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From: Vlad Buslov <vladbu@mellanox.com>
To: netdev@vger.kernel.org
Cc: jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us,
	davem@davemloft.net, ast@kernel.org, daniel@iogearbox.net,
	Vlad Buslov <vladbu@mellanox.com>
Subject: [PATCH net-next v4 03/17] net: sched: refactor tc_ctl_chain() to use block->lock
Date: Mon, 11 Feb 2019 10:55:34 +0200
Message-ID: <20190211085548.7190-4-vladbu@mellanox.com> (raw)
In-Reply-To: <20190211085548.7190-1-vladbu@mellanox.com>

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: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
---
 net/sched/cls_api.c | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 2ebf8e53038a..b5db0f79db14 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -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 */
-- 
2.13.6


  parent reply index

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-11  8:55 [PATCH net-next v4 00/17] Refactor classifier API to work with chain/classifiers without rtnl lock Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 01/17] net: sched: protect block state with mutex Vlad Buslov
2019-02-11 14:15   ` Jiri Pirko
2019-02-11  8:55 ` [PATCH net-next v4 02/17] net: sched: protect chain->explicitly_created with block->lock Vlad Buslov
2019-02-11 14:15   ` Jiri Pirko
2019-02-11  8:55 ` Vlad Buslov [this message]
2019-02-11  8:55 ` [PATCH net-next v4 04/17] net: sched: protect block->chain0 " Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 05/17] net: sched: traverse chains in block with tcf_get_next_chain() Vlad Buslov
2019-02-15 22:21   ` Cong Wang
2019-02-18 10:07     ` Vlad Buslov
2019-02-18 18:26       ` Cong Wang
2019-02-19 16:04         ` Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 06/17] net: sched: protect chain template accesses with block lock Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 07/17] net: sched: protect filter_chain list with filter_chain_lock mutex Vlad Buslov
2019-02-14 18:24   ` Ido Schimmel
2019-02-15 10:02     ` Vlad Buslov
2019-02-15 11:30       ` Ido Schimmel
2019-02-15 12:11         ` [PATCH] net: sched: matchall: verify that filter is not NULL in mall_walk() Vlad Buslov
2019-02-15 13:47           ` Ido Schimmel
2019-02-16  0:24           ` Cong Wang
2019-02-18 12:00             ` Vlad Buslov
2019-02-17 21:27           ` David Miller
2019-02-15 12:15         ` [PATCH net-next v4 07/17] net: sched: protect filter_chain list with filter_chain_lock mutex Vlad Buslov
2019-02-15 15:35         ` Vlad Buslov
2019-02-19  5:26           ` Cong Wang
2019-02-19 12:31             ` Vlad Buslov
2019-02-20 22:43               ` Cong Wang
2019-02-21 15:49                 ` Vlad Buslov
2019-02-19  5:08       ` Cong Wang
2019-02-19 15:20         ` Vlad Buslov
2019-02-20 23:00           ` Cong Wang
2019-02-21 17:11             ` Vlad Buslov
2019-02-15 22:35   ` Cong Wang
2019-02-18 11:06     ` Vlad Buslov
2019-02-18 18:31       ` Cong Wang
2019-02-11  8:55 ` [PATCH net-next v4 08/17] net: sched: introduce reference counting for tcf_proto Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 09/17] net: sched: traverse classifiers in chain with tcf_get_next_proto() Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 10/17] net: sched: refactor tp insert/delete for concurrent execution Vlad Buslov
2019-02-15 23:17   ` Cong Wang
2019-02-18 11:19     ` Vlad Buslov
2019-02-18 19:55       ` Cong Wang
2019-02-19 10:25         ` Vlad Buslov
2019-02-18 19:53   ` Cong Wang
2019-02-11  8:55 ` [PATCH net-next v4 11/17] net: sched: prevent insertion of new classifiers during chain flush Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 12/17] net: sched: track rtnl lock status when validating extensions Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 13/17] net: sched: extend proto ops with 'put' callback Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 14/17] net: sched: extend proto ops to support unlocked classifiers Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 15/17] net: sched: add flags to Qdisc class ops struct Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 16/17] net: sched: refactor tcf_block_find() into standalone functions Vlad Buslov
2019-02-11  8:55 ` [PATCH net-next v4 17/17] net: sched: unlock rules update API Vlad Buslov
2019-02-18 18:56   ` Cong Wang
2019-02-12 18:42 ` [PATCH net-next v4 00/17] Refactor classifier API to work with chain/classifiers without rtnl lock David Miller

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