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, 1581 deletions

diff --git a/net/dccp/feat.c b/net/dccp/feat.c
deleted file mode 100644
index f7554dcdaaba..000000000000
--- a/net/dccp/feat.c
+++ /dev/null
@@ -1,1581 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- *  net/dccp/feat.c
- *
- *  Feature negotiation for the DCCP protocol (RFC 4340, section 6)
- *
- *  Copyright (c) 2008 Gerrit Renker <[email protected]>
- *  Rewrote from scratch, some bits from earlier code by
- *  Copyright (c) 2005 Andrea Bittau <[email protected]>
- *
- *  ASSUMPTIONS
- *  -----------
- *  o Feature negotiation is coordinated with connection setup (as in TCP), wild
- *    changes of parameters of an established connection are not supported.
- *  o Changing non-negotiable (NN) values is supported in state OPEN/PARTOPEN.
- *  o All currently known SP features have 1-byte quantities. If in the future
- *    extensions of RFCs 4340..42 define features with item lengths larger than
- *    one byte, a feature-specific extension of the code will be required.
- */
-#include <linux/module.h>
-#include <linux/slab.h>
-#include "ccid.h"
-#include "feat.h"
-
-/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */
-unsigned long	sysctl_dccp_sequence_window __read_mostly = 100;
-int		sysctl_dccp_rx_ccid	    __read_mostly = 2,
-		sysctl_dccp_tx_ccid	    __read_mostly = 2;
-
-/*
- * Feature activation handlers.
- *
- * These all use an u64 argument, to provide enough room for NN/SP features. At
- * this stage the negotiated values have been checked to be within their range.
- */
-static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
-{
-	struct dccp_sock *dp = dccp_sk(sk);
-	struct ccid *new_ccid = ccid_new(ccid, sk, rx);
-
-	if (new_ccid == NULL)
-		return -ENOMEM;
-
-	if (rx) {
-		ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
-		dp->dccps_hc_rx_ccid = new_ccid;
-	} else {
-		ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
-		dp->dccps_hc_tx_ccid = new_ccid;
-	}
-	return 0;
-}
-
-static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
-{
-	struct dccp_sock *dp = dccp_sk(sk);
-
-	if (rx) {
-		dp->dccps_r_seq_win = seq_win;
-		/* propagate changes to update SWL/SWH */
-		dccp_update_gsr(sk, dp->dccps_gsr);
-	} else {
-		dp->dccps_l_seq_win = seq_win;
-		/* propagate changes to update AWL */
-		dccp_update_gss(sk, dp->dccps_gss);
-	}
-	return 0;
-}
-
-static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx)
-{
-	if (rx)
-		dccp_sk(sk)->dccps_r_ack_ratio = ratio;
-	else
-		dccp_sk(sk)->dccps_l_ack_ratio = ratio;
-	return 0;
-}
-
-static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
-{
-	struct dccp_sock *dp = dccp_sk(sk);
-
-	if (rx) {
-		if (enable && dp->dccps_hc_rx_ackvec == NULL) {
-			dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any());
-			if (dp->dccps_hc_rx_ackvec == NULL)
-				return -ENOMEM;
-		} else if (!enable) {
-			dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
-			dp->dccps_hc_rx_ackvec = NULL;
-		}
-	}
-	return 0;
-}
-
-static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
-{
-	if (!rx)
-		dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
-	return 0;
-}
-
-/*
- * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that
- * `rx' holds when the sending peer informs about his partial coverage via a
- * ChangeR() option. In the other case, we are the sender and the receiver
- * announces its coverage via ChangeL() options. The policy here is to honour
- * such communication by enabling the corresponding partial coverage - but only
- * if it has not been set manually before; the warning here means that all
- * packets will be dropped.
- */
-static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx)
-{
-	struct dccp_sock *dp = dccp_sk(sk);
-
-	if (rx)
-		dp->dccps_pcrlen = cscov;
-	else {
-		if (dp->dccps_pcslen == 0)
-			dp->dccps_pcslen = cscov;
-		else if (cscov > dp->dccps_pcslen)
-			DCCP_WARN("CsCov %u too small, peer requires >= %u\n",
-				  dp->dccps_pcslen, (u8)cscov);
-	}
-	return 0;
-}
-
-static const struct {
-	u8			feat_num;		/* DCCPF_xxx */
-	enum dccp_feat_type	rxtx;			/* RX or TX  */
-	enum dccp_feat_type	reconciliation;		/* SP or NN  */
-	u8			default_value;		/* as in 6.4 */
-	int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
-/*
- *    Lookup table for location and type of features (from RFC 4340/4342)
- *  +--------------------------+----+-----+----+----+---------+-----------+
- *  | Feature                  | Location | Reconc. | Initial |  Section  |
- *  |                          | RX | TX  | SP | NN |  Value  | Reference |
- *  +--------------------------+----+-----+----+----+---------+-----------+
- *  | DCCPF_CCID               |    |  X  | X  |    |   2     | 10        |
- *  | DCCPF_SHORT_SEQNOS       |    |  X  | X  |    |   0     |  7.6.1    |
- *  | DCCPF_SEQUENCE_WINDOW    |    |  X  |    | X  | 100     |  7.5.2    |
- *  | DCCPF_ECN_INCAPABLE      | X  |     | X  |    |   0     | 12.1      |
- *  | DCCPF_ACK_RATIO          |    |  X  |    | X  |   2     | 11.3      |
- *  | DCCPF_SEND_ACK_VECTOR    | X  |     | X  |    |   0     | 11.5      |
- *  | DCCPF_SEND_NDP_COUNT     |    |  X  | X  |    |   0     |  7.7.2    |
- *  | DCCPF_MIN_CSUM_COVER     | X  |     | X  |    |   0     |  9.2.1    |
- *  | DCCPF_DATA_CHECKSUM      | X  |     | X  |    |   0     |  9.3.1    |
- *  | DCCPF_SEND_LEV_RATE      | X  |     | X  |    |   0     | 4342/8.4  |
- *  +--------------------------+----+-----+----+----+---------+-----------+
- */
-} dccp_feat_table[] = {
-	{ DCCPF_CCID,		 FEAT_AT_TX, FEAT_SP, 2,   dccp_hdlr_ccid     },
-	{ DCCPF_SHORT_SEQNOS,	 FEAT_AT_TX, FEAT_SP, 0,   NULL },
-	{ DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win  },
-	{ DCCPF_ECN_INCAPABLE,	 FEAT_AT_RX, FEAT_SP, 0,   NULL },
-	{ DCCPF_ACK_RATIO,	 FEAT_AT_TX, FEAT_NN, 2,   dccp_hdlr_ack_ratio},
-	{ DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0,   dccp_hdlr_ackvec   },
-	{ DCCPF_SEND_NDP_COUNT,  FEAT_AT_TX, FEAT_SP, 0,   dccp_hdlr_ndp      },
-	{ DCCPF_MIN_CSUM_COVER,  FEAT_AT_RX, FEAT_SP, 0,   dccp_hdlr_min_cscov},
-	{ DCCPF_DATA_CHECKSUM,	 FEAT_AT_RX, FEAT_SP, 0,   NULL },
-	{ DCCPF_SEND_LEV_RATE,	 FEAT_AT_RX, FEAT_SP, 0,   NULL },
-};
-#define DCCP_FEAT_SUPPORTED_MAX		ARRAY_SIZE(dccp_feat_table)
-
-/**
- * dccp_feat_index  -  Hash function to map feature number into array position
- * @feat_num: feature to hash, one of %dccp_feature_numbers
- *
- * Returns consecutive array index or -1 if the feature is not understood.
