net_sched: return correct value for *notify* functions

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 <gaozengmo@jd.com>
Signed-off-by: Zhike Wang <wangzhike@jd.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 2c2aac4ac721c94d8c198f4d49ea24146b9906c7..dc10525e90e7073563f9a3b220fc092323946a19 100644 (file)
--- 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
index 352b46f98440a06e184dbc409d6eb5a90e32226a..fb8f138b97763bdf917b202ba1b93ad773d0407f 100644 (file)
--- 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