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Date: Wed, 19 Nov 2008 09:53:50 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Eric Dumazet <dada1@...mosbay.com>
Cc: David Miller <davem@...emloft.net>,
Corey Minyard <minyard@....org>,
Stephen Hemminger <shemminger@...tta.com>,
benny+usenet@...rsen.dk,
Linux Netdev List <netdev@...r.kernel.org>,
Christoph Lameter <cl@...ux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Evgeniy Polyakov <zbr@...emap.net>,
Christian Bell <christian@...i.com>
Subject: Re: [PATCH 3/3] net: Convert TCP & DCCP hash tables to use RCU /
hlist_nulls
On Thu, Nov 13, 2008 at 02:15:31PM +0100, Eric Dumazet wrote:
> RCU was added to UDP lookups, using a fast infrastructure :
> - sockets kmem_cache use SLAB_DESTROY_BY_RCU and dont pay the
> price of call_rcu() at freeing time.
> - hlist_nulls permits to use few memory barriers.
>
> This patch uses same infrastructure for TCP/DCCP established
> and timewait sockets.
>
> Thanks to SLAB_DESTROY_BY_RCU, no slowdown for applications
> using short lived TCP connections. A followup patch, converting
> rwlocks to spinlocks will even speedup this case.
>
> __inet_lookup_established() is pretty fast now we dont have to
> dirty a contended cache line (read_lock/read_unlock)
>
> Only established and timewait hashtable are converted to RCU
> (bind table and listen table are still using traditional locking)
Looks good to me!
Reviewed-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> Signed-off-by: Eric Dumazet <dada1@...mosbay.com>
> ---
> include/net/inet_hashtables.h | 4 -
> include/net/inet_timewait_sock.h | 10 +--
> net/core/sock.c | 4 +
> net/dccp/ipv4.c | 1
> net/dccp/ipv6.c | 1
> net/dccp/proto.c | 4 -
> net/ipv4/inet_diag.c | 6 +-
> net/ipv4/inet_hashtables.c | 78 ++++++++++++++++++++---------
> net/ipv4/inet_timewait_sock.c | 26 +++++----
> net/ipv4/tcp.c | 4 -
> net/ipv4/tcp_ipv4.c | 25 ++++-----
> net/ipv6/inet6_hashtables.c | 70 +++++++++++++++++---------
> net/ipv6/tcp_ipv6.c | 1
> 13 files changed, 150 insertions(+), 84 deletions(-)
> diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
> index cb31fbf..4818960 100644
> --- a/include/net/inet_hashtables.h
> +++ b/include/net/inet_hashtables.h
> @@ -41,8 +41,8 @@
> * I'll experiment with dynamic table growth later.
> */
> struct inet_ehash_bucket {
> - struct hlist_head chain;
> - struct hlist_head twchain;
> + struct hlist_nulls_head chain;
> + struct hlist_nulls_head twchain;
> };
>
> /* There are a few simple rules, which allow for local port reuse by
> diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
> index 80e4977..4b8ece2 100644
> --- a/include/net/inet_timewait_sock.h
> +++ b/include/net/inet_timewait_sock.h
> @@ -110,7 +110,7 @@ struct inet_timewait_sock {
> #define tw_state __tw_common.skc_state
> #define tw_reuse __tw_common.skc_reuse
> #define tw_bound_dev_if __tw_common.skc_bound_dev_if
> -#define tw_node __tw_common.skc_node
> +#define tw_node __tw_common.skc_nulls_node
> #define tw_bind_node __tw_common.skc_bind_node
> #define tw_refcnt __tw_common.skc_refcnt
> #define tw_hash __tw_common.skc_hash
> @@ -137,10 +137,10 @@ struct inet_timewait_sock {
> struct hlist_node tw_death_node;
> };
>
> -static inline void inet_twsk_add_node(struct inet_timewait_sock *tw,
> - struct hlist_head *list)
> +static inline void inet_twsk_add_node_rcu(struct inet_timewait_sock *tw,
> + struct hlist_nulls_head *list)
> {
> - hlist_add_head(&tw->tw_node, list);
> + hlist_nulls_add_head_rcu(&tw->tw_node, list);
> }
>
> static inline void inet_twsk_add_bind_node(struct inet_timewait_sock *tw,
