Merge tag 'net-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Paolo Abeni:
 "Core:

   - Implement the Device Memory TCP transmit path, allowing zero-copy
     data transmission on top of TCP from e.g. GPU memory to the wire.

   - Move all the IPv6 routing tables management outside the RTNL scope,
     under its own lock and RCU. The route control path is now 3x times
     faster.

   - Convert queue related netlink ops to instance lock, reducing again
     the scope of the RTNL lock. This improves the control plane
     scalability.

   - Refactor the software crc32c implementation, removing unneeded
     abstraction layers and improving significantly the related
     micro-benchmarks.

   - Optimize the GRO engine for UDP-tunneled traffic, for a 10%
     performance improvement in related stream tests.

   - Cover more per-CPU storage with local nested BH locking; this is a
     prep work to remove the current per-CPU lock in local_bh_disable()
     on PREMPT_RT.

   - Introduce and use nlmsg_payload helper, combining buffer bounds
     verification with accessing payload carried by netlink messages.

  Netfilter:

   - Rewrite the procfs conntrack table implementation, improving
     considerably the dump performance. A lot of user-space tools still
     use this interface.

   - Implement support for wildcard netdevice in netdev basechain and
     flowtables.

   - Integrate conntrack information into nft trace infrastructure.

   - Export set count and backend name to userspace, for better
     introspection.

  BPF:

   - BPF qdisc support: BPF-qdisc can be implemented with BPF struct_ops
     programs and can be controlled in similar way to traditional qdiscs
     using the "tc qdisc" command.

   - Refactor the UDP socket iterator, addressing long standing issues
     WRT duplicate hits or missed sockets.

  Protocols:

   - Improve TCP receive buffer auto-tuning and increase the default
     upper bound for the receive buffer; overall this improves the
     single flow maximum thoughput on 200Gbs link by over 60%.

   - Add AFS GSSAPI security class to AF_RXRPC; it provides transport
     security for connections to the AFS fileserver and VL server.

   - Improve TCP multipath routing, so that the sources address always
     matches the nexthop device.

   - Introduce SO_PASSRIGHTS for AF_UNIX, to allow disabling SCM_RIGHTS,
     and thus preventing DoS caused by passing around problematic FDs.

   - Retire DCCP socket. DCCP only receives updates for bugs, and major
     distros disable it by default. Its removal allows for better
     organisation of TCP fields to reduce the number of cache lines hit
     in the fast path.

   - Extend TCP drop-reason support to cover PAWS checks.

  Driver API:

   - Reorganize PTP ioctl flag support to require an explicit opt-in for
     the drivers, avoiding the problem of drivers not rejecting new
     unsupported flags.

   - Converted several device drivers to timestamping APIs.

   - Introduce per-PHY ethtool dump helpers, improving the support for
     dump operations targeting PHYs.

  Tests and tooling:

   - Add support for classic netlink in user space C codegen, so that
     ynl-c can now read, create and modify links, routes addresses and
     qdisc layer configuration.

   - Add ynl sub-types for binary attributes, allowing ynl-c to output
     known struct instead of raw binary data, clarifying the classic
     netlink output.

   - Extend MPTCP selftests to improve the code-coverage.

   - Add tests for XDP tail adjustment in AF_XDP.

  New hardware / drivers:

   - OpenVPN virtual driver: offload OpenVPN data channels processing to
     the kernel-space, increasing the data transfer throughput WRT the
     user-space implementation.

   - Renesas glue driver for the gigabit ethernet RZ/V2H(P) SoC.

   - Broadcom asp-v3.0 ethernet driver.

   - AMD Renoir ethernet device.

   - ReakTek MT9888 2.5G ethernet PHY driver.

   - Aeonsemi 10G C45 PHYs driver.

  Drivers:

   - Ethernet high-speed NICs:
       - nVidia/Mellanox (mlx5):
           - refactor the steering table handling to significantly
             reduce the amount of memory used
           - add support for complex matches in H/W flow steering
           - improve flow streeing error handling
           - convert to netdev instance locking
       - Intel (100G, ice, igb, ixgbe, idpf):
           - ice: add switchdev support for LLDP traffic over VF
           - ixgbe: add firmware manipulation and regions devlink support
           - igb: introduce support for frame transmission premption
           - igb: adds persistent NAPI configuration
           - idpf: introduce RDMA support
           - idpf: add initial PTP support
       - Meta (fbnic):
           - extend hardware stats coverage
           - add devlink dev flash support
       - Broadcom (bnxt):
           - add support for RX-side device memory TCP
       - Wangxun (txgbe):
           - implement support for udp tunnel offload
           - complete PTP and SRIOV support for AML 25G/10G devices

