Commit ca065d0c authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

udp: no longer use SLAB_DESTROY_BY_RCU

Tom Herbert would like not touching UDP socket refcnt for encapsulated
traffic. For this to happen, we need to use normal RCU rules, with a grace
period before freeing a socket. UDP sockets are not short lived in the
high usage case, so the added cost of call_rcu() should not be a concern.

This actually removes a lot of complexity in UDP stack.

Multicast receives no longer need to hold a bucket spinlock.

Note that ip early demux still needs to take a reference on the socket.

Same remark for functions used by xt_socket and xt_PROXY netfilter modules,
but this might be changed later.

Performance for a single UDP socket receiving flood traffic from
many RX queues/cpus.

Simple udp_rx using simple recvfrom() loop :
438 kpps instead of 374 kpps : 17 % increase of the peak rate.

v2: Addressed Willem de Bruijn feedback in multicast handling
 - keep early demux break in __udp4_lib_demux_lookup()
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Tom Herbert <tom@herbertland.com>
Cc: Willem de Bruijn <willemb@google.com>
Tested-by: default avatarTom Herbert <tom@herbertland.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a4298e45
......@@ -98,11 +98,11 @@ static inline bool udp_get_no_check6_rx(struct sock *sk)
return udp_sk(sk)->no_check6_rx;
}
#define udp_portaddr_for_each_entry(__sk, node, list) \
hlist_nulls_for_each_entry(__sk, node, list, __sk_common.skc_portaddr_node)
#define udp_portaddr_for_each_entry(__sk, list) \
hlist_for_each_entry(__sk, list, __sk_common.skc_portaddr_node)
#define udp_portaddr_for_each_entry_rcu(__sk, node, list) \
hlist_nulls_for_each_entry_rcu(__sk, node, list, __sk_common.skc_portaddr_node)
#define udp_portaddr_for_each_entry_rcu(__sk, list) \
hlist_for_each_entry_rcu(__sk, list, __sk_common.skc_portaddr_node)
#define IS_UDPLITE(__sk) (udp_sk(__sk)->pcflag)
......
......@@ -178,7 +178,7 @@ struct sock_common {
int skc_bound_dev_if;
union {
struct hlist_node skc_bind_node;
struct hlist_nulls_node skc_portaddr_node;
struct hlist_node skc_portaddr_node;
};
struct proto *skc_prot;
possible_net_t skc_net;
......@@ -670,18 +670,18 @@ static inline void sk_add_bind_node(struct sock *sk,
hlist_for_each_entry(__sk, list, sk_bind_node)
/**
* sk_nulls_for_each_entry_offset - iterate over a list at a given struct offset
* sk_for_each_entry_offset_rcu - iterate over a list at a given struct offset
* @tpos: the type * to use as a loop cursor.
* @pos: the &struct hlist_node to use as a loop cursor.
* @head: the head for your list.
* @offset: offset of hlist_node within the struct.
*
*/
#define sk_nulls_for_each_entry_offset(tpos, pos, head, offset) \
for (pos = (head)->first; \
(!is_a_nulls(pos)) && \
#define sk_for_each_entry_offset_rcu(tpos, pos, head, offset) \
for (pos = rcu_dereference((head)->first); \
pos != NULL && \
({ tpos = (typeof(*tpos) *)((void *)pos - offset); 1;}); \
pos = pos->next)
pos = rcu_dereference(pos->next))
static inline struct user_namespace *sk_user_ns(struct sock *sk)
{
......
......@@ -59,7 +59,7 @@ struct udp_skb_cb {
* @lock: spinlock protecting changes to head/count
*/
struct udp_hslot {
struct hlist_nulls_head head;
struct hlist_head head;
int count;
spinlock_t lock;
} __attribute__((aligned(2 * sizeof(long))));
......
......@@ -143,10 +143,9 @@ static int udp_lib_lport_inuse(struct net *net, __u16 num,
unsigned int log)
{
struct sock *sk2;
struct hlist_nulls_node *node;
kuid_t uid = sock_i_uid(sk);
sk_nulls_for_each(sk2, node, &hslot->head) {
