linux-stable.git/net/ipv4/tcp_timer.c, branch v6.4.3 Linux kernel stable tree tcp: fix mishandling when the sack compression is deferred. 2023-06-01T11:15:12+00:00 fuyuanli fuyuanli@didiglobal.com 2023-05-31T08:01:50+00:00 30c6f0bf9579debce27e45fac34fdc97e46acacc In this patch, we mainly try to handle sending a compressed ack correctly if it's deferred. Here are more details in the old logic: When sack compression is triggered in the tcp_compressed_ack_kick(), if the sock is owned by user, it will set TCP_DELACK_TIMER_DEFERRED and then defer to the release cb phrase. Later once user releases the sock, tcp_delack_timer_handler() should send a ack as expected, which, however, cannot happen due to lack of ICSK_ACK_TIMER flag. Therefore, the receiver would not sent an ack until the sender's retransmission timeout. It definitely increases unnecessary latency. Fixes: 5d9f4262b7ea ("tcp: add SACK compression") Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: fuyuanli <fuyuanli@didiglobal.com> Signed-off-by: Jason Xing <kerneljasonxing@gmail.com> Link: https://lore.kernel.org/netdev/20230529113804.GA20300@didi-ThinkCentre-M920t-N000/ Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20230531080150.GA20424@didi-ThinkCentre-M920t-N000 Signed-off-by: Paolo Abeni <pabeni@redhat.com> 
In this patch, we mainly try to handle sending a compressed ack
correctly if it's deferred.

Here are more details in the old logic:
When sack compression is triggered in the tcp_compressed_ack_kick(),
if the sock is owned by user, it will set TCP_DELACK_TIMER_DEFERRED
and then defer to the release cb phrase. Later once user releases
the sock, tcp_delack_timer_handler() should send a ack as expected,
which, however, cannot happen due to lack of ICSK_ACK_TIMER flag.
Therefore, the receiver would not sent an ack until the sender's
retransmission timeout. It definitely increases unnecessary latency.

Fixes: 5d9f4262b7ea ("tcp: add SACK compression")
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: fuyuanli <fuyuanli@didiglobal.com>
Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://lore.kernel.org/netdev/20230529113804.GA20300@didi-ThinkCentre-M920t-N000/
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230531080150.GA20424@didi-ThinkCentre-M920t-N000
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
tcp: annotate lockless access to sk->sk_err 2023-03-17T08:25:05+00:00 Eric Dumazet edumazet@google.com 2023-03-15T20:57:44+00:00 e13ec3da05d130f0d10da8e1fbe1be26dcdb0e27 tcp_poll() reads sk->sk_err without socket lock held/owned. We should used READ_ONCE() here, and update writers to use WRITE_ONCE(). Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
tcp_poll() reads sk->sk_err without socket lock held/owned.

We should used READ_ONCE() here, and update writers
to use WRITE_ONCE().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: annotate lockless accesses to sk->sk_err_soft 2023-03-17T08:25:05+00:00 Eric Dumazet edumazet@google.com 2023-03-15T20:57:41+00:00 cee1af825d65b8122627fc2efbc36c1bd51ee103 This field can be read/written without lock synchronization. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
This field can be read/written without lock synchronization.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: Make SYN ACK RTO tunable by BPF programs with TFO 2022-08-17T09:19:22+00:00 Jie Meng jmeng@fb.com 2022-08-15T20:29:00+00:00 8ea731d4c2ce721a29b17c7a1ee82c28b80f00ba Instead of the hardcoded TCP_TIMEOUT_INIT, this diff calls tcp_timeout_init to initiate req->timeout like the non TFO SYN ACK case. Tested using the following packetdrill script, on a host with a BPF program that sets the initial connect timeout to 10ms. `../../common/defaults.sh` // Initialize connection 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_TCP, TCP_FASTOPEN, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 +0 < S 0:0(0) win 32792 <mss 1000,sackOK,FO TFO_COOKIE> +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK> +.01 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK> +.02 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK> +.04 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK> +.01 < . 1:1(0) ack 1 win 32792 +0 accept(3, ..., ...) = 4 Signed-off-by: Jie Meng <jmeng@fb.com> Acked-by: Neal Cardwell <ncardwell@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Instead of the hardcoded TCP_TIMEOUT_INIT, this diff calls tcp_timeout_init
to initiate req->timeout like the non TFO SYN ACK case.

