udp: add low latency socket poll support

Add upport for busy-polling on UDP sockets. In __udp[46]_lib_rcv add a call to sk_mark_ll() to copy the napi_id from the skb into the sk. This is done at the earliest possible moment, right after we identify which socket this skb is for. In __skb_recv_datagram When there is no data and the user tries to read we busy poll. Signed-off-by: Alexander Duyck <[email protected]> Signed-off-by: Jesse Brandeburg <[email protected]> Signed-off-by: Eliezer Tamir <[email protected]> Acked-by: Eric Dumazet <[email protected]> Tested-by: Willem de Bruijn <[email protected]> Signed-off-by: David S. Miller <[email protected]>
josf · Jun 11, 2013 · a5b5047 · a5b5047
1 parent 0602129
commit a5b5047
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Showing 3 changed files with 14 additions and 2 deletions.
diff --git a/net/core/datagram.c b/net/core/datagram.c
@@ -56,6 +56,7 @@
 #include <net/sock.h>
 #include <net/tcp_states.h>
 #include <trace/events/skb.h>
+#include <net/ll_poll.h>
 
 /*
  *	Is a socket 'connection oriented' ?
@@ -207,6 +208,9 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
 		}
 		spin_unlock_irqrestore(&queue->lock, cpu_flags);
 
+		if (sk_valid_ll(sk) && sk_poll_ll(sk, flags & MSG_DONTWAIT))
+			continue;
+
 		/* User doesn't want to wait */
 		error = -EAGAIN;
 		if (!timeo)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
@@ -109,6 +109,7 @@
 #include <trace/events/udp.h>
 #include <linux/static_key.h>
 #include <trace/events/skb.h>
+#include <net/ll_poll.h>
 #include "udp_impl.h"
 
 struct udp_table udp_table __read_mostly;
@@ -1709,7 +1710,10 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 	sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
 
 	if (sk != NULL) {
-		int ret = udp_queue_rcv_skb(sk, skb);
+		int ret;
+
+		sk_mark_ll(sk, skb);
+		ret = udp_queue_rcv_skb(sk, skb);
 		sock_put(sk);
 
 		/* a return value > 0 means to resubmit the input, but

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
@@ -46,6 +46,7 @@
 #include <net/ip6_checksum.h>
 #include <net/xfrm.h>
 #include <net/inet6_hashtables.h>
+#include <net/ll_poll.h>
 
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
@@ -841,7 +842,10 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 	 */
 	sk = __udp6_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
 	if (sk != NULL) {
-		int ret = udpv6_queue_rcv_skb(sk, skb);
+		int ret;
+
+		sk_mark_ll(sk, skb);
+		ret = udpv6_queue_rcv_skb(sk, skb);
 		sock_put(sk);
 
 		/* a return value > 0 means to resubmit the input, but