net: speedup udp receive path
Since commit 95766fff ([UDP]: Add memory accounting.),
each received packet needs one extra sock_lock()/sock_release() pair.
This added latency because of possible backlog handling. Then later,
ticket spinlocks added yet another latency source in case of DDOS.
This patch introduces lock_sock_bh() and unlock_sock_bh()
synchronization primitives, avoiding one atomic operation and backlog
processing.
skb_free_datagram_locked() uses them instead of full blown
lock_sock()/release_sock(). skb is orphaned inside locked section for
proper socket memory reclaim, and finally freed outside of it.
UDP receive path now take the socket spinlock only once.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sock.h b/include/net/sock.h
index cf12b1e..d361c77 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1021,6 +1021,16 @@
SINGLE_DEPTH_NESTING)
#define bh_unlock_sock(__sk) spin_unlock(&((__sk)->sk_lock.slock))
+static inline void lock_sock_bh(struct sock *sk)
+{
+ spin_lock_bh(&sk->sk_lock.slock);
+}
+
+static inline void unlock_sock_bh(struct sock *sk)
+{
+ spin_unlock_bh(&sk->sk_lock.slock);
+}
+
extern struct sock *sk_alloc(struct net *net, int family,
gfp_t priority,
struct proto *prot);
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 5574a5d..95b851f 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -229,9 +229,13 @@
void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb)
{
- lock_sock(sk);
- skb_free_datagram(sk, skb);
- release_sock(sk);
+ lock_sock_bh(sk);
+ skb_orphan(skb);
+ sk_mem_reclaim_partial(sk);
+ unlock_sock_bh(sk);
+
+ /* skb is now orphaned, might be freed outside of locked section */
+ consume_skb(skb);
}
EXPORT_SYMBOL(skb_free_datagram_locked);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 63eb56b..1f86965 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1062,10 +1062,10 @@
spin_unlock_bh(&rcvq->lock);
if (!skb_queue_empty(&list_kill)) {
- lock_sock(sk);
+ lock_sock_bh(sk);
__skb_queue_purge(&list_kill);
sk_mem_reclaim_partial(sk);
- release_sock(sk);
+ unlock_sock_bh(sk);
}
return res;
}
@@ -1196,10 +1196,10 @@
return err;
csum_copy_err:
- lock_sock(sk);
+ lock_sock_bh(sk);
if (!skb_kill_datagram(sk, skb, flags))
UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
- release_sock(sk);
+ unlock_sock_bh(sk);
if (noblock)
return -EAGAIN;
@@ -1624,9 +1624,9 @@
void udp_destroy_sock(struct sock *sk)
{
- lock_sock(sk);
+ lock_sock_bh(sk);
udp_flush_pending_frames(sk);
- release_sock(sk);
+ unlock_sock_bh(sk);
}
/*
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 3ead20a..91c60f0 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -424,7 +424,7 @@
return err;
csum_copy_err:
- lock_sock(sk);
+ lock_sock_bh(sk);
if (!skb_kill_datagram(sk, skb, flags)) {
if (is_udp4)
UDP_INC_STATS_USER(sock_net(sk),
@@ -433,7 +433,7 @@
UDP6_INC_STATS_USER(sock_net(sk),
UDP_MIB_INERRORS, is_udplite);
}
- release_sock(sk);
+ unlock_sock_bh(sk);
if (flags & MSG_DONTWAIT)
return -EAGAIN;