sk_for_each(sk2, &hslot->head) {
if (net_eq(sock_net(sk2), net) &&
sk2 != sk &&
(bitmap || udp_sk(sk2)->udp_port_hash == num) &&
......@@ -177,12 +176,11 @@ static int udp_lib_lport_inuse2(struct net *net, __u16 num,
bool match_wildcard))
{
struct sock *sk2;
struct hlist_nulls_node *node;
kuid_t uid = sock_i_uid(sk);
int res = 0;
spin_lock(&hslot2->lock);
udp_portaddr_for_each_entry(sk2, node, &hslot2->head) {
udp_portaddr_for_each_entry(sk2, &hslot2->head) {
if (net_eq(sock_net(sk2), net) &&
sk2 != sk &&
(udp_sk(sk2)->udp_port_hash == num) &&
......@@ -207,11 +205,10 @@ static int udp_reuseport_add_sock(struct sock *sk, struct udp_hslot *hslot,
bool match_wildcard))
{
struct net *net = sock_net(sk);
struct hlist_nulls_node *node;
kuid_t uid = sock_i_uid(sk);
struct sock *sk2;
sk_nulls_for_each(sk2, node, &hslot->head) {
sk_for_each(sk2, &hslot->head) {
if (net_eq(sock_net(sk2), net) &&
sk2 != sk &&
sk2->sk_family == sk->sk_family &&
......@@ -333,17 +330,18 @@ found:
goto fail_unlock;
}
sk_nulls_add_node_rcu(sk, &hslot->head);
sk_add_node_rcu(sk, &hslot->head);
hslot->count++;
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
spin_lock(&hslot2->lock);
hlist_nulls_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
hlist_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
&hslot2->head);
hslot2->count++;
spin_unlock(&hslot2->lock);
}
sock_set_flag(sk, SOCK_RCU_FREE);
error = 0;
fail_unlock:
spin_unlock_bh(&hslot->lock);
......@@ -497,37 +495,27 @@ static struct sock *udp4_lib_lookup2(struct net *net,
struct sk_buff *skb)
{
struct sock *sk, *result;
struct hlist_nulls_node *node;
int score, badness, matches = 0, reuseport = 0;
bool select_ok = true;
u32 hash = 0;
begin:
result = NULL;
badness = 0;
udp_portaddr_for_each_entry_rcu(sk, node, &hslot2->head) {
udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
score = compute_score2(sk, net, saddr, sport,
daddr, hnum, dif);
if (score > badness) {
result = sk;
badness = score;
reuseport = sk->sk_reuseport;
if (reuseport) {
hash = udp_ehashfn(net, daddr, hnum,
saddr, sport);
if (select_ok) {
struct sock *sk2;
sk2 = reuseport_select_sock(sk, hash, skb,
result = reuseport_select_sock(sk, hash, skb,
sizeof(struct udphdr));
if (sk2) {
result = sk2;
select_ok = false;
goto found;
}
}
if (result)
return result;
matches = 1;
}
badness = score;
result = sk;
} else if (score == badness && reuseport) {
matches++;
if (reciprocal_scale(hash, matches) == 0)
......@@ -535,23 +523,6 @@ begin:
hash = next_pseudo_random32(hash);
}
}
/*
* 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) != slot2)
goto begin;
if (result) {
found:
if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
result = NULL;
else if (unlikely(compute_score2(result, net, saddr, sport,
daddr, hnum, dif) < badness)) {
sock_put(result);
goto begin;
}
}
return result;
}
......@@ -563,15 +534,12 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
int dif, struct udp_table *udptable, struct sk_buff *skb)
{
struct sock *sk, *result;
struct hlist_nulls_node *node;
unsigned short hnum = ntohs(dport);
unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask);
struct udp_hslot *hslot2, *hslot = &udptable->hash[slot];
int score, badness, matches = 0, reuseport = 0;
bool select_ok = true;
u32 hash = 0;
rcu_read_lock();
if (hslot->count > 10) {
hash2 = udp4_portaddr_hash(net, daddr, hnum);
slot2 = hash2 & udptable->mask;
......@@ -593,35 +561,27 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
htonl(INADDR_ANY), hnum, dif,
hslot2, slot2, skb);
}
rcu_read_unlock();
return result;
}
begin:
result = NULL;
badness = 0;
