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Hello,
On Wed, 1 Jul 2020, Andrew Sy Kim wrote:
> When expire_nodest_conn=1 and a destination is deleted, IPVS does not
> expire the existing connections until the next matching incoming packet.
> If there are many connection entries from a single client to a single
> destination, many packets may get dropped before all the connections are
> expired (more likely with lots of UDP traffic). An optimization can be
> made where upon deletion of a destination, IPVS queues up delayed work
> to immediately expire any connections with a deleted destination. This
> ensures any reused source ports from a client (within the IPVS timeouts)
> are scheduled to new real servers instead of silently dropped.
>
> This patch was applied on top of Julian's patch "ipvs: allow
> connection reuse for unconfirmed conntrack":
> https://marc.info/?l=netfilter-devel&m=159361668110823&w=2
Above paragraph should be after the following --- line
>
> Signed-off-by: Andrew Sy Kim <kim.andrewsy@xxxxxxxxx>
> ---
> include/net/ip_vs.h | 29 ++++++++++++++++++++
> net/netfilter/ipvs/ip_vs_conn.c | 36 +++++++++++++++++++++++++
> net/netfilter/ipvs/ip_vs_core.c | 47 ++++++++++++++-------------------
> net/netfilter/ipvs/ip_vs_ctl.c | 22 +++++++++++++++
> 4 files changed, 107 insertions(+), 27 deletions(-)
>
> diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> index 011f407b76fe..91a9e1d590a6 100644
> --- a/include/net/ip_vs.h
> +++ b/include/net/ip_vs.h
> @@ -14,6 +14,7 @@
> #include <linux/spinlock.h> /* for struct rwlock_t */
> #include <linux/atomic.h> /* for struct atomic_t */
> #include <linux/refcount.h> /* for struct refcount_t */
> +#include <linux/workqueue.h>
>
> #include <linux/compiler.h>
> #include <linux/timer.h>
> @@ -886,6 +887,8 @@ struct netns_ipvs {
> atomic_t conn_out_counter;
>
> #ifdef CONFIG_SYSCTL
> + /* delayed work for expiring no dest connections */
> + struct delayed_work expire_nodest_conn_work;
> /* 1/rate drop and drop-entry variables */
> struct delayed_work defense_work; /* Work handler */
> int drop_rate;
> @@ -1051,6 +1054,11 @@ static inline int sysctl_conn_reuse_mode(struct
> netns_ipvs *ipvs)
> return ipvs->sysctl_conn_reuse_mode;
> }
>
> +static inline int sysctl_expire_nodest_conn(struct netns_ipvs *ipvs)
> +{
> + return ipvs->sysctl_expire_nodest_conn;
> +}
> +
> static inline int sysctl_schedule_icmp(struct netns_ipvs *ipvs)
> {
> return ipvs->sysctl_schedule_icmp;
> @@ -1138,6 +1146,11 @@ static inline int sysctl_conn_reuse_mode(struct
> netns_ipvs *ipvs)
> return 1;
> }
>
> +static inline int sysctl_expire_nodest_conn(struct netns_ipvs *ipvs)
> +{
> + return 0;
> +}
> +
> static inline int sysctl_schedule_icmp(struct netns_ipvs *ipvs)
> {
> return 0;
> @@ -1507,6 +1520,22 @@ static inline int ip_vs_todrop(struct netns_ipvs *ipvs)
> static inline int ip_vs_todrop(struct netns_ipvs *ipvs) { return 0; }
> #endif
>
> +#ifdef CONFIG_SYSCTL
> +/* Enqueue delayed work for expiring no dest connections
> + * Only run when sysctl_expire_nodest=1
> + */
> +static inline void ip_vs_enqueue_expire_nodest_conns(struct netns_ipvs *ipvs)
> +{
> + if (sysctl_expire_nodest_conn(ipvs))
> + queue_delayed_work(system_long_wq,
> + &ipvs->expire_nodest_conn_work, 1);
> +}
> +
> +void ip_vs_expire_nodest_conn_flush(struct netns_ipvs *ipvs);
> +#else
> +static inline void ip_vs_enqueue_expire_nodest_conns(struct netns_ipvs) {}
> +#endif
> +
> #define IP_VS_DFWD_METHOD(dest) (atomic_read(&(dest)->conn_flags) & \
> IP_VS_CONN_F_FWD_MASK)
>
> diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
> index b3921ae92740..7a5f57949fb9 100644
> --- a/net/netfilter/ipvs/ip_vs_conn.c
> +++ b/net/netfilter/ipvs/ip_vs_conn.c
> @@ -1389,6 +1389,42 @@ static void ip_vs_conn_flush(struct netns_ipvs *ipvs)
> goto flush_again;
> }
> }
> +
> +#ifdef CONFIG_SYSCTL
> +void ip_vs_expire_nodest_conn_flush(struct netns_ipvs *ipvs)
> +{
> + int idx;
> + struct ip_vs_conn *cp, *cp_c;
> + struct ip_vs_dest *dest;
> +
> + rcu_read_lock();
> + for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {
> + hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) {
> + if (cp->ipvs != ipvs)
> + continue;
> +
> + dest = cp->dest;
> + if (!dest || (dest->flags & IP_VS_DEST_F_AVAILABLE))
> + continue;
> +
It is better if we have here:
if (atomic_read(&cp->n_control))
continue;
> + cp_c = cp->control;