> @@ -175,7 +175,7 @@ static inline int inet_twsk_del_dead_node(struct inet_timewait_sock *tw)
> }
>
> #define inet_twsk_for_each(tw, node, head) \
> - hlist_for_each_entry(tw, node, head, tw_node)
> + hlist_nulls_for_each_entry(tw, node, head, tw_node)
>
> #define inet_twsk_for_each_inmate(tw, node, jail) \
> hlist_for_each_entry(tw, node, jail, tw_death_node)
> diff --git a/net/core/sock.c b/net/core/sock.c
> index ded1eb5..38de9c3 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -2082,7 +2082,9 @@ int proto_register(struct proto *prot, int alloc_slab)
> prot->twsk_prot->twsk_slab =
> kmem_cache_create(timewait_sock_slab_name,
> prot->twsk_prot->twsk_obj_size,
> - 0, SLAB_HWCACHE_ALIGN,
> + 0,
> + SLAB_HWCACHE_ALIGN |
> + prot->slab_flags,
> NULL);
> if (prot->twsk_prot->twsk_slab == NULL)
> goto out_free_timewait_sock_slab_name;
> diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
> index 528baa2..d1dd952 100644
> --- a/net/dccp/ipv4.c
> +++ b/net/dccp/ipv4.c
> @@ -938,6 +938,7 @@ static struct proto dccp_v4_prot = {
> .orphan_count = &dccp_orphan_count,
> .max_header = MAX_DCCP_HEADER,
> .obj_size = sizeof(struct dccp_sock),
> + .slab_flags = SLAB_DESTROY_BY_RCU,
> .rsk_prot = &dccp_request_sock_ops,
> .twsk_prot = &dccp_timewait_sock_ops,
> .h.hashinfo = &dccp_hashinfo,
> diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
> index 4aa1148..f033e84 100644
> --- a/net/dccp/ipv6.c
> +++ b/net/dccp/ipv6.c
> @@ -1140,6 +1140,7 @@ static struct proto dccp_v6_prot = {
> .orphan_count = &dccp_orphan_count,
> .max_header = MAX_DCCP_HEADER,
> .obj_size = sizeof(struct dccp6_sock),
> + .slab_flags = SLAB_DESTROY_BY_RCU,
> .rsk_prot = &dccp6_request_sock_ops,
> .twsk_prot = &dccp6_timewait_sock_ops,
> .h.hashinfo = &dccp_hashinfo,
> diff --git a/net/dccp/proto.c b/net/dccp/proto.c
> index 46cb349..1117d4d 100644
> --- a/net/dccp/proto.c
> +++ b/net/dccp/proto.c
> @@ -1090,8 +1090,8 @@ static int __init dccp_init(void)
> }
>
> for (i = 0; i < dccp_hashinfo.ehash_size; i++) {
> - INIT_HLIST_HEAD(&dccp_hashinfo.ehash[i].chain);
> - INIT_HLIST_HEAD(&dccp_hashinfo.ehash[i].twchain);
> + INIT_HLIST_NULLS_HEAD(&dccp_hashinfo.ehash[i].chain, i);
> + INIT_HLIST_NULLS_HEAD(&dccp_hashinfo.ehash[i].twchain, i);
> }
>
> if (inet_ehash_locks_alloc(&dccp_hashinfo))
> diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
> index 564230d..41b3672 100644
> --- a/net/ipv4/inet_diag.c
> +++ b/net/ipv4/inet_diag.c
> @@ -778,18 +778,19 @@ skip_listen_ht:
> struct inet_ehash_bucket *head = &hashinfo->ehash[i];
> rwlock_t *lock = inet_ehash_lockp(hashinfo, i);
> struct sock *sk;
> - struct hlist_node *node;
> + struct hlist_nulls_node *node;
>
> num = 0;
>
> - if (hlist_empty(&head->chain) && hlist_empty(&head->twchain))
> + if (hlist_nulls_empty(&head->chain) &&
> + hlist_nulls_empty(&head->twchain))
> continue;
>
> if (i > s_i)
> s_num = 0;
>
> read_lock_bh(lock);
> - sk_for_each(sk, node, &head->chain) {
> + sk_nulls_for_each(sk, node, &head->chain) {
> struct inet_sock *inet = inet_sk(sk);
>
> if (num < s_num)
> diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
> index be41ebb..fd269cf 100644
> --- a/net/ipv4/inet_hashtables.c
> +++ b/net/ipv4/inet_hashtables.c
> @@ -223,35 +223,65 @@ struct sock * __inet_lookup_established(struct net *net,
> INET_ADDR_COOKIE(acookie, saddr, daddr)
> const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
> struct sock *sk;
> - const struct hlist_node *node;
> + const struct hlist_nulls_node *node;
> /* Optimize here for direct hit, only listening connections can
> * have wildcards anyways.
