[PATCH 5.18 062/231] netfilter: ecache: use dedicated list for event redelivery

Greg Kroah-Hartman
2022-07-19T12:56:53Z

From: Florian Westphal <fw@strlen.de>

[ Upstream commit 2ed3bf188b33630cf9d93b996ebf001847a00b5a ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/netfilter/nf_conntrack.h | 3 +-
include/net/netfilter/nf_conntrack_ecache.h | 2 -
net/netfilter/nf_conntrack_core.c | 33 +++++-
net/netfilter/nf_conntrack_ecache.c | 117 +++++++++-----------
4 files changed, 82 insertions(+), 73 deletions(-)

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 69e6c6a218be..28672a944499 100644
--- 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 6c4c490a3e34..a6135b5030dd 100644
--- 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 0164e5f522e8..ca1d1d105163 100644
--- 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 0cb2da0a759a..2752859479b2 100644
--- 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 */
}
--
2.35.1