   - Ethernet NICs embedded and virtual:
       - Google (gve):
           - add device memory TCP TX support
       - Amazon (ena):
           - support persistent per-NAPI config
       - Airoha:
           - add H/W support for L2 traffic offload
           - add per flow stats for flow offloading
       - RealTek (rtl8211): add support for WoL magic packet
       - Synopsys (stmmac):
           - dwmac-socfpga 1000BaseX support
           - add Loongson-2K3000 support
           - introduce support for hardware-accelerated VLAN stripping
       - Broadcom (bcmgenet):
           - expose more H/W stats
       - Freescale (enetc, dpaa2-eth):
           - enetc: add MAC filter, VLAN filter RSS and loopback support
           - dpaa2-eth: convert to H/W timestamping APIs
       - vxlan: convert FDB table to rhashtable, for better scalabilty
       - veth: apply qdisc backpressure on full ring to reduce TX drops

   - Ethernet switches:
       - Microchip (kzZ88x3): add ETS scheduler support

   - Ethernet PHYs:
       - RealTek (rtl8211):
           - add support for WoL magic packet
           - add support for PHY LEDs

   - CAN:
       - Adds RZ/G3E CANFD support to the rcar_canfd driver.
       - Preparatory work for CAN-XL support.
       - Add self-tests framework with support for CAN physical interfaces.

   - WiFi:
       - mac80211:
           - scan improvements with multi-link operation (MLO)
       - Qualcomm (ath12k):
           - enable AHB support for IPQ5332
           - add monitor interface support to QCN9274
           - add multi-link operation support to WCN7850
           - add 802.11d scan offload support to WCN7850
           - monitor mode for WCN7850, better 6 GHz regulatory
       - Qualcomm (ath11k):
           - restore hibernation support
       - MediaTek (mt76):
           - WiFi-7 improvements
           - implement support for mt7990
       - Intel (iwlwifi):
           - enhanced multi-link single-radio (EMLSR) support on 5 GHz links
           - rework device configuration
       - RealTek (rtw88):
           - improve throughput for RTL8814AU
       - RealTek (rtw89):
           - add multi-link operation support
           - STA/P2P concurrency improvements
           - support different SAR configs by antenna

   - Bluetooth:
       - introduce HCI Driver protocol
       - btintel_pcie: do not generate coredump for diagnostic events
       - btusb: add HCI Drv commands for configuring altsetting
       - btusb: add RTL8851BE device 0x0bda:0xb850
       - btusb: add new VID/PID 13d3/3584 for MT7922
       - btusb: add new VID/PID 13d3/3630 and 13d3/3613 for MT7925
       - btnxpuart: implement host-wakeup feature"

* tag 'net-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1611 commits)
  selftests/bpf: Fix bpf selftest build warning
  selftests: netfilter: Fix skip of wildcard interface test
  net: phy: mscc: Stop clearing the the UDPv4 checksum for L2 frames
  net: openvswitch: Fix the dead loop of MPLS parse
  calipso: Don't call calipso functions for AF_INET sk.
  selftests/tc-testing: Add a test for HFSC eltree double add with reentrant enqueue behaviour on netem
  net_sched: hfsc: Address reentrant enqueue adding class to eltree twice
  octeontx2-pf: QOS: Refactor TC_HTB_LEAF_DEL_LAST callback
  octeontx2-pf: QOS: Perform cache sync on send queue teardown
  net: mana: Add support for Multi Vports on Bare metal
  net: devmem: ncdevmem: remove unused variable
  net: devmem: ksft: upgrade rx test to send 1K data
  net: devmem: ksft: add 5 tuple FS support
  net: devmem: ksft: add exit_wait to make rx test pass
  net: devmem: ksft: add ipv4 support
  net: devmem: preserve sockc_err
  page_pool: fix ugly page_pool formatting
  net: devmem: move list_add to net_devmem_bind_dmabuf.
  selftests: netfilter: nft_queue.sh: include file transfer duration in log message
  net: phy: mscc: Fix memory leak when using one step timestamping
  ...