- */
-static int dccp_feat_index(u8 feat_num)
-{
-	/* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
-	if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
-		return feat_num - 1;
-
-	/*
-	 * Other features: add cases for new feature types here after adding
-	 * them to the above table.
-	 */
-	switch (feat_num) {
-	case DCCPF_SEND_LEV_RATE:
-			return DCCP_FEAT_SUPPORTED_MAX - 1;
-	}
-	return -1;
-}
-
-static u8 dccp_feat_type(u8 feat_num)
-{
-	int idx = dccp_feat_index(feat_num);
-
-	if (idx < 0)
-		return FEAT_UNKNOWN;
-	return dccp_feat_table[idx].reconciliation;
-}
-
-static int dccp_feat_default_value(u8 feat_num)
-{
-	int idx = dccp_feat_index(feat_num);
-	/*
-	 * There are no default values for unknown features, so encountering a
-	 * negative index here indicates a serious problem somewhere else.
-	 */
-	DCCP_BUG_ON(idx < 0);
-
-	return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
-}
-
-/*
- *	Debugging and verbose-printing section
- */
-static const char *dccp_feat_fname(const u8 feat)
-{
-	static const char *const feature_names[] = {
-		[DCCPF_RESERVED]	= "Reserved",
-		[DCCPF_CCID]		= "CCID",
-		[DCCPF_SHORT_SEQNOS]	= "Allow Short Seqnos",
-		[DCCPF_SEQUENCE_WINDOW]	= "Sequence Window",
-		[DCCPF_ECN_INCAPABLE]	= "ECN Incapable",
-		[DCCPF_ACK_RATIO]	= "Ack Ratio",
-		[DCCPF_SEND_ACK_VECTOR]	= "Send ACK Vector",
-		[DCCPF_SEND_NDP_COUNT]	= "Send NDP Count",
-		[DCCPF_MIN_CSUM_COVER]	= "Min. Csum Coverage",
-		[DCCPF_DATA_CHECKSUM]	= "Send Data Checksum",
-	};
-	if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
-		return feature_names[DCCPF_RESERVED];
-
-	if (feat ==  DCCPF_SEND_LEV_RATE)
-		return "Send Loss Event Rate";
-	if (feat >= DCCPF_MIN_CCID_SPECIFIC)
-		return "CCID-specific";
-
-	return feature_names[feat];
-}
-
-static const char *const dccp_feat_sname[] = {
-	"DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE",
-};
-
-#ifdef CONFIG_IP_DCCP_DEBUG
-static const char *dccp_feat_oname(const u8 opt)
-{
-	switch (opt) {
-	case DCCPO_CHANGE_L:  return "Change_L";
-	case DCCPO_CONFIRM_L: return "Confirm_L";
-	case DCCPO_CHANGE_R:  return "Change_R";
-	case DCCPO_CONFIRM_R: return "Confirm_R";
-	}
-	return NULL;
-}
-
-static void dccp_feat_printval(u8 feat_num, dccp_feat_val const *val)
-{
-	u8 i, type = dccp_feat_type(feat_num);
-
-	if (val == NULL || (type == FEAT_SP && val->sp.vec == NULL))
-		dccp_pr_debug_cat("(NULL)");
-	else if (type == FEAT_SP)
-		for (i = 0; i < val->sp.len; i++)
-			dccp_pr_debug_cat("%s%u", i ? " " : "", val->sp.vec[i]);
-	else if (type == FEAT_NN)
-		dccp_pr_debug_cat("%llu", (unsigned long long)val->nn);
-	else
-		dccp_pr_debug_cat("unknown type %u", type);
-}
-
-static void dccp_feat_printvals(u8 feat_num, u8 *list, u8 len)
-{
-	u8 type = dccp_feat_type(feat_num);
-	dccp_feat_val fval = { .sp.vec = list, .sp.len = len };
-
-	if (type == FEAT_NN)
-		fval.nn = dccp_decode_value_var(list, len);
-	dccp_feat_printval(feat_num, &fval);
-}
-
-static void dccp_feat_print_entry(struct dccp_feat_entry const *entry)
-{
-	dccp_debug("   * %s %s = ", entry->is_local ? "local" : "remote",
-				    dccp_feat_fname(entry->feat_num));
-	dccp_feat_printval(entry->feat_num, &entry->val);
-	dccp_pr_debug_cat(", state=%s %s\n", dccp_feat_sname[entry->state],
-			  entry->needs_confirm ? "(Confirm pending)" : "");
-}
-
-#define dccp_feat_print_opt(opt, feat, val, len, mandatory)	do {	      \
-	dccp_pr_debug("%s(%s, ", dccp_feat_oname(opt), dccp_feat_fname(feat));\
-	dccp_feat_printvals(feat, val, len);				      \
-	dccp_pr_debug_cat(") %s\n", mandatory ? "!" : "");	} while (0)
-
-#define dccp_feat_print_fnlist(fn_list)  {		\
-	const struct dccp_feat_entry *___entry;		\
-							\
-	dccp_pr_debug("List Dump:\n");			\
-	list_for_each_entry(___entry, fn_list, node)	\
-		dccp_feat_print_entry(___entry);	\
-}
-#else	/* ! CONFIG_IP_DCCP_DEBUG */
-#define dccp_feat_print_opt(opt, feat, val, len, mandatory)
-#define dccp_feat_print_fnlist(fn_list)
-#endif
-
-static int __dccp_feat_activate(struct sock *sk, const int idx,
-				const bool is_local, dccp_feat_val const *fval)
-{
-	bool rx;
-	u64 val;
-
-	if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX)
-		return -1;
-	if (dccp_feat_table[idx].activation_hdlr == NULL)
-		return 0;
-
-	if (fval == NULL) {
-		val = dccp_feat_table[idx].default_value;
-	} else if (dccp_feat_table[idx].reconciliation == FEAT_SP) {
-		if (fval->sp.vec == NULL) {
-			/*
-			 * This can happen when an empty Confirm is sent
-			 * for an SP (i.e. known) feature. In this case
-			 * we would be using the default anyway.
