Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 515 insertions, 0 deletions

diff --git a/net/smc/smc_rx.c b/net/smc/smc_rx.c
new file mode 100644
index 000000000..4380d32f5
--- /dev/null
+++ b/net/smc/smc_rx.c
@@ -0,0 +1,515 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ * Manage RMBE
+ * copy new RMBE data into user space
+ *
+ * Copyright IBM Corp. 2016
+ *
+ * Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
+ */
+
+#include <linux/net.h>
+#include <linux/rcupdate.h>
+#include <linux/sched/signal.h>
+#include <linux/splice.h>
+
+#include <net/sock.h>
+#include <trace/events/sock.h>
+
+#include "smc.h"
+#include "smc_core.h"
+#include "smc_cdc.h"
+#include "smc_tx.h" /* smc_tx_consumer_update() */
+#include "smc_rx.h"
+#include "smc_stats.h"
+#include "smc_tracepoint.h"
+
+/* callback implementation to wakeup consumers blocked with smc_rx_wait().
+ * indirectly called by smc_cdc_msg_recv_action().
+ */
+static void smc_rx_wake_up(struct sock *sk)
+{
+	struct socket_wq *wq;
+
+	trace_sk_data_ready(sk);
+
+	/* derived from sock_def_readable() */
+	/* called already in smc_listen_work() */
+	rcu_read_lock();
+	wq = rcu_dereference(sk->sk_wq);
+	if (skwq_has_sleeper(wq))
+		wake_up_interruptible_sync_poll(&wq->wait, EPOLLIN | EPOLLPRI |
+						EPOLLRDNORM | EPOLLRDBAND);
+	sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
+	if ((sk->sk_shutdown == SHUTDOWN_MASK) ||
+	    (sk->sk_state == SMC_CLOSED))
+		sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
+	rcu_read_unlock();
+}
+
+/* Update consumer cursor
+ *   @conn   connection to update
+ *   @cons   consumer cursor
+ *   @len    number of Bytes consumed
+ *   Returns:
+ *   1 if we should end our receive, 0 otherwise
+ */
+static int smc_rx_update_consumer(struct smc_sock *smc,
+				  union smc_host_cursor cons, size_t len)
+{
+	struct smc_connection *conn = &smc->conn;
+	struct sock *sk = &smc->sk;
+	bool force = false;
+	int diff, rc = 0;
+
+	smc_curs_add(conn->rmb_desc->len, &cons, len);
+
+	/* did we process urgent data? */
+	if (conn->urg_state == SMC_URG_VALID || conn->urg_rx_skip_pend) {
+		diff = smc_curs_comp(conn->rmb_desc->len, &cons,
+				     &conn->urg_curs);
+		if (sock_flag(sk, SOCK_URGINLINE)) {
+			if (diff == 0) {
+				force = true;
+				rc = 1;
+				conn->urg_state = SMC_URG_READ;
+			}
+		} else {
+			if (diff == 1) {
+				/* skip urgent byte */
+				force = true;
+				smc_curs_add(conn->rmb_desc->len, &cons, 1);
+				conn->urg_rx_skip_pend = false;
+			} else if (diff < -1)
+				/* we read past urgent byte */
+				conn->urg_state = SMC_URG_READ;
+		}
+	}
+
+	smc_curs_copy(&conn->local_tx_ctrl.cons, &cons, conn);
+
+	/* send consumer cursor update if required */
+	/* similar to advertising new TCP rcv_wnd if required */
+	smc_tx_consumer_update(conn, force);
+
+	return rc;
+}
+
+static void smc_rx_update_cons(struct smc_sock *smc, size_t len)
+{
+	struct smc_connection *conn = &smc->conn;
+	union smc_host_cursor cons;
+
+	smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
+	smc_rx_update_consumer(smc, cons, len);
+}
+
+struct smc_spd_priv {
+	struct smc_sock *smc;
+	size_t		 len;
+};
+
+static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,
+				    struct pipe_buffer *buf)
+{
+	struct smc_spd_priv *priv = (struct smc_spd_priv *)buf->private;
+	struct smc_sock *smc = priv->smc;
+	struct smc_connection *conn;
+	struct sock *sk = &smc->sk;
+
+	if (sk->sk_state == SMC_CLOSED ||
+	    sk->sk_state == SMC_PEERFINCLOSEWAIT ||
+	    sk->sk_state == SMC_APPFINCLOSEWAIT)
+		goto out;
+	conn = &smc->conn;
+	lock_sock(sk);
+	smc_rx_update_cons(smc, priv->len);
+	release_sock(sk);
+	if (atomic_sub_and_test(priv->len, &conn->splice_pending))
+		smc_rx_wake_up(sk);
+out:
+	kfree(priv);
+	put_page(buf->page);
+	sock_put(sk);
+}
+
+static const struct pipe_buf_operations smc_pipe_ops = {
+	.release = smc_rx_pipe_buf_release,
+	.get = generic_pipe_buf_get
+};
+
+static void smc_rx_spd_release(struct splice_pipe_desc *spd,
+			       unsigned int i)
+{
+	put_page(spd->pages[i]);
+}
+
+static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
+			 struct smc_sock *smc)
+{
+	struct smc_link_group *lgr = smc->conn.lgr;
+	int offset = offset_in_page(src);
+	struct partial_page *partial;
+	struct splice_pipe_desc spd;
+	struct smc_spd_priv **priv;
+	struct page **pages;
+	int bytes, nr_pages;
+	int i;
+
+	nr_pages = !lgr->is_smcd && smc->conn.rmb_desc->is_vm ?
