netfilter: ctnetlink: remove refcounting in dying list dumping

There is no need to keep the object alive via refcount, use a cookie and
then use that as the skip hint for dump resumption.

Unlike the two earlier, similar patches in this file, this is a cleanup
without intended side effects.

Signed-off-by: Florian Westphal <fw@strlen.de>

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 50fd6809380fa95a2cd93a7a84ecc9800fb662d6..3a04665adf9927de9c45d49a948bee24b42011e4 100644 (file)
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -60,7 +60,7 @@ MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("List and change connection tracking table");
 
 struct ctnetlink_list_dump_ctx {
-       struct nf_conn *last;
+       unsigned long last_id;
        unsigned int cpu;
        bool done;
 };
@@ -1733,16 +1733,6 @@ static int ctnetlink_get_conntrack(struct sk_buff *skb,
        return nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);
 }
 
-static int ctnetlink_done_list(struct netlink_callback *cb)
-{
-       struct ctnetlink_list_dump_ctx *ctx = (void *)cb->ctx;
-
-       if (ctx->last)
-               nf_ct_put(ctx->last);
-
-       return 0;
-}
-
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
 static int ctnetlink_dump_one_entry(struct sk_buff *skb,
                                    struct netlink_callback *cb,
@@ -1757,11 +1747,11 @@ static int ctnetlink_dump_one_entry(struct sk_buff *skb,
        if (l3proto && nf_ct_l3num(ct) != l3proto)
                return 0;
 
-       if (ctx->last) {
-               if (ct != ctx->last)
+       if (ctx->last_id) {
+               if (ctnetlink_get_id(ct) != ctx->last_id)
                        return 0;
 
-               ctx->last = NULL;
+               ctx->last_id = 0;
        }
 
        /* We can't dump extension info for the unconfirmed
@@ -1775,12 +1765,8 @@ static int ctnetlink_dump_one_entry(struct sk_buff *skb,
                                  cb->nlh->nlmsg_seq,
                                  NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
                                  ct, dying, 0);
-       if (res < 0) {
-               if (!refcount_inc_not_zero(&ct->ct_general.use))
-                       return 0;
-
-               ctx->last = ct;
-       }
+       if (res < 0)
+               ctx->last_id = ctnetlink_get_id(ct);
 
        return res;
 }
@@ -1796,10 +1782,10 @@ static int
 ctnetlink_dump_dying(struct sk_buff *skb, struct netlink_callback *cb)
 {
        struct ctnetlink_list_dump_ctx *ctx = (void *)cb->ctx;
-       struct nf_conn *last = ctx->last;
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
        const struct net *net = sock_net(skb->sk);
        struct nf_conntrack_net_ecache *ecache_net;
+       unsigned long last_id = ctx->last_id;
        struct nf_conntrack_tuple_hash *h;
        struct hlist_nulls_node *n;
 #endif
@@ -1807,7 +1793,7 @@ ctnetlink_dump_dying(struct sk_buff *skb, struct netlink_callback *cb)
        if (ctx->done)
                return 0;
 
-       ctx->last = NULL;
+       ctx->last_id = 0;
 
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
        ecache_net = nf_conn_pernet_ecache(net);
@@ -1818,24 +1804,21 @@ ctnetlink_dump_dying(struct sk_buff *skb, struct netlink_callback *cb)
                int res;
 
                ct = nf_ct_tuplehash_to_ctrack(h);
-               if (last && last != ct)
+               if (last_id && last_id != ctnetlink_get_id(ct))
                        continue;
 
                res = ctnetlink_dump_one_entry(skb, cb, ct, true);
                if (res < 0) {
                        spin_unlock_bh(&ecache_net->dying_lock);
-                       nf_ct_put(last);
                        return skb->len;
                }
 
-               nf_ct_put(last);
-               last = NULL;
+               last_id = 0;
        }
 
        spin_unlock_bh(&ecache_net->dying_lock);
 #endif
        ctx->done = true;
-       nf_ct_put(last);
 
        return skb->len;
 }
@@ -1847,7 +1830,6 @@ static int ctnetlink_get_ct_dying(struct sk_buff *skb,
        if (info->nlh->nlmsg_flags & NLM_F_DUMP) {
                struct netlink_dump_control c = {
                        .dump = ctnetlink_dump_dying,
-                       .done = ctnetlink_done_list,
                };
                return netlink_dump_start(info->sk, skb, info->nlh, &c);
        }
@@ -1862,7 +1844,6 @@ static int ctnetlink_get_ct_unconfirmed(struct sk_buff *skb,
        if (info->nlh->nlmsg_flags & NLM_F_DUMP) {
                struct netlink_dump_control c = {
                        .dump = ctnetlink_dump_unconfirmed,
-                       .done = ctnetlink_done_list,
                };
                return netlink_dump_start(info->sk, skb, info->nlh, &c);
        }