1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
7 * Generic INET transport hashtables
9 * Authors: Lotsa people, from code originally in tcp
12 #include <linux/module.h>
13 #include <linux/random.h>
14 #include <linux/sched.h>
15 #include <linux/slab.h>
16 #include <linux/wait.h>
17 #include <linux/vmalloc.h>
18 #include <linux/memblock.h>
20 #include <net/addrconf.h>
21 #include <net/inet_connection_sock.h>
22 #include <net/inet_hashtables.h>
23 #if IS_ENABLED(CONFIG_IPV6)
24 #include <net/inet6_hashtables.h>
26 #include <net/secure_seq.h>
29 #include <net/sock_reuseport.h>
31 static u32 inet_ehashfn(const struct net *net, const __be32 laddr,
32 const __u16 lport, const __be32 faddr,
35 static u32 inet_ehash_secret __read_mostly;
37 net_get_random_once(&inet_ehash_secret, sizeof(inet_ehash_secret));
39 return __inet_ehashfn(laddr, lport, faddr, fport,
40 inet_ehash_secret + net_hash_mix(net));
43 /* This function handles inet_sock, but also timewait and request sockets
46 static u32 sk_ehashfn(const struct sock *sk)
48 #if IS_ENABLED(CONFIG_IPV6)
49 if (sk->sk_family == AF_INET6 &&
50 !ipv6_addr_v4mapped(&sk->sk_v6_daddr))
51 return inet6_ehashfn(sock_net(sk),
52 &sk->sk_v6_rcv_saddr, sk->sk_num,
53 &sk->sk_v6_daddr, sk->sk_dport);
55 return inet_ehashfn(sock_net(sk),
56 sk->sk_rcv_saddr, sk->sk_num,
57 sk->sk_daddr, sk->sk_dport);
61 * Allocate and initialize a new local port bind bucket.
62 * The bindhash mutex for snum's hash chain must be held here.
64 struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,
66 struct inet_bind_hashbucket *head,
67 const unsigned short snum,
70 struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
73 write_pnet(&tb->ib_net, net);
77 tb->fastreuseport = 0;
78 INIT_HLIST_HEAD(&tb->owners);
79 hlist_add_head(&tb->node, &head->chain);
85 * Caller must hold hashbucket lock for this tb with local BH disabled
87 void inet_bind_bucket_destroy(struct kmem_cache *cachep, struct inet_bind_bucket *tb)
89 if (hlist_empty(&tb->owners)) {
90 __hlist_del(&tb->node);
91 kmem_cache_free(cachep, tb);
95 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
96 const unsigned short snum)
98 inet_sk(sk)->inet_num = snum;
99 sk_add_bind_node(sk, &tb->owners);
100 inet_csk(sk)->icsk_bind_hash = tb;
104 * Get rid of any references to a local port held by the given sock.
106 static void __inet_put_port(struct sock *sk)
108 struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
109 const int bhash = inet_bhashfn(sock_net(sk), inet_sk(sk)->inet_num,
110 hashinfo->bhash_size);
111 struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
112 struct inet_bind_bucket *tb;
114 spin_lock(&head->lock);
115 tb = inet_csk(sk)->icsk_bind_hash;
116 __sk_del_bind_node(sk);
117 inet_csk(sk)->icsk_bind_hash = NULL;
118 inet_sk(sk)->inet_num = 0;
119 inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
120 spin_unlock(&head->lock);
123 void inet_put_port(struct sock *sk)
129 EXPORT_SYMBOL(inet_put_port);
131 int __inet_inherit_port(const struct sock *sk, struct sock *child)
133 struct inet_hashinfo *table = sk->sk_prot->h.hashinfo;
134 unsigned short port = inet_sk(child)->inet_num;
135 const int bhash = inet_bhashfn(sock_net(sk), port,
137 struct inet_bind_hashbucket *head = &table->bhash[bhash];
138 struct inet_bind_bucket *tb;
141 spin_lock(&head->lock);
142 tb = inet_csk(sk)->icsk_bind_hash;
144 spin_unlock(&head->lock);
147 if (tb->port != port) {
148 l3mdev = inet_sk_bound_l3mdev(sk);
150 /* NOTE: using tproxy and redirecting skbs to a proxy
151 * on a different listener port breaks the assumption
152 * that the listener socket's icsk_bind_hash is the same
153 * as that of the child socket. We have to look up or
154 * create a new bind bucket for the child here. */
155 inet_bind_bucket_for_each(tb, &head->chain) {