Tested using the following packetdrill script, on a host with a BPF
program that sets the initial connect timeout to 10ms.

`../../common/defaults.sh`

// Initialize connection
    0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_TCP, TCP_FASTOPEN, [1], 4) = 0
   +0 bind(3, ..., ...) = 0
   +0 listen(3, 1) = 0

   +0 < S 0:0(0) win 32792 <mss 1000,sackOK,FO TFO_COOKIE>
   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
   +.01 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
   +.02 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
   +.04 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
   +.01 < . 1:1(0) ack 1 win 32792

   +0 accept(3, ..., ...) = 4

Signed-off-by: Jie Meng <jmeng@fb.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-07-21T20:03:39+00:00 Jakub Kicinski kuba@kernel.org 2022-07-21T20:03:39+00:00 6e0e846ee2ab01bc44254e6a0a6a6a0db1cba16d No conflicts. Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
No conflicts.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp: Fix a data-race around sysctl_tcp_thin_linear_timeouts. 2022-07-20T09:14:50+00:00 Kuniyuki Iwashima kuniyu@amazon.com 2022-07-18T17:26:47+00:00 7c6f2a86ca590d5187a073d987e9599985fb1c7c While reading sysctl_tcp_thin_linear_timeouts, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 36e31b0af587 ("net: TCP thin linear timeouts") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
While reading sysctl_tcp_thin_linear_timeouts, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its reader.

Fixes: 36e31b0af587 ("net: TCP thin linear timeouts")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: Fix data-races around some timeout sysctl knobs. 2022-07-18T11:21:54+00:00 Kuniyuki Iwashima kuniyu@amazon.com 2022-07-15T17:17:50+00:00 39e24435a776e9de5c6dd188836cf2523547804b While reading these sysctl knobs, they can be changed concurrently. Thus, we need to add READ_ONCE() to their readers. - tcp_retries1 - tcp_retries2 - tcp_orphan_retries - tcp_fin_timeout Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
While reading these sysctl knobs, they can be changed concurrently.
Thus, we need to add READ_ONCE() to their readers.

  - tcp_retries1
  - tcp_retries2
  - tcp_orphan_retries
  - tcp_fin_timeout

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: Fix data-races around sysctl_tcp_syn(ack)?_retries. 2022-07-18T11:21:54+00:00 Kuniyuki Iwashima kuniyu@amazon.com 2022-07-15T17:17:46+00:00 20a3b1c0f603e8c55c3396abd12dfcfb523e4d3c While reading sysctl_tcp_syn(ack)?_retries, they can be changed concurrently. Thus, we need to add READ_ONCE() to their readers. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
While reading sysctl_tcp_syn(ack)?_retries, they can be changed
concurrently.  Thus, we need to add READ_ONCE() to their readers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: Fix a data-race around sysctl_tcp_mtu_probe_floor. 2022-07-15T10:49:56+00:00 Kuniyuki Iwashima kuniyu@amazon.com 2022-07-13T20:52:03+00:00 8e92d4423615a5257d0d871fc067aa561f597deb While reading sysctl_tcp_mtu_probe_floor, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: c04b79b6cfd7 ("tcp: add new tcp_mtu_probe_floor sysctl") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
While reading sysctl_tcp_mtu_probe_floor, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: c04b79b6cfd7 ("tcp: add new tcp_mtu_probe_floor sysctl")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: Fix data-races around sysctl_tcp_min_snd_mss. 2022-07-15T10:49:56+00:00 Kuniyuki Iwashima kuniyu@amazon.com 2022-07-13T20:52:02+00:00 78eb166cdefcc3221c8c7c1e2d514e91a2eb5014 While reading sysctl_tcp_min_snd_mss, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 5f3e2bf008c2 ("tcp: add tcp_min_snd_mss sysctl") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
While reading sysctl_tcp_min_snd_mss, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 5f3e2bf008c2 ("tcp: add tcp_min_snd_mss sysctl")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>