+		   PAGE_ALIGN(len + offset) / PAGE_SIZE : 1;
+
+	pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
+	if (!pages)
+		goto out;
+	partial = kcalloc(nr_pages, sizeof(*partial), GFP_KERNEL);
+	if (!partial)
+		goto out_page;
+	priv = kcalloc(nr_pages, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		goto out_part;
+	for (i = 0; i < nr_pages; i++) {
+		priv[i] = kzalloc(sizeof(**priv), GFP_KERNEL);
+		if (!priv[i])
+			goto out_priv;
+	}
+
+	if (lgr->is_smcd ||
+	    (!lgr->is_smcd && !smc->conn.rmb_desc->is_vm)) {
+		/* smcd or smcr that uses physically contiguous RMBs */
+		priv[0]->len = len;
+		priv[0]->smc = smc;
+		partial[0].offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
+		partial[0].len = len;
+		partial[0].private = (unsigned long)priv[0];
+		pages[0] = smc->conn.rmb_desc->pages;
+	} else {
+		int size, left = len;
+		void *buf = src;
+		/* smcr that uses virtually contiguous RMBs*/
+		for (i = 0; i < nr_pages; i++) {
+			size = min_t(int, PAGE_SIZE - offset, left);
+			priv[i]->len = size;
+			priv[i]->smc = smc;
+			pages[i] = vmalloc_to_page(buf);
+			partial[i].offset = offset;
+			partial[i].len = size;
+			partial[i].private = (unsigned long)priv[i];
+			buf += size / sizeof(*buf);
+			left -= size;
+			offset = 0;
+		}
+	}
+	spd.nr_pages_max = nr_pages;
+	spd.nr_pages = nr_pages;
+	spd.pages = pages;
+	spd.partial = partial;
+	spd.ops = &smc_pipe_ops;
+	spd.spd_release = smc_rx_spd_release;
+
+	bytes = splice_to_pipe(pipe, &spd);
+	if (bytes > 0) {
+		sock_hold(&smc->sk);
+		if (!lgr->is_smcd && smc->conn.rmb_desc->is_vm) {
+			for (i = 0; i < PAGE_ALIGN(bytes + offset) / PAGE_SIZE; i++)
+				get_page(pages[i]);
+		} else {
+			get_page(smc->conn.rmb_desc->pages);
+		}
+		atomic_add(bytes, &smc->conn.splice_pending);
+	}
+	kfree(priv);
+	kfree(partial);
+	kfree(pages);
+
+	return bytes;
+
+out_priv:
+	for (i = (i - 1); i >= 0; i--)
+		kfree(priv[i]);
+	kfree(priv);
+out_part:
+	kfree(partial);
+out_page:
+	kfree(pages);
+out:
+	return -ENOMEM;
+}
+
+static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
+{
+	return atomic_read(&conn->bytes_to_rcv) &&
+	       !atomic_read(&conn->splice_pending);
+}
+
+/* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
+ *   @smc    smc socket
+ *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
+ *   @fcrit  add'l criterion to evaluate as function pointer
+ * Returns:
+ * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
+ * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
+ */
+int smc_rx_wait(struct smc_sock *smc, long *timeo,
+		int (*fcrit)(struct smc_connection *conn))
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	struct smc_connection *conn = &smc->conn;
+	struct smc_cdc_conn_state_flags *cflags =
+					&conn->local_tx_ctrl.conn_state_flags;
+	struct sock *sk = &smc->sk;
+	int rc;
+
+	if (fcrit(conn))
+		return 1;
+	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	add_wait_queue(sk_sleep(sk), &wait);
+	rc = sk_wait_event(sk, timeo,
+			   sk->sk_err ||
+			   cflags->peer_conn_abort ||
+			   sk->sk_shutdown & RCV_SHUTDOWN ||
+			   conn->killed ||
+			   fcrit(conn),
+			   &wait);
+	remove_wait_queue(sk_sleep(sk), &wait);
+	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	return rc;
+}
+
+static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
+			   int flags)
+{
+	struct smc_connection *conn = &smc->conn;
+	union smc_host_cursor cons;
+	struct sock *sk = &smc->sk;
+	int rc = 0;