> */
> unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
> - struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash);
> - rwlock_t *lock = inet_ehash_lockp(hashinfo, hash);
> + unsigned int slot = hash & (hashinfo->ehash_size - 1);
> + struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
>
> - prefetch(head->chain.first);
> - read_lock(lock);
> - sk_for_each(sk, node, &head->chain) {
> + rcu_read_lock();
> +begin:
> + sk_nulls_for_each_rcu(sk, node, &head->chain) {
> if (INET_MATCH(sk, net, hash, acookie,
> - saddr, daddr, ports, dif))
> - goto hit; /* You sunk my battleship! */
> + saddr, daddr, ports, dif)) {
> + if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
> + goto begintw;
> + if (unlikely(!INET_MATCH(sk, net, hash, acookie,
> + saddr, daddr, ports, dif))) {
> + sock_put(sk);
> + goto begin;
> + }
> + goto out;
> + }
> }
> + /*
> + * if the nulls value we got at the end of this lookup is
> + * not the expected one, we must restart lookup.
> + * We probably met an item that was moved to another chain.
> + */
> + if (get_nulls_value(node) != slot)
> + goto begin;
>
> +begintw:
> /* Must check for a TIME_WAIT'er before going to listener hash. */
> - sk_for_each(sk, node, &head->twchain) {
> + sk_nulls_for_each_rcu(sk, node, &head->twchain) {
> if (INET_TW_MATCH(sk, net, hash, acookie,
> - saddr, daddr, ports, dif))
> - goto hit;
> + saddr, daddr, ports, dif)) {
> + if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
> + sk = NULL;
> + goto out;
> + }
> + if (unlikely(!INET_TW_MATCH(sk, net, hash, acookie,
> + saddr, daddr, ports, dif))) {
> + sock_put(sk);
> + goto begintw;
> + }
> + goto out;
> + }
> }
> + /*
> + * if the nulls value we got at the end of this lookup is
> + * not the expected one, we must restart lookup.
> + * We probably met an item that was moved to another chain.
> + */
> + if (get_nulls_value(node) != slot)
> + goto begintw;
> sk = NULL;
> out:
> - read_unlock(lock);
> + rcu_read_unlock();
> return sk;
> -hit:
> - sock_hold(sk);
> - goto out;
> }
> EXPORT_SYMBOL_GPL(__inet_lookup_established);
>
> @@ -272,14 +302,14 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row,
> struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
> rwlock_t *lock = inet_ehash_lockp(hinfo, hash);
> struct sock *sk2;
> - const struct hlist_node *node;
> + const struct hlist_nulls_node *node;
> struct inet_timewait_sock *tw;
>
> prefetch(head->chain.first);
> write_lock(lock);
>
> /* Check TIME-WAIT sockets first. */
> - sk_for_each(sk2, node, &head->twchain) {
> + sk_nulls_for_each(sk2, node, &head->twchain) {
> tw = inet_twsk(sk2);
>
> if (INET_TW_MATCH(sk2, net, hash, acookie,
> @@ -293,7 +323,7 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row,
> tw = NULL;
>
> /* And established part... */
> - sk_for_each(sk2, node, &head->chain) {
> + sk_nulls_for_each(sk2, node, &head->chain) {
> if (INET_MATCH(sk2, net, hash, acookie,
> saddr, daddr, ports, dif))
> goto not_unique;
> @@ -306,7 +336,7 @@ unique:
> inet->sport = htons(lport);
> sk->sk_hash = hash;
> WARN_ON(!sk_unhashed(sk));
> - __sk_add_node(sk, &head->chain);
> + __sk_nulls_add_node_rcu(sk, &head->chain);
> sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
> write_unlock(lock);
>
> @@ -338,7 +368,7 @@ static inline u32 inet_sk_port_offset(const struct sock *sk)
> void __inet_hash_nolisten(struct sock *sk)
> {
> struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
> - struct hlist_head *list;
> + struct hlist_nulls_head *list;
> rwlock_t *lock;
> struct inet_ehash_bucket *head;
>
> @@ -350,7 +380,7 @@ void __inet_hash_nolisten(struct sock *sk)
> lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
>
> write_lock(lock);
> - __sk_add_node(sk, list);
> + __sk_nulls_add_node_rcu(sk, list);
> sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
> write_unlock(lock);
> }
> @@ -400,13 +430,15 @@ void inet_unhash(struct sock *sk)
