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Message-Id: <1455236930-17919-3-git-send-email-edumazet@google.com>
Date: Thu, 11 Feb 2016 16:28:50 -0800
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Eric Dumazet <edumazet@...gle.com>,
Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH v2 net-next 2/2] tcp/dccp: better use of ephemeral ports in bind()
Implement strategy used in __inet_hash_connect() in opposite way :
Try to find a candidate using odd ports, then fallback to even ports.
We no longer disable BH for whole traversal, but one bucket at a time.
We also use cond_resched() to yield cpu to other tasks if needed.
I removed one indentation level and tried to mirror the loop we have
in __inet_hash_connect() and variable names to ease code maintenance.
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/ipv4/inet_connection_sock.c | 240 +++++++++++++++++++---------------------
1 file changed, 114 insertions(+), 126 deletions(-)
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index c16a2e6273d9..3d28c6d5c3c3 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -91,165 +91,153 @@ EXPORT_SYMBOL_GPL(inet_csk_bind_conflict);
/* Obtain a reference to a local port for the given sock,
* if snum is zero it means select any available local port.
+ * We try to allocate an odd port (and leave even ports for connect())
*/
int inet_csk_get_port(struct sock *sk, unsigned short snum)
{
- struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
+ bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
+ struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
+ int ret = 1, attempts = 5, port = snum;
+ int smallest_size = -1, smallest_port;
struct inet_bind_hashbucket *head;
- struct inet_bind_bucket *tb;
- int ret, attempts = 5;
struct net *net = sock_net(sk);
- int smallest_size = -1, smallest_rover;
+ int i, low, high, attempt_half;
+ struct inet_bind_bucket *tb;
kuid_t uid = sock_i_uid(sk);
- int attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
+ u32 remaining, offset;
- local_bh_disable();
- if (!snum) {
- int remaining, rover, low, high;
+ if (port) {
+have_port:
+ head = &hinfo->bhash[inet_bhashfn(net, port,
+ hinfo->bhash_size)];
+ spin_lock_bh(&head->lock);
+ inet_bind_bucket_for_each(tb, &head->chain)
+ if (net_eq(ib_net(tb), net) && tb->port == port)
+ goto tb_found;
+ goto tb_not_found;
+ }
again:
- inet_get_local_port_range(net, &low, &high);
- if (attempt_half) {
- int half = low + ((high - low) >> 1);
-
- if (attempt_half == 1)
- high = half;
- else
- low = half;
- }
- remaining = (high - low) + 1;
- smallest_rover = rover = prandom_u32() % remaining + low;
-
- smallest_size = -1;
- do {
- if (inet_is_local_reserved_port(net, rover))
- goto next_nolock;
- head = &hashinfo->bhash[inet_bhashfn(net, rover,
- hashinfo->bhash_size)];
- spin_lock(&head->lock);
- inet_bind_bucket_for_each(tb, &head->chain)
- if (net_eq(ib_net(tb), net) && tb->port == rover) {
- if (((tb->fastreuse > 0 &&
- sk->sk_reuse &&
- sk->sk_state != TCP_LISTEN) ||
- (tb->fastreuseport > 0 &&
- sk->sk_reuseport &&
- !rcu_access_pointer(sk->sk_reuseport_cb) &&
- uid_eq(tb->fastuid, uid))) &&
- (tb->num_owners < smallest_size || smallest_size == -1)) {
- smallest_size = tb->num_owners;
- smallest_rover = rover;
- }
- if (!inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, false)) {
- snum = rover;
- goto tb_found;
- }
- goto next;
+ attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
+other_half_scan:
+ inet_get_local_port_range(net, &low, &high);
+ high++; /* [32768, 60999] -> [32768, 61000[ */
+ if (high - low < 4)
+ attempt_half = 0;
+ if (attempt_half) {
+ int half = low + (((high - low) >> 2) << 1);
+
+ if (attempt_half == 1)
+ high = half;
+ else
+ low = half;
+ }
+ remaining = high - low;
+ if (likely(remaining > 1))
+ remaining &= ~1U;
+
+ offset = prandom_u32() % remaining;
+ /* __inet_hash_connect() favors ports having @low parity
+ * We do the opposite to not pollute connect() users.
+ */
+ offset |= 1U;
+ smallest_size = -1;
+ smallest_port = low; /* avoid compiler warning */
+
+other_parity_scan:
+ port = low + offset;
+ for (i = 0; i < remaining; i += 2, port += 2) {
+ if (unlikely(port >= high))
+ port -= remaining;
+ if (inet_is_local_reserved_port(net, port))
+ continue;
+ head = &hinfo->bhash[inet_bhashfn(net, port,
+ hinfo->bhash_size)];
+ spin_lock_bh(&head->lock);
+ inet_bind_bucket_for_each(tb, &head->chain)
+ if (net_eq(ib_net(tb), net) && tb->port == port) {
+ if (((tb->fastreuse > 0 && reuse) ||
+ (tb->fastreuseport > 0 &&
+ sk->sk_reuseport &&
+ !rcu_access_pointer(sk->sk_reuseport_cb) &&
+ uid_eq(tb->fastuid, uid))) &&
+ (tb->num_owners < smallest_size || smallest_size == -1)) {
+ smallest_size = tb->num_owners;
+ smallest_port = port;
}
- break;
- next:
- spin_unlock(&head->lock);
- next_nolock:
- if (++rover > high)
- rover = low;
- } while (--remaining > 0);
-
- /* Exhausted local port range during search? It is not
- * possible for us to be holding one of the bind hash
- * locks if this test triggers, because if 'remaining'
- * drops to zero, we broke out of the do/while loop at
- * the top level, not from the 'break;' statement.
