netdev - [PATCH net-next] netlink: let core handle error cases in dump operations

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Date: Wed,  6 Mar 2024 10:24:26 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] netlink: let core handle error cases in dump operations

After commit b5a899154aa9 ("netlink: handle EMSGSIZE errors
in the core"), we can remove some code that was not 100 % correct
anyway.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/rtnetlink.c    | 5 +----
 net/ipv4/devinet.c      | 4 ----
 net/ipv4/fib_frontend.c | 7 +------
 net/ipv6/addrconf.c     | 7 +------
 4 files changed, 3 insertions(+), 20 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 780b330f8ef9fa4881b9d51570d1a65f5171ee5d..7eac6765df098fd685937ace63dfb5add9c77731 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2267,11 +2267,8 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
 				       nlh->nlmsg_seq, 0, flags,
 				       ext_filter_mask, 0, NULL, 0,
 				       netnsid, GFP_KERNEL);
-		if (err < 0) {
-			if (likely(skb->len))
-				err = skb->len;
+		if (err < 0)
 			break;
-		}
 	}
 	cb->seq = tgt_net->dev_base_seq;
 	nl_dump_check_consistent(cb, nlmsg_hdr(skb));
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 4daa8124f247c256c4f8c1ff29ac621570af0755..7a437f0d41905e6acfdc35743afba3a7abfd0dd5 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1900,8 +1900,6 @@ static int inet_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
 			goto done;
 	}
 done:
-	if (err < 0 && likely(skb->len))
-		err = skb->len;
 	if (fillargs.netnsid >= 0)
 		put_net(tgt_net);
 	rcu_read_unlock();
@@ -2312,8 +2310,6 @@ static int inet_netconf_dump_devconf(struct sk_buff *skb,
 		ctx->all_default++;
 	}
 done:
-	if (err < 0 && likely(skb->len))
-		err = skb->len;
 	rcu_read_unlock();
 	return err;
 }
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index bf3a2214fe29b6f9b494581b293259e6c5ce6f8c..48741352a88a72e0232977cc9f2cf172f45df89b 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1026,8 +1026,6 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 			goto unlock;
 		}
 		err = fib_table_dump(tb, skb, cb, &filter);
-		if (err < 0 && skb->len)
-			err = skb->len;
 		goto unlock;
 	}
 
@@ -1045,11 +1043,8 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 				memset(&cb->args[2], 0, sizeof(cb->args) -
 						 2 * sizeof(cb->args[0]));
 			err = fib_table_dump(tb, skb, cb, &filter);
-			if (err < 0) {
-				if (likely(skb->len))
-					err = skb->len;
+			if (err < 0)
 				goto out;
-			}
 			dumped = 1;
 next:
 			e++;
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 2f84e6ecf19f48602cadb47bc378c9b5a1cdbf65..f786b65d12e43c53ed36535880f6e6d35879a44e 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -793,8 +793,6 @@ static int inet6_netconf_dump_devconf(struct sk_buff *skb,
 		ctx->all_default++;
 	}
 done:
-	if (err < 0 && likely(skb->len))
-		err = skb->len;
 	rcu_read_unlock();
 	return err;
 }
@@ -6158,11 +6156,8 @@ static int inet6_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
 					NETLINK_CB(cb->skb).portid,
 					cb->nlh->nlmsg_seq,
 					RTM_NEWLINK, NLM_F_MULTI);
-		if (err < 0) {
-			if (likely(skb->len))
-				err = skb->len;
+		if (err < 0)
 			break;
-		}
 	}
 	rcu_read_unlock();
 
-- 
2.44.0.278.ge034bb2e1d-goog