netdev - [PATCH net-next] net: sched: remove redundant 'rtnl

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Message-Id: <20201127151205.23492-1-vladbu@nvidia.com>
Date:   Fri, 27 Nov 2020 17:12:05 +0200
From:   Vlad Buslov <vladbu@...dia.com>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, Vlad Buslov <vladbu@...dia.com>
Subject: [PATCH net-next] net: sched: remove redundant 'rtnl_held' argument

Functions tfilter_notify_chain() and tcf_get_next_proto() are always called
with rtnl lock held in current implementation. Moreover, attempting to call
them without rtnl lock would cause a warning down the call chain in
function __tcf_get_next_proto() that requires the lock to be held by
callers. Remove the 'rtnl_held' argument in order to simplify the code and
make rtnl lock requirement explicit.

Signed-off-by: Vlad Buslov <vladbu@...dia.com>
---
 include/net/pkt_cls.h |  2 +-
 net/sched/cls_api.c   | 18 ++++++++----------
 net/sched/sch_api.c   |  4 ++--
 3 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index 133f9ad4d4f9..0f2a9c44171c 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -48,7 +48,7 @@ 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, bool rtnl_held);
+				     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,
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index ff3e943febaa..37b77bd30974 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -991,13 +991,12 @@ __tcf_get_next_proto(struct tcf_chain *chain, struct tcf_proto *tp)
  */
 
 struct tcf_proto *
-tcf_get_next_proto(struct tcf_chain *chain, struct tcf_proto *tp,
-		   bool rtnl_held)
+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, rtnl_held, NULL);
+		tcf_proto_put(tp, true, NULL);
 
 	return tp_next;
 }
@@ -1924,15 +1923,14 @@ static int tfilter_del_notify(struct net *net, struct sk_buff *oskb,
 static void tfilter_notify_chain(struct net *net, struct sk_buff *oskb,
 				 struct tcf_block *block, struct Qdisc *q,
 				 u32 parent, struct nlmsghdr *n,
-				 struct tcf_chain *chain, int event,
-				 bool rtnl_held)
+				 struct tcf_chain *chain, int event)
 {
 	struct tcf_proto *tp;
 
-	for (tp = tcf_get_next_proto(chain, NULL, rtnl_held);
-	     tp; tp = tcf_get_next_proto(chain, tp, rtnl_held))
+	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, rtnl_held);
+			       q, parent, NULL, event, false, true);
 }
 
 static void tfilter_put(struct tcf_proto *tp, void *fh)
@@ -2262,7 +2260,7 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
 
 	if (prio == 0) {
 		tfilter_notify_chain(net, skb, block, q, parent, n,
-				     chain, RTM_DELTFILTER, rtnl_held);
+				     chain, RTM_DELTFILTER);
 		tcf_chain_flush(chain, rtnl_held);
 		err = 0;
 		goto errout;
@@ -2895,7 +2893,7 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n,
 		break;
 	case RTM_DELCHAIN:
 		tfilter_notify_chain(net, skb, block, q, parent, n,
-				     chain, RTM_DELTFILTER, true);
+				     chain, RTM_DELTFILTER);
 		/* Flush the chain first as the user requested chain removal. */
 		tcf_chain_flush(chain, true);
 		/* In case the chain was successfully deleted, put a reference
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 1a2d2471b078..51cb553e4317 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1943,8 +1943,8 @@ static int tc_bind_class_walker(struct Qdisc *q, unsigned long cl,
 	     chain = tcf_get_next_chain(block, chain)) {
 		struct tcf_proto *tp;
 
-		for (tp = tcf_get_next_proto(chain, NULL, true);
-		     tp; tp = tcf_get_next_proto(chain, tp, true)) {
+		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;
-- 
2.21.0