netfilter: ecache: use dedicated list for event redelivery

This disentangles event redelivery and the percpu dying list.

Because entries are now stored on a dedicated list, all
entries are in NFCT_ECACHE_DESTROY_FAIL state and all entries
still have confirmed bit set -- the reference count is at least 1.

The 'struct net' back-pointer can be removed as well.

The pcpu dying list will be removed eventually, it has no functionality.

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

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 69e6c6a..28672a9 100644 (file)
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -45,7 +45,8 @@ union nf_conntrack_expect_proto {
 
 struct nf_conntrack_net_ecache {
        struct delayed_work dwork;
-       struct netns_ct *ct_net;
+       spinlock_t dying_lock;
+       struct hlist_nulls_head dying_list;
 };
 
 struct nf_conntrack_net {

diff --git a/include/net/netfilter/nf_conntrack_ecache.h b/include/net/netfilter/nf_conntrack_ecache.h
index 6c4c490..a6135b5 100644 (file)
--- a/include/net/netfilter/nf_conntrack_ecache.h
+++ b/include/net/netfilter/nf_conntrack_ecache.h
@@ -14,7 +14,6 @@
 #include <net/netfilter/nf_conntrack_extend.h>
 
 enum nf_ct_ecache_state {
-       NFCT_ECACHE_UNKNOWN,            /* destroy event not sent */
        NFCT_ECACHE_DESTROY_FAIL,       /* tried but failed to send destroy event */
        NFCT_ECACHE_DESTROY_SENT,       /* sent destroy event after failure */
 };
@@ -23,7 +22,6 @@ struct nf_conntrack_ecache {
        unsigned long cache;            /* bitops want long */
        u16 ctmask;                     /* bitmask of ct events to be delivered */
        u16 expmask;                    /* bitmask of expect events to be delivered */
-       enum nf_ct_ecache_state state:8;/* ecache state */
        u32 missed;                     /* missed events */
        u32 portid;                     /* netlink portid of destroyer */
 };

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 0164e5f..ca1d1d1 100644 (file)
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -660,15 +660,12 @@ void nf_ct_destroy(struct nf_conntrack *nfct)
 }
 EXPORT_SYMBOL(nf_ct_destroy);
 
-static void nf_ct_delete_from_lists(struct nf_conn *ct)
+static void __nf_ct_delete_from_lists(struct nf_conn *ct)
 {
        struct net *net = nf_ct_net(ct);
        unsigned int hash, reply_hash;
        unsigned int sequence;
 
-       nf_ct_helper_destroy(ct);
-
-       local_bh_disable();
        do {
                sequence = read_seqcount_begin(&nf_conntrack_generation);
                hash = hash_conntrack(net,
@@ -681,12 +678,33 @@ static void nf_ct_delete_from_lists(struct nf_conn *ct)
 
        clean_from_lists(ct);
        nf_conntrack_double_unlock(hash, reply_hash);
+}
 
+static void nf_ct_delete_from_lists(struct nf_conn *ct)
+{
+       nf_ct_helper_destroy(ct);
+       local_bh_disable();
+
+       __nf_ct_delete_from_lists(ct);
        nf_ct_add_to_dying_list(ct);
 
        local_bh_enable();
 }
 
+static void nf_ct_add_to_ecache_list(struct nf_conn *ct)
+{
+#ifdef CONFIG_NF_CONNTRACK_EVENTS
+       struct nf_conntrack_net *cnet = nf_ct_pernet(nf_ct_net(ct));
+
+       spin_lock(&cnet->ecache.dying_lock);
+       hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
+                                &cnet->ecache.dying_list);
+       spin_unlock(&cnet->ecache.dying_lock);
+#else
+       nf_ct_add_to_dying_list(ct);
+#endif
+}
+
 bool nf_ct_delete(struct nf_conn *ct, u32 portid, int report)
 {
        struct nf_conn_tstamp *tstamp;
@@ -709,7 +727,12 @@ bool nf_ct_delete(struct nf_conn *ct, u32 portid, int report)
                /* destroy event was not delivered. nf_ct_put will
                 * be done by event cache worker on redelivery.
                 */
-               nf_ct_delete_from_lists(ct);
+               nf_ct_helper_destroy(ct);
+               local_bh_disable();
+               __nf_ct_delete_from_lists(ct);
+               nf_ct_add_to_ecache_list(ct);
+               local_bh_enable();
+
                nf_conntrack_ecache_work(nf_ct_net(ct), NFCT_ECACHE_DESTROY_FAIL);
                return false;
        }

diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c
index 0cb2da0..2752859 100644 (file)
--- a/net/netfilter/nf_conntrack_ecache.c
+++ b/net/netfilter/nf_conntrack_ecache.c
@@ -16,7 +16,6 @@
 #include <linux/vmalloc.h>
 #include <linux/stddef.h>
 #include <linux/err.h>
-#include <linux/percpu.h>
 #include <linux/kernel.h>
 #include <linux/netdevice.h>
 #include <linux/slab.h>
@@ -29,8 +28,9 @@
 
 static DEFINE_MUTEX(nf_ct_ecache_mutex);
 
-#define ECACHE_RETRY_WAIT (HZ/10)
-#define ECACHE_STACK_ALLOC (256 / sizeof(void *))
+#define DYING_NULLS_VAL                        ((1 << 30) + 1)
+#define ECACHE_MAX_JIFFIES             msecs_to_jiffies(10)
+#define ECACHE_RETRY_JIFFIES           msecs_to_jiffies(10)
 
 enum retry_state {
        STATE_CONGESTED,
@@ -38,58 +38,58 @@ enum retry_state {
        STATE_DONE,
 };
 
-static enum retry_state ecache_work_evict_list(struct ct_pcpu *pcpu)
+static enum retry_state ecache_work_evict_list(struct nf_conntrack_net *cnet)
 {
-       struct nf_conn *refs[ECACHE_STACK_ALLOC];
+       unsigned long stop = jiffies + ECACHE_MAX_JIFFIES;
+       struct hlist_nulls_head evicted_list;
        enum retry_state ret = STATE_DONE;
        struct nf_conntrack_tuple_hash *h;
        struct hlist_nulls_node *n;
-       unsigned int evicted = 0;
+       unsigned int sent;
 
-       spin_lock(&pcpu->lock);
+       INIT_HLIST_NULLS_HEAD(&evicted_list, DYING_NULLS_VAL);
 
-       hlist_nulls_for_each_entry(h, n, &pcpu->dying, hnnode) {
+next:
+       sent = 0;
+       spin_lock_bh(&cnet->ecache.dying_lock);
+
+       hlist_nulls_for_each_entry_safe(h, n, &cnet->ecache.dying_list, hnnode) {
                struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
-               struct nf_conntrack_ecache *e;
-
-               if (!nf_ct_is_confirmed(ct))
-                       continue;
-
-               /* This ecache access is safe because the ct is on the
-                * pcpu dying list and we hold the spinlock -- the entry
-                * cannot be free'd until after the lock is released.
-                *
-                * This is true even if ct has a refcount of 0: the
-                * cpu that is about to free the entry must remove it
-                * from the dying list and needs the lock to do so.
-                */
-               e = nf_ct_ecache_find(ct);
-               if (!e || e->state != NFCT_ECACHE_DESTROY_FAIL)
-                       continue;
 
-               /* ct is in NFCT_ECACHE_DESTROY_FAIL state, this means
-                * the worker owns this entry: the ct will remain valid
-                * until the worker puts its ct reference.
+               /* The worker owns all entries, ct remains valid until nf_ct_put
+                * in the loop below.
                 */
                if (nf_conntrack_event(IPCT_DESTROY, ct)) {
                        ret = STATE_CONGESTED;
                        break;
                }
 
-               e->state = NFCT_ECACHE_DESTROY_SENT;
-               refs[evicted] = ct;
+               hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
+               hlist_nulls_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode, &evicted_list);
 