+
+	if (sock_flag(sk, SOCK_URGINLINE) ||
+	    !(conn->urg_state == SMC_URG_VALID) ||
+	    conn->urg_state == SMC_URG_READ)
+		return -EINVAL;
+
+	SMC_STAT_INC(smc, urg_data_cnt);
+	if (conn->urg_state == SMC_URG_VALID) {
+		if (!(flags & MSG_PEEK))
+			smc->conn.urg_state = SMC_URG_READ;
+		msg->msg_flags |= MSG_OOB;
+		if (len > 0) {
+			if (!(flags & MSG_TRUNC))
+				rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
+			len = 1;
+			smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
+			if (smc_curs_diff(conn->rmb_desc->len, &cons,
+					  &conn->urg_curs) > 1)
+				conn->urg_rx_skip_pend = true;
+			/* Urgent Byte was already accounted for, but trigger
+			 * skipping the urgent byte in non-inline case
+			 */
+			if (!(flags & MSG_PEEK))
+				smc_rx_update_consumer(smc, cons, 0);
+		} else {
+			msg->msg_flags |= MSG_TRUNC;
+		}
+
+		return rc ? -EFAULT : len;
+	}
+
+	if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
+		return 0;
+
+	return -EAGAIN;
+}
+
+static bool smc_rx_recvmsg_data_available(struct smc_sock *smc)
+{
+	struct smc_connection *conn = &smc->conn;
+
+	if (smc_rx_data_available(conn))
+		return true;
+	else if (conn->urg_state == SMC_URG_VALID)
+		/* we received a single urgent Byte - skip */
+		smc_rx_update_cons(smc, 0);
+	return false;
+}
+
+/* smc_rx_recvmsg - receive data from RMBE
+ * @msg:	copy data to receive buffer
+ * @pipe:	copy data to pipe if set - indicates splice() call
+ *
+ * rcvbuf consumer: main API called by socket layer.
+ * Called under sk lock.
+ */
+int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
+		   struct pipe_inode_info *pipe, size_t len, int flags)
+{
+	size_t copylen, read_done = 0, read_remaining = len;
+	size_t chunk_len, chunk_off, chunk_len_sum;
+	struct smc_connection *conn = &smc->conn;
+	int (*func)(struct smc_connection *conn);
+	union smc_host_cursor cons;
+	int readable, chunk;
+	char *rcvbuf_base;
+	struct sock *sk;
+	int splbytes;
+	long timeo;
+	int target;		/* Read at least these many bytes */
+	int rc;
+
+	if (unlikely(flags & MSG_ERRQUEUE))
+		return -EINVAL; /* future work for sk.sk_family == AF_SMC */
+
+	sk = &smc->sk;
+	if (sk->sk_state == SMC_LISTEN)
+		return -ENOTCONN;
+	if (flags & MSG_OOB)
+		return smc_rx_recv_urg(smc, msg, len, flags);
+	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
+
+	readable = atomic_read(&conn->bytes_to_rcv);
+	if (readable >= conn->rmb_desc->len)
+		SMC_STAT_RMB_RX_FULL(smc, !conn->lnk);
+
+	if (len < readable)
+		SMC_STAT_RMB_RX_SIZE_SMALL(smc, !conn->lnk);
+	/* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
+	rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
+
+	do { /* while (read_remaining) */
+		if (read_done >= target || (pipe && read_done))
+			break;
+
+		if (conn->killed)
+			break;
+
+		if (smc_rx_recvmsg_data_available(smc))
+			goto copy;
+
+		if (sk->sk_shutdown & RCV_SHUTDOWN) {
+			/* smc_cdc_msg_recv_action() could have run after
+			 * above smc_rx_recvmsg_data_available()
+			 */
+			if (smc_rx_recvmsg_data_available(smc))
+				goto copy;
+			break;
+		}
+
+		if (read_done) {
+			if (sk->sk_err ||
+			    sk->sk_state == SMC_CLOSED ||
+			    !timeo ||
+			    signal_pending(current))
+				break;
+		} else {
+			if (sk->sk_err) {
+				read_done = sock_error(sk);
+				break;
+			}
+			if (sk->sk_state == SMC_CLOSED) {
+				if (!sock_flag(sk, SOCK_DONE)) {
+					/* This occurs when user tries to read
+					 * from never connected socket.
