Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'tcp-__tcp_close-changes'
Eric Dumazet says:
====================
tcp: __tcp_close() changes
First patch fixes a rare bug.
Second patch adds a corresponding packetdrill test.
Third patch is a small optimization.
====================
Link: https://patch.msgid.link/20250903084720.1168904-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+39
-6
+7
-6
net/ipv4/tcp.c
+7
-6
net/ipv4/tcp.c
···
3099
3099
3100
3100
void __tcp_close(struct sock *sk, long timeout)
3101
3101
{
3102
+
bool data_was_unread = false;
3102
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struct sk_buff *skb;
3103
-
int data_was_unread = 0;
3104
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int state;
3105
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3106
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WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
···
3118
3118
* descriptor close, not protocol-sourced closes, because the
3119
3119
* reader process may not have drained the data yet!
3120
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*/
3121
-
while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
3122
-
u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq;
3121
+
while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
3122
+
u32 end_seq = TCP_SKB_CB(skb)->end_seq;
3123
3123
3124
3124
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
3125
-
len--;
3126
-
data_was_unread += len;
3127
-
__kfree_skb(skb);
3125
+
end_seq--;
3126
+
if (after(end_seq, tcp_sk(sk)->copied_seq))
3127
+
data_was_unread = true;
3128
+
tcp_eat_recv_skb(sk, skb);
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}
3129
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/* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
+32
tools/testing/selftests/net/packetdrill/tcp_close_no_rst.pkt
+32
tools/testing/selftests/net/packetdrill/tcp_close_no_rst.pkt
···
1
+
// SPDX-License-Identifier: GPL-2.0
2
+
3
+
--mss=1000
4
+
5
+
`./defaults.sh`
6
+
7
+
// Initialize connection
8
+
0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
9
+
+0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
10
+
+0 bind(3, ..., ...) = 0
11
+
+0 listen(3, 1) = 0
12
+
13
+
+0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop>
14
+
+0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
15
+
+.1 < . 1:1(0) ack 1 win 32792
16
+
17
+
18
+
+0 accept(3, ..., ...) = 4
19
+
+0 < . 1:1001(1000) ack 1 win 32792
20
+
+0 > . 1:1(0) ack 1001
21
+
+0 read(4, ..., 1000) = 1000
22
+
23
+
// resend the payload + a FIN
24
+
+0 < F. 1:1001(1000) ack 1 win 32792
25
+
// Why do we have a delay and no dsack ?
26
+
+0~+.04 > . 1:1(0) ack 1002
27
+
28
+
+0 close(4) = 0
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+
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+
// According to RFC 2525, section 2.17
31
+
// we should _not_ send an RST here, because there was no data to consume.
32
+
+0 > F. 1:1(0) ack 1002