156 if (net_eq(ib_net(tb), sock_net(sk)) &&
157 tb->l3mdev == l3mdev && tb->port == port)
161 tb = inet_bind_bucket_create(table->bind_bucket_cachep,
162 sock_net(sk), head, port,
165 spin_unlock(&head->lock);
169 inet_csk_update_fastreuse(tb, child);
171 inet_bind_hash(child, tb, port);
172 spin_unlock(&head->lock);
176 EXPORT_SYMBOL_GPL(__inet_inherit_port);
178 static struct inet_listen_hashbucket *
179 inet_lhash2_bucket_sk(struct inet_hashinfo *h, struct sock *sk)
183 #if IS_ENABLED(CONFIG_IPV6)
184 if (sk->sk_family == AF_INET6)
185 hash = ipv6_portaddr_hash(sock_net(sk),
186 &sk->sk_v6_rcv_saddr,
187 inet_sk(sk)->inet_num);
190 hash = ipv4_portaddr_hash(sock_net(sk),
191 inet_sk(sk)->inet_rcv_saddr,
192 inet_sk(sk)->inet_num);
193 return inet_lhash2_bucket(h, hash);
196 static inline int compute_score(struct sock *sk, struct net *net,
197 const unsigned short hnum, const __be32 daddr,
198 const int dif, const int sdif)
202 if (net_eq(sock_net(sk), net) && sk->sk_num == hnum &&
203 !ipv6_only_sock(sk)) {
204 if (sk->sk_rcv_saddr != daddr)
207 if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
209 score = sk->sk_bound_dev_if ? 2 : 1;
211 if (sk->sk_family == PF_INET)
213 if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
219 static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk,
220 struct sk_buff *skb, int doff,
221 __be32 saddr, __be16 sport,
222 __be32 daddr, unsigned short hnum)
224 struct sock *reuse_sk = NULL;
227 if (sk->sk_reuseport) {
228 phash = inet_ehashfn(net, daddr, hnum, saddr, sport);
229 reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
235 * Here are some nice properties to exploit here. The BSD API
236 * does not allow a listening sock to specify the remote port nor the
237 * remote address for the connection. So always assume those are both
238 * wildcarded during the search since they can never be otherwise.
241 /* called with rcu_read_lock() : No refcount taken on the socket */
242 static struct sock *inet_lhash2_lookup(struct net *net,
243 struct inet_listen_hashbucket *ilb2,
244 struct sk_buff *skb, int doff,
245 const __be32 saddr, __be16 sport,
246 const __be32 daddr, const unsigned short hnum,
247 const int dif, const int sdif)
249 struct sock *sk, *result = NULL;
250 struct hlist_nulls_node *node;
251 int score, hiscore = 0;
253 sk_nulls_for_each_rcu(sk, node, &ilb2->nulls_head) {
254 score = compute_score(sk, net, hnum, daddr, dif, sdif);
255 if (score > hiscore) {
256 result = lookup_reuseport(net, sk, skb, doff,
257 saddr, sport, daddr, hnum);
269 static inline struct sock *inet_lookup_run_bpf(struct net *net,
270 struct inet_hashinfo *hashinfo,
271 struct sk_buff *skb, int doff,
272 __be32 saddr, __be16 sport,
273 __be32 daddr, u16 hnum, const int dif)
275 struct sock *sk, *reuse_sk;
278 if (hashinfo != &tcp_hashinfo)
279 return NULL; /* only TCP is supported */
281 no_reuseport = bpf_sk_lookup_run_v4(net, IPPROTO_TCP, saddr, sport,
282 daddr, hnum, dif, &sk);
283 if (no_reuseport || IS_ERR_OR_NULL(sk))
286 reuse_sk = lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum);
292 struct sock *__inet_lookup_listener(struct net *net,
293 struct inet_hashinfo *hashinfo,
294 struct sk_buff *skb, int doff,
295 const __be32 saddr, __be16 sport,
296 const __be32 daddr, const unsigned short hnum,
297 const int dif, const int sdif)
299 struct inet_listen_hashbucket *ilb2;
300 struct sock *result = NULL;
303 /* Lookup redirect from BPF */
304 if (static_branch_unlikely(&bpf_sk_lookup_enabled)) {
305 result = inet_lookup_run_bpf(net, hashinfo, skb, doff,
306 saddr, sport, daddr, hnum, dif);
311 hash2 = ipv4_portaddr_hash(net, daddr, hnum);
312 ilb2 = inet_lhash2_bucket(hashinfo, hash2);
314 result = inet_lhash2_lookup(net, ilb2, skb, doff,
315 saddr, sport, daddr, hnum,