> local_bh_disable();
> inet_listen_wlock(hashinfo);
> lock = &hashinfo->lhash_lock;
> + if (__sk_del_node_init(sk))
> + sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
> } else {
> lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
> write_lock_bh(lock);
> + if (__sk_nulls_del_node_init_rcu(sk))
> + sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
> }
>
> - if (__sk_del_node_init(sk))
> - sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
> write_unlock_bh(lock);
> out:
> if (sk->sk_state == TCP_LISTEN)
> diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
> index 1c5fd38..6068995 100644
> --- a/net/ipv4/inet_timewait_sock.c
> +++ b/net/ipv4/inet_timewait_sock.c
> @@ -23,12 +23,12 @@ static void __inet_twsk_kill(struct inet_timewait_sock *tw,
> rwlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash);
>
> write_lock(lock);
> - if (hlist_unhashed(&tw->tw_node)) {
> + if (hlist_nulls_unhashed(&tw->tw_node)) {
> write_unlock(lock);
> return;
> }
> - __hlist_del(&tw->tw_node);
> - sk_node_init(&tw->tw_node);
> + hlist_nulls_del_rcu(&tw->tw_node);
> + sk_nulls_node_init(&tw->tw_node);
> write_unlock(lock);
>
> /* Disassociate with bind bucket. */
> @@ -92,13 +92,17 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
>
> write_lock(lock);
>
> - /* Step 2: Remove SK from established hash. */
> - if (__sk_del_node_init(sk))
> - sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
> -
> - /* Step 3: Hash TW into TIMEWAIT chain. */
> - inet_twsk_add_node(tw, &ehead->twchain);
> + /*
> + * Step 2: Hash TW into TIMEWAIT chain.
> + * Should be done before removing sk from established chain
> + * because readers are lockless and search established first.
> + */
> atomic_inc(&tw->tw_refcnt);
> + inet_twsk_add_node_rcu(tw, &ehead->twchain);
> +
> + /* Step 3: Remove SK from established hash. */
> + if (__sk_nulls_del_node_init_rcu(sk))
> + sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
>
> write_unlock(lock);
> }
> @@ -416,7 +420,7 @@ void inet_twsk_purge(struct net *net, struct inet_hashinfo *hashinfo,
> {
> struct inet_timewait_sock *tw;
> struct sock *sk;
> - struct hlist_node *node;
> + struct hlist_nulls_node *node;
> int h;
>
> local_bh_disable();
> @@ -426,7 +430,7 @@ void inet_twsk_purge(struct net *net, struct inet_hashinfo *hashinfo,
> rwlock_t *lock = inet_ehash_lockp(hashinfo, h);
> restart:
> write_lock(lock);
> - sk_for_each(sk, node, &head->twchain) {
> + sk_nulls_for_each(sk, node, &head->twchain) {
>
> tw = inet_twsk(sk);
> if (!net_eq(twsk_net(tw), net) ||
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index f60a591..044224a 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -2707,8 +2707,8 @@ void __init tcp_init(void)
> thash_entries ? 0 : 512 * 1024);
> tcp_hashinfo.ehash_size = 1 << tcp_hashinfo.ehash_size;
> for (i = 0; i < tcp_hashinfo.ehash_size; i++) {
> - INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain);
> - INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].twchain);
> + INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
> + INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].twchain, i);
> }
> if (inet_ehash_locks_alloc(&tcp_hashinfo))
> panic("TCP: failed to alloc ehash_locks");
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index d49233f..b2e3ab2 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -1857,16 +1857,16 @@ EXPORT_SYMBOL(tcp_v4_destroy_sock);
> #ifdef CONFIG_PROC_FS
> /* Proc filesystem TCP sock list dumping. */
>
> -static inline struct inet_timewait_sock *tw_head(struct hlist_head *head)
> +static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head)
> {
> - return hlist_empty(head) ? NULL :
> + return hlist_nulls_empty(head) ? NULL :
> list_entry(head->first, struct inet_timewait_sock, tw_node);
> }
>
> static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
> {
> - return tw->tw_node.next ?
> - hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
> + return !is_a_nulls(tw->tw_node.next) ?
> + hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
> }
>
> static void *listening_get_next(struct seq_file *seq, void *cur)
> @@ -1954,8 +1954,8 @@ static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
>
> static inline int empty_bucket(struct tcp_iter_state *st)
> {
> - return hlist_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
> - hlist_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
> + return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
> + hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
> }
>
> static void *established_get_first(struct seq_file *seq)
> @@ -1966,7 +1966,7 @@ static void *established_get_first(struct seq_file *seq)
>
> for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
> struct sock *sk;
> - struct hlist_node *node;
> + struct hlist_nulls_node *node;
> struct inet_timewait_sock *tw;
> rwlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
>
> @@ -1975,7 +1975,7 @@ static void *established_get_first(struct seq_file *seq)
> continue;
>
> read_lock_bh(lock);
> - sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
> + sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
> if (sk->sk_family != st->family ||
> !net_eq(sock_net(sk), net)) {
> continue;
> @@ -2004,7 +2004,7 @@ static void *established_get_next(struct seq_file *seq, void *cur)
> {
> struct sock *sk = cur;
> struct inet_timewait_sock *tw;
> - struct hlist_node *node;
> + struct hlist_nulls_node *node;
> struct tcp_iter_state *st = seq->private;
> struct net *net = seq_file_net(seq);
>
> @@ -2032,11 +2032,11 @@ get_tw:
> return NULL;
>
> read_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
> - sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain);
> + sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
> } else
> - sk = sk_next(sk);
> + sk = sk_nulls_next(sk);
>
> - sk_for_each_from(sk, node) {
> + sk_nulls_for_each_from(sk, node) {
> if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
> goto found;
> }
> @@ -2375,6 +2375,7 @@ struct proto tcp_prot = {
> .sysctl_rmem = sysctl_tcp_rmem,
> .max_header = MAX_TCP_HEADER,
> .obj_size = sizeof(struct tcp_sock),
> + .slab_flags = SLAB_DESTROY_BY_RCU,
> .twsk_prot = &tcp_timewait_sock_ops,
> .rsk_prot = &tcp_request_sock_ops,
> .h.hashinfo = &tcp_hashinfo,
> diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
> index 1646a56..c1b4d40 100644
> --- a/net/ipv6/inet6_hashtables.c
> +++ b/net/ipv6/inet6_hashtables.c
> @@ -25,24 +25,28 @@
> void __inet6_hash(struct sock *sk)
> {
> struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
> - struct hlist_head *list;
> rwlock_t *lock;
>
> WARN_ON(!sk_unhashed(sk));
>
> if (sk->sk_state == TCP_LISTEN) {
> + struct hlist_head *list;
> +
> list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
> lock = &hashinfo->lhash_lock;
> inet_listen_wlock(hashinfo);
> + __sk_add_node(sk, list);
> } else {
> unsigned int hash;
> + struct hlist_nulls_head *list;
> +
> sk->sk_hash = hash = inet6_sk_ehashfn(sk);
> list = &inet_ehash_bucket(hashinfo, hash)->chain;
> lock = inet_ehash_lockp(hashinfo, hash);
> write_lock(lock);
> + __sk_nulls_add_node_rcu(sk, list);
> }
>
> - __sk_add_node(sk, list);
> sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
> write_unlock(lock);
> }
> @@ -63,33 +67,53 @@ struct sock *__inet6_lookup_established(struct net *net,
> const int dif)
> {
> struct sock *sk;
> - const struct hlist_node *node;
> + const struct hlist_nulls_node *node;
> const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
> /* Optimize here for direct hit, only listening connections can
> * have wildcards anyways.
