2018-07-11 15:46:52

by Yafang Shao

Subject: [PATCH net-next 1/2] tcp: remove redundant rcv_nxt update

tcp_rcv_nxt_update() is already executed in tcp_data_queue().
This line is redundant.

See bellow,
tcp_queue_rcv
tcp_rcv_nxt_update(tcp_sk(sk), TCP_SKB_CB(skb)->end_seq);
tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq); <<<< redundant

Signed-off-by: Yafang Shao <[email protected]>
---
net/ipv4/tcp_input.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 814ea43..3a54faf 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4695,7 +4695,6 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
}

eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);
- tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);
if (skb->len)
tcp_event_data_recv(sk, skb);
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
--
1.8.3.1

2018-07-11 15:35:33

by Yafang Shao

Subject: [PATCH net-next 2/2] tcp: refactor tcp_queue_rcv

There're are some code similar to tcp_queue_rcv() in tcp_ofo_queue(),
so refactor tcp_queue_rcv() to make it be used in tcp_ofo_queue().

After this change, skb->sk is set when skb is moved from ofo queue into
receive queue instead of when queued into ofo queue.

Signed-off-by: Yafang Shao <[email protected]>
---
net/ipv4/tcp_input.c | 52 ++++++++++++++++++++++------------------------------
1 file changed, 22 insertions(+), 30 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 3a54faf..92d4499 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4367,6 +4367,21 @@ static void tcp_drop(struct sock *sk, struct sk_buff *skb)
__kfree_skb(skb);
}

+static int __must_check
+tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, bool *fragstolen)
+{
+ int eaten;
+ struct sk_buff *tail = skb_peek_tail(&sk->sk_receive_queue);
+
+ eaten = tail && tcp_try_coalesce(sk, tail, skb, fragstolen);
+ tcp_rcv_nxt_update(tcp_sk(sk), TCP_SKB_CB(skb)->end_seq);
+ if (!eaten) {
+ __skb_queue_tail(&sk->sk_receive_queue, skb);
+ skb_set_owner_r(skb, sk);
+ }
+ return eaten;
+}
+
/* This one checks to see if we can put data from the
* out_of_order queue into the receive_queue.
*/
@@ -4375,7 +4390,7 @@ static void tcp_ofo_queue(struct sock *sk)
struct tcp_sock *tp = tcp_sk(sk);
__u32 dsack_high = tp->rcv_nxt;
bool fin, fragstolen, eaten;
- struct sk_buff *skb, *tail;
+ struct sk_buff *skb;
struct rb_node *p;

p = rb_first(&tp->out_of_order_queue);
@@ -4402,13 +4417,9 @@ static void tcp_ofo_queue(struct sock *sk)
tp->rcv_nxt, TCP_SKB_CB(skb)->seq,
TCP_SKB_CB(skb)->end_seq);

- tail = skb_peek_tail(&sk->sk_receive_queue);
- eaten = tail && tcp_try_coalesce(sk, tail, skb, &fragstolen);
- tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);
+ eaten = tcp_queue_rcv(sk, skb, &fragstolen);
fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
- if (!eaten)
- __skb_queue_tail(&sk->sk_receive_queue, skb);
- else
+ if (eaten)
kfree_skb_partial(skb, fragstolen);

if (unlikely(fin)) {
@@ -4573,28 +4584,9 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
if (skb) {
tcp_grow_window(sk, skb);
skb_condense(skb);
- skb_set_owner_r(skb, sk);
}
}

-static int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int hdrlen,
- bool *fragstolen)
-{
- int eaten;
- struct sk_buff *tail = skb_peek_tail(&sk->sk_receive_queue);
-
- __skb_pull(skb, hdrlen);
- eaten = (tail &&
- tcp_try_coalesce(sk, tail,
- skb, fragstolen)) ? 1 : 0;
- tcp_rcv_nxt_update(tcp_sk(sk), TCP_SKB_CB(skb)->end_seq);
- if (!eaten) {
- __skb_queue_tail(&sk->sk_receive_queue, skb);
- skb_set_owner_r(skb, sk);
- }
- return eaten;
-}
-
int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size)
{
struct sk_buff *skb;
@@ -4634,7 +4626,7 @@ int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size)
TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + size;
TCP_SKB_CB(skb)->ack_seq = tcp_sk(sk)->snd_una - 1;

- if (tcp_queue_rcv(sk, skb, 0, &fragstolen)) {
+ if (tcp_queue_rcv(sk, skb, &fragstolen)) {
WARN_ON_ONCE(fragstolen); /* should not happen */
__kfree_skb(skb);
}
@@ -4694,7 +4686,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
goto drop;
}

- eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);
+ eaten = tcp_queue_rcv(sk, skb, &fragstolen);
if (skb->len)
tcp_event_data_recv(sk, skb);
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
@@ -5529,8 +5521,8 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPHPHITS);

/* Bulk data transfer: receiver */
- eaten = tcp_queue_rcv(sk, skb, tcp_header_len,
- &fragstolen);
+ __skb_pull(skb, tcp_header_len);
+ eaten = tcp_queue_rcv(sk, skb, &fragstolen);

tcp_event_data_recv(sk, skb);

--
1.8.3.1

2018-07-11 17:25:21

by Eric Dumazet

Subject: Re: [PATCH net-next 2/2] tcp: refactor tcp_queue_rcv

Hi Yafang
On Wed, Jul 11, 2018 at 6:17 AM Yafang Shao <[email protected]> wrote:
>
> There're are some code similar to tcp_queue_rcv() in tcp_ofo_queue(),
> so refactor tcp_queue_rcv() to make it be used in tcp_ofo_queue().
>
> After this change, skb->sk is set when skb is moved from ofo queue into
> receive queue instead of when queued into ofo queue.

Why would you do that ???

I urge you to test this on hosts connected to the wild Internet :/

2018-07-11 23:44:16

by Eric Dumazet

Subject: Re: [PATCH net-next 1/2] tcp: remove redundant rcv_nxt update

On 07/11/2018 06:16 AM, Yafang Shao wrote:
> tcp_rcv_nxt_update() is already executed in tcp_data_queue().
> This line is redundant.
>
> See bellow,
> tcp_queue_rcv
> tcp_rcv_nxt_update(tcp_sk(sk), TCP_SKB_CB(skb)->end_seq);
> tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq); <<<< redundant
>
> Signed-off-by: Yafang Shao <[email protected]>
> ---

This patch is fine (but not the following)

Signed-off-by: Eric Dumazet <[email protected]>

Thanks.