320 /* Lookup lhash2 with INADDR_ANY */
321 hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
322 ilb2 = inet_lhash2_bucket(hashinfo, hash2);
324 result = inet_lhash2_lookup(net, ilb2, skb, doff,
325 saddr, sport, htonl(INADDR_ANY), hnum,
332 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
334 /* All sockets share common refcount, but have different destructors */
335 void sock_gen_put(struct sock *sk)
337 if (!refcount_dec_and_test(&sk->sk_refcnt))
340 if (sk->sk_state == TCP_TIME_WAIT)
341 inet_twsk_free(inet_twsk(sk));
342 else if (sk->sk_state == TCP_NEW_SYN_RECV)
343 reqsk_free(inet_reqsk(sk));
347 EXPORT_SYMBOL_GPL(sock_gen_put);
349 void sock_edemux(struct sk_buff *skb)
351 sock_gen_put(skb->sk);
353 EXPORT_SYMBOL(sock_edemux);
355 struct sock *__inet_lookup_established(struct net *net,
356 struct inet_hashinfo *hashinfo,
357 const __be32 saddr, const __be16 sport,
358 const __be32 daddr, const u16 hnum,
359 const int dif, const int sdif)
361 INET_ADDR_COOKIE(acookie, saddr, daddr);
362 const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
364 const struct hlist_nulls_node *node;
365 /* Optimize here for direct hit, only listening connections can
366 * have wildcards anyways.
368 unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
369 unsigned int slot = hash & hashinfo->ehash_mask;
370 struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
373 sk_nulls_for_each_rcu(sk, node, &head->chain) {
374 if (sk->sk_hash != hash)
376 if (likely(inet_match(net, sk, acookie, ports, dif, sdif))) {
377 if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
379 if (unlikely(!inet_match(net, sk, acookie,
380 ports, dif, sdif))) {
388 * if the nulls value we got at the end of this lookup is
389 * not the expected one, we must restart lookup.
390 * We probably met an item that was moved to another chain.
392 if (get_nulls_value(node) != slot)
399 EXPORT_SYMBOL_GPL(__inet_lookup_established);
401 /* called with local bh disabled */
402 static int __inet_check_established(struct inet_timewait_death_row *death_row,
403 struct sock *sk, __u16 lport,
404 struct inet_timewait_sock **twp)
406 struct inet_hashinfo *hinfo = death_row->hashinfo;
407 struct inet_sock *inet = inet_sk(sk);
408 __be32 daddr = inet->inet_rcv_saddr;
409 __be32 saddr = inet->inet_daddr;
410 int dif = sk->sk_bound_dev_if;
411 struct net *net = sock_net(sk);
412 int sdif = l3mdev_master_ifindex_by_index(net, dif);
413 INET_ADDR_COOKIE(acookie, saddr, daddr);
414 const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
415 unsigned int hash = inet_ehashfn(net, daddr, lport,
416 saddr, inet->inet_dport);
417 struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
418 spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
420 const struct hlist_nulls_node *node;
421 struct inet_timewait_sock *tw = NULL;
425 sk_nulls_for_each(sk2, node, &head->chain) {
426 if (sk2->sk_hash != hash)
429 if (likely(inet_match(net, sk2, acookie, ports, dif, sdif))) {
430 if (sk2->sk_state == TCP_TIME_WAIT) {
432 if (twsk_unique(sk, sk2, twp))
439 /* Must record num and sport now. Otherwise we will see
440 * in hash table socket with a funny identity.
442 inet->inet_num = lport;
443 inet->inet_sport = htons(lport);
445 WARN_ON(!sk_unhashed(sk));
446 __sk_nulls_add_node_rcu(sk, &head->chain);
448 sk_nulls_del_node_init_rcu((struct sock *)tw);
449 __NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);
452 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
457 /* Silly. Should hash-dance instead... */
458 inet_twsk_deschedule_put(tw);
464 return -EADDRNOTAVAIL;
467 static u64 inet_sk_port_offset(const struct sock *sk)
469 const struct inet_sock *inet = inet_sk(sk);
471 return secure_ipv4_port_ephemeral(inet->inet_rcv_saddr,
476 /* Searches for an exsiting socket in the ehash bucket list.