-			 */
-			DCCP_CRIT("Feature #%d undefined: using default", idx);
-			val = dccp_feat_table[idx].default_value;
-		} else {
-			val = fval->sp.vec[0];
-		}
-	} else {
-		val = fval->nn;
-	}
-
-	/* Location is RX if this is a local-RX or remote-TX feature */
-	rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX));
-
-	dccp_debug("   -> activating %s %s, %sval=%llu\n", rx ? "RX" : "TX",
-		   dccp_feat_fname(dccp_feat_table[idx].feat_num),
-		   fval ? "" : "default ",  (unsigned long long)val);
-
-	return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
-}
-
-/**
- * dccp_feat_activate  -  Activate feature value on socket
- * @sk: fully connected DCCP socket (after handshake is complete)
- * @feat_num: feature to activate, one of %dccp_feature_numbers
- * @local: whether local (1) or remote (0) @feat_num is meant
- * @fval: the value (SP or NN) to activate, or NULL to use the default value
- *
- * For general use this function is preferable over __dccp_feat_activate().
- */
-static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local,
-			      dccp_feat_val const *fval)
-{
-	return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval);
-}
-
-/* Test for "Req'd" feature (RFC 4340, 6.4) */
-static inline int dccp_feat_must_be_understood(u8 feat_num)
-{
-	return	feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
-		feat_num == DCCPF_SEQUENCE_WINDOW;
-}
-
-/* copy constructor, fval must not already contain allocated memory */
-static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
-{
-	fval->sp.len = len;
-	if (fval->sp.len > 0) {
-		fval->sp.vec = kmemdup(val, len, gfp_any());
-		if (fval->sp.vec == NULL) {
-			fval->sp.len = 0;
-			return -ENOMEM;
-		}
-	}
-	return 0;
-}
-
-static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
-{
-	if (unlikely(val == NULL))
-		return;
-	if (dccp_feat_type(feat_num) == FEAT_SP)
-		kfree(val->sp.vec);
-	memset(val, 0, sizeof(*val));
-}
-
-static struct dccp_feat_entry *
-	      dccp_feat_clone_entry(struct dccp_feat_entry const *original)
-{
-	struct dccp_feat_entry *new;
-	u8 type = dccp_feat_type(original->feat_num);
-
-	if (type == FEAT_UNKNOWN)
-		return NULL;
-
-	new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
-	if (new == NULL)
-		return NULL;
-
-	if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
-						      original->val.sp.vec,
-						      original->val.sp.len)) {
-		kfree(new);
-		return NULL;
-	}
-	return new;
-}
-
-static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
-{
-	if (entry != NULL) {
-		dccp_feat_val_destructor(entry->feat_num, &entry->val);
-		kfree(entry);
-	}
-}
-
-/*
- * List management functions
- *
- * Feature negotiation lists rely on and maintain the following invariants:
- * - each feat_num in the list is known, i.e. we know its type and default value
- * - each feat_num/is_local combination is unique (old entries are overwritten)
- * - SP values are always freshly allocated
- * - list is sorted in increasing order of feature number (faster lookup)
- */
-static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
-						     u8 feat_num, bool is_local)
-{
-	struct dccp_feat_entry *entry;
-
-	list_for_each_entry(entry, fn_list, node) {
-		if (entry->feat_num == feat_num && entry->is_local == is_local)
-			return entry;
-		else if (entry->feat_num > feat_num)
-			break;
-	}
-	return NULL;
-}
-
-/**
- * dccp_feat_entry_new  -  Central list update routine (called by all others)
- * @head:  list to add to
- * @feat:  feature number
- * @local: whether the local (1) or remote feature with number @feat is meant
- *
- * This is the only constructor and serves to ensure the above invariants.
- */
-static struct dccp_feat_entry *
-	      dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
-{
-	struct dccp_feat_entry *entry;
-
-	list_for_each_entry(entry, head, node)
-		if (entry->feat_num == feat && entry->is_local == local) {
-			dccp_feat_val_destructor(entry->feat_num, &entry->val);
-			return entry;
-		} else if (entry->feat_num > feat) {
-			head = &entry->node;
-			break;
-		}
-
-	entry = kmalloc(sizeof(*entry), gfp_any());
-	if (entry != NULL) {
-		entry->feat_num = feat;
-		entry->is_local = local;
-		list_add_tail(&entry->node, head);
-	}
-	return entry;
-}
-
-/**
- * dccp_feat_push_change  -  Add/overwrite a Change option in the list
- * @fn_list: feature-negotiation list to update
- * @feat: one of %dccp_feature_numbers
- * @local: whether local (1) or remote (0) @feat_num is meant
- * @mandatory: whether to use Mandatory feature negotiation options
- * @fval: pointer to NN/SP value to be inserted (will be copied)
- */
-static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
-				 u8 mandatory, dccp_feat_val *fval)
-{
-	struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
-
-	if (new == NULL)
-		return -ENOMEM;
-
-	new->feat_num	     = feat;
-	new->is_local	     = local;
-	new->state	     = FEAT_INITIALISING;
-	new->needs_confirm   = false;
-	new->empty_confirm   = false;
-	new->val	     = *fval;
-	new->needs_mandatory = mandatory;
-
-	return 0;
-}
-
-/**
- * dccp_feat_push_confirm  -  Add a Confirm entry to the FN list
- * @fn_list: feature-negotiation list to add to
- * @feat: one of %dccp_feature_numbers
- * @local: whether local (1) or remote (0) @feat_num is being confirmed
- * @fval: pointer to NN/SP value to be inserted or NULL
- *
- * Returns 0 on success, a Reset code for further processing otherwise.
- */
-static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
-				  dccp_feat_val *fval)
-{
-	struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
-
-	if (new == NULL)
-		return DCCP_RESET_CODE_TOO_BUSY;
-
-	new->feat_num	     = feat;
-	new->is_local	     = local;
-	new->state	     = FEAT_STABLE;	/* transition in 6.6.2 */
-	new->needs_confirm   = true;
-	new->empty_confirm   = (fval == NULL);
-	new->val.nn	     = 0;		/* zeroes the whole structure */
-	if (!new->empty_confirm)
-		new->val     = *fval;
-	new->needs_mandatory = false;
-
-	return 0;
-}
-
-static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
-{
-	return dccp_feat_push_confirm(fn_list, feat, local, NULL);
-}
-
-static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
-{
-	list_del(&entry->node);
-	dccp_feat_entry_destructor(entry);
-}
-
-void dccp_feat_list_purge(struct list_head *fn_list)
-{
-	struct dccp_feat_entry *entry, *next;
-
-	list_for_each_entry_safe(entry, next, fn_list, node)
-		dccp_feat_entry_destructor(entry);
-	INIT_LIST_HEAD(fn_list);
-}
-EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
-
-/* generate @to as full clone of @from - @to must not contain any nodes */
-int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
-{
-	struct dccp_feat_entry *entry, *new;
-
-	INIT_LIST_HEAD(to);
-	list_for_each_entry(entry, from, node) {
-		new = dccp_feat_clone_entry(entry);
-		if (new == NULL)
-			goto cloning_failed;
-		list_add_tail(&new->node, to);
-	}
-	return 0;
-
-cloning_failed:
-	dccp_feat_list_purge(to);
-	return -ENOMEM;
-}
-
-/**
- * dccp_feat_valid_nn_length  -  Enforce length constraints on NN options
- * @feat_num: feature to return length of, one of %dccp_feature_numbers
- *
- * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
- * incoming options are accepted as long as their values are valid.
