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 <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/datagram.c b/net/core/datagram.c
index b71423d..9cbaba9 100644 (file)
--- 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
index c7338ec..2955b25 100644 (file)
--- 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
index b580853..f77e34c 100644 (file)
--- 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