Thread (27 messages) 27 messages, 6 authors, 2013-05-30
STALE4748d REVIEWED: 1 (1M)

[PATCH v6 net-next 3/5] tcp: add TCP support for low latency receive poll.

From: Eliezer Tamir <hidden>
Date: 2013-05-29 06:40:22
Also in: lkml
Subsystem: networking [general], networking [tcp], the rest · Maintainers: "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds

Adds busy-poll support for TCP.
Copy the napi_id from an incomming skb to the sk in tcp_v[46]_rcv().
when there is no data in the socket we busy-poll in tcp_recvmsg().
This is a good example of how to add busy-poll support to new protocols.

Signed-off-by: Alexander Duyck <redacted>
Signed-off-by: Jesse Brandeburg <redacted>
Tested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eliezer Tamir <redacted>
---

 net/ipv4/tcp.c      |    5 +++++
 net/ipv4/tcp_ipv4.c |    2 ++
 net/ipv6/tcp_ipv6.c |    2 ++
 3 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index ba4186e..becd105 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -279,6 +279,7 @@
 
 #include <asm/uaccess.h>
 #include <asm/ioctls.h>
+#include <net/ll_poll.h>
 
 int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
 
@@ -1551,6 +1552,10 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	struct sk_buff *skb;
 	u32 urg_hole = 0;
 
+	if (sk_valid_ll(sk) && skb_queue_empty(&sk->sk_receive_queue)
+	    && (sk->sk_state == TCP_ESTABLISHED))
+		sk_poll_ll(sk, nonblock);
+
 	lock_sock(sk);
 
 	err = -ENOTCONN;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d20ede0..35fd8bc 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -75,6 +75,7 @@
 #include <net/netdma.h>
 #include <net/secure_seq.h>
 #include <net/tcp_memcontrol.h>
+#include <net/ll_poll.h>
 
 #include <linux/inet.h>
 #include <linux/ipv6.h>
@@ -2011,6 +2012,7 @@ process:
 	if (sk_filter(sk, skb))
 		goto discard_and_relse;
 
+	sk_mark_ll(sk, skb);
 	skb->dev = NULL;
 
 	bh_lock_sock_nested(sk);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 0a17ed9..5cffa5c 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -63,6 +63,7 @@
 #include <net/inet_common.h>
 #include <net/secure_seq.h>
 #include <net/tcp_memcontrol.h>
+#include <net/ll_poll.h>
 
 #include <asm/uaccess.h>
 
@@ -1498,6 +1499,7 @@ process:
 	if (sk_filter(sk, skb))
 		goto discard_and_relse;
 
+	sk_mark_ll(sk, skb);
 	skb->dev = NULL;
 
 	bh_lock_sock_nested(sk);


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