udp: use it's own memory accounting schema

Completely avoid default sock memory accounting and replace it
with udp-specific accounting.

Since the new memory accounting model encapsulates completely
the required locking, remove the socket lock on both enqueue and
dequeue, and avoid using the backlog on enqueue.

Be sure to clean-up rx queue memory on socket destruction, using
udp its own sk_destruct.

Tested using pktgen with random src port, 64 bytes packet,
wire-speed on a 10G link as sender and udp_sink as the receiver,
using an l4 tuple rxhash to stress the contention, and one or more
udp_sink instances with reuseport.

nr readers      Kpps (vanilla)  Kpps (patched)
1               170             440
3               1250            2150
6               3000            3650
9               4200            4450
12              5700            6250

v4 -> v5:
  - avoid unneeded test in first_packet_length

v3 -> v4:
  - remove useless sk_rcvqueues_full() call

v2 -> v3:
  - do not set the now unsed backlog_rcv callback

v1 -> v2:
  - add memory pressure support
  - fixed dropwatch accounting for ipv6

Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 17 insertions, 5 deletions

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 57625f6..e2a55dc 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -39,6 +39,7 @@
 #include <net/checksum.h>
 #include <net/ip.h>
 #include <net/ipv6.h>
+#include <net/udp.h>
 #include <net/tcp.h>
 #include <net/tcp_states.h>
 #include <asm/uaccess.h>
@@ -129,6 +130,18 @@ static void svc_release_skb(struct svc_rqst *rqstp)
 	}
 }
 
+static void svc_release_udp_skb(struct svc_rqst *rqstp)
+{
+	struct sk_buff *skb = rqstp->rq_xprt_ctxt;
+
+	if (skb) {
+		rqstp->rq_xprt_ctxt = NULL;
+
+		dprintk("svc: service %p, releasing skb %p\n", rqstp, skb);
+		consume_skb(skb);
+	}
+}
+
 union svc_pktinfo_u {
 	struct in_pktinfo pkti;
 	struct in6_pktinfo pkti6;
@@ -575,7 +588,7 @@ static int svc_udp_recvfrom(struct svc_rqst *rqstp)
 			goto out_free;
 		}
 		local_bh_enable();
-		skb_free_datagram_locked(svsk->sk_sk, skb);
+		consume_skb(skb);
 	} else {
 		/* we can use it in-place */
 		rqstp->rq_arg.head[0].iov_base = skb->data;
@@ -602,8 +615,7 @@ static int svc_udp_recvfrom(struct svc_rqst *rqstp)
 
 	return len;
 out_free:
-	trace_kfree_skb(skb, svc_udp_recvfrom);
-	skb_free_datagram_locked(svsk->sk_sk, skb);
+	kfree_skb(skb);
 	return 0;
 }
 
@@ -660,7 +672,7 @@ static struct svc_xprt_ops svc_udp_ops = {
 	.xpo_create = svc_udp_create,
 	.xpo_recvfrom = svc_udp_recvfrom,
 	.xpo_sendto = svc_udp_sendto,
-	.xpo_release_rqst = svc_release_skb,
+	.xpo_release_rqst = svc_release_udp_skb,
 	.xpo_detach = svc_sock_detach,
 	.xpo_free = svc_sock_free,
 	.xpo_prep_reply_hdr = svc_udp_prep_reply_hdr,
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 0137af1..1758665 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1083,7 +1083,7 @@ static void xs_udp_data_receive(struct sock_xprt *transport)
 		skb = skb_recv_datagram(sk, 0, 1, &err);
 		if (skb != NULL) {
 			xs_udp_data_read_skb(&transport->xprt, sk, skb);
-			skb_free_datagram_locked(sk, skb);
+			consume_skb(skb);
 			continue;
 		}
 		if (!test_and_clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))