477 * Returns true if found, false otherwise.
479 static bool inet_ehash_lookup_by_sk(struct sock *sk,
480 struct hlist_nulls_head *list)
482 const __portpair ports = INET_COMBINED_PORTS(sk->sk_dport, sk->sk_num);
483 const int sdif = sk->sk_bound_dev_if;
484 const int dif = sk->sk_bound_dev_if;
485 const struct hlist_nulls_node *node;
486 struct net *net = sock_net(sk);
489 INET_ADDR_COOKIE(acookie, sk->sk_daddr, sk->sk_rcv_saddr);
491 sk_nulls_for_each_rcu(esk, node, list) {
492 if (esk->sk_hash != sk->sk_hash)
494 if (sk->sk_family == AF_INET) {
495 if (unlikely(inet_match(net, esk, acookie,
496 ports, dif, sdif))) {
500 #if IS_ENABLED(CONFIG_IPV6)
501 else if (sk->sk_family == AF_INET6) {
502 if (unlikely(inet6_match(net, esk,
504 &sk->sk_v6_rcv_saddr,
505 ports, dif, sdif))) {
514 /* Insert a socket into ehash, and eventually remove another one
515 * (The another one can be a SYN_RECV or TIMEWAIT)
516 * If an existing socket already exists, socket sk is not inserted,
517 * and sets found_dup_sk parameter to true.
519 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk)
521 struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
522 struct hlist_nulls_head *list;
523 struct inet_ehash_bucket *head;
527 WARN_ON_ONCE(!sk_unhashed(sk));
529 sk->sk_hash = sk_ehashfn(sk);
530 head = inet_ehash_bucket(hashinfo, sk->sk_hash);
532 lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
536 WARN_ON_ONCE(sk->sk_hash != osk->sk_hash);
537 ret = sk_nulls_del_node_init_rcu(osk);
538 } else if (found_dup_sk) {
539 *found_dup_sk = inet_ehash_lookup_by_sk(sk, list);
545 __sk_nulls_add_node_rcu(sk, list);
552 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk, bool *found_dup_sk)
554 bool ok = inet_ehash_insert(sk, osk, found_dup_sk);
557 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
559 this_cpu_inc(*sk->sk_prot->orphan_count);
560 inet_sk_set_state(sk, TCP_CLOSE);
561 sock_set_flag(sk, SOCK_DEAD);
562 inet_csk_destroy_sock(sk);
566 EXPORT_SYMBOL_GPL(inet_ehash_nolisten);
568 static int inet_reuseport_add_sock(struct sock *sk,
569 struct inet_listen_hashbucket *ilb)
571 struct inet_bind_bucket *tb = inet_csk(sk)->icsk_bind_hash;
572 const struct hlist_nulls_node *node;
574 kuid_t uid = sock_i_uid(sk);
576 sk_nulls_for_each_rcu(sk2, node, &ilb->nulls_head) {
578 sk2->sk_family == sk->sk_family &&
579 ipv6_only_sock(sk2) == ipv6_only_sock(sk) &&
580 sk2->sk_bound_dev_if == sk->sk_bound_dev_if &&
581 inet_csk(sk2)->icsk_bind_hash == tb &&
582 sk2->sk_reuseport && uid_eq(uid, sock_i_uid(sk2)) &&
583 inet_rcv_saddr_equal(sk, sk2, false))
584 return reuseport_add_sock(sk, sk2,
585 inet_rcv_saddr_any(sk));
588 return reuseport_alloc(sk, inet_rcv_saddr_any(sk));
591 int __inet_hash(struct sock *sk, struct sock *osk)
593 struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
594 struct inet_listen_hashbucket *ilb2;
597 if (sk->sk_state != TCP_LISTEN) {
599 inet_ehash_nolisten(sk, osk, NULL);
603 WARN_ON(!sk_unhashed(sk));
604 ilb2 = inet_lhash2_bucket_sk(hashinfo, sk);
606 spin_lock(&ilb2->lock);
607 if (sk->sk_reuseport) {
608 err = inet_reuseport_add_sock(sk, ilb2);
612 if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
613 sk->sk_family == AF_INET6)
614 __sk_nulls_add_node_tail_rcu(sk, &ilb2->nulls_head);
616 __sk_nulls_add_node_rcu(sk, &ilb2->nulls_head);
617 sock_set_flag(sk, SOCK_RCU_FREE);
618 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
620 spin_unlock(&ilb2->lock);
624 EXPORT_SYMBOL(__inet_hash);
626 int inet_hash(struct sock *sk)
630 if (sk->sk_state != TCP_CLOSE)
631 err = __inet_hash(sk, NULL);
635 EXPORT_SYMBOL_GPL(inet_hash);
637 void inet_unhash(struct sock *sk)
639 struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
644 if (sk->sk_state == TCP_LISTEN) {
645 struct inet_listen_hashbucket *ilb2;
647 ilb2 = inet_lhash2_bucket_sk(hashinfo, sk);
648 /* Don't disable bottom halves while acquiring the lock to
649 * avoid circular locking dependency on PREEMPT_RT.