-               if (++evicted >= ARRAY_SIZE(refs)) {
+               if (time_after(stop, jiffies)) {
                        ret = STATE_RESTART;
                        break;
                }
+
+               if (sent++ > 16) {
+                       spin_unlock_bh(&cnet->ecache.dying_lock);
+                       cond_resched();
+                       goto next;
+               }
        }
 
-       spin_unlock(&pcpu->lock);
+       spin_unlock_bh(&cnet->ecache.dying_lock);
 
-       /* can't _put while holding lock */
-       while (evicted)
-               nf_ct_put(refs[--evicted]);
+       hlist_nulls_for_each_entry_safe(h, n, &evicted_list, hnnode) {
+               struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
+
+               hlist_nulls_add_fake(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
+               hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode);
+               nf_ct_put(ct);
+
+               cond_resched();
+       }
 
        return ret;
 }
@@ -97,35 +97,20 @@ static enum retry_state ecache_work_evict_list(struct ct_pcpu *pcpu)
 static void ecache_work(struct work_struct *work)
 {
        struct nf_conntrack_net *cnet = container_of(work, struct nf_conntrack_net, ecache.dwork.work);
-       struct netns_ct *ctnet = cnet->ecache.ct_net;
-       int cpu, delay = -1;
-       struct ct_pcpu *pcpu;
-
-       local_bh_disable();
-
-       for_each_possible_cpu(cpu) {
-               enum retry_state ret;
-
-               pcpu = per_cpu_ptr(ctnet->pcpu_lists, cpu);
-
-               ret = ecache_work_evict_list(pcpu);
-
-               switch (ret) {
-               case STATE_CONGESTED:
-                       delay = ECACHE_RETRY_WAIT;
-                       goto out;
-               case STATE_RESTART:
-                       delay = 0;
-                       break;
-               case STATE_DONE:
-                       break;
-               }
+       int ret, delay = -1;
+
+       ret = ecache_work_evict_list(cnet);
+       switch (ret) {
+       case STATE_CONGESTED:
+               delay = ECACHE_RETRY_JIFFIES;
+               break;
+       case STATE_RESTART:
+               delay = 0;
+               break;
+       case STATE_DONE:
+               break;
        }
 
- out:
-       local_bh_enable();
-
-       ctnet->ecache_dwork_pending = delay > 0;
        if (delay >= 0)
                schedule_delayed_work(&cnet->ecache.dwork, delay);
 }
@@ -199,7 +184,6 @@ int nf_conntrack_eventmask_report(unsigned int events, struct nf_conn *ct,
                 */
                if (e->portid == 0 && portid != 0)
                        e->portid = portid;
-               e->state = NFCT_ECACHE_DESTROY_FAIL;
        }
 
        return ret;
@@ -297,8 +281,10 @@ void nf_conntrack_ecache_work(struct net *net, enum nf_ct_ecache_state state)
                schedule_delayed_work(&cnet->ecache.dwork, HZ);
                net->ct.ecache_dwork_pending = true;
        } else if (state == NFCT_ECACHE_DESTROY_SENT) {
-               net->ct.ecache_dwork_pending = false;
-               mod_delayed_work(system_wq, &cnet->ecache.dwork, 0);
+               if (!hlist_nulls_empty(&cnet->ecache.dying_list))
+                       mod_delayed_work(system_wq, &cnet->ecache.dwork, 0);
+               else
+                       net->ct.ecache_dwork_pending = false;
        }
 }
 
@@ -311,8 +297,9 @@ void nf_conntrack_ecache_pernet_init(struct net *net)
 
        net->ct.sysctl_events = nf_ct_events;
 
-       cnet->ecache.ct_net = &net->ct;
        INIT_DELAYED_WORK(&cnet->ecache.dwork, ecache_work);
+       INIT_HLIST_NULLS_HEAD(&cnet->ecache.dying_list, DYING_NULLS_VAL);
+       spin_lock_init(&cnet->ecache.dying_lock);
 
        BUILD_BUG_ON(__IPCT_MAX >= 16); /* e->ctmask is u16 */
 }