net_sched: return correct value for *notify* functions

wangzk320 · davem330 · commit 5b5f99b18690 · 2019-03-13T13:48:27.000-07:00
It is confusing to directly use return value of netlink_send()/
netlink_unicast() as the return value of *notify*, as it may be not
error at all.

Example: in tc_del_tfilter(), after calling tfilter_del_notify(), it will
goto errout if (err). However, the netlink_send()/netlink_unicast() will
return positive value even for successful case. So it may not call
tcf_chain_tp_remove() and so on to clean up the resource, as a result,
resource is leaked.

It may be easier to only check the return value of tfilter_del_nofiy(),
but it is more clean to correct all related functions.

Co-developed-by: Zengmo Gao &lt;gaozengmo@jd.com&gt;
Signed-off-by: Zhike Wang &lt;wangzhike@jd.com&gt;
Acked-by: Cong Wang &lt;xiyou.wangcong@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
@@ -1893,6 +1893,7 @@ static int tfilter_notify(struct net *net, struct sk_buff *oskb,
 {
 	struct sk_buff *skb;
 	u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
+	int err = 0;
 
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
 	if (!skb)
@@ -1906,10 +1907,14 @@ static int tfilter_notify(struct net *net, struct sk_buff *oskb,
 	}
 
 	if (unicast)
-		return netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
+		err = netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
+	else
+		err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
+				     n->nlmsg_flags & NLM_F_ECHO);
 
-	return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
-			      n->nlmsg_flags & NLM_F_ECHO);
+	if (err > 0)
+		err = 0;
+	return err;
 }
 
 static int tfilter_del_notify(struct net *net, struct sk_buff *oskb,
@@ -1941,12 +1946,15 @@ static int tfilter_del_notify(struct net *net, struct sk_buff *oskb,
 	}
 
 	if (unicast)
-		return netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
-
-	err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
-			     n->nlmsg_flags & NLM_F_ECHO);
+		err = netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
+	else
+		err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
+				     n->nlmsg_flags & NLM_F_ECHO);
 	if (err < 0)
 		NL_SET_ERR_MSG(extack, "Failed to send filter delete notification");
+
+	if (err > 0)
+		err = 0;
 	return err;
 }
 
@@ -2688,6 +2696,7 @@ static int tc_chain_notify(struct tcf_chain *chain, struct sk_buff *oskb,
 	struct tcf_block *block = chain->block;
 	struct net *net = block->net;
 	struct sk_buff *skb;
+	int err = 0;
 
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
 	if (!skb)
@@ -2701,9 +2710,14 @@ static int tc_chain_notify(struct tcf_chain *chain, struct sk_buff *oskb,
 	}
 
 	if (unicast)
-		return netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
+		err = netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
+	else
+		err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
+				     flags & NLM_F_ECHO);
 
-	return rtnetlink_send(skb, net, portid, RTNLGRP_TC, flags & NLM_F_ECHO);
+	if (err > 0)
+		err = 0;
+	return err;
 }
 
 static int tc_chain_notify_delete(const struct tcf_proto_ops *tmplt_ops,
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
@@ -1824,6 +1824,7 @@ static int tclass_notify(struct net *net, struct sk_buff *oskb,
 {
 	struct sk_buff *skb;
 	u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
+	int err = 0;
 
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
 	if (!skb)
@@ -1834,8 +1835,11 @@ static int tclass_notify(struct net *net, struct sk_buff *oskb,
 		return -EINVAL;
 	}
 
-	return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
-			      n->nlmsg_flags & NLM_F_ECHO);
+	err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
+			     n->nlmsg_flags & NLM_F_ECHO);
+	if (err > 0)
+		err = 0;
+	return err;
 }
 
 static int tclass_del_notify(struct net *net,
@@ -1866,8 +1870,11 @@ static int tclass_del_notify(struct net *net,
 		return err;
 	}
 
-	return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
-			      n->nlmsg_flags & NLM_F_ECHO);
+	err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
+			     n->nlmsg_flags & NLM_F_ECHO);
+	if (err > 0)
+		err = 0;
+	return err;
 }
 
 #ifdef CONFIG_NET_CLS

Original file line number	Diff line number	Diff line change
`@@ -1824,6 +1824,7 @@ static int tclass_notify(struct net net, struct sk_buff oskb,`
`1824`	`1824`	`{`
`1825`	`1825`	`struct sk_buff *skb;`
`1826`	`1826`	`u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;`
	`1827`	`+ int err = 0;`
`1827`	`1828`
`1828`	`1829`	`skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);`
`1829`	`1830`	`if (!skb)`
`@@ -1834,8 +1835,11 @@ static int tclass_notify(struct net net, struct sk_buff oskb,`
`1834`	`1835`	`return -EINVAL;`
`1835`	`1836`	`}`
`1836`	`1837`
`1837`		`- return rtnetlink_send(skb, net, portid, RTNLGRP_TC,`
`1838`		`- n->nlmsg_flags & NLM_F_ECHO);`
	`1838`	`+ err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,`
	`1839`	`+ n->nlmsg_flags & NLM_F_ECHO);`
	`1840`	`+ if (err > 0)`
	`1841`	`+ err = 0;`
	`1842`	`+ return err;`
`1839`	`1843`	`}`
`1840`	`1844`
`1841`	`1845`	`static int tclass_del_notify(struct net *net,`
`@@ -1866,8 +1870,11 @@ static int tclass_del_notify(struct net *net,`
`1866`	`1870`	`return err;`
`1867`	`1871`	`}`
`1868`	`1872`
`1869`		`- return rtnetlink_send(skb, net, portid, RTNLGRP_TC,`
`1870`		`- n->nlmsg_flags & NLM_F_ECHO);`
	`1873`	`+ err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,`
	`1874`	`+ n->nlmsg_flags & NLM_F_ECHO);`
	`1875`	`+ if (err > 0)`
	`1876`	`+ err = 0;`
	`1877`	`+ return err;`
`1871`	`1878`	`}`
`1872`	`1879`
`1873`	`1880`	`#ifdef CONFIG_NET_CLS`