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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /net/ipv4/tcp_recovery.c
downloadlinux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz
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Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ...
Diffstat (limited to '')
-rw-r--r--net/ipv4/tcp_recovery.c237
1 files changed, 237 insertions, 0 deletions
diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
new file mode 100644
index 000000000..50abaa941
--- /dev/null
+++ b/net/ipv4/tcp_recovery.c
@@ -0,0 +1,237 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/tcp.h>
+#include <net/tcp.h>
+
+static u32 tcp_rack_reo_wnd(const struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ if (!tp->reord_seen) {
+ /* If reordering has not been observed, be aggressive during
+ * the recovery or starting the recovery by DUPACK threshold.
+ */
+ if (inet_csk(sk)->icsk_ca_state >= TCP_CA_Recovery)
+ return 0;
+
+ if (tp->sacked_out >= tp->reordering &&
+ !(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_recovery) &
+ TCP_RACK_NO_DUPTHRESH))
+ return 0;
+ }
+
+ /* To be more reordering resilient, allow min_rtt/4 settling delay.
+ * Use min_rtt instead of the smoothed RTT because reordering is
+ * often a path property and less related to queuing or delayed ACKs.
+ * Upon receiving DSACKs, linearly increase the window up to the
+ * smoothed RTT.
+ */
+ return min((tcp_min_rtt(tp) >> 2) * tp->rack.reo_wnd_steps,
+ tp->srtt_us >> 3);
+}
+
+s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb, u32 reo_wnd)
+{
+ return tp->rack.rtt_us + reo_wnd -
+ tcp_stamp_us_delta(tp->tcp_mstamp, tcp_skb_timestamp_us(skb));
+}
+
+/* RACK loss detection (IETF draft draft-ietf-tcpm-rack-01):
+ *
+ * Marks a packet lost, if some packet sent later has been (s)acked.
+ * The underlying idea is similar to the traditional dupthresh and FACK
+ * but they look at different metrics:
+ *
+ * dupthresh: 3 OOO packets delivered (packet count)
+ * FACK: sequence delta to highest sacked sequence (sequence space)
+ * RACK: sent time delta to the latest delivered packet (time domain)
+ *
+ * The advantage of RACK is it applies to both original and retransmitted
+ * packet and therefore is robust against tail losses. Another advantage
+ * is being more resilient to reordering by simply allowing some
+ * "settling delay", instead of tweaking the dupthresh.
+ *
+ * When tcp_rack_detect_loss() detects some packets are lost and we
+ * are not already in the CA_Recovery state, either tcp_rack_reo_timeout()
+ * or tcp_time_to_recover()'s "Trick#1: the loss is proven" code path will
+ * make us enter the CA_Recovery state.
+ */
+static void tcp_rack_detect_loss(struct sock *sk, u32 *reo_timeout)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct sk_buff *skb, *n;
+ u32 reo_wnd;
+
+ *reo_timeout = 0;
+ reo_wnd = tcp_rack_reo_wnd(sk);
+ list_for_each_entry_safe(skb, n, &tp->tsorted_sent_queue,
+ tcp_tsorted_anchor) {
+ struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
+ s32 remaining;
+
+ /* Skip ones marked lost but not yet retransmitted */
+ if ((scb->sacked & TCPCB_LOST) &&
+ !(scb->sacked & TCPCB_SACKED_RETRANS))
+ continue;
+
+ if (!tcp_skb_sent_after(tp->rack.mstamp,
+ tcp_skb_timestamp_us(skb),
+ tp->rack.end_seq, scb->end_seq))
+ break;
+
+ /* A packet is lost if it has not been s/acked beyond
+ * the recent RTT plus the reordering window.
+ */
+ remaining = tcp_rack_skb_timeout(tp, skb, reo_wnd);
+ if (remaining <= 0) {
+ tcp_mark_skb_lost(sk, skb);
+ list_del_init(&skb->tcp_tsorted_anchor);
+ } else {
+ /* Record maximum wait time */
+ *reo_timeout = max_t(u32, *reo_timeout, remaining);
+ }
+ }
+}
+
+bool tcp_rack_mark_lost(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ u32 timeout;
+
+ if (!tp->rack.advanced)
+ return false;
+
+ /* Reset the advanced flag to avoid unnecessary queue scanning */
+ tp->rack.advanced = 0;
+ tcp_rack_detect_loss(sk, &timeout);
+ if (timeout) {
+ timeout = usecs_to_jiffies(timeout) + TCP_TIMEOUT_MIN;
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_REO_TIMEOUT,
+ timeout, inet_csk(sk)->icsk_rto);
+ }
+ return !!timeout;
+}
+
+/* Record the most recently (re)sent time among the (s)acked packets
+ * This is "Step 3: Advance RACK.xmit_time and update RACK.RTT" from
+ * draft-cheng-tcpm-rack-00.txt
+ */
+void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
+ u64 xmit_time)
+{
+ u32 rtt_us;
+
+ rtt_us = tcp_stamp_us_delta(tp->tcp_mstamp, xmit_time);
+ if (rtt_us < tcp_min_rtt(tp) && (sacked & TCPCB_RETRANS)) {
+ /* If the sacked packet was retransmitted, it's ambiguous
+ * whether the retransmission or the original (or the prior
+ * retransmission) was sacked.