> + IP_VS_DBG(4, "del connection\n");
> + ip_vs_conn_del(cp);
> + if (cp_c && !atomic_read(&cp_c->n_control)) {
> + IP_VS_DBG(4, "del controlling connection\n");
> + ip_vs_conn_del(cp_c);
> + }
> + }
> + cond_resched_rcu();
> +
> + /* netns clean up started, abort delayed work */
> + if (!ipvs->enable)
> + return;
> + }
> + rcu_read_unlock();
> +}
> +#endif
> +
> /*
> * per netns init and exit
> */
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index b4a6b7662f3f..e3668a6e54e4 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -694,16 +694,10 @@ static int sysctl_nat_icmp_send(struct netns_ipvs *ipvs)
> return ipvs->sysctl_nat_icmp_send;
> }
>
> -static int sysctl_expire_nodest_conn(struct netns_ipvs *ipvs)
> -{
> - return ipvs->sysctl_expire_nodest_conn;
> -}
> -
> #else
>
> static int sysctl_snat_reroute(struct netns_ipvs *ipvs) { return 0; }
> static int sysctl_nat_icmp_send(struct netns_ipvs *ipvs) { return 0; }
> -static int sysctl_expire_nodest_conn(struct netns_ipvs *ipvs) { return 0; }
>
> #endif
>
> @@ -2097,36 +2091,35 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int
> hooknum, struct sk_buff *skb, int
> }
> }
>
> - if (unlikely(!cp)) {
> - int v;
> -
> - if (!ip_vs_try_to_schedule(ipvs, af, skb, pd, &v, &cp, &iph))
> - return v;
> - }
> -
> - IP_VS_DBG_PKT(11, af, pp, skb, iph.off, "Incoming packet");
> -
> /* Check the server status */
> - if (cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) {
> + if (cp && cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) {
> /* the destination server is not available */
> + if (sysctl_expire_nodest_conn(ipvs)) {
> + bool old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);
>
> - __u32 flags = cp->flags;
> -
> - /* when timer already started, silently drop the packet.*/
> - if (timer_pending(&cp->timer))
> - __ip_vs_conn_put(cp);
> - else
> - ip_vs_conn_put(cp);
> + if (!old_ct)
> + cp->flags &= ~IP_VS_CONN_F_NFCT;
>
> - if (sysctl_expire_nodest_conn(ipvs) &&
> - !(flags & IP_VS_CONN_F_ONE_PACKET)) {
> - /* try to expire the connection immediately */
> ip_vs_conn_expire_now(cp);
> + __ip_vs_conn_put(cp);
> + if (old_ct)
> + return NF_DROP;
> + cp = NULL;
> + } else {
> + __ip_vs_conn_put(cp);
> + return NF_DROP;
> }
> + }
>
> - return NF_DROP;
> + if (unlikely(!cp)) {
> + int v;
> +
> + if (!ip_vs_try_to_schedule(ipvs, af, skb, pd, &v, &cp, &iph))
> + return v;
> }
>
> + IP_VS_DBG_PKT(11, af, pp, skb, iph.off, "Incoming packet");
> +
> ip_vs_in_stats(cp, skb);
> ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pd);
> if (cp->packet_xmit)
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 4af83f466dfc..f984d2c881ff 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -210,6 +210,17 @@ static void update_defense_level(struct netns_ipvs *ipvs)
> local_bh_enable();
> }
>
> +/* Handler for delayed work for expiring no
> + * destination connections
> + */
> +static void expire_nodest_conn_handler(struct work_struct *work)
> +{
> + struct netns_ipvs *ipvs;
> +
> + ipvs = container_of(work, struct netns_ipvs,
> + expire_nodest_conn_work.work);
> + ip_vs_expire_nodest_conn_flush(ipvs);
> +}
>
> /*
> * Timer for checking the defense
> @@ -1164,6 +1175,12 @@ static void __ip_vs_del_dest(struct netns_ipvs *ipvs,
> struct ip_vs_dest *dest,
> list_add(&dest->t_list, &ipvs->dest_trash);
> dest->idle_start = 0;
> spin_unlock_bh(&ipvs->dest_trash_lock);
> +
> + /* Queue up delayed work to expire all no destination connections.
> + * No-op when CONFIG_SYSCTL is disabled.
> + */
> + if (!cleanup)
> + ip_vs_enqueue_expire_nodest_conns(ipvs);
> }
>
>
> @@ -4086,6 +4103,10 @@ static int __net_init
> ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
> queue_delayed_work(system_long_wq, &ipvs->defense_work,
> DEFENSE_TIMER_PERIOD);
>
> + /* Init delayed work for expiring no dest conn */
> + INIT_DELAYED_WORK(&ipvs->expire_nodest_conn_work,
> + expire_nodest_conn_handler);
> +
> return 0;
> }
>
> @@ -4093,6 +4114,7 @@ static void __net_exit
> ip_vs_control_net_cleanup_sysctl(struct netns_ipvs *ipvs)
> {
> struct net *net = ipvs->net;
>
> + cancel_delayed_work_sync(&ipvs->expire_nodest_conn_work);
> cancel_delayed_work_sync(&ipvs->defense_work);
> cancel_work_sync(&ipvs->defense_work.work);
> unregister_net_sysctl_table(ipvs->sysctl_hdr);
> --
> 2.20.1
Regards
--
Julian Anastasov <ja@xxxxxx>
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