netdev - [PATCH net-next v3] net: assign err to 0 at begin in do

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Date:   Thu, 16 Nov 2017 19:59:48 +0800
From:   yuan linyu <cugyly@....com>
To:     netdev@...r.kernel.org
Cc:     "David S . Miller" <davem@...emloft.net>,
        yuan linyu <Linyu.Yuan@...atel-sbell.com.cn>
Subject: [PATCH net-next v3] net: assign err to 0 at begin in do_setlink() function

From: yuan linyu <Linyu.Yuan@...atel-sbell.com.cn>

each netlink attribute have proper process when error happen,
when exit one attribute process, it implies that no error,
so err = 0; is useless.

assign err = 0; at beginning if all attributes not set.

v1 -> v2:
	fix review comment from David, clear err before
	nla_for_each_nested()

v2 -> v3:
	maybe wrong understanding of David comment,
	provide a new version

Signed-off-by: yuan linyu <Linyu.Yuan@...atel-sbell.com.cn>
---
 net/core/rtnetlink.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index dabba2a..54f792b 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2075,7 +2075,7 @@ static int do_setlink(const struct sk_buff *skb,
 		      struct nlattr **tb, char *ifname, int status)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
-	int err;
+	int err = 0;
 
 	if (tb[IFLA_NET_NS_PID] || tb[IFLA_NET_NS_FD]) {
 		struct net *net = rtnl_link_get_net(dev_net(dev), tb);
@@ -2253,7 +2253,6 @@ static int do_setlink(const struct sk_buff *skb,
 			status |= DO_SETLINK_NOTIFY;
 		}
 	}
-	err = 0;
 
 	if (tb[IFLA_VF_PORTS]) {
 		struct nlattr *port[IFLA_PORT_MAX+1];
@@ -2261,9 +2260,10 @@ static int do_setlink(const struct sk_buff *skb,
 		int vf;
 		int rem;
 
-		err = -EOPNOTSUPP;
-		if (!ops->ndo_set_vf_port)
+		if (!ops->ndo_set_vf_port) {
+			err = -EOPNOTSUPP;
 			goto errout;
+		}
 
 		nla_for_each_nested(attr, tb[IFLA_VF_PORTS], rem) {
 			if (nla_type(attr) != IFLA_VF_PORT ||
@@ -2286,7 +2286,6 @@ static int do_setlink(const struct sk_buff *skb,
 			status |= DO_SETLINK_NOTIFY;
 		}
 	}
-	err = 0;
 
 	if (tb[IFLA_PORT_SELF]) {
 		struct nlattr *port[IFLA_PORT_MAX+1];
@@ -2326,7 +2325,6 @@ static int do_setlink(const struct sk_buff *skb,
 			status |= DO_SETLINK_NOTIFY;
 		}
 	}
-	err = 0;
 
 	if (tb[IFLA_PROTO_DOWN]) {
 		err = dev_change_proto_down(dev,
-- 
2.7.4