+ *
+ * If the original is lost, there is no ambiguity. Otherwise
+ * we assume the original can be delayed up to aRTT + min_rtt.
+ * the aRTT term is bounded by the fast recovery or timeout,
+ * so it's at least one RTT (i.e., retransmission is at least
+ * an RTT later).
+ */
+ return;
+ }
+ tp->rack.advanced = 1;
+ tp->rack.rtt_us = rtt_us;
+ if (tcp_skb_sent_after(xmit_time, tp->rack.mstamp,
+ end_seq, tp->rack.end_seq)) {
+ tp->rack.mstamp = xmit_time;
+ tp->rack.end_seq = end_seq;
+ }
+}
+
+/* We have waited long enough to accommodate reordering. Mark the expired
+ * packets lost and retransmit them.
+ */
+void tcp_rack_reo_timeout(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ u32 timeout, prior_inflight;
+ u32 lost = tp->lost;
+
+ prior_inflight = tcp_packets_in_flight(tp);
+ tcp_rack_detect_loss(sk, &timeout);
+ if (prior_inflight != tcp_packets_in_flight(tp)) {
+ if (inet_csk(sk)->icsk_ca_state != TCP_CA_Recovery) {
+ tcp_enter_recovery(sk, false);
+ if (!inet_csk(sk)->icsk_ca_ops->cong_control)
+ tcp_cwnd_reduction(sk, 1, tp->lost - lost, 0);
+ }
+ tcp_xmit_retransmit_queue(sk);
+ }
+ if (inet_csk(sk)->icsk_pending != ICSK_TIME_RETRANS)
+ tcp_rearm_rto(sk);
+}
+
+/* Updates the RACK's reo_wnd based on DSACK and no. of recoveries.
+ *
+ * If a DSACK is received that seems like it may have been due to reordering
+ * triggering fast recovery, increment reo_wnd by min_rtt/4 (upper bounded
+ * by srtt), since there is possibility that spurious retransmission was
+ * due to reordering delay longer than reo_wnd.
+ *
+ * Persist the current reo_wnd value for TCP_RACK_RECOVERY_THRESH (16)
+ * no. of successful recoveries (accounts for full DSACK-based loss
+ * recovery undo). After that, reset it to default (min_rtt/4).
+ *
+ * At max, reo_wnd is incremented only once per rtt. So that the new
+ * DSACK on which we are reacting, is due to the spurious retx (approx)
+ * after the reo_wnd has been updated last time.
+ *
+ * reo_wnd is tracked in terms of steps (of min_rtt/4), rather than
+ * absolute value to account for change in rtt.
+ */
+void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ if ((READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_recovery) &
+ TCP_RACK_STATIC_REO_WND) ||
+ !rs->prior_delivered)
+ return;
+
+ /* Disregard DSACK if a rtt has not passed since we adjusted reo_wnd */
+ if (before(rs->prior_delivered, tp->rack.last_delivered))
+ tp->rack.dsack_seen = 0;
+
+ /* Adjust the reo_wnd if update is pending */
+ if (tp->rack.dsack_seen) {
+ tp->rack.reo_wnd_steps = min_t(u32, 0xFF,
+ tp->rack.reo_wnd_steps + 1);
+ tp->rack.dsack_seen = 0;
+ tp->rack.last_delivered = tp->delivered;
+ tp->rack.reo_wnd_persist = TCP_RACK_RECOVERY_THRESH;
+ } else if (!tp->rack.reo_wnd_persist) {
+ tp->rack.reo_wnd_steps = 1;
+ }
+}
+
+/* RFC6582 NewReno recovery for non-SACK connection. It simply retransmits
+ * the next unacked packet upon receiving
+ * a) three or more DUPACKs to start the fast recovery
+ * b) an ACK acknowledging new data during the fast recovery.
+ */
+void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced)
+{
+ const u8 state = inet_csk(sk)->icsk_ca_state;
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ if ((state < TCP_CA_Recovery && tp->sacked_out >= tp->reordering) ||
+ (state == TCP_CA_Recovery && snd_una_advanced)) {
+ struct sk_buff *skb = tcp_rtx_queue_head(sk);
+ u32 mss;
+
+ if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST)
+ return;
+
+ mss = tcp_skb_mss(skb);
+ if (tcp_skb_pcount(skb) > 1 && skb->len > mss)
+ tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb,
+ mss, mss, GFP_ATOMIC);
+
+ tcp_mark_skb_lost(sk, skb);
+ }
+}