1 files changed, 0 insertions, 794 deletions

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
deleted file mode 100644
index d6b30700af67..000000000000
--- a/net/dccp/ccids/ccid2.c
+++ /dev/null
@@ -1,794 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- *  Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
- *
- *  Changes to meet Linux coding standards, and DCCP infrastructure fixes.
- *
- *  Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
- */
-
-/*
- * This implementation should follow RFC 4341
- */
-#include <linux/slab.h>
-#include "../feat.h"
-#include "ccid2.h"
-
-
-#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
-static bool ccid2_debug;
-#define ccid2_pr_debug(format, a...)	DCCP_PR_DEBUG(ccid2_debug, format, ##a)
-#else
-#define ccid2_pr_debug(format, a...)
-#endif
-
-static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hc)
-{
-	struct ccid2_seq *seqp;
-	int i;
-
-	/* check if we have space to preserve the pointer to the buffer */
-	if (hc->tx_seqbufc >= (sizeof(hc->tx_seqbuf) /
-			       sizeof(struct ccid2_seq *)))
-		return -ENOMEM;
-
-	/* allocate buffer and initialize linked list */
-	seqp = kmalloc_array(CCID2_SEQBUF_LEN, sizeof(struct ccid2_seq),
-			     gfp_any());
-	if (seqp == NULL)
-		return -ENOMEM;
-
-	for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) {
-		seqp[i].ccid2s_next = &seqp[i + 1];
-		seqp[i + 1].ccid2s_prev = &seqp[i];
-	}
-	seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp;
-	seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
-
-	/* This is the first allocation.  Initiate the head and tail.  */
-	if (hc->tx_seqbufc == 0)
-		hc->tx_seqh = hc->tx_seqt = seqp;
-	else {
-		/* link the existing list with the one we just created */
-		hc->tx_seqh->ccid2s_next = seqp;
-		seqp->ccid2s_prev = hc->tx_seqh;
-
-		hc->tx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
-		seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hc->tx_seqt;
-	}
-
-	/* store the original pointer to the buffer so we can free it */
-	hc->tx_seqbuf[hc->tx_seqbufc] = seqp;
-	hc->tx_seqbufc++;
-
-	return 0;
-}
-
-static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
-{
-	if (ccid2_cwnd_network_limited(ccid2_hc_tx_sk(sk)))
-		return CCID_PACKET_WILL_DEQUEUE_LATER;
-	return CCID_PACKET_SEND_AT_ONCE;
-}
-
-static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
-{
-	u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2);
-
-	/*
-	 * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
-	 * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
-	 * acceptable since this causes starvation/deadlock whenever cwnd < 2.
-	 * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
-	 */
-	if (val == 0 || val > max_ratio) {
-		DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
-		val = max_ratio;
-	}
-	dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO,
-				   min_t(u32, val, DCCPF_ACK_RATIO_MAX));
-}
-
-static void ccid2_check_l_ack_ratio(struct sock *sk)
-{
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-
-	/*
-	 * After a loss, idle period, application limited period, or RTO we
-	 * need to check that the ack ratio is still less than the congestion
-	 * window. Otherwise, we will send an entire congestion window of
-	 * packets and got no response because we haven't sent ack ratio
-	 * packets yet.
-	 * If the ack ratio does need to be reduced, we reduce it to half of
-	 * the congestion window (or 1 if that's zero) instead of to the
-	 * congestion window. This prevents problems if one ack is lost.
-	 */
-	if (dccp_feat_nn_get(sk, DCCPF_ACK_RATIO) > hc->tx_cwnd)
-		ccid2_change_l_ack_ratio(sk, hc->tx_cwnd/2 ? : 1U);
-}
-
-static void ccid2_change_l_seq_window(struct sock *sk, u64 val)
-{
-	dccp_feat_signal_nn_change(sk, DCCPF_SEQUENCE_WINDOW,
-				   clamp_val(val, DCCPF_SEQ_WMIN,
-						  DCCPF_SEQ_WMAX));
-}
-
-static void dccp_tasklet_schedule(struct sock *sk)
-{
-	struct tasklet_struct *t = &dccp_sk(sk)->dccps_xmitlet;
-
-	if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
-		sock_hold(sk);
-		__tasklet_schedule(t);
-	}