- */
-static u8 dccp_feat_valid_nn_length(u8 feat_num)
-{
-	if (feat_num == DCCPF_ACK_RATIO)	/* RFC 4340, 11.3 and 6.6.8 */
-		return 2;
-	if (feat_num == DCCPF_SEQUENCE_WINDOW)	/* RFC 4340, 7.5.2 and 6.5  */
-		return 6;
-	return 0;
-}
-
-static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
-{
-	switch (feat_num) {
-	case DCCPF_ACK_RATIO:
-		return val <= DCCPF_ACK_RATIO_MAX;
-	case DCCPF_SEQUENCE_WINDOW:
-		return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
-	}
-	return 0;	/* feature unknown - so we can't tell */
-}
-
-/* check that SP values are within the ranges defined in RFC 4340 */
-static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
-{
-	switch (feat_num) {
-	case DCCPF_CCID:
-		return val == DCCPC_CCID2 || val == DCCPC_CCID3;
-	/* Type-check Boolean feature values: */
-	case DCCPF_SHORT_SEQNOS:
-	case DCCPF_ECN_INCAPABLE:
-	case DCCPF_SEND_ACK_VECTOR:
-	case DCCPF_SEND_NDP_COUNT:
-	case DCCPF_DATA_CHECKSUM:
-	case DCCPF_SEND_LEV_RATE:
-		return val < 2;
-	case DCCPF_MIN_CSUM_COVER:
-		return val < 16;
-	}
-	return 0;			/* feature unknown */
-}
-
-static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
-{
-	if (sp_list == NULL || sp_len < 1)
-		return 0;
-	while (sp_len--)
-		if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
-			return 0;
-	return 1;
-}
-
-/**
- * dccp_feat_insert_opts  -  Generate FN options from current list state
- * @skb: next sk_buff to be sent to the peer
- * @dp: for client during handshake and general negotiation
- * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
- */
-int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
-			  struct sk_buff *skb)
-{
-	struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
-	struct dccp_feat_entry *pos, *next;
-	u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
-	bool rpt;
-
-	/* put entries into @skb in the order they appear in the list */
-	list_for_each_entry_safe_reverse(pos, next, fn, node) {
-		opt  = dccp_feat_genopt(pos);
-		type = dccp_feat_type(pos->feat_num);
-		rpt  = false;
-
-		if (pos->empty_confirm) {
-			len = 0;
-			ptr = NULL;
-		} else {
-			if (type == FEAT_SP) {
-				len = pos->val.sp.len;
-				ptr = pos->val.sp.vec;
-				rpt = pos->needs_confirm;
-			} else if (type == FEAT_NN) {
-				len = dccp_feat_valid_nn_length(pos->feat_num);
-				ptr = nn_in_nbo;
-				dccp_encode_value_var(pos->val.nn, ptr, len);
-			} else {
-				DCCP_BUG("unknown feature %u", pos->feat_num);
-				return -1;
-			}
-		}
-		dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0);
-
-		if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
-			return -1;
-		if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
-			return -1;
-
-		if (skb->sk->sk_state == DCCP_OPEN &&
-		    (opt == DCCPO_CONFIRM_R || opt == DCCPO_CONFIRM_L)) {
-			/*
-			 * Confirms don't get retransmitted (6.6.3) once the
-			 * connection is in state OPEN
-			 */
-			dccp_feat_list_pop(pos);
-		} else {
-			/*
-			 * Enter CHANGING after transmitting the Change
-			 * option (6.6.2).
-			 */
-			if (pos->state == FEAT_INITIALISING)
-				pos->state = FEAT_CHANGING;
-		}
-	}
-	return 0;
-}
-
-/**
- * __feat_register_nn  -  Register new NN value on socket
- * @fn: feature-negotiation list to register with
- * @feat: an NN feature from %dccp_feature_numbers
- * @mandatory: use Mandatory option if 1
- * @nn_val: value to register (restricted to 4 bytes)
- *
- * Note that NN features are local by definition (RFC 4340, 6.3.2).
- */
-static int __feat_register_nn(struct list_head *fn, u8 feat,
-			      u8 mandatory, u64 nn_val)
-{
-	dccp_feat_val fval = { .nn = nn_val };
-
-	if (dccp_feat_type(feat) != FEAT_NN ||
-	    !dccp_feat_is_valid_nn_val(feat, nn_val))
-		return -EINVAL;
-
-	/* Don't bother with default values, they will be activated anyway. */
-	if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
-		return 0;
-
-	return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
-}
-
-/**
- * __feat_register_sp  -  Register new SP value/list on socket
- * @fn: feature-negotiation list to register with
- * @feat: an SP feature from %dccp_feature_numbers
- * @is_local: whether the local (1) or the remote (0) @feat is meant
- * @mandatory: use Mandatory option if 1
- * @sp_val: SP value followed by optional preference list
- * @sp_len: length of @sp_val in bytes
- */
-static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
-			      u8 mandatory, u8 const *sp_val, u8 sp_len)
-{
-	dccp_feat_val fval;
-
-	if (dccp_feat_type(feat) != FEAT_SP ||
-	    !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
-		return -EINVAL;
-
-	/* Avoid negotiating alien CCIDs by only advertising supported ones */
-	if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
-		return -EOPNOTSUPP;
-
-	if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
-		return -ENOMEM;
-
-	if (dccp_feat_push_change(fn, feat, is_local, mandatory, &fval)) {
-		kfree(fval.sp.vec);
-		return -ENOMEM;
-	}
-
-	return 0;
-}
-
-/**
- * dccp_feat_register_sp  -  Register requests to change SP feature values
- * @sk: client or listening socket
- * @feat: one of %dccp_feature_numbers
- * @is_local: whether the local (1) or remote (0) @feat is meant
- * @list: array of preferred values, in descending order of preference
- * @len: length of @list in bytes
- */
-int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
-			  u8 const *list, u8 len)
-{	 /* any changes must be registered before establishing the connection */
-	if (sk->sk_state != DCCP_CLOSED)
-		return -EISCONN;
-	if (dccp_feat_type(feat) != FEAT_SP)
-		return -EINVAL;
-	return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
-				  0, list, len);
-}
-
-/**
- * dccp_feat_nn_get  -  Query current/pending value of NN feature
- * @sk: DCCP socket of an established connection
- * @feat: NN feature number from %dccp_feature_numbers
- *
- * For a known NN feature, returns value currently being negotiated, or
- * current (confirmed) value if no negotiation is going on.
