_locked: 
/* called with RTNL */

static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb)

{

	struct tcf_chain *chain, *chain_prev;

	struct net *net = sock_net(skb->sk);

	struct nlattr *tca[TCA_MAX + 1];

	struct Qdisc *q = NULL;

	struct tcf_block *block;

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

	struct tcf_chain *chain;

	long index_start;

	long index;

	u32 parent;
@@ -2980,11 +2980,8 @@ static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb) 
	index_start = cb->args[0];

	index = 0;



	for (chain = __tcf_get_next_chain(block, NULL);

	     chain;

	     chain_prev = chain,

		     chain = __tcf_get_next_chain(block, chain),

		     tcf_chain_put(chain_prev)) {

	mutex_lock(&block->lock);

	list_for_each_entry(chain, &block->chain_list, list) {

		if ((tca[TCA_CHAIN] &&

		     nla_get_u32(tca[TCA_CHAIN]) != chain->index))

			continue;
@@ -2992,17 +2989,18 @@ static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb) 
			index++;

			continue;

		}

		if (tcf_chain_held_by_acts_only(chain))

			continue;

		err = tc_chain_fill_node(chain->tmplt_ops, chain->tmplt_priv,

					 chain->index, net, skb, block,

					 NETLINK_CB(cb->skb).portid,

					 cb->nlh->nlmsg_seq, NLM_F_MULTI,

					 RTM_NEWCHAIN);

		if (err <= 0) {

			tcf_chain_put(chain);

		if (err <= 0)

			break;

		}

		index++;

	}

	mutex_unlock(&block->lock);



	if (tcm->tcm_ifindex == TCM_IFINDEX_MAGIC_BLOCK)

		tcf_block_refcnt_put(block, true);

CRA Git | Maintained and supported by SUSTech CRA and CCSE