-}
-
-static void ccid2_hc_tx_rto_expire(struct timer_list *t)
-{
-	struct ccid2_hc_tx_sock *hc = from_timer(hc, t, tx_rtotimer);
-	struct sock *sk = hc->sk;
-	const bool sender_was_blocked = ccid2_cwnd_network_limited(hc);
-
-	bh_lock_sock(sk);
-	if (sock_owned_by_user(sk)) {
-		sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5);
-		goto out;
-	}
-
-	ccid2_pr_debug("RTO_EXPIRE\n");
-
-	if (sk->sk_state == DCCP_CLOSED)
-		goto out;
-
-	/* back-off timer */
-	hc->tx_rto <<= 1;
-	if (hc->tx_rto > DCCP_RTO_MAX)
-		hc->tx_rto = DCCP_RTO_MAX;
-
-	/* adjust pipe, cwnd etc */
-	hc->tx_ssthresh = hc->tx_cwnd / 2;
-	if (hc->tx_ssthresh < 2)
-		hc->tx_ssthresh = 2;
-	hc->tx_cwnd	= 1;
-	hc->tx_pipe	= 0;
-
-	/* clear state about stuff we sent */
-	hc->tx_seqt = hc->tx_seqh;
-	hc->tx_packets_acked = 0;
-
-	/* clear ack ratio state. */
-	hc->tx_rpseq    = 0;
-	hc->tx_rpdupack = -1;
-	ccid2_change_l_ack_ratio(sk, 1);
-
-	/* if we were blocked before, we may now send cwnd=1 packet */
-	if (sender_was_blocked)
-		dccp_tasklet_schedule(sk);
-	/* restart backed-off timer */
-	sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
-out:
-	bh_unlock_sock(sk);
-	sock_put(sk);
-}
-
-/*
- *	Congestion window validation (RFC 2861).
- */
-static bool ccid2_do_cwv = true;
-module_param(ccid2_do_cwv, bool, 0644);
-MODULE_PARM_DESC(ccid2_do_cwv, "Perform RFC2861 Congestion Window Validation");
-
-/**
- * ccid2_update_used_window  -  Track how much of cwnd is actually used
- * @hc: socket to update window
- * @new_wnd: new window values to add into the filter
- *
- * This is done in addition to CWV. The sender needs to have an idea of how many
- * packets may be in flight, to set the local Sequence Window value accordingly
- * (RFC 4340, 7.5.2). The CWV mechanism is exploited to keep track of the
- * maximum-used window. We use an EWMA low-pass filter to filter out noise.
- */
-static void ccid2_update_used_window(struct ccid2_hc_tx_sock *hc, u32 new_wnd)
-{
-	hc->tx_expected_wnd = (3 * hc->tx_expected_wnd + new_wnd) / 4;
-}
-
-/* This borrows the code of tcp_cwnd_application_limited() */
-static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now)
-{
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-	/* don't reduce cwnd below the initial window (IW) */
-	u32 init_win = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache),
-	    win_used = max(hc->tx_cwnd_used, init_win);
-
-	if (win_used < hc->tx_cwnd) {
-		hc->tx_ssthresh = max(hc->tx_ssthresh,
-				     (hc->tx_cwnd >> 1) + (hc->tx_cwnd >> 2));
-		hc->tx_cwnd = (hc->tx_cwnd + win_used) >> 1;
-	}
-	hc->tx_cwnd_used  = 0;
-	hc->tx_cwnd_stamp = now;
-
-	ccid2_check_l_ack_ratio(sk);
-}
-
-/* This borrows the code of tcp_cwnd_restart() */
-static void ccid2_cwnd_restart(struct sock *sk, const u32 now)
-{
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-	u32 cwnd = hc->tx_cwnd, restart_cwnd,
-	    iwnd = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache);
-	s32 delta = now - hc->tx_lsndtime;
-
-	hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2));
-
-	/* don't reduce cwnd below the initial window (IW) */
-	restart_cwnd = min(cwnd, iwnd);
-
-	while ((delta -= hc->tx_rto) >= 0 && cwnd > restart_cwnd)
-		cwnd >>= 1;
-	hc->tx_cwnd = max(cwnd, restart_cwnd);
-	hc->tx_cwnd_stamp = now;
-	hc->tx_cwnd_used  = 0;
-
-	ccid2_check_l_ack_ratio(sk);
-}
-
-static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
-{
-	struct dccp_sock *dp = dccp_sk(sk);
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-	const u32 now = ccid2_jiffies32;
-	struct ccid2_seq *next;
-
-	/* slow-start after idle periods (RFC 2581, RFC 2861) */
-	if (ccid2_do_cwv && !hc->tx_pipe &&
-	    (s32)(now - hc->tx_lsndtime) >= hc->tx_rto)
-		ccid2_cwnd_restart(sk, now);
-
-	hc->tx_lsndtime = now;
-	hc->tx_pipe    += 1;
-
-	/* see whether cwnd was fully used (RFC 2861), update expected window */
-	if (ccid2_cwnd_network_limited(hc)) {
-		ccid2_update_used_window(hc, hc->tx_cwnd);
-		hc->tx_cwnd_used  = 0;
-		hc->tx_cwnd_stamp = now;
-	} else {
-		if (hc->tx_pipe > hc->tx_cwnd_used)
