kernel/net/ipv4/tcp_nv.c, branch linux-6.2.y

tcp: add accessors to read/set tp->snd_cwnd

2022-04-06T19:05:41Z

We had various bugs over the years with code breaking the assumption that tp->snd_cwnd is greater than zero. Lately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added in commit 8b8a321ff72c ("tcp: fix zero cwnd in tcp_cwnd_reduction") can trigger, and without a repro we would have to spend considerable time finding the bug. Instead of complaining too late, we want to catch where and when tp->snd_cwnd is set to an illegal value. Signed-off-by: Eric Dumazet Suggested-by: Yuchung Cheng Cc: Neal Cardwell Acked-by: Yuchung Cheng Link: https://lore.kernel.org/r/20220405233538.947344-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski

net/ipv4/tcp_nv.c: remove superfluous header files from tcp_nv.c

2021-09-27T11:47:39Z

tcp_nv.c hasn't use any macro or function declared in mm.h. Thus, these files can be removed from tcp_nv.c safely without affecting the compilation of the net module. Signed-off-by: Mianhan Liu Signed-off-by: David S. Miller

treewide: Add SPDX license identifier for more missed files

2019-05-21T08:50:45Z

Add SPDX license identifiers to all files which: - Have no license information of any form - Have MODULE_LICENCE("GPL*") inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

tcp_nv: fix potential integer overflow in tcpnv_acked

2018-01-31T15:26:30Z

Add suffix ULL to constant 80000 in order to avoid a potential integer overflow and give the compiler complete information about the proper arithmetic to use. Notice that this constant is used in a context that expects an expression of type u64. The current cast to u64 effectively applies to the whole expression as an argument of type u64 to be passed to div64_u64, but it does not prevent it from being evaluated using 32-bit arithmetic instead of 64-bit arithmetic. Also, once the expression is properly evaluated using 64-bit arithmentic, there is no need for the parentheses and the external cast to u64. Addresses-Coverity-ID: 1357588 ("Unintentional integer overflow") Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller

bpf: Support passing args to sock_ops bpf function

2018-01-26T00:41:14Z

Adds support for passing up to 4 arguments to sock_ops bpf functions. It reusues the reply union, so the bpf_sock_ops structures are not increased in size. Signed-off-by: Lawrence Brakmo Signed-off-by: Alexei Starovoitov

tcp_nv: use do_div() instead of expensive div64_u64()

2017-11-04T13:34:52Z

Average RTT is 32-bit thus full 64-bit division is redundant. Signed-off-by: Konstantin Khlebnikov Suggested-by: Stephen Hemminger Suggested-by: Eric Dumazet Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2017-11-04T00:26:51Z

Files removed in 'net-next' had their license header updated in 'net'. We take the remove from 'net-next'. Signed-off-by: David S. Miller

tcp_nv: fix division by zero in tcpnv_acked()

2017-11-02T07:16:27Z

Average RTT could become zero. This happened in real life at least twice. This patch treats zero as 1us. Signed-off-by: Konstantin Khlebnikov Acked-by: Lawrence Brakmo Signed-off-by: David S. Miller

bpf: Add BPF_SOCKET_OPS_BASE_RTT support to tcp_nv

2017-10-22T02:12:05Z

TCP_NV will try to get the base RTT from a socket_ops BPF program if one is loaded. NV will then use the base RTT to bound its min RTT (its notion of the base RTT). It uses the base RTT as an upper bound and 80% of the base RTT as its lower bound. In other words, NV will consider filtered RTTs larger than base RTT as a sign of congestion. As a result, there is no minRTT inflation when there is a lot of congestion. For example, in a DC where the RTTs are less than 40us when there is no congestion, a base RTT value of 80us improves the performance of NV. The difference between the uncongested RTT and the base RTT provided represents how much queueing we are willing to have (in practice it can be higher). NV has been tunned to reduce congestion when there are many flows at the cost of one flow not achieving full bandwith utilization. When a reasonable base RTT is provided, one NV flow can now fully utilize the full bandwidth. In addition, the performance is also improved when there are many flows. In the following examples the NV results are using a kernel with this patch set (i.e. both NV results are using the new nv_loss_dec_factor). With one host sending to another host and only one flow the goodputs are: Cubic: 9.3 Gbps, NV: 5.5 Gbps, NV (baseRTT=80us): 9.2 Gbps With 2 hosts sending to one host (1 flow per host, the goodput per flow is: Cubic: 4.6 Gbps, NV: 4.5 Gbps, NV (baseRTT=80us)L 4.6 Gbps But the RTTs seen by a ping process in the sender is: Cubic: 3.3ms NV: 97us, NV (baseRTT=80us): 146us With a lot of flows things look even better for NV with baseRTT. Here we have 3 hosts sending to one host. Each sending host has 6 flows: 1 stream, 4x1MB RPC, 1x10KB RPC. Cubic, NV and NV with baseRTT all fully utilize the full available bandwidth. However, the distribution of bandwidth among the flows is very different. For the 10KB RPC flow: Cubic: 27Mbps, NV: 111Mbps, NV (baseRTT=80us): 222Mbps The 99% latencies for the 10KB flows are: Cubic: 26ms, NV: 1ms, NV (baseRTT=80us): 500us The RTT seen by a ping process at the senders: Cubic: 3.2ms NV: 720us, NV (baseRTT=80us): 330us Signed-off-by: Lawrence Brakmo Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

tcp: consolidate congestion control undo functions

2017-08-07T04:25:10Z

Most TCP congestion controls are using identical logic to undo cwnd except BBR. This patch consolidates these similar functions to the one used currently by Reno and others. Suggested-by: Neal Cardwell Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: David S. Miller