- */
-u64 dccp_feat_nn_get(struct sock *sk, u8 feat)
-{
-	if (dccp_feat_type(feat) == FEAT_NN) {
-		struct dccp_sock *dp = dccp_sk(sk);
-		struct dccp_feat_entry *entry;
-
-		entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1);
-		if (entry != NULL)
-			return entry->val.nn;
-
-		switch (feat) {
-		case DCCPF_ACK_RATIO:
-			return dp->dccps_l_ack_ratio;
-		case DCCPF_SEQUENCE_WINDOW:
-			return dp->dccps_l_seq_win;
-		}
-	}
-	DCCP_BUG("attempt to look up unsupported feature %u", feat);
-	return 0;
-}
-EXPORT_SYMBOL_GPL(dccp_feat_nn_get);
-
-/**
- * dccp_feat_signal_nn_change  -  Update NN values for an established connection
- * @sk: DCCP socket of an established connection
- * @feat: NN feature number from %dccp_feature_numbers
- * @nn_val: the new value to use
- *
- * This function is used to communicate NN updates out-of-band.
- */
-int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val)
-{
-	struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
-	dccp_feat_val fval = { .nn = nn_val };
-	struct dccp_feat_entry *entry;
-
-	if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN)
-		return 0;
-
-	if (dccp_feat_type(feat) != FEAT_NN ||
-	    !dccp_feat_is_valid_nn_val(feat, nn_val))
-		return -EINVAL;
-
-	if (nn_val == dccp_feat_nn_get(sk, feat))
-		return 0;	/* already set or negotiation under way */
-
-	entry = dccp_feat_list_lookup(fn, feat, 1);
-	if (entry != NULL) {
-		dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n",
-			      (unsigned long long)entry->val.nn,
-			      (unsigned long long)nn_val);
-		dccp_feat_list_pop(entry);
-	}
-
-	inet_csk_schedule_ack(sk);
-	return dccp_feat_push_change(fn, feat, 1, 0, &fval);
-}
-EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change);
-
-/*
- *	Tracking features whose value depend on the choice of CCID
- *
- * This is designed with an extension in mind so that a list walk could be done
- * before activating any features. However, the existing framework was found to
- * work satisfactorily up until now, the automatic verification is left open.
- * When adding new CCIDs, add a corresponding dependency table here.
- */
-static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
-{
-	static const struct ccid_dependency ccid2_dependencies[2][2] = {
-		/*
-		 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
-		 * feature and Send Ack Vector is an RX feature, `is_local'
-		 * needs to be reversed.
-		 */
-		{	/* Dependencies of the receiver-side (remote) CCID2 */
-			{
-				.dependent_feat	= DCCPF_SEND_ACK_VECTOR,
-				.is_local	= true,
-				.is_mandatory	= true,
-				.val		= 1
-			},
-			{ 0, 0, 0, 0 }
-		},
-		{	/* Dependencies of the sender-side (local) CCID2 */
-			{
-				.dependent_feat	= DCCPF_SEND_ACK_VECTOR,
-				.is_local	= false,
-				.is_mandatory	= true,
-				.val		= 1
-			},
-			{ 0, 0, 0, 0 }
-		}
-	};
-	static const struct ccid_dependency ccid3_dependencies[2][5] = {
-		{	/*
-			 * Dependencies of the receiver-side CCID3
-			 */
-			{	/* locally disable Ack Vectors */
-				.dependent_feat	= DCCPF_SEND_ACK_VECTOR,
-				.is_local	= true,
-				.is_mandatory	= false,
-				.val		= 0
-			},
-			{	/* see below why Send Loss Event Rate is on */
-				.dependent_feat	= DCCPF_SEND_LEV_RATE,
-				.is_local	= true,
-				.is_mandatory	= true,
-				.val		= 1
-			},
-			{	/* NDP Count is needed as per RFC 4342, 6.1.1 */
-				.dependent_feat	= DCCPF_SEND_NDP_COUNT,
-				.is_local	= false,
-				.is_mandatory	= true,
-				.val		= 1
-			},
-			{ 0, 0, 0, 0 },
-		},
-		{	/*
-			 * CCID3 at the TX side: we request that the HC-receiver
-			 * will not send Ack Vectors (they will be ignored, so
-			 * Mandatory is not set); we enable Send Loss Event Rate
-			 * (Mandatory since the implementation does not support
-			 * the Loss Intervals option of RFC 4342, 8.6).
-			 * The last two options are for peer's information only.
-			*/
-			{
-				.dependent_feat	= DCCPF_SEND_ACK_VECTOR,
-				.is_local	= false,
-				.is_mandatory	= false,
-				.val		= 0
-			},
-			{
-				.dependent_feat	= DCCPF_SEND_LEV_RATE,
-				.is_local	= false,
-				.is_mandatory	= true,
-				.val		= 1
-			},
-			{	/* this CCID does not support Ack Ratio */
-				.dependent_feat	= DCCPF_ACK_RATIO,
-				.is_local	= true,
-				.is_mandatory	= false,
-				.val		= 0
-			},
-			{	/* tell receiver we are sending NDP counts */
-				.dependent_feat	= DCCPF_SEND_NDP_COUNT,
-				.is_local	= true,
-				.is_mandatory	= false,
-				.val		= 1
-			},
-			{ 0, 0, 0, 0 }
-		}
-	};
-	switch (ccid) {
-	case DCCPC_CCID2:
-		return ccid2_dependencies[is_local];
-	case DCCPC_CCID3:
-		return ccid3_dependencies[is_local];
-	default:
-		return NULL;
-	}
-}
-
-/**
- * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
- * @fn: feature-negotiation list to update
- * @id: CCID number to track
- * @is_local: whether TX CCID (1) or RX CCID (0) is meant
- *
- * This function needs to be called after registering all other features.