-			hc->tx_cwnd_used = hc->tx_pipe;
-
-		ccid2_update_used_window(hc, hc->tx_cwnd_used);
-
-		if (ccid2_do_cwv && (s32)(now - hc->tx_cwnd_stamp) >= hc->tx_rto)
-			ccid2_cwnd_application_limited(sk, now);
-	}
-
-	hc->tx_seqh->ccid2s_seq   = dp->dccps_gss;
-	hc->tx_seqh->ccid2s_acked = 0;
-	hc->tx_seqh->ccid2s_sent  = now;
-
-	next = hc->tx_seqh->ccid2s_next;
-	/* check if we need to alloc more space */
-	if (next == hc->tx_seqt) {
-		if (ccid2_hc_tx_alloc_seq(hc)) {
-			DCCP_CRIT("packet history - out of memory!");
-			/* FIXME: find a more graceful way to bail out */
-			return;
-		}
-		next = hc->tx_seqh->ccid2s_next;
-		BUG_ON(next == hc->tx_seqt);
-	}
-	hc->tx_seqh = next;
-
-	ccid2_pr_debug("cwnd=%d pipe=%d\n", hc->tx_cwnd, hc->tx_pipe);
-
-	/*
-	 * FIXME: The code below is broken and the variables have been removed
-	 * from the socket struct. The `ackloss' variable was always set to 0,
-	 * and with arsent there are several problems:
-	 *  (i) it doesn't just count the number of Acks, but all sent packets;
-	 *  (ii) it is expressed in # of packets, not # of windows, so the
-	 *  comparison below uses the wrong formula: Appendix A of RFC 4341
-	 *  comes up with the number K = cwnd / (R^2 - R) of consecutive windows
-	 *  of data with no lost or marked Ack packets. If arsent were the # of
-	 *  consecutive Acks received without loss, then Ack Ratio needs to be
-	 *  decreased by 1 when
-	 *	      arsent >=  K * cwnd / R  =  cwnd^2 / (R^3 - R^2)
-	 *  where cwnd / R is the number of Acks received per window of data
-	 *  (cf. RFC 4341, App. A). The problems are that
-	 *  - arsent counts other packets as well;
-	 *  - the comparison uses a formula different from RFC 4341;
-	 *  - computing a cubic/quadratic equation each time is too complicated.
-	 *  Hence a different algorithm is needed.
-	 */
-#if 0
-	/* Ack Ratio.  Need to maintain a concept of how many windows we sent */
-	hc->tx_arsent++;
-	/* We had an ack loss in this window... */
-	if (hc->tx_ackloss) {
-		if (hc->tx_arsent >= hc->tx_cwnd) {
-			hc->tx_arsent  = 0;
-			hc->tx_ackloss = 0;
-		}
-	} else {
-		/* No acks lost up to now... */
-		/* decrease ack ratio if enough packets were sent */
-		if (dp->dccps_l_ack_ratio > 1) {
-			/* XXX don't calculate denominator each time */
-			int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
-				    dp->dccps_l_ack_ratio;
-
-			denom = hc->tx_cwnd * hc->tx_cwnd / denom;
-
-			if (hc->tx_arsent >= denom) {
-				ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
-				hc->tx_arsent = 0;
-			}
-		} else {
-			/* we can't increase ack ratio further [1] */
-			hc->tx_arsent = 0; /* or maybe set it to cwnd*/
-		}
-	}
-#endif
-
-	sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
-
-#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
-	do {
-		struct ccid2_seq *seqp = hc->tx_seqt;
-
-		while (seqp != hc->tx_seqh) {
-			ccid2_pr_debug("out seq=%llu acked=%d time=%u\n",
-				       (unsigned long long)seqp->ccid2s_seq,
-				       seqp->ccid2s_acked, seqp->ccid2s_sent);
-			seqp = seqp->ccid2s_next;
-		}
-	} while (0);
-	ccid2_pr_debug("=========\n");
-#endif
-}
-
-/**
- * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm
- * @sk: socket to perform estimator on
- * @mrtt: measured RTT
- *
- * This code is almost identical with TCP's tcp_rtt_estimator(), since
- * - it has a higher sampling frequency (recommended by RFC 1323),
- * - the RTO does not collapse into RTT due to RTTVAR going towards zero,
- * - it is simple (cf. more complex proposals such as Eifel timer or research
- *   which suggests that the gain should be set according to window size),
- * - in tests it was found to work well with CCID2 [gerrit].
- */
-static void ccid2_rtt_estimator(struct sock *sk, const long mrtt)
-{
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-	long m = mrtt ? : 1;
-
-	if (hc->tx_srtt == 0) {
-		/* First measurement m */
-		hc->tx_srtt = m << 3;
-		hc->tx_mdev = m << 1;
-
-		hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk));
-		hc->tx_rttvar   = hc->tx_mdev_max;
-
