[PATCH v2 net-next] phonet: no longer hold RTNL in route_dumpit()
From: Eric Dumazet <edumazet@google.com>
Date: 2024-05-07 12:17:50
Subsystem:
networking [general], phonet protocol, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Remi Denis-Courmont, Linus Torvalds
route_dumpit() already relies on RCU, RTNL is not needed. Also change return value at the end of a dump. This allows NLMSG_DONE to be appended to the current skb at the end of a dump, saving a couple of recvmsg() system calls. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Remi Denis-Courmont <courmisch@gmail.com> --- v2: break;; -> break; (Jakub) --- net/phonet/pn_netlink.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/net/phonet/pn_netlink.c b/net/phonet/pn_netlink.c
index 59aebe29689077bfa77d37516aea4617fe3b8a50..92245fdfa846cb8b9747764a3330e17d8c6b1f16 100644
--- a/net/phonet/pn_netlink.c
+++ b/net/phonet/pn_netlink.c@@ -178,7 +178,7 @@ static int fill_route(struct sk_buff *skb, struct net_device *dev, u8 dst, rtm->rtm_type = RTN_UNICAST; rtm->rtm_flags = 0; if (nla_put_u8(skb, RTA_DST, dst) || - nla_put_u32(skb, RTA_OIF, dev->ifindex)) + nla_put_u32(skb, RTA_OIF, READ_ONCE(dev->ifindex))) goto nla_put_failure; nlmsg_end(skb, nlh); return 0;
@@ -263,6 +263,7 @@ static int route_doit(struct sk_buff *skb, struct nlmsghdr *nlh, static int route_dumpit(struct sk_buff *skb, struct netlink_callback *cb) { struct net *net = sock_net(skb->sk); + int err = 0; u8 addr; rcu_read_lock();
@@ -272,16 +273,16 @@ static int route_dumpit(struct sk_buff *skb, struct netlink_callback *cb) if (!dev) continue; - if (fill_route(skb, dev, addr << 2, NETLINK_CB(cb->skb).portid, - cb->nlh->nlmsg_seq, RTM_NEWROUTE) < 0) - goto out; + err = fill_route(skb, dev, addr << 2, + NETLINK_CB(cb->skb).portid, + cb->nlh->nlmsg_seq, RTM_NEWROUTE); + if (err < 0) + break; } - -out: rcu_read_unlock(); cb->args[0] = addr; - return skb->len; + return err; } int __init phonet_netlink_register(void)
@@ -301,6 +302,6 @@ int __init phonet_netlink_register(void) rtnl_register_module(THIS_MODULE, PF_PHONET, RTM_DELROUTE, route_doit, NULL, 0); rtnl_register_module(THIS_MODULE, PF_PHONET, RTM_GETROUTE, - NULL, route_dumpit, 0); + NULL, route_dumpit, RTNL_FLAG_DUMP_UNLOCKED); return 0; }
--
2.45.0.rc1.225.g2a3ae87e7f-goog