- */
-static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
-{
-	const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
-	int i, rc = (table == NULL);
-
-	for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
-		if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
-			rc = __feat_register_sp(fn, table[i].dependent_feat,
-						    table[i].is_local,
-						    table[i].is_mandatory,
-						    &table[i].val, 1);
-		else
-			rc = __feat_register_nn(fn, table[i].dependent_feat,
-						    table[i].is_mandatory,
-						    table[i].val);
-	return rc;
-}
-
-/**
- * dccp_feat_finalise_settings  -  Finalise settings before starting negotiation
- * @dp: client or listening socket (settings will be inherited)
- *
- * This is called after all registrations (socket initialisation, sysctls, and
- * sockopt calls), and before sending the first packet containing Change options
- * (ie. client-Request or server-Response), to ensure internal consistency.
- */
-int dccp_feat_finalise_settings(struct dccp_sock *dp)
-{
-	struct list_head *fn = &dp->dccps_featneg;
-	struct dccp_feat_entry *entry;
-	int i = 2, ccids[2] = { -1, -1 };
-
-	/*
-	 * Propagating CCIDs:
-	 * 1) not useful to propagate CCID settings if this host advertises more
-	 *    than one CCID: the choice of CCID  may still change - if this is
-	 *    the client, or if this is the server and the client sends
-	 *    singleton CCID values.
-	 * 2) since is that propagate_ccid changes the list, we defer changing
-	 *    the sorted list until after the traversal.
-	 */
-	list_for_each_entry(entry, fn, node)
-		if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
-			ccids[entry->is_local] = entry->val.sp.vec[0];
-	while (i--)
-		if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
-			return -1;
-	dccp_feat_print_fnlist(fn);
-	return 0;
-}
-
-/**
- * dccp_feat_server_ccid_dependencies  -  Resolve CCID-dependent features
- * @dreq: server socket to resolve
- *
- * It is the server which resolves the dependencies once the CCID has been
- * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
- */
-int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
-{
-	struct list_head *fn = &dreq->dreq_featneg;
-	struct dccp_feat_entry *entry;
-	u8 is_local, ccid;
-
-	for (is_local = 0; is_local <= 1; is_local++) {
-		entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
-
-		if (entry != NULL && !entry->empty_confirm)
-			ccid = entry->val.sp.vec[0];
-		else
-			ccid = dccp_feat_default_value(DCCPF_CCID);
-
-		if (dccp_feat_propagate_ccid(fn, ccid, is_local))
-			return -1;
-	}
-	return 0;
-}
-
-/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
-static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
-{
-	u8 c, s;
-
-	for (s = 0; s < slen; s++)
-		for (c = 0; c < clen; c++)
-			if (servlist[s] == clilist[c])
-				return servlist[s];
-	return -1;
-}
-
-/**
- * dccp_feat_prefer  -  Move preferred entry to the start of array
- * @preferred_value: entry to move to start of array
- * @array: array of preferred entries
- * @array_len: size of the array
- *
- * Reorder the @array_len elements in @array so that @preferred_value comes
- * first. Returns >0 to indicate that @preferred_value does occur in @array.
- */
-static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
-{
-	u8 i, does_occur = 0;
-
-	if (array != NULL) {
-		for (i = 0; i < array_len; i++)
-			if (array[i] == preferred_value) {
-				array[i] = array[0];
-				does_occur++;
-			}
-		if (does_occur)
-			array[0] = preferred_value;
-	}
-	return does_occur;
-}
-
-/**
- * dccp_feat_reconcile  -  Reconcile SP preference lists
- *  @fv: SP list to reconcile into
- *  @arr: received SP preference list
- *  @len: length of @arr in bytes
- *  @is_server: whether this side is the server (and @fv is the server's list)
- *  @reorder: whether to reorder the list in @fv after reconciling with @arr
- * When successful, > 0 is returned and the reconciled list is in @fval.
- * A value of 0 means that negotiation failed (no shared entry).
- */
-static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
-			       bool is_server, bool reorder)
-{
-	int rc;
-
-	if (!fv->sp.vec || !arr) {
-		DCCP_CRIT("NULL feature value or array");
-		return 0;
-	}
-
-	if (is_server)
-		rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
-	else
-		rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
-
-	if (!reorder)
-		return rc;
-	if (rc < 0)
-		return 0;
-
-	/*
-	 * Reorder list: used for activating features and in dccp_insert_fn_opt.
-	 */
-	return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
-}
-
-/**
- * dccp_feat_change_recv  -  Process incoming ChangeL/R options
- * @fn: feature-negotiation list to update
- * @is_mandatory: whether the Change was preceded by a Mandatory option
- * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
- * @feat: one of %dccp_feature_numbers
- * @val: NN value or SP value/preference list
- * @len: length of @val in bytes
- * @server: whether this node is the server (1) or the client (0)
- */
-static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
-				u8 feat, u8 *val, u8 len, const bool server)
-{
-	u8 defval, type = dccp_feat_type(feat);
-	const bool local = (opt == DCCPO_CHANGE_R);
-	struct dccp_feat_entry *entry;
-	dccp_feat_val fval;
-
-	if (len == 0 || type == FEAT_UNKNOWN)		/* 6.1 and 6.6.8 */
-		goto unknown_feature_or_value;
-
-	dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
-
-	/*
-	 *	Negotiation of NN features: Change R is invalid, so there is no
-	 *	simultaneous negotiation; hence we do not look up in the list.
-	 */
-	if (type == FEAT_NN) {
-		if (local || len > sizeof(fval.nn))
-			goto unknown_feature_or_value;
-
-		/* 6.3.2: "The feature remote MUST accept any valid value..." */
-		fval.nn = dccp_decode_value_var(val, len);
-		if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
-			goto unknown_feature_or_value;
-
-		return dccp_feat_push_confirm(fn, feat, local, &fval);
-	}
-
-	/*
-	 *	Unidirectional/simultaneous negotiation of SP features (6.3.1)
-	 */
-	entry = dccp_feat_list_lookup(fn, feat, local);
-	if (entry == NULL) {
-		/*
-		 * No particular preferences have been registered. We deal with
-		 * this situation by assuming that all valid values are equally
-		 * acceptable, and apply the following checks:
-		 * - if the peer's list is a singleton, we accept a valid value;
-		 * - if we are the server, we first try to see if the peer (the
-		 *   client) advertises the default value. If yes, we use it,
-		 *   otherwise we accept the preferred value;
-		 * - else if we are the client, we use the first list element.
