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


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