sk_nulls_for_each_rcu(sk, node, &hslot->head) {
sk_for_each_rcu(sk, &hslot->head) {
score = compute_score(sk, net, saddr, hnum, sport,
daddr, dport, dif);
if (score > badness) {
result = sk;
badness = score;
reuseport = sk->sk_reuseport;
if (reuseport) {
hash = udp_ehashfn(net, daddr, hnum,
saddr, sport);
if (select_ok) {
struct sock *sk2;
sk2 = reuseport_select_sock(sk, hash, skb,
result = reuseport_select_sock(sk, hash, skb,
sizeof(struct udphdr));
if (sk2) {
result = sk2;
select_ok = false;
goto found;
}
}
if (result)
return result;
matches = 1;
}
result = sk;
badness = score;
} else if (score == badness && reuseport) {
matches++;
if (reciprocal_scale(hash, matches) == 0)
......@@ -629,25 +589,6 @@ begin:
hash = next_pseudo_random32(hash);
}
}
/*
* 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;
if (result) {
found:
if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
result = NULL;
else if (unlikely(compute_score(result, net, saddr, hnum, sport,
daddr, dport, dif) < badness)) {
sock_put(result);
goto begin;
}
}
rcu_read_unlock();
return result;
}
EXPORT_SYMBOL_GPL(__udp4_lib_lookup);
......@@ -663,13 +604,24 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
udptable, skb);
}
/* Must be called under rcu_read_lock().
* Does increment socket refcount.
*/
#if IS_ENABLED(CONFIG_NETFILTER_XT_MATCH_SOCKET) || \
IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TPROXY)
struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
__be32 daddr, __be16 dport, int dif)
{
return __udp4_lib_lookup(net, saddr, sport, daddr, dport, dif,
&udp_table, NULL);
struct sock *sk;
sk = __udp4_lib_lookup(net, saddr, sport, daddr, dport,
dif, &udp_table, NULL);
if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
sk = NULL;
return sk;
}
EXPORT_SYMBOL_GPL(udp4_lib_lookup);
#endif
static inline bool __udp_is_mcast_sock(struct net *net, struct sock *sk,
__be16 loc_port, __be32 loc_addr,
......@@ -771,7 +723,7 @@ void __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
sk->sk_err = err;
sk->sk_error_report(sk);
out:
sock_put(sk);
return;
}
void udp_err(struct sk_buff *skb, u32 info)
......@@ -1474,13 +1426,13 @@ void udp_lib_unhash(struct sock *sk)
spin_lock_bh(&hslot->lock);
if (rcu_access_pointer(sk->sk_reuseport_cb))
reuseport_detach_sock(sk);
if (sk_nulls_del_node_init_rcu(sk)) {
if (sk_del_node_init_rcu(sk)) {
hslot->count--;
inet_sk(sk)->inet_num = 0;
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
spin_lock(&hslot2->lock);
hlist_nulls_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
hlist_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
hslot2->count--;
spin_unlock(&hslot2->lock);
}
......@@ -1513,12 +1465,12 @@ void udp_lib_rehash(struct sock *sk, u16 newhash)
if (hslot2 != nhslot2) {
spin_lock(&hslot2->lock);
hlist_nulls_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
hlist_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
hslot2->count--;
spin_unlock(&hslot2->lock);
spin_lock(&nhslot2->lock);
hlist_nulls_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
hlist_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
&nhslot2->head);
nhslot2->count++;
spin_unlock(&nhslot2->lock);
......@@ -1697,35 +1649,6 @@ drop:
return -1;
}
static void flush_stack(struct sock **stack, unsigned int count,
struct sk_buff *skb, unsigned int final)
{
unsigned int i;
struct sk_buff *skb1 = NULL;
struct sock *sk;
for (i = 0; i < count; i++) {
sk = stack[i];
if (likely(!skb1))
skb1 = (i == final) ? skb : skb_clone(skb, GFP_ATOMIC);
if (!skb1) {
atomic_inc(&sk->sk_drops);
UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_RCVBUFERRORS,
