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Message-ID: <67f5cb70-14a4-4455-8372-f039da2f15c2@kernel.org>
Date: Wed, 3 Apr 2024 10:13:16 -0600
From: David Ahern <dsahern@...nel.org>
To: Eric Dumazet <edumazet@...gle.com>, "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
Subject: Re: [PATCH net-next] ipv6: remove RTNL protection from
ip6addrlbl_dump()
On 4/3/24 6:39 AM, Eric Dumazet wrote:
> diff --git a/net/ipv6/addrlabel.c b/net/ipv6/addrlabel.c
> index 17ac45aa7194ce9c148ed95e14dd575d17feeb98..961e853543b64cd2060ef693ae3ad32a44780aa1 100644
> --- a/net/ipv6/addrlabel.c
> +++ b/net/ipv6/addrlabel.c
> @@ -234,7 +234,8 @@ static int __ip6addrlbl_add(struct net *net, struct ip6addrlbl_entry *newp,
> hlist_add_head_rcu(&newp->list, &net->ipv6.ip6addrlbl_table.head);
> out:
> if (!ret)
> - net->ipv6.ip6addrlbl_table.seq++;
> + WRITE_ONCE(net->ipv6.ip6addrlbl_table.seq,
> + net->ipv6.ip6addrlbl_table.seq + 1);
> return ret;
> }
>
> @@ -445,7 +446,7 @@ static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
> };
>
> static int ip6addrlbl_fill(struct sk_buff *skb,
> - struct ip6addrlbl_entry *p,
> + const struct ip6addrlbl_entry *p,
> u32 lseq,
> u32 portid, u32 seq, int event,
> unsigned int flags)
> @@ -498,7 +499,7 @@ static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
> struct net *net = sock_net(skb->sk);
> struct ip6addrlbl_entry *p;
> int idx = 0, s_idx = cb->args[0];
> - int err;
> + int err = 0;
>
> if (cb->strict_check) {
> err = ip6addrlbl_valid_dump_req(nlh, cb->extack);
> @@ -510,7 +511,7 @@ static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
> hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
> if (idx >= s_idx) {
> err = ip6addrlbl_fill(skb, p,
> - net->ipv6.ip6addrlbl_table.seq,
> + READ_ONCE(net->ipv6.ip6addrlbl_table.seq),
seems like this should be read once on entry, and the same value used
for all iterations.
> NETLINK_CB(cb->skb).portid,
> nlh->nlmsg_seq,
> RTM_NEWADDRLABEL,
> @@ -522,7 +523,7 @@ static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
> }
> rcu_read_unlock();
> cb->args[0] = idx;
> - return skb->len;
> + return err;
> }
>
> static inline int ip6addrlbl_msgsize(void)
> @@ -614,7 +615,7 @@ static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
>
> rcu_read_lock();
> p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
> - lseq = net->ipv6.ip6addrlbl_table.seq;
> + lseq = READ_ONCE(net->ipv6.ip6addrlbl_table.seq);
> if (p)
> err = ip6addrlbl_fill(skb, p, lseq,
> NETLINK_CB(in_skb).portid,
> @@ -647,6 +648,7 @@ int __init ipv6_addr_label_rtnl_register(void)
> return ret;
> ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETADDRLABEL,
> ip6addrlbl_get,
> - ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED);
> + ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED |
> + RTNL_FLAG_DUMP_UNLOCKED);
> return ret;
> }
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