netdev - [PATCH net-next] netns: no longer hold RTNL in rtnl_net

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Message-ID: <20240416140739.967941-1-edumazet@google.com>
Date: Tue, 16 Apr 2024 14:07:39 +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>, Guillaume Nault <gnault@...hat.com>
Subject: [PATCH net-next] netns: no longer hold RTNL in rtnl_net_dumpid()

- rtnl_net_dumpid() is already fully RCU protected,
  RTNL is not needed there.

- Fix return value at the end of a dump,
  so that NLMSG_DONE can be appended to current skb,
  saving one recvmsg() system call.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Guillaume Nault <gnault@...hat.com>
---
 net/core/net_namespace.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index f0540c5575157135b1dc5dece2220f81a408fb7e..2f5190aa2f15cec2e934ebee9c502fb426cf0d7d 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -1090,7 +1090,7 @@ static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
 end:
 	if (net_cb.fillargs.add_ref)
 		put_net(net_cb.tgt_net);
-	return err < 0 ? err : skb->len;
+	return err;
 }
 
 static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
@@ -1205,7 +1205,8 @@ void __init net_ns_init(void)
 	rtnl_register(PF_UNSPEC, RTM_NEWNSID, rtnl_net_newid, NULL,
 		      RTNL_FLAG_DOIT_UNLOCKED);
 	rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, rtnl_net_dumpid,
-		      RTNL_FLAG_DOIT_UNLOCKED);
+		      RTNL_FLAG_DOIT_UNLOCKED |
+		      RTNL_FLAG_DUMP_UNLOCKED);
 }
 
 static void free_exit_list(struct pernet_operations *ops, struct list_head *net_exit_list)
-- 
2.44.0.683.g7961c838ac-goog