IS_UDPLITE(sk));
UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS,
IS_UDPLITE(sk));
}
if (skb1 && udp_queue_rcv_skb(sk, skb1) <= 0)
skb1 = NULL;
sock_put(sk);
}
if (unlikely(skb1))
kfree_skb(skb1);
}
/* For TCP sockets, sk_rx_dst is protected by socket lock
* For UDP, we use xchg() to guard against concurrent changes.
*/
......@@ -1749,14 +1672,14 @@ static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
struct udp_table *udptable,
int proto)
{
struct sock *sk, *stack[256 / sizeof(struct sock *)];
struct hlist_nulls_node *node;
struct sock *sk, *first = NULL;
unsigned short hnum = ntohs(uh->dest);
struct udp_hslot *hslot = udp_hashslot(udptable, net, hnum);
int dif = skb->dev->ifindex;
unsigned int count = 0, offset = offsetof(typeof(*sk), sk_nulls_node);
unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10);
bool inner_flushed = false;
unsigned int offset = offsetof(typeof(*sk), sk_node);
int dif = skb->dev->ifindex;
struct hlist_node *node;
struct sk_buff *nskb;
if (use_hash2) {
hash2_any = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum) &
......@@ -1767,23 +1690,28 @@ start_lookup:
offset = offsetof(typeof(*sk), __sk_common.skc_portaddr_node);
}
spin_lock(&hslot->lock);
sk_nulls_for_each_entry_offset(sk, node, &hslot->head, offset) {
if (__udp_is_mcast_sock(net, sk,
uh->dest, daddr,
uh->source, saddr,
dif, hnum)) {
if (unlikely(count == ARRAY_SIZE(stack))) {
flush_stack(stack, count, skb, ~0);
inner_flushed = true;
count = 0;
}
stack[count++] = sk;
sock_hold(sk);
sk_for_each_entry_offset_rcu(sk, node, &hslot->head, offset) {
if (!__udp_is_mcast_sock(net, sk, uh->dest, daddr,
uh->source, saddr, dif, hnum))
continue;
if (!first) {
first = sk;
continue;
}
}
nskb = skb_clone(skb, GFP_ATOMIC);
spin_unlock(&hslot->lock);
if (unlikely(!nskb)) {
atomic_inc(&sk->sk_drops);
UDP_INC_STATS_BH(net, UDP_MIB_RCVBUFERRORS,
IS_UDPLITE(sk));
UDP_INC_STATS_BH(net, UDP_MIB_INERRORS,
IS_UDPLITE(sk));
continue;
}
if (udp_queue_rcv_skb(sk, nskb) > 0)
consume_skb(nskb);
}
/* Also lookup *:port if we are using hash2 and haven't done so yet. */
if (use_hash2 && hash2 != hash2_any) {
......@@ -1791,16 +1719,13 @@ start_lookup:
goto start_lookup;
}
/*
* do the slow work with no lock held
*/
if (count) {
flush_stack(stack, count, skb, count - 1);
if (first) {
if (udp_queue_rcv_skb(first, skb) > 0)
consume_skb(skb);
} else {
if (!inner_flushed)
UDP_INC_STATS_BH(net, UDP_MIB_IGNOREDMULTI,
proto == IPPROTO_UDPLITE);
consume_skb(skb);
kfree_skb(skb);
UDP_INC_STATS_BH(net, UDP_MIB_IGNOREDMULTI,
proto == IPPROTO_UDPLITE);
}
return 0;
}
......@@ -1897,7 +1822,6 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
inet_compute_pseudo);
ret = udp_queue_rcv_skb(sk, skb);
sock_put(sk);
/* a return value > 0 means to resubmit the input, but
* it wants the return to be -protocol, or 0
......@@ -1958,49 +1882,24 @@ static struct sock *__udp4_lib_mcast_demux_lookup(struct net *net,
int dif)
{
struct sock *sk, *result;
struct hlist_nulls_node *node;
unsigned short hnum = ntohs(loc_port);
unsigned int count, slot = udp_hashfn(net, hnum, udp_table.mask);
unsigned int slot = udp_hashfn(net, hnum, udp_table.mask);
struct udp_hslot *hslot = &udp_table.hash[slot];
/* Do not bother scanning a too big list */
if (hslot->count > 10)
return NULL;
rcu_read_lock();
begin:
count = 0;
result = NULL;
sk_nulls_for_each_rcu(sk, node, &hslot->head) {
if (__udp_is_mcast_sock(net, sk,
loc_port, loc_addr,
rmt_port, rmt_addr,
dif, hnum)) {
sk_for_each_rcu(sk, &hslot->head) {
if (__udp_is_mcast_sock(net, sk, loc_port, loc_addr,
rmt_port, rmt_addr, dif, hnum)) {