> */
> unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
> - struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash);
> - rwlock_t *lock = inet_ehash_lockp(hashinfo, hash);
> + unsigned int slot = hash & (hashinfo->ehash_size - 1);
> + struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
>
> - prefetch(head->chain.first);
> - read_lock(lock);
> - sk_for_each(sk, node, &head->chain) {
> +
> + rcu_read_lock();
> +begin:
> + sk_nulls_for_each_rcu(sk, node, &head->chain) {
> /* For IPV6 do the cheaper port and family tests first. */
> - if (INET6_MATCH(sk, net, hash, saddr, daddr, ports, dif))
> - goto hit; /* You sunk my battleship! */
> + if (INET6_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
> + if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
> + goto begintw;
> + if (!INET6_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
> + sock_put(sk);
> + goto begin;
> + }
> + goto out;
> + }
> }
> + if (get_nulls_value(node) != slot)
> + goto begin;
> +
> +begintw:
> /* Must check for a TIME_WAIT'er before going to listener hash. */
> - sk_for_each(sk, node, &head->twchain) {
> - if (INET6_TW_MATCH(sk, net, hash, saddr, daddr, ports, dif))
> - goto hit;
> + sk_nulls_for_each_rcu(sk, node, &head->twchain) {
> + if (INET6_TW_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
> + if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
> + sk = NULL;
> + goto out;
> + }
> + if (!INET6_TW_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
> + sock_put(sk);
> + goto begintw;
> + }
> + goto out;
> + }
> }
> - read_unlock(lock);
> - return NULL;
> -
> -hit:
> - sock_hold(sk);
> - read_unlock(lock);
> + if (get_nulls_value(node) != slot)
> + goto begintw;
> + sk = NULL;
> +out:
> + rcu_read_unlock();
> return sk;
> }
> EXPORT_SYMBOL(__inet6_lookup_established);
> @@ -172,14 +196,14 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row,
> struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
> rwlock_t *lock = inet_ehash_lockp(hinfo, hash);
> struct sock *sk2;
> - const struct hlist_node *node;
> + const struct hlist_nulls_node *node;
> struct inet_timewait_sock *tw;
>
> prefetch(head->chain.first);
> write_lock(lock);
>
> /* Check TIME-WAIT sockets first. */
> - sk_for_each(sk2, node, &head->twchain) {
> + sk_nulls_for_each(sk2, node, &head->twchain) {
> tw = inet_twsk(sk2);
>
> if (INET6_TW_MATCH(sk2, net, hash, saddr, daddr, ports, dif)) {
> @@ -192,7 +216,7 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row,
> tw = NULL;
>
> /* And established part... */
> - sk_for_each(sk2, node, &head->chain) {
> + sk_nulls_for_each(sk2, node, &head->chain) {
> if (INET6_MATCH(sk2, net, hash, saddr, daddr, ports, dif))
> goto not_unique;
> }
> @@ -203,7 +227,7 @@ unique:
> inet->num = lport;
> inet->sport = htons(lport);
> WARN_ON(!sk_unhashed(sk));
> - __sk_add_node(sk, &head->chain);
> + __sk_nulls_add_node_rcu(sk, &head->chain);
> sk->sk_hash = hash;
> sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
> write_unlock(lock);
> diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> index 9842764..b357870 100644
> --- a/net/ipv6/tcp_ipv6.c
> +++ b/net/ipv6/tcp_ipv6.c
> @@ -2043,6 +2043,7 @@ struct proto tcpv6_prot = {
> .sysctl_rmem = sysctl_tcp_rmem,
> .max_header = MAX_TCP_HEADER,
> .obj_size = sizeof(struct tcp6_sock),
> + .slab_flags = SLAB_DESTROY_BY_RCU,
> .twsk_prot = &tcp6_timewait_sock_ops,
> .rsk_prot = &tcp6_request_sock_ops,
> .h.hashinfo = &tcp_hashinfo,
--
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