-		hc->tx_rtt_seq  = dccp_sk(sk)->dccps_gss;
-	} else {
-		/* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */
-		m -= (hc->tx_srtt >> 3);
-		hc->tx_srtt += m;
-
-		/* Similarly, update scaled mdev with regard to |m| */
-		if (m < 0) {
-			m = -m;
-			m -= (hc->tx_mdev >> 2);
-			/*
-			 * This neutralises RTO increase when RTT < SRTT - mdev
-			 * (see P. Sarolahti, A. Kuznetsov,"Congestion Control
-			 * in Linux TCP", USENIX 2002, pp. 49-62).
-			 */
-			if (m > 0)
-				m >>= 3;
-		} else {
-			m -= (hc->tx_mdev >> 2);
-		}
-		hc->tx_mdev += m;
-
-		if (hc->tx_mdev > hc->tx_mdev_max) {
-			hc->tx_mdev_max = hc->tx_mdev;
-			if (hc->tx_mdev_max > hc->tx_rttvar)
-				hc->tx_rttvar = hc->tx_mdev_max;
-		}
-
-		/*
-		 * Decay RTTVAR at most once per flight, exploiting that
-		 *  1) pipe <= cwnd <= Sequence_Window = W  (RFC 4340, 7.5.2)
-		 *  2) AWL = GSS-W+1 <= GAR <= GSS          (RFC 4340, 7.5.1)
-		 * GAR is a useful bound for FlightSize = pipe.
-		 * AWL is probably too low here, as it over-estimates pipe.
-		 */
-		if (after48(dccp_sk(sk)->dccps_gar, hc->tx_rtt_seq)) {
-			if (hc->tx_mdev_max < hc->tx_rttvar)
-				hc->tx_rttvar -= (hc->tx_rttvar -
-						  hc->tx_mdev_max) >> 2;
-			hc->tx_rtt_seq  = dccp_sk(sk)->dccps_gss;
-			hc->tx_mdev_max = tcp_rto_min(sk);
-		}
-	}
-
-	/*
-	 * Set RTO from SRTT and RTTVAR
-	 * As in TCP, 4 * RTTVAR >= TCP_RTO_MIN, giving a minimum RTO of 200 ms.
-	 * This agrees with RFC 4341, 5:
-	 *	"Because DCCP does not retransmit data, DCCP does not require
-	 *	 TCP's recommended minimum timeout of one second".
-	 */
-	hc->tx_rto = (hc->tx_srtt >> 3) + hc->tx_rttvar;
-
-	if (hc->tx_rto > DCCP_RTO_MAX)
-		hc->tx_rto = DCCP_RTO_MAX;
-}
-
-static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp,
-			  unsigned int *maxincr)
-{
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-	struct dccp_sock *dp = dccp_sk(sk);
-	int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio;
-
-	if (hc->tx_cwnd < dp->dccps_l_seq_win &&
-	    r_seq_used < dp->dccps_r_seq_win) {
-		if (hc->tx_cwnd < hc->tx_ssthresh) {
-			if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) {
-				hc->tx_cwnd += 1;
-				*maxincr    -= 1;
-				hc->tx_packets_acked = 0;
-			}
-		} else if (++hc->tx_packets_acked >= hc->tx_cwnd) {
-			hc->tx_cwnd += 1;
-			hc->tx_packets_acked = 0;
-		}
-	}
-
-	/*
-	 * Adjust the local sequence window and the ack ratio to allow about
-	 * 5 times the number of packets in the network (RFC 4340 7.5.2)
-	 */
-	if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win)
-		ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2);
-	else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2)
-		ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U);
-
-	if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win)
-		ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win * 2);
-	else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2)
-		ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win / 2);
-
-	/*
-	 * FIXME: RTT is sampled several times per acknowledgment (for each
-	 * entry in the Ack Vector), instead of once per Ack (as in TCP SACK).
-	 * This causes the RTT to be over-estimated, since the older entries
-	 * in the Ack Vector have earlier sending times.
-	 * The cleanest solution is to not use the ccid2s_sent field at all
-	 * and instead use DCCP timestamps: requires changes in other places.
-	 */
-	ccid2_rtt_estimator(sk, ccid2_jiffies32 - seqp->ccid2s_sent);
-}
-
-static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
-{
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-
-	if ((s32)(seqp->ccid2s_sent - hc->tx_last_cong) < 0) {
-		ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
-		return;
-	}
-
-	hc->tx_last_cong = ccid2_jiffies32;
-
-	hc->tx_cwnd      = hc->tx_cwnd / 2 ? : 1U;
-	hc->tx_ssthresh  = max(hc->tx_cwnd, 2U);
-
-	ccid2_check_l_ack_ratio(sk);
-}
-
-static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type,
-				     u8 option, u8 *optval, u8 optlen)
-{
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-
-	switch (option) {