-		 */
-		if (dccp_feat_clone_sp_val(&fval, val, 1))
-			return DCCP_RESET_CODE_TOO_BUSY;
-
-		if (len > 1 && server) {
-			defval = dccp_feat_default_value(feat);
-			if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
-				fval.sp.vec[0] = defval;
-		} else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
-			kfree(fval.sp.vec);
-			goto unknown_feature_or_value;
-		}
-
-		/* Treat unsupported CCIDs like invalid values */
-		if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
-			kfree(fval.sp.vec);
-			goto not_valid_or_not_known;
-		}
-
-		if (dccp_feat_push_confirm(fn, feat, local, &fval)) {
-			kfree(fval.sp.vec);
-			return DCCP_RESET_CODE_TOO_BUSY;
-		}
-
-		return 0;
-	} else if (entry->state == FEAT_UNSTABLE) {	/* 6.6.2 */
-		return 0;
-	}
-
-	if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
-		entry->empty_confirm = false;
-	} else if (is_mandatory) {
-		return DCCP_RESET_CODE_MANDATORY_ERROR;
-	} else if (entry->state == FEAT_INITIALISING) {
-		/*
-		 * Failed simultaneous negotiation (server only): try to `save'
-		 * the connection by checking whether entry contains the default
-		 * value for @feat. If yes, send an empty Confirm to signal that
-		 * the received Change was not understood - which implies using
-		 * the default value.
-		 * If this also fails, we use Reset as the last resort.
-		 */
-		WARN_ON(!server);
-		defval = dccp_feat_default_value(feat);
-		if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
-			return DCCP_RESET_CODE_OPTION_ERROR;
-		entry->empty_confirm = true;
-	}
-	entry->needs_confirm   = true;
-	entry->needs_mandatory = false;
-	entry->state	       = FEAT_STABLE;
-	return 0;
-
-unknown_feature_or_value:
-	if (!is_mandatory)
-		return dccp_push_empty_confirm(fn, feat, local);
-
-not_valid_or_not_known:
-	return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
-			    : DCCP_RESET_CODE_OPTION_ERROR;
-}
-
-/**
- * dccp_feat_confirm_recv  -  Process received Confirm options
- * @fn: feature-negotiation list to update
- * @is_mandatory: whether @opt was preceded by a Mandatory option
- * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
- * @feat: one of %dccp_feature_numbers
- * @val: NN value or SP value/preference list
- * @len: length of @val in bytes
- * @server: whether this node is server (1) or client (0)
- */
-static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
-				 u8 feat, u8 *val, u8 len, const bool server)
-{
-	u8 *plist, plen, type = dccp_feat_type(feat);
-	const bool local = (opt == DCCPO_CONFIRM_R);
-	struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);
-
-	dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
-
-	if (entry == NULL) {	/* nothing queued: ignore or handle error */
-		if (is_mandatory && type == FEAT_UNKNOWN)
-			return DCCP_RESET_CODE_MANDATORY_ERROR;
-
-		if (!local && type == FEAT_NN)		/* 6.3.2 */
-			goto confirmation_failed;
-		return 0;
-	}
-
-	if (entry->state != FEAT_CHANGING)		/* 6.6.2 */
-		return 0;
-
-	if (len == 0) {
-		if (dccp_feat_must_be_understood(feat))	/* 6.6.7 */
-			goto confirmation_failed;
-		/*
-		 * Empty Confirm during connection setup: this means reverting
-		 * to the `old' value, which in this case is the default. Since
-		 * we handle default values automatically when no other values
-		 * have been set, we revert to the old value by removing this
-		 * entry from the list.
-		 */
-		dccp_feat_list_pop(entry);
-		return 0;
-	}
-
-	if (type == FEAT_NN) {
-		if (len > sizeof(entry->val.nn))
-			goto confirmation_failed;
-
-		if (entry->val.nn == dccp_decode_value_var(val, len))
-			goto confirmation_succeeded;
-
-		DCCP_WARN("Bogus Confirm for non-existing value\n");
-		goto confirmation_failed;
-	}
-
-	/*
-	 * Parsing SP Confirms: the first element of @val is the preferred
-	 * SP value which the peer confirms, the remainder depends on @len.
-	 * Note that only the confirmed value need to be a valid SP value.
-	 */
-	if (!dccp_feat_is_valid_sp_val(feat, *val))
-		goto confirmation_failed;
-
-	if (len == 1) {		/* peer didn't supply a preference list */
-		plist = val;
-		plen  = len;
-	} else {		/* preferred value + preference list */
-		plist = val + 1;
-		plen  = len - 1;
-	}
-
-	/* Check whether the peer got the reconciliation right (6.6.8) */
-	if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
-		DCCP_WARN("Confirm selected the wrong value %u\n", *val);
-		return DCCP_RESET_CODE_OPTION_ERROR;
-	}
-	entry->val.sp.vec[0] = *val;
-
-confirmation_succeeded:
-	entry->state = FEAT_STABLE;
-	return 0;
-
-confirmation_failed:
-	DCCP_WARN("Confirmation failed\n");
-	return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
-			    : DCCP_RESET_CODE_OPTION_ERROR;
-}
-
-/**
- * dccp_feat_handle_nn_established  -  Fast-path reception of NN options
- * @sk:		socket of an established DCCP connection
- * @mandatory:	whether @opt was preceded by a Mandatory option
- * @opt:	%DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only)
- * @feat:	NN number, one of %dccp_feature_numbers
- * @val:	NN value
- * @len:	length of @val in bytes
- *
- * This function combines the functionality of change_recv/confirm_recv, with
- * the following differences (reset codes are the same):
- *    - cleanup after receiving the Confirm;
- *    - values are directly activated after successful parsing;
- *    - deliberately restricted to NN features.
- * The restriction to NN features is essential since SP features can have non-
- * predictable outcomes (depending on the remote configuration), and are inter-
- * dependent (CCIDs for instance cause further dependencies).
- */
-static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt,
-					  u8 feat, u8 *val, u8 len)
-{
-	struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
-	const bool local = (opt == DCCPO_CONFIRM_R);
-	struct dccp_feat_entry *entry;
-	u8 type = dccp_feat_type(feat);
-	dccp_feat_val fval;
-
-	dccp_feat_print_opt(opt, feat, val, len, mandatory);
-
-	/* Ignore non-mandatory unknown and non-NN features */
-	if (type == FEAT_UNKNOWN) {
-		if (local && !mandatory)
-			return 0;
-		goto fast_path_unknown;
-	} else if (type != FEAT_NN) {
-		return 0;
-	}
-
-	/*
-	 * We don't accept empty Confirms, since in fast-path feature
-	 * negotiation the values are enabled immediately after sending
-	 * the Change option.
-	 * Empty Changes on the other hand are invalid (RFC 4340, 6.1).
-	 */
-	if (len == 0 || len > sizeof(fval.nn))
-		goto fast_path_unknown;
-
-	if (opt == DCCPO_CHANGE_L) {
-		fval.nn = dccp_decode_value_var(val, len);
-		if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
-			goto fast_path_unknown;
-
-		if (dccp_feat_push_confirm(fn, feat, local, &fval) ||
-		    dccp_feat_activate(sk, feat, local, &fval))
-			return DCCP_RESET_CODE_TOO_BUSY;
-
-		/* set the `Ack Pending' flag to piggyback a Confirm */
-		inet_csk_schedule_ack(sk);
-
-	} else if (opt == DCCPO_CONFIRM_R) {
-		entry = dccp_feat_list_lookup(fn, feat, local);
-		if (entry == NULL || entry->state != FEAT_CHANGING)
-			return 0;
-
-		fval.nn = dccp_decode_value_var(val, len);
-		/*
-		 * Just ignore a value that doesn't match our current value.