- */
- ret = 1;
- if (remaining <= 0) {
- if (smallest_size != -1) {
- snum = smallest_rover;
- goto have_snum;
+ if (!inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, false))
+ goto tb_found;
+ goto next_port;
}
- if (attempt_half == 1) {
- /* OK we now try the upper half of the range */
- attempt_half = 2;
- goto again;
- }
- goto fail;
- }
- /* OK, here is the one we will use. HEAD is
- * non-NULL and we hold it's mutex.
- */
- snum = rover;
- } else {
-have_snum:
- head = &hashinfo->bhash[inet_bhashfn(net, snum,
- hashinfo->bhash_size)];
- spin_lock(&head->lock);
- inet_bind_bucket_for_each(tb, &head->chain)
- if (net_eq(ib_net(tb), net) && tb->port == snum)
- goto tb_found;
+ goto tb_not_found;
+next_port:
+ spin_unlock_bh(&head->lock);
+ cond_resched();
}
- tb = NULL;
- goto tb_not_found;
+
+ if (smallest_size != -1) {
+ port = smallest_port;
+ goto have_port;
+ }
+ offset--;
+ if (!(offset & 1))
+ goto other_parity_scan;
+
+ if (attempt_half == 1) {
+ /* OK we now try the upper half of the range */
+ attempt_half = 2;
+ goto other_half_scan;
+ }
+ return ret;
+
+tb_not_found:
+ tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
+ net, head, port);
+ if (!tb)
+ goto fail_unlock;
tb_found:
if (!hlist_empty(&tb->owners)) {
if (sk->sk_reuse == SK_FORCE_REUSE)
goto success;
- if (((tb->fastreuse > 0 &&
- sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
+ if (((tb->fastreuse > 0 && reuse) ||
(tb->fastreuseport > 0 &&
- sk->sk_reuseport &&
- !rcu_access_pointer(sk->sk_reuseport_cb) &&
- uid_eq(tb->fastuid, uid))) && smallest_size == -1) {
+ sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
+ smallest_size == -1)
goto success;
- } else {
- ret = 1;
- if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, true)) {
- if (((sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
- (tb->fastreuseport > 0 &&
- sk->sk_reuseport &&
- !rcu_access_pointer(sk->sk_reuseport_cb) &&
- uid_eq(tb->fastuid, uid))) &&
- smallest_size != -1 && --attempts >= 0) {
- spin_unlock(&head->lock);
- goto again;
- }
-
- goto fail_unlock;
+ if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, true)) {
+ if ((reuse ||
+ (tb->fastreuseport > 0 &&
+ sk->sk_reuseport &&
+ !rcu_access_pointer(sk->sk_reuseport_cb) &&
+ uid_eq(tb->fastuid, uid))) &&
+ smallest_size != -1 && --attempts >= 0) {
+ spin_unlock_bh(&head->lock);
+ goto again;
}
+ goto fail_unlock;
}
- }
-tb_not_found:
- ret = 1;
- if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep,
- net, head, snum)) == NULL)
- goto fail_unlock;
- if (hlist_empty(&tb->owners)) {
- if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
- tb->fastreuse = 1;
- else
+ if (!reuse)
tb->fastreuse = 0;
+ if (!sk->sk_reuseport || !uid_eq(tb->fastuid, uid))
+ tb->fastreuseport = 0;
+ } else {
+ tb->fastreuse = reuse;
if (sk->sk_reuseport) {
tb->fastreuseport = 1;
tb->fastuid = uid;
- } else
- tb->fastreuseport = 0;
- } else {
- if (tb->fastreuse &&
- (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
- tb->fastreuse = 0;
- if (tb->fastreuseport &&
- (!sk->sk_reuseport || !uid_eq(tb->fastuid, uid)))
+ } else {
tb->fastreuseport = 0;
+ }
}
success:
if (!inet_csk(sk)->icsk_bind_hash)
- inet_bind_hash(sk, tb, snum);
+ inet_bind_hash(sk, tb, port);
WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
ret = 0;
fail_unlock:
- spin_unlock(&head->lock);
-fail:
- local_bh_enable();
+ spin_unlock_bh(&head->lock);
return ret;
}
EXPORT_SYMBOL_GPL(inet_csk_get_port);
--
2.7.0.rc3.207.g0ac5344
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