-	case DCCPO_ACK_VECTOR_0:
-	case DCCPO_ACK_VECTOR_1:
-		return dccp_ackvec_parsed_add(&hc->tx_av_chunks, optval, optlen,
-					      option - DCCPO_ACK_VECTOR_0);
-	}
-	return 0;
-}
-
-static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
-{
-	struct dccp_sock *dp = dccp_sk(sk);
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-	const bool sender_was_blocked = ccid2_cwnd_network_limited(hc);
-	struct dccp_ackvec_parsed *avp;
-	u64 ackno, seqno;
-	struct ccid2_seq *seqp;
-	int done = 0;
-	unsigned int maxincr = 0;
-
-	/* check reverse path congestion */
-	seqno = DCCP_SKB_CB(skb)->dccpd_seq;
-
-	/* XXX this whole "algorithm" is broken.  Need to fix it to keep track
-	 * of the seqnos of the dupacks so that rpseq and rpdupack are correct
-	 * -sorbo.
-	 */
-	/* need to bootstrap */
-	if (hc->tx_rpdupack == -1) {
-		hc->tx_rpdupack = 0;
-		hc->tx_rpseq    = seqno;
-	} else {
-		/* check if packet is consecutive */
-		if (dccp_delta_seqno(hc->tx_rpseq, seqno) == 1)
-			hc->tx_rpseq = seqno;
-		/* it's a later packet */
-		else if (after48(seqno, hc->tx_rpseq)) {
-			hc->tx_rpdupack++;
-
-			/* check if we got enough dupacks */
-			if (hc->tx_rpdupack >= NUMDUPACK) {
-				hc->tx_rpdupack = -1; /* XXX lame */
-				hc->tx_rpseq    = 0;
-#ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__
-				/*
-				 * FIXME: Ack Congestion Control is broken; in
-				 * the current state instabilities occurred with
-				 * Ack Ratios greater than 1; causing hang-ups
-				 * and long RTO timeouts. This needs to be fixed
-				 * before opening up dynamic changes. -- gerrit
-				 */
-				ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
-#endif
-			}
-		}
-	}
-
-	/* check forward path congestion */
-	if (dccp_packet_without_ack(skb))
-		return;
-
-	/* still didn't send out new data packets */
-	if (hc->tx_seqh == hc->tx_seqt)
-		goto done;
-
-	ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
-	if (after48(ackno, hc->tx_high_ack))
-		hc->tx_high_ack = ackno;
-
-	seqp = hc->tx_seqt;
-	while (before48(seqp->ccid2s_seq, ackno)) {
-		seqp = seqp->ccid2s_next;
-		if (seqp == hc->tx_seqh) {
-			seqp = hc->tx_seqh->ccid2s_prev;
-			break;
-		}
-	}
-
-	/*
-	 * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
-	 * packets per acknowledgement. Rounding up avoids that cwnd is not
-	 * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
-	 */
-	if (hc->tx_cwnd < hc->tx_ssthresh)
-		maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
-
-	/* go through all ack vectors */
-	list_for_each_entry(avp, &hc->tx_av_chunks, node) {
-		/* go through this ack vector */
-		for (; avp->len--; avp->vec++) {
-			u64 ackno_end_rl = SUB48(ackno,
-						 dccp_ackvec_runlen(avp->vec));
-
-			ccid2_pr_debug("ackvec %llu |%u,%u|\n",
-				       (unsigned long long)ackno,
-				       dccp_ackvec_state(avp->vec) >> 6,
-				       dccp_ackvec_runlen(avp->vec));
-			/* if the seqno we are analyzing is larger than the
-			 * current ackno, then move towards the tail of our
-			 * seqnos.
-			 */
-			while (after48(seqp->ccid2s_seq, ackno)) {
-				if (seqp == hc->tx_seqt) {
-					done = 1;
-					break;
-				}
-				seqp = seqp->ccid2s_prev;
-			}
-			if (done)
-				break;
-
-			/* check all seqnos in the range of the vector
-			 * run length
-			 */
-			while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
-				const u8 state = dccp_ackvec_state(avp->vec);
-
-				/* new packet received or marked */
-				if (state != DCCPAV_NOT_RECEIVED &&
-				    !seqp->ccid2s_acked) {
-					if (state == DCCPAV_ECN_MARKED)
-						ccid2_congestion_event(sk,
-								       seqp);
-					else
-						ccid2_new_ack(sk, seqp,
-							      &maxincr);
-
-					seqp->ccid2s_acked = 1;
-					ccid2_pr_debug("Got ack for %llu\n",
-						       (unsigned long long)seqp->ccid2s_seq);
-					hc->tx_pipe--;
-				}
-				if (seqp == hc->tx_seqt) {
-					done = 1;
-					break;
-				}
-				seqp = seqp->ccid2s_prev;
-			}
-			if (done)
-				break;
-
-			ackno = SUB48(ackno_end_rl, 1);
-		}
-		if (done)
-			break;
-	}
-
-	/* The state about what is acked should be correct now