if (result)
return NULL;
result = sk;
++count;
}
}
/*
* 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;
if (result) {
if (count != 1 ||
unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
result = NULL;
else if (unlikely(!__udp_is_mcast_sock(net, result,
loc_port, loc_addr,
rmt_port, rmt_addr,
dif, hnum))) {
sock_put(result);
result = NULL;
}
}
rcu_read_unlock();
return result;
}
......@@ -2013,37 +1912,22 @@ static struct sock *__udp4_lib_demux_lookup(struct net *net,
__be16 rmt_port, __be32 rmt_addr,
int dif)
{
struct sock *sk, *result;
struct hlist_nulls_node *node;
unsigned short hnum = ntohs(loc_port);
unsigned int hash2 = udp4_portaddr_hash(net, loc_addr, hnum);
unsigned int slot2 = hash2 & udp_table.mask;
struct udp_hslot *hslot2 = &udp_table.hash2[slot2];
INET_ADDR_COOKIE(acookie, rmt_addr, loc_addr);
const __portpair ports = INET_COMBINED_PORTS(rmt_port, hnum);
struct sock *sk;
rcu_read_lock();
result = NULL;
udp_portaddr_for_each_entry_rcu(sk, node, &hslot2->head) {
if (INET_MATCH(sk, net, acookie,
rmt_addr, loc_addr, ports, dif))
result = sk;
udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
if (INET_MATCH(sk, net, acookie, rmt_addr,
loc_addr, ports, dif))
return sk;
/* Only check first socket in chain */
break;
}
if (result) {
if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
result = NULL;
else if (unlikely(!INET_MATCH(sk, net, acookie,
rmt_addr, loc_addr,
ports, dif))) {
sock_put(result);
result = NULL;
}
}
rcu_read_unlock();
return result;
return NULL;
}
void udp_v4_early_demux(struct sk_buff *skb)
......@@ -2051,7 +1935,7 @@ void udp_v4_early_demux(struct sk_buff *skb)
struct net *net = dev_net(skb->dev);
const struct iphdr *iph;
const struct udphdr *uh;
struct sock *sk;
struct sock *sk = NULL;
struct dst_entry *dst;
int dif = skb->dev->ifindex;
int ours;
......@@ -2083,11 +1967,9 @@ void udp_v4_early_demux(struct sk_buff *skb)
} else if (skb->pkt_type == PACKET_HOST) {
sk = __udp4_lib_demux_lookup(net, uh->dest, iph->daddr,
uh->source, iph->saddr, dif);
} else {
return;
}
if (!sk)
if (!sk || !atomic_inc_not_zero_hint(&sk->sk_refcnt, 2))
return;
skb->sk = sk;
......@@ -2387,14 +2269,13 @@ static struct sock *udp_get_first(struct seq_file *seq, int start)
for (state->bucket = start; state->bucket <= state->udp_table->mask;
++state->bucket) {
struct hlist_nulls_node *node;
struct udp_hslot *hslot = &state->udp_table->hash[state->bucket];
if (hlist_nulls_empty(&hslot->head))
if (hlist_empty(&hslot->head))
continue;
spin_lock_bh(&hslot->lock);
sk_nulls_for_each(sk, node, &hslot->head) {
sk_for_each(sk, &hslot->head) {
if (!net_eq(sock_net(sk), net))
continue;
if (sk->sk_family == state->family)
......@@ -2413,7 +2294,7 @@ static struct sock *udp_get_next(struct seq_file *seq, struct sock *sk)
struct net *net = seq_file_net(seq);
do {
sk = sk_nulls_next(sk);
sk = sk_next(sk);
} while (sk && (!net_eq(sock_net(sk), net) || sk->sk_family != state->family));
if (!sk) {
......@@ -2622,12 +2503,12 @@ void __init udp_table_init(struct udp_table *table, const char *name)
table->hash2 = table->hash + (table->mask + 1);
for (i = 0; i <= table->mask; i++) {
INIT_HLIST_NULLS_HEAD(&table->hash[i].head, i);
INIT_HLIST_HEAD(&table->hash[i].head);
table->hash[i].count = 0;
spin_lock_init(&table->hash[i].lock);
}
for (i = 0; i <= table->mask; i++) {
INIT_HLIST_NULLS_HEAD(&table->hash2[i].head, i);
INIT_HLIST_HEAD(&table->hash2[i].head);
table->hash2[i].count = 0;
spin_lock_init(&table->hash2[i].lock);
}
......
......@@ -36,10 +36,11 @@ static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,