-		 * If the option changes twice within two RTTs, then at least
-		 * one CONFIRM will be received for the old value after a
-		 * new CHANGE was sent.
-		 */
-		if (fval.nn != entry->val.nn)
-			return 0;
-
-		/* Only activate after receiving the Confirm option (6.6.1). */
-		dccp_feat_activate(sk, feat, local, &fval);
-
-		/* It has been confirmed - so remove the entry */
-		dccp_feat_list_pop(entry);
-
-	} else {
-		DCCP_WARN("Received illegal option %u\n", opt);
-		goto fast_path_failed;
-	}
-	return 0;
-
-fast_path_unknown:
-	if (!mandatory)
-		return dccp_push_empty_confirm(fn, feat, local);
-
-fast_path_failed:
-	return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
-			 : DCCP_RESET_CODE_OPTION_ERROR;
-}
-
-/**
- * dccp_feat_parse_options  -  Process Feature-Negotiation Options
- * @sk: for general use and used by the client during connection setup
- * @dreq: used by the server during connection setup
- * @mandatory: whether @opt was preceded by a Mandatory option
- * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
- * @feat: one of %dccp_feature_numbers
- * @val: value contents of @opt
- * @len: length of @val in bytes
- *
- * Returns 0 on success, a Reset code for ending the connection otherwise.
- */
-int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
-			    u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
-{
-	struct dccp_sock *dp = dccp_sk(sk);
-	struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
-	bool server = false;
-
-	switch (sk->sk_state) {
-	/*
-	 *	Negotiation during connection setup
-	 */
-	case DCCP_LISTEN:
-		server = true;
-		fallthrough;
-	case DCCP_REQUESTING:
-		switch (opt) {
-		case DCCPO_CHANGE_L:
-		case DCCPO_CHANGE_R:
-			return dccp_feat_change_recv(fn, mandatory, opt, feat,
-						     val, len, server);
-		case DCCPO_CONFIRM_R:
-		case DCCPO_CONFIRM_L:
-			return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
-						      val, len, server);
-		}
-		break;
-	/*
-	 *	Support for exchanging NN options on an established connection.
-	 */
-	case DCCP_OPEN:
-	case DCCP_PARTOPEN:
-		return dccp_feat_handle_nn_established(sk, mandatory, opt, feat,
-						       val, len);
-	}
-	return 0;	/* ignore FN options in all other states */
-}
-
-/**
- * dccp_feat_init  -  Seed feature negotiation with host-specific defaults
- * @sk: Socket to initialize.
- *
- * This initialises global defaults, depending on the value of the sysctls.
- * These can later be overridden by registering changes via setsockopt calls.
- * The last link in the chain is finalise_settings, to make sure that between
- * here and the start of actual feature negotiation no inconsistencies enter.
- *
- * All features not appearing below use either defaults or are otherwise
- * later adjusted through dccp_feat_finalise_settings().
- */
-int dccp_feat_init(struct sock *sk)
-{
-	struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
-	u8 on = 1, off = 0;
-	int rc;
-	struct {
-		u8 *val;
-		u8 len;
-	} tx, rx;
-
-	/* Non-negotiable (NN) features */
-	rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,
-				    sysctl_dccp_sequence_window);
-	if (rc)
-		return rc;
-
-	/* Server-priority (SP) features */
-
-	/* Advertise that short seqnos are not supported (7.6.1) */
-	rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1);
-	if (rc)
-		return rc;
-
-	/* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */
-	rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1);
-	if (rc)
-		return rc;
-
-	/*
-	 * We advertise the available list of CCIDs and reorder according to
-	 * preferences, to avoid failure resulting from negotiating different
-	 * singleton values (which always leads to failure).
-	 * These settings can still (later) be overridden via sockopts.
-	 */
-	if (ccid_get_builtin_ccids(&tx.val, &tx.len))
-		return -ENOBUFS;
-	if (ccid_get_builtin_ccids(&rx.val, &rx.len)) {
-		kfree(tx.val);
-		return -ENOBUFS;
-	}
-
-	if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) ||
-	    !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len))
-		goto free_ccid_lists;
-
-	rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);
-	if (rc)
-		goto free_ccid_lists;
-
-	rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len);
-
-free_ccid_lists:
-	kfree(tx.val);
-	kfree(rx.val);
-	return rc;
-}
-
-int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
-{
-	struct dccp_sock *dp = dccp_sk(sk);
-	struct dccp_feat_entry *cur, *next;
-	int idx;
-	dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = {
-		 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL }
-	};
-
-	list_for_each_entry(cur, fn_list, node) {
-		/*
-		 * An empty Confirm means that either an unknown feature type
-		 * or an invalid value was present. In the first case there is
-		 * nothing to activate, in the other the default value is used.
-		 */
-		if (cur->empty_confirm)
-			continue;
-
-		idx = dccp_feat_index(cur->feat_num);
-		if (idx < 0) {
-			DCCP_BUG("Unknown feature %u", cur->feat_num);
-			goto activation_failed;
-		}
-		if (cur->state != FEAT_STABLE) {
-			DCCP_CRIT("Negotiation of %s %s failed in state %s",
-				  cur->is_local ? "local" : "remote",
-				  dccp_feat_fname(cur->feat_num),
-				  dccp_feat_sname[cur->state]);
-			goto activation_failed;
-		}
-		fvals[idx][cur->is_local] = &cur->val;
-	}
-
-	/*
-	 * Activate in decreasing order of index, so that the CCIDs are always
-	 * activated as the last feature. This avoids the case where a CCID
-	 * relies on the initialisation of one or more features that it depends
-	 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features).
-	 */
-	for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;)
-		if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) ||
-		    __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) {
-			DCCP_CRIT("Could not activate %d", idx);
-			goto activation_failed;
-		}
-
-	/* Clean up Change options which have been confirmed already */
-	list_for_each_entry_safe(cur, next, fn_list, node)
-		if (!cur->needs_confirm)
-			dccp_feat_list_pop(cur);
-
-	dccp_pr_debug("Activation OK\n");
-	return 0;
-
-activation_failed:
-	/*
-	 * We clean up everything that may have been allocated, since
-	 * it is difficult to track at which stage negotiation failed.
-	 * This is ok, since all allocation functions below are robust
-	 * against NULL arguments.
-	 */
-	ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
-	ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
-	dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
-	dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
-	dp->dccps_hc_rx_ackvec = NULL;
-	return -1;
-}