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Date: Mon, 2 May 2022 11:23:42 -0700
From: Cong Wang <xiyou.wangcong@...il.com>
To: netdev@...r.kernel.org
Cc: bpf@...r.kernel.org, Cong Wang <cong.wang@...edance.com>,
Eric Dumazet <edumazet@...gle.com>,
John Fastabend <john.fastabend@...il.com>,
Daniel Borkmann <daniel@...earbox.net>,
Jakub Sitnicki <jakub@...udflare.com>
Subject: [Patch bpf-next v2 1/4] tcp: introduce tcp_read_skb()
From: Cong Wang <cong.wang@...edance.com>
This patch inroduces tcp_read_skb() based on tcp_read_sock(),
a preparation for the next patch which actually introduces
a new sock ops.
TCP is special here, because it has tcp_read_sock() which is
mainly used by splice(). tcp_read_sock() supports partial read
and arbitrary offset, neither of them is needed for sockmap.
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: John Fastabend <john.fastabend@...il.com>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Jakub Sitnicki <jakub@...udflare.com>
Signed-off-by: Cong Wang <cong.wang@...edance.com>
---
include/net/tcp.h | 2 ++
net/ipv4/tcp.c | 63 +++++++++++++++++++++++++++++++++++++++++------
2 files changed, 57 insertions(+), 8 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 94a52ad1101c..ab7516e5cc56 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -667,6 +667,8 @@ void tcp_get_info(struct sock *, struct tcp_info *);
/* Read 'sendfile()'-style from a TCP socket */
int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
sk_read_actor_t recv_actor);
+int tcp_read_skb(struct sock *sk, read_descriptor_t *desc,
+ sk_read_actor_t recv_actor);
void tcp_initialize_rcv_mss(struct sock *sk);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index db55af9eb37b..8d48126e3694 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1600,7 +1600,7 @@ static void tcp_eat_recv_skb(struct sock *sk, struct sk_buff *skb)
__kfree_skb(skb);
}
-static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
+static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off, bool unlink)
{
struct sk_buff *skb;
u32 offset;
@@ -1613,6 +1613,8 @@ static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
}
if (offset < skb->len || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) {
*off = offset;
+ if (unlink)
+ __skb_unlink(skb, &sk->sk_receive_queue);
return skb;
}
/* This looks weird, but this can happen if TCP collapsing
@@ -1646,7 +1648,7 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
if (sk->sk_state == TCP_LISTEN)
return -ENOTCONN;
- while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
+ while ((skb = tcp_recv_skb(sk, seq, &offset, false)) != NULL) {
if (offset < skb->len) {
int used;
size_t len;
@@ -1677,7 +1679,7 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
* getting here: tcp_collapse might have deleted it
* while aggregating skbs from the socket queue.
*/
- skb = tcp_recv_skb(sk, seq - 1, &offset);
+ skb = tcp_recv_skb(sk, seq - 1, &offset, false);
if (!skb)
break;
/* TCP coalescing might have appended data to the skb.
@@ -1702,13 +1704,58 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
/* Clean up data we have read: This will do ACK frames. */
if (copied > 0) {
- tcp_recv_skb(sk, seq, &offset);
+ tcp_recv_skb(sk, seq, &offset, false);
tcp_cleanup_rbuf(sk, copied);
}
return copied;
}
EXPORT_SYMBOL(tcp_read_sock);
+int tcp_read_skb(struct sock *sk, read_descriptor_t *desc,
+ sk_read_actor_t recv_actor)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ u32 seq = tp->copied_seq;
+ struct sk_buff *skb;
+ int copied = 0;
+ u32 offset;
+
+ if (sk->sk_state == TCP_LISTEN)
+ return -ENOTCONN;
+
+ while ((skb = tcp_recv_skb(sk, seq, &offset, true)) != NULL) {
+ int used = recv_actor(desc, skb, 0, skb->len);
+
+ if (used <= 0) {
+ if (!copied)
+ copied = used;
+ break;
+ }
+ seq += used;
+ copied += used;
+
+ if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
+ kfree_skb(skb);
+ ++seq;
+ break;
+ }
+ kfree_skb(skb);
+ if (!desc->count)
+ break;
+ WRITE_ONCE(tp->copied_seq, seq);
+ }
+ WRITE_ONCE(tp->copied_seq, seq);
+
+ tcp_rcv_space_adjust(sk);
+
+ /* Clean up data we have read: This will do ACK frames. */
+ if (copied > 0)
+ tcp_cleanup_rbuf(sk, copied);
+
+ return copied;
+}
+EXPORT_SYMBOL(tcp_read_skb);
+
int tcp_peek_len(struct socket *sock)
{
return tcp_inq(sock->sk);
@@ -1890,7 +1937,7 @@ static int receive_fallback_to_copy(struct sock *sk,
struct sk_buff *skb;
u32 offset;
- skb = tcp_recv_skb(sk, tcp_sk(sk)->copied_seq, &offset);
+ skb = tcp_recv_skb(sk, tcp_sk(sk)->copied_seq, &offset, false);
if (skb)
tcp_zerocopy_set_hint_for_skb(sk, zc, skb, offset);
}
@@ -1937,7 +1984,7 @@ static int tcp_zc_handle_leftover(struct tcp_zerocopy_receive *zc,
if (skb) {
offset = *seq - TCP_SKB_CB(skb)->seq;
} else {
- skb = tcp_recv_skb(sk, *seq, &offset);
+ skb = tcp_recv_skb(sk, *seq, &offset, false);
if (TCP_SKB_CB(skb)->has_rxtstamp) {
tcp_update_recv_tstamps(skb, tss);
zc->msg_flags |= TCP_CMSG_TS;
@@ -2130,7 +2177,7 @@ static int tcp_zerocopy_receive(struct sock *sk,
skb = skb->next;
offset = seq - TCP_SKB_CB(skb)->seq;
} else {
- skb = tcp_recv_skb(sk, seq, &offset);
+ skb = tcp_recv_skb(sk, seq, &offset, false);
}
if (TCP_SKB_CB(skb)->has_rxtstamp) {
@@ -2186,7 +2233,7 @@ static int tcp_zerocopy_receive(struct sock *sk,
tcp_rcv_space_adjust(sk);
/* Clean up data we have read: This will do ACK frames. */
- tcp_recv_skb(sk, seq, &offset);
+ tcp_recv_skb(sk, seq, &offset, false);
tcp_cleanup_rbuf(sk, length + copylen);
ret = 0;
if (length == zc->length)
--
2.32.0
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