BMC/Intel-BMC/linux.git/net/ipv4/tcp_input.c, branch dev-4.6

tcp: Merge tx_flags and tskey in tcp_shifted_skb

2016-04-21T18:40:55+00:00

After receiving sacks, tcp_shifted_skb() will collapse skbs if possible. tx_flags and tskey also have to be merged. This patch reuses the tcp_skb_collapse_tstamp() to handle them. BPF Output Before: ~~~~~ BPF Output After: ~~~~~ <...>-2024 [007] d.s. 88.644374: : ee_data:14599 Packetdrill Script: ~~~~~ +0 `sysctl -q -w net.ipv4.tcp_min_tso_segs=10` +0 `sysctl -q -w net.ipv4.tcp_no_metrics_save=1` +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 0.100 < S 0:0(0) win 32792 0.100 > S. 0:0(0) ack 1 0.200 < . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 0.200 write(4, ..., 1460) = 1460 +0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0 0.200 write(4, ..., 13140) = 13140 0.200 > P. 1:1461(1460) ack 1 0.200 > . 1461:8761(7300) ack 1 0.200 > P. 8761:14601(5840) ack 1 0.300 < . 1:1(0) ack 1 win 257 0.300 > P. 1:1461(1460) ack 1 0.400 < . 1:1(0) ack 14601 win 257 0.400 close(4) = 0 0.400 > F. 14601:14601(0) ack 1 0.500 < F. 1:1(0) ack 14602 win 257 0.500 > . 14602:14602(0) ack 2 Signed-off-by: Martin KaFai Lau Cc: Eric Dumazet Cc: Neal Cardwell Cc: Soheil Hassas Yeganeh Cc: Willem de Bruijn Cc: Yuchung Cheng Acked-by: Soheil Hassas Yeganeh Tested-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller

tcp: Fix SOF_TIMESTAMPING_TX_ACK when handling dup acks

2016-04-21T17:45:43+00:00

Assuming SOF_TIMESTAMPING_TX_ACK is on. When dup acks are received, it could incorrectly think that a skb has already been acked and queue a SCM_TSTAMP_ACK cmsg to the sk->sk_error_queue. In tcp_ack_tstamp(), it checks 'between(shinfo->tskey, prior_snd_una, tcp_sk(sk)->snd_una - 1)'. If prior_snd_una == tcp_sk(sk)->snd_una like the following packetdrill script, between() returns true but the tskey is actually not acked. e.g. try between(3, 2, 1). The fix is to replace between() with one before() and one !before(). By doing this, the -1 offset on the tcp_sk(sk)->snd_una can also be removed. A packetdrill script is used to reproduce the dup ack scenario. Due to the lacking cmsg support in packetdrill (may be I cannot find it), a BPF prog is used to kprobe to sock_queue_err_skb() and print out the value of serr->ee.ee_data. Both the packetdrill and the bcc BPF script is attached at the end of this commit message. BPF Output Before Fix: ~~~~~~ <...>-2056 [001] d.s. 433.927987: : ee_data:1459 #incorrect packetdrill-2056 [001] d.s. 433.929563: : ee_data:1459 #incorrect packetdrill-2056 [001] d.s. 433.930765: : ee_data:1459 #incorrect packetdrill-2056 [001] d.s. 434.028177: : ee_data:1459 packetdrill-2056 [001] d.s. 434.029686: : ee_data:14599 BPF Output After Fix: ~~~~~~ <...>-2049 [000] d.s. 113.517039: : ee_data:1459 <...>-2049 [000] d.s. 113.517253: : ee_data:14599 BCC BPF Script: ~~~~~~ #!/usr/bin/env python from __future__ import print_function from bcc import BPF bpf_text = """ #include #include #include #include #ifdef memset #undef memset #endif int trace_err_skb(struct pt_regs *ctx) { struct sk_buff *skb = (struct sk_buff *)ctx->si; struct sock *sk = (struct sock *)ctx->di; struct sock_exterr_skb *serr; u32 ee_data = 0; if (!sk || !skb) return 0; serr = SKB_EXT_ERR(skb); bpf_probe_read(&ee_data, sizeof(ee_data), &serr->ee.ee_data); bpf_trace_printk("ee_data:%u\\n", ee_data); return 0; }; """ b = BPF(text=bpf_text) b.attach_kprobe(event="sock_queue_err_skb", fn_name="trace_err_skb") print("Attached to kprobe") b.trace_print() Packetdrill Script: ~~~~~~ +0 `sysctl -q -w net.ipv4.tcp_min_tso_segs=10` +0 `sysctl -q -w net.ipv4.tcp_no_metrics_save=1` +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 0.100 < S 0:0(0) win 32792 0.100 > S. 0:0(0) ack 1 0.200 < . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 +0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0 0.200 write(4, ..., 1460) = 1460 0.200 write(4, ..., 13140) = 13140 0.200 > P. 1:1461(1460) ack 1 0.200 > . 1461:8761(7300) ack 1 0.200 > P. 8761:14601(5840) ack 1 0.300 < . 1:1(0) ack 1 win 257 0.300 < . 1:1(0) ack 1 win 257 0.300 < . 1:1(0) ack 1 win 257 0.300 > P. 1:1461(1460) ack 1 0.400 < . 1:1(0) ack 14601 win 257 0.400 close(4) = 0 0.400 > F. 14601:14601(0) ack 1 0.500 < F. 1:1(0) ack 14602 win 257 0.500 > . 14602:14602(0) ack 2 Signed-off-by: Martin KaFai Lau Cc: Eric Dumazet Cc: Neal Cardwell Cc: Soheil Hassas Yeganeh Cc: Willem de Bruijn Cc: Yuchung Cheng Acked-by: Soheil Hassas Yeganeh Tested-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller

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

2016-02-23T05:09:14+00:00

Conflicts: drivers/net/phy/bcm7xxx.c drivers/net/phy/marvell.c drivers/net/vxlan.c All three conflicts were cases of simple overlapping changes. Signed-off-by: David S. Miller

tcp: do not set rtt_min to 1

2016-02-16T21:07:13+00:00

There are some cases where rtt_us derives from deltas of jiffies, instead of using usec timestamps. Since we want to track minimal rtt, better to assume a delta of 0 jiffie might be in fact be very close to 1 jiffie. It is kind of sad jiffies_to_usecs(1) calls a function instead of simply using a constant. Fixes: f672258391b42 ("tcp: track min RTT using windowed min-filter") Signed-off-by: Eric Dumazet Signed-off-by: Neal Cardwell Cc: Yuchung Cheng Signed-off-by: David S. Miller

ipv4: Namespaceify tcp reordering sysctl knob

2016-02-07T19:35:10+00:00

Signed-off-by: Nikolay Borisov Signed-off-by: David S. Miller

ipv4: Namespaceify tcp syncookies sysctl knob

2016-02-07T19:35:10+00:00

Signed-off-by: Nikolay Borisov Signed-off-by: David S. Miller

tcp: tcp_cong_control helper

2016-02-07T19:09:51+00:00

Refactor and consolidate cwnd and rate updates into a new function tcp_cong_control(). Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: make congestion control more robust against reordering

2016-02-07T19:09:51+00:00

This change enables congestion control to update cwnd based on not only packet cumulatively acked but also packets delivered out-of-order. This makes congestion control robust against packet reordering because it may raise cwnd as long as packets are being delivered once reordering has been detected (i.e., it only cares the amount of packets delivered, not the ordering among them). Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: refactor pkts acked accounting

2016-02-07T19:09:51+00:00

A small refactoring that gets number of packets cumulatively acked from tcp_clean_rtx_queue() directly. Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: new delivery accounting

2016-02-07T19:09:51+00:00

This patch changes the accounting of how many packets are newly acked or sacked when the sender receives an ACK. The current approach basically computes newly_acked_sacked = (prior_packets - prior_sacked) - (tp->packets_out - tp->sacked_out) where prior_packets and prior_sacked out are snapshot at the beginning of the ACK processing. The new approach tracks the delivery information via a new TCP state variable "delivered" which monotically increases as new packets are delivered in order or out-of-order. The reason for this change is that the current approach is brittle that produces negative or inaccurate estimate. 1) For non-SACK connections, an ACK that advances the SND.UNA could reset the DUPACK counters (tp->sacked_out) in tcp_process_loss() or tcp_fastretrans_alert(). This inflates the inflight suddenly and causes under-estimate or even negative estimate. Here is a real example: before after (processing ACK) packets_out 75 73 sacked_out 23 0 ca state Loss Open The old approach computes (75-23) - (73 - 0) = -21 delivered while the new approach computes 1 delivered since it considers the 2nd-24th packets are delivered OOO. 2) MSS change would re-count packets_out and sacked_out so the estimate is in-accurate and can even become negative. E.g., the inflight is doubled when MSS is halved. 3) Spurious retransmission signaled by DSACK is not accounted The new approach is simpler and more robust. For SACK connections, tp->delivered increments as packets are being acked or sacked in SACK and ACK processing. For non-sack connections, it's done in tcp_remove_reno_sacks() and tcp_add_reno_sack(). When an ACK advances the SND.UNA, tp->delivered is incremented by the number of packets ACKed (less the current number of DUPACKs received plus one packet hole). Upon receiving a DUPACK, tp->delivered is incremented assuming one out-of-order packet is delivered. Upon receiving a DSACK, tp->delivered is incremtened assuming one retransmission is delivered in tcp_sacktag_write_queue(). Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller