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phonet: no longer hold RTNL in route_dumpit()

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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>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240507121748.416287-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-05-07 12:17:48 +00:00 committed by Jakub Kicinski
parent 8d8b1a422c
commit 58a4ff5d77
1 changed files with 9 additions and 8 deletions
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17
net/phonet/pn_netlink.c
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@ -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_type = RTN_UNICAST;
rtm->rtm_flags = 0; rtm->rtm_flags = 0;
if (nla_put_u8(skb, RTA_DST, dst) || 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; goto nla_put_failure;
nlmsg_end(skb, nlh); nlmsg_end(skb, nlh);
return 0; 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) static int route_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
{ {
struct net *net = sock_net(skb->sk); struct net *net = sock_net(skb->sk);
int err = 0;
u8 addr; u8 addr;
rcu_read_lock(); rcu_read_lock();
@ -272,16 +273,16 @@ static int route_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
if (!dev) if (!dev)
continue; continue;
if (fill_route(skb, dev, addr << 2, NETLINK_CB(cb->skb).portid, err = fill_route(skb, dev, addr << 2,
cb->nlh->nlmsg_seq, RTM_NEWROUTE) < 0) NETLINK_CB(cb->skb).portid,
goto out; cb->nlh->nlmsg_seq, RTM_NEWROUTE);
if (err < 0)
break;
} }
out:
rcu_read_unlock(); rcu_read_unlock();
cb->args[0] = addr; cb->args[0] = addr;
return skb->len; return err;
} }
int __init phonet_netlink_register(void) 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, rtnl_register_module(THIS_MODULE, PF_PHONET, RTM_DELROUTE,
route_doit, NULL, 0); route_doit, NULL, 0);
rtnl_register_module(THIS_MODULE, PF_PHONET, RTM_GETROUTE, rtnl_register_module(THIS_MODULE, PF_PHONET, RTM_GETROUTE,
NULL, route_dumpit, 0); NULL, route_dumpit, RTNL_FLAG_DUMP_UNLOCKED);
return 0; return 0;
} }