651 spin_lock(&ilb2->lock);
652 if (sk_unhashed(sk)) {
653 spin_unlock(&ilb2->lock);
657 if (rcu_access_pointer(sk->sk_reuseport_cb))
658 reuseport_stop_listen_sock(sk);
660 __sk_nulls_del_node_init_rcu(sk);
661 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
662 spin_unlock(&ilb2->lock);
664 spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
667 if (sk_unhashed(sk)) {
668 spin_unlock_bh(lock);
671 __sk_nulls_del_node_init_rcu(sk);
672 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
673 spin_unlock_bh(lock);
676 EXPORT_SYMBOL_GPL(inet_unhash);
678 /* RFC 6056 3.3.4. Algorithm 4: Double-Hash Port Selection Algorithm
679 * Note that we use 32bit integers (vs RFC 'short integers')
680 * because 2^16 is not a multiple of num_ephemeral and this
681 * property might be used by clever attacker.
682 * RFC claims using TABLE_LENGTH=10 buckets gives an improvement, though
683 * attacks were since demonstrated, thus we use 65536 instead to really
684 * give more isolation and privacy, at the expense of 256kB of kernel
687 #define INET_TABLE_PERTURB_SHIFT 16
688 #define INET_TABLE_PERTURB_SIZE (1 << INET_TABLE_PERTURB_SHIFT)
689 static u32 *table_perturb;
691 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
692 struct sock *sk, u64 port_offset,
693 int (*check_established)(struct inet_timewait_death_row *,
694 struct sock *, __u16, struct inet_timewait_sock **))
696 struct inet_hashinfo *hinfo = death_row->hashinfo;
697 struct inet_timewait_sock *tw = NULL;
698 struct inet_bind_hashbucket *head;
699 int port = inet_sk(sk)->inet_num;
700 struct net *net = sock_net(sk);
701 struct inet_bind_bucket *tb;
702 u32 remaining, offset;
703 int ret, i, low, high;
708 head = &hinfo->bhash[inet_bhashfn(net, port,
710 tb = inet_csk(sk)->icsk_bind_hash;
711 spin_lock_bh(&head->lock);
712 if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
713 inet_ehash_nolisten(sk, NULL, NULL);
714 spin_unlock_bh(&head->lock);
717 spin_unlock(&head->lock);
718 /* No definite answer... Walk to established hash table */
719 ret = check_established(death_row, sk, port, NULL);
724 l3mdev = inet_sk_bound_l3mdev(sk);
726 inet_get_local_port_range(net, &low, &high);
727 high++; /* [32768, 60999] -> [32768, 61000[ */
728 remaining = high - low;
729 if (likely(remaining > 1))
732 net_get_random_once(table_perturb,
733 INET_TABLE_PERTURB_SIZE * sizeof(*table_perturb));
734 index = port_offset & (INET_TABLE_PERTURB_SIZE - 1);
736 offset = READ_ONCE(table_perturb[index]) + (port_offset >> 32);
739 /* In first pass we try ports of @low parity.
740 * inet_csk_get_port() does the opposite choice.
