netfilter: conntrack: gre: convert rwlock to rcu

We can use gre.  Lock is only needed when a new expectation is added.

In case a single spinlock proves to be problematic we can either add one
per netns or use an array of locks combined with net_hash_mix() or similar
to pick the 'correct' one.

But given this is only needed for an expectation rather than per packet
a single one should be ok.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/linux/netfilter/nf_conntrack_proto_gre.h b/include/linux/netfilter/nf_conntrack_proto_gre.h
index 6989e2e..222c9d3 100644 (file)
--- a/include/linux/netfilter/nf_conntrack_proto_gre.h
+++ b/include/linux/netfilter/nf_conntrack_proto_gre.h
@@ -19,6 +19,7 @@ struct nf_conn;
 struct nf_ct_gre_keymap {
        struct list_head list;
        struct nf_conntrack_tuple tuple;
+       struct rcu_head rcu;
 };
 
 enum grep_conntrack {

diff --git a/net/netfilter/nf_conntrack_proto_gre.c b/net/netfilter/nf_conntrack_proto_gre.c
index 8899b51..34dd894 100644 (file)
--- a/net/netfilter/nf_conntrack_proto_gre.c
+++ b/net/netfilter/nf_conntrack_proto_gre.c
@@ -49,6 +49,8 @@ static const unsigned int gre_timeouts[GRE_CT_MAX] = {
 };
 
 static unsigned int proto_gre_net_id __read_mostly;
+/* used when expectation is added */
+static DEFINE_SPINLOCK(keymap_lock);
 
 static inline struct netns_proto_gre *gre_pernet(struct net *net)
 {
@@ -60,12 +62,12 @@ static void nf_ct_gre_keymap_flush(struct net *net)
        struct netns_proto_gre *net_gre = gre_pernet(net);
        struct nf_ct_gre_keymap *km, *tmp;
 
-       write_lock_bh(&net_gre->keymap_lock);
+       spin_lock_bh(&keymap_lock);
        list_for_each_entry_safe(km, tmp, &net_gre->keymap_list, list) {
-               list_del(&km->list);
-               kfree(km);
+               list_del_rcu(&km->list);
+               kfree_rcu(km, rcu);
        }
-       write_unlock_bh(&net_gre->keymap_lock);
+       spin_unlock_bh(&keymap_lock);
 }
 
 static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km,
@@ -85,14 +87,12 @@ static __be16 gre_keymap_lookup(struct net *net, struct nf_conntrack_tuple *t)
        struct nf_ct_gre_keymap *km;
        __be16 key = 0;
 
-       read_lock_bh(&net_gre->keymap_lock);
-       list_for_each_entry(km, &net_gre->keymap_list, list) {
+       list_for_each_entry_rcu(km, &net_gre->keymap_list, list) {
                if (gre_key_cmpfn(km, t)) {
                        key = km->tuple.src.u.gre.key;
                        break;
                }
        }
-       read_unlock_bh(&net_gre->keymap_lock);
 
        pr_debug("lookup src key 0x%x for ", key);
        nf_ct_dump_tuple(t);
@@ -112,14 +112,10 @@ int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
        kmp = &ct_pptp_info->keymap[dir];
        if (*kmp) {
                /* check whether it's a retransmission */
-               read_lock_bh(&net_gre->keymap_lock);
-               list_for_each_entry(km, &net_gre->keymap_list, list) {
-                       if (gre_key_cmpfn(km, t) && km == *kmp) {
-                               read_unlock_bh(&net_gre->keymap_lock);
+               list_for_each_entry_rcu(km, &net_gre->keymap_list, list) {
+                       if (gre_key_cmpfn(km, t) && km == *kmp)
                                return 0;
-                       }
                }
-               read_unlock_bh(&net_gre->keymap_lock);
                pr_debug("trying to override keymap_%s for ct %p\n",
                         dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct);
                return -EEXIST;
@@ -134,9 +130,9 @@ int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
        pr_debug("adding new entry %p: ", km);
        nf_ct_dump_tuple(&km->tuple);
 
-       write_lock_bh(&net_gre->keymap_lock);
+       spin_lock_bh(&keymap_lock);
        list_add_tail(&km->list, &net_gre->keymap_list);
-       write_unlock_bh(&net_gre->keymap_lock);
+       spin_unlock_bh(&keymap_lock);
 
        return 0;
 }
@@ -145,24 +141,22 @@ EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add);
 /* destroy the keymap entries associated with specified master ct */
 void nf_ct_gre_keymap_destroy(struct nf_conn *ct)
 {
-       struct net *net = nf_ct_net(ct);
-       struct netns_proto_gre *net_gre = gre_pernet(net);
        struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct);
        enum ip_conntrack_dir dir;
 
        pr_debug("entering for ct %p\n", ct);
 
-       write_lock_bh(&net_gre->keymap_lock);
+       spin_lock_bh(&keymap_lock);
        for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) {
                if (ct_pptp_info->keymap[dir]) {
                        pr_debug("removing %p from list\n",
                                 ct_pptp_info->keymap[dir]);
-                       list_del(&ct_pptp_info->keymap[dir]->list);
-                       kfree(ct_pptp_info->keymap[dir]);
+                       list_del_rcu(&ct_pptp_info->keymap[dir]->list);
+                       kfree_rcu(ct_pptp_info->keymap[dir], rcu);
                        ct_pptp_info->keymap[dir] = NULL;
                }
        }
-       write_unlock_bh(&net_gre->keymap_lock);
+       spin_unlock_bh(&keymap_lock);
 }
 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy);
 
@@ -365,7 +359,6 @@ static int gre_init_net(struct net *net)
        struct nf_proto_net *nf = &net_gre->nf;
        int i;
 
-       rwlock_init(&net_gre->keymap_lock);
        INIT_LIST_HEAD(&net_gre->keymap_list);
        for (i = 0; i < GRE_CT_MAX; i++)
                net_gre->gre_timeouts[i] = gre_timeouts[i];