+					 */
+					read_done = -ENOTCONN;
+					break;
+				}
+				break;
+			}
+			if (!timeo)
+				return -EAGAIN;
+			if (signal_pending(current)) {
+				read_done = sock_intr_errno(timeo);
+				break;
+			}
+		}
+
+		if (!smc_rx_data_available(conn)) {
+			smc_rx_wait(smc, &timeo, smc_rx_data_available);
+			continue;
+		}
+
+copy:
+		/* initialize variables for 1st iteration of subsequent loop */
+		/* could be just 1 byte, even after waiting on data above */
+		readable = atomic_read(&conn->bytes_to_rcv);
+		splbytes = atomic_read(&conn->splice_pending);
+		if (!readable || (msg && splbytes)) {
+			if (splbytes)
+				func = smc_rx_data_available_and_no_splice_pend;
+			else
+				func = smc_rx_data_available;
+			smc_rx_wait(smc, &timeo, func);
+			continue;
+		}
+
+		smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
+		/* subsequent splice() calls pick up where previous left */
+		if (splbytes)
+			smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
+		if (conn->urg_state == SMC_URG_VALID &&
+		    sock_flag(&smc->sk, SOCK_URGINLINE) &&
+		    readable > 1)
+			readable--;	/* always stop at urgent Byte */
+		/* not more than what user space asked for */
+		copylen = min_t(size_t, read_remaining, readable);
+		/* determine chunks where to read from rcvbuf */
+		/* either unwrapped case, or 1st chunk of wrapped case */
+		chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
+				  cons.count);
+		chunk_len_sum = chunk_len;
+		chunk_off = cons.count;
+		smc_rmb_sync_sg_for_cpu(conn);
+		for (chunk = 0; chunk < 2; chunk++) {
+			if (!(flags & MSG_TRUNC)) {
+				if (msg) {
+					rc = memcpy_to_msg(msg, rcvbuf_base +
+							   chunk_off,
+							   chunk_len);
+				} else {
+					rc = smc_rx_splice(pipe, rcvbuf_base +
+							chunk_off, chunk_len,
+							smc);
+				}
+				if (rc < 0) {
+					if (!read_done)
+						read_done = -EFAULT;
+					goto out;
+				}
+			}
+			read_remaining -= chunk_len;
+			read_done += chunk_len;
+
+			if (chunk_len_sum == copylen)
+				break; /* either on 1st or 2nd iteration */
+			/* prepare next (== 2nd) iteration */
+			chunk_len = copylen - chunk_len; /* remainder */
+			chunk_len_sum += chunk_len;
+			chunk_off = 0; /* modulo offset in recv ring buffer */
+		}
+
+		/* update cursors */
+		if (!(flags & MSG_PEEK)) {
+			/* increased in recv tasklet smc_cdc_msg_rcv() */
+			smp_mb__before_atomic();
+			atomic_sub(copylen, &conn->bytes_to_rcv);
+			/* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
+			smp_mb__after_atomic();
+			if (msg && smc_rx_update_consumer(smc, cons, copylen))
+				goto out;
+		}
+
+		trace_smc_rx_recvmsg(smc, copylen);
+	} while (read_remaining);
+out:
+	return read_done;
+}
+
+/* Initialize receive properties on connection establishment. NB: not __init! */
+void smc_rx_init(struct smc_sock *smc)
+{
+	smc->sk.sk_data_ready = smc_rx_wake_up;
+	atomic_set(&smc->conn.splice_pending, 0);
+	smc->conn.urg_state = SMC_URG_READ;
+}