-	 * Check for NUMDUPACK
-	 */
-	seqp = hc->tx_seqt;
-	while (before48(seqp->ccid2s_seq, hc->tx_high_ack)) {
-		seqp = seqp->ccid2s_next;
-		if (seqp == hc->tx_seqh) {
-			seqp = hc->tx_seqh->ccid2s_prev;
-			break;
-		}
-	}
-	done = 0;
-	while (1) {
-		if (seqp->ccid2s_acked) {
-			done++;
-			if (done == NUMDUPACK)
-				break;
-		}
-		if (seqp == hc->tx_seqt)
-			break;
-		seqp = seqp->ccid2s_prev;
-	}
-
-	/* If there are at least 3 acknowledgements, anything unacknowledged
-	 * below the last sequence number is considered lost
-	 */
-	if (done == NUMDUPACK) {
-		struct ccid2_seq *last_acked = seqp;
-
-		/* check for lost packets */
-		while (1) {
-			if (!seqp->ccid2s_acked) {
-				ccid2_pr_debug("Packet lost: %llu\n",
-					       (unsigned long long)seqp->ccid2s_seq);
-				/* XXX need to traverse from tail -> head in
-				 * order to detect multiple congestion events in
-				 * one ack vector.
-				 */
-				ccid2_congestion_event(sk, seqp);
-				hc->tx_pipe--;
-			}
-			if (seqp == hc->tx_seqt)
-				break;
-			seqp = seqp->ccid2s_prev;
-		}
-
-		hc->tx_seqt = last_acked;
-	}
-
-	/* trim acked packets in tail */
-	while (hc->tx_seqt != hc->tx_seqh) {
-		if (!hc->tx_seqt->ccid2s_acked)
-			break;
-
-		hc->tx_seqt = hc->tx_seqt->ccid2s_next;
-	}
-
-	/* restart RTO timer if not all outstanding data has been acked */
-	if (hc->tx_pipe == 0)
-		sk_stop_timer(sk, &hc->tx_rtotimer);
-	else
-		sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
-done:
-	/* check if incoming Acks allow pending packets to be sent */
-	if (sender_was_blocked && !ccid2_cwnd_network_limited(hc))
-		dccp_tasklet_schedule(sk);
-	dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
-}
-
-static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
-{
-	struct ccid2_hc_tx_sock *hc = ccid_priv(ccid);
-	struct dccp_sock *dp = dccp_sk(sk);
-	u32 max_ratio;
-
-	/* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
-	hc->tx_ssthresh = ~0U;
-
-	/* Use larger initial windows (RFC 4341, section 5). */
-	hc->tx_cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache);
-	hc->tx_expected_wnd = hc->tx_cwnd;
-
-	/* Make sure that Ack Ratio is enabled and within bounds. */
-	max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2);
-	if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
-		dp->dccps_l_ack_ratio = max_ratio;
-
-	/* XXX init ~ to window size... */
-	if (ccid2_hc_tx_alloc_seq(hc))
-		return -ENOMEM;
-
-	hc->tx_rto	 = DCCP_TIMEOUT_INIT;
-	hc->tx_rpdupack  = -1;
-	hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_jiffies32;
-	hc->tx_cwnd_used = 0;
-	hc->sk		 = sk;
-	timer_setup(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 0);
-	INIT_LIST_HEAD(&hc->tx_av_chunks);
-	return 0;
-}
-
-static void ccid2_hc_tx_exit(struct sock *sk)
-{
-	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-	int i;
-
-	sk_stop_timer(sk, &hc->tx_rtotimer);
-
-	for (i = 0; i < hc->tx_seqbufc; i++)
-		kfree(hc->tx_seqbuf[i]);
-	hc->tx_seqbufc = 0;
-	dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
-}
-
-static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
-{
-	struct ccid2_hc_rx_sock *hc = ccid2_hc_rx_sk(sk);
-
-	if (!dccp_data_packet(skb))
-		return;
-
-	if (++hc->rx_num_data_pkts >= dccp_sk(sk)->dccps_r_ack_ratio) {
-		dccp_send_ack(sk);
-		hc->rx_num_data_pkts = 0;
-	}
-}
-
-struct ccid_operations ccid2_ops = {
-	.ccid_id		  = DCCPC_CCID2,
-	.ccid_name		  = "TCP-like",
-	.ccid_hc_tx_obj_size	  = sizeof(struct ccid2_hc_tx_sock),
-	.ccid_hc_tx_init	  = ccid2_hc_tx_init,
-	.ccid_hc_tx_exit	  = ccid2_hc_tx_exit,
-	.ccid_hc_tx_send_packet	  = ccid2_hc_tx_send_packet,
-	.ccid_hc_tx_packet_sent	  = ccid2_hc_tx_packet_sent,
-	.ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options,
-	.ccid_hc_tx_packet_recv	  = ccid2_hc_tx_packet_recv,
-	.ccid_hc_rx_obj_size	  = sizeof(struct ccid2_hc_rx_sock),
-	.ccid_hc_rx_packet_recv	  = ccid2_hc_rx_packet_recv,
-};
-
-#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
-module_param(ccid2_debug, bool, 0644);
-MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages");
-#endif