745 for (i = 0; i < remaining; i += 2, port += 2) {
746 if (unlikely(port >= high))
748 if (inet_is_local_reserved_port(net, port))
750 head = &hinfo->bhash[inet_bhashfn(net, port,
752 spin_lock_bh(&head->lock);
754 /* Does not bother with rcv_saddr checks, because
755 * the established check is already unique enough.
757 inet_bind_bucket_for_each(tb, &head->chain) {
758 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
760 if (tb->fastreuse >= 0 ||
761 tb->fastreuseport >= 0)
763 WARN_ON(hlist_empty(&tb->owners));
764 if (!check_established(death_row, sk,
771 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
772 net, head, port, l3mdev);
774 spin_unlock_bh(&head->lock);
778 tb->fastreuseport = -1;
781 spin_unlock_bh(&head->lock);
786 if ((offset & 1) && remaining > 1)
787 goto other_parity_scan;
789 return -EADDRNOTAVAIL;
792 /* Here we want to add a little bit of randomness to the next source
793 * port that will be chosen. We use a max() with a random here so that
794 * on low contention the randomness is maximal and on high contention
795 * it may be inexistent.
797 i = max_t(int, i, (prandom_u32() & 7) * 2);
798 WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + 2);
800 /* Head lock still held and bh's disabled */
801 inet_bind_hash(sk, tb, port);
802 if (sk_unhashed(sk)) {
803 inet_sk(sk)->inet_sport = htons(port);
804 inet_ehash_nolisten(sk, (struct sock *)tw, NULL);
807 inet_twsk_bind_unhash(tw, hinfo);
808 spin_unlock(&head->lock);
810 inet_twsk_deschedule_put(tw);
816 * Bind a port for a connect operation and hash it.
818 int inet_hash_connect(struct inet_timewait_death_row *death_row,
823 if (!inet_sk(sk)->inet_num)
824 port_offset = inet_sk_port_offset(sk);
825 return __inet_hash_connect(death_row, sk, port_offset,
826 __inet_check_established);
828 EXPORT_SYMBOL_GPL(inet_hash_connect);
830 static void init_hashinfo_lhash2(struct inet_hashinfo *h)
834 for (i = 0; i <= h->lhash2_mask; i++) {
835 spin_lock_init(&h->lhash2[i].lock);
836 INIT_HLIST_NULLS_HEAD(&h->lhash2[i].nulls_head,
837 i + LISTENING_NULLS_BASE);
841 void __init inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
842 unsigned long numentries, int scale,
843 unsigned long low_limit,
844 unsigned long high_limit)
846 h->lhash2 = alloc_large_system_hash(name,
855 init_hashinfo_lhash2(h);
857 /* this one is used for source ports of outgoing connections */
858 table_perturb = alloc_large_system_hash("Table-perturb",
859 sizeof(*table_perturb),
860 INET_TABLE_PERTURB_SIZE,
862 INET_TABLE_PERTURB_SIZE,
863 INET_TABLE_PERTURB_SIZE);
866 int inet_hashinfo2_init_mod(struct inet_hashinfo *h)
868 h->lhash2 = kmalloc_array(INET_LHTABLE_SIZE, sizeof(*h->lhash2), GFP_KERNEL);
872 h->lhash2_mask = INET_LHTABLE_SIZE - 1;
873 /* INET_LHTABLE_SIZE must be a power of 2 */
874 BUG_ON(INET_LHTABLE_SIZE & h->lhash2_mask);
876 init_hashinfo_lhash2(h);
879 EXPORT_SYMBOL_GPL(inet_hashinfo2_init_mod);
881 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
883 unsigned int locksz = sizeof(spinlock_t);
884 unsigned int i, nblocks = 1;
887 /* allocate 2 cache lines or at least one spinlock per cpu */
888 nblocks = max(2U * L1_CACHE_BYTES / locksz, 1U);
889 nblocks = roundup_pow_of_two(nblocks * num_possible_cpus());
891 /* no more locks than number of hash buckets */
892 nblocks = min(nblocks, hashinfo->ehash_mask + 1);
894 hashinfo->ehash_locks = kvmalloc_array(nblocks, locksz, GFP_KERNEL);
895 if (!hashinfo->ehash_locks)
898 for (i = 0; i < nblocks; i++)
899 spin_lock_init(&hashinfo->ehash_locks[i]);
901 hashinfo->ehash_locks_mask = nblocks - 1;
904 EXPORT_SYMBOL_GPL(inet_ehash_locks_alloc);