Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 831 insertions, 0 deletions

diff --git a/net/rds/recv.c b/net/rds/recv.c
new file mode 100644
index 000000000..5b426dc36
--- /dev/null
+++ b/net/rds/recv.c
@@ -0,0 +1,831 @@
+/*
+ * Copyright (c) 2006, 2019 Oracle and/or its affiliates. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <net/sock.h>
+#include <linux/in.h>
+#include <linux/export.h>
+#include <linux/time.h>
+#include <linux/rds.h>
+
+#include "rds.h"
+
+void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
+		 struct in6_addr *saddr)
+{
+	refcount_set(&inc->i_refcount, 1);
+	INIT_LIST_HEAD(&inc->i_item);
+	inc->i_conn = conn;
+	inc->i_saddr = *saddr;
+	inc->i_usercopy.rdma_cookie = 0;
+	inc->i_usercopy.rx_tstamp = ktime_set(0, 0);
+
+	memset(inc->i_rx_lat_trace, 0, sizeof(inc->i_rx_lat_trace));
+}
+EXPORT_SYMBOL_GPL(rds_inc_init);
+
+void rds_inc_path_init(struct rds_incoming *inc, struct rds_conn_path *cp,
+		       struct in6_addr  *saddr)
+{
+	refcount_set(&inc->i_refcount, 1);
+	INIT_LIST_HEAD(&inc->i_item);
+	inc->i_conn = cp->cp_conn;
+	inc->i_conn_path = cp;
+	inc->i_saddr = *saddr;
+	inc->i_usercopy.rdma_cookie = 0;
+	inc->i_usercopy.rx_tstamp = ktime_set(0, 0);
+}
+EXPORT_SYMBOL_GPL(rds_inc_path_init);
+
+static void rds_inc_addref(struct rds_incoming *inc)
+{
+	rdsdebug("addref inc %p ref %d\n", inc, refcount_read(&inc->i_refcount));
+	refcount_inc(&inc->i_refcount);
+}
+
+void rds_inc_put(struct rds_incoming *inc)
+{
+	rdsdebug("put inc %p ref %d\n", inc, refcount_read(&inc->i_refcount));
+	if (refcount_dec_and_test(&inc->i_refcount)) {
+		BUG_ON(!list_empty(&inc->i_item));
+
+		inc->i_conn->c_trans->inc_free(inc);
+	}
+}
+EXPORT_SYMBOL_GPL(rds_inc_put);
+
+static void rds_recv_rcvbuf_delta(struct rds_sock *rs, struct sock *sk,
+				  struct rds_cong_map *map,
+				  int delta, __be16 port)
+{
+	int now_congested;
+
+	if (delta == 0)
+		return;
+
+	rs->rs_rcv_bytes += delta;
+	if (delta > 0)
+		rds_stats_add(s_recv_bytes_added_to_socket, delta);
+	else
+		rds_stats_add(s_recv_bytes_removed_from_socket, -delta);
+
+	/* loop transport doesn't send/recv congestion updates */
+	if (rs->rs_transport->t_type == RDS_TRANS_LOOP)
+		return;
+
+	now_congested = rs->rs_rcv_bytes > rds_sk_rcvbuf(rs);
+
+	rdsdebug("rs %p (%pI6c:%u) recv bytes %d buf %d "
+	  "now_cong %d delta %d\n",
+	  rs, &rs->rs_bound_addr,
+	  ntohs(rs->rs_bound_port), rs->rs_rcv_bytes,
+	  rds_sk_rcvbuf(rs), now_congested, delta);
+
+	/* wasn't -> am congested */
+	if (!rs->rs_congested && now_congested) {
+		rs->rs_congested = 1;
+		rds_cong_set_bit(map, port);
+		rds_cong_queue_updates(map);
+	}
+	/* was -> aren't congested */
+	/* Require more free space before reporting uncongested to prevent
+	   bouncing cong/uncong state too often */
+	else if (rs->rs_congested && (rs->rs_rcv_bytes < (rds_sk_rcvbuf(rs)/2))) {
+		rs->rs_congested = 0;
+		rds_cong_clear_bit(map, port);
+		rds_cong_queue_updates(map);
+	}
+
+	/* do nothing if no change in cong state */
+}
+
+static void rds_conn_peer_gen_update(struct rds_connection *conn,
+				     u32 peer_gen_num)
+{
+	int i;
+	struct rds_message *rm, *tmp;
+	unsigned long flags;
+
+	WARN_ON(conn->c_trans->t_type != RDS_TRANS_TCP);
+	if (peer_gen_num != 0) {
+		if (conn->c_peer_gen_num != 0 &&
+		    peer_gen_num != conn->c_peer_gen_num) {
+			for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+				struct rds_conn_path *cp;
+
+				cp = &conn->c_path[i];
+				spin_lock_irqsave(&cp->cp_lock, flags);
+				cp->cp_next_tx_seq = 1;
+				cp->cp_next_rx_seq = 0;
+				list_for_each_entry_safe(rm, tmp,
+							 &cp->cp_retrans,
+							 m_conn_item) {
+					set_bit(RDS_MSG_FLUSH, &rm->m_flags);
+				}
+				spin_unlock_irqrestore(&cp->cp_lock, flags);
+			}
+		}
+		conn->c_peer_gen_num = peer_gen_num;
+	}
+}
+
+/*
+ * Process all extension headers that come with this message.
+ */
+static void rds_recv_incoming_exthdrs(struct rds_incoming *inc, struct rds_sock *rs)
+{
+	struct rds_header *hdr = &inc->i_hdr;
+	unsigned int pos = 0, type, len;
+	union {
+		struct rds_ext_header_version version;
+		struct rds_ext_header_rdma rdma;
+		struct rds_ext_header_rdma_dest rdma_dest;
+	} buffer;
+
+	while (1) {
+		len = sizeof(buffer);
+		type = rds_message_next_extension(hdr, &pos, &buffer, &len);
+		if (type == RDS_EXTHDR_NONE)
+			break;
+		/* Process extension header here */
+		switch (type) {
+		case RDS_EXTHDR_RDMA:
+			rds_rdma_unuse(rs, be32_to_cpu(buffer.rdma.h_rdma_rkey), 0);
+			break;
+
+		case RDS_EXTHDR_RDMA_DEST:
+			/* We ignore the size for now. We could stash it
+			 * somewhere and use it for error checking. */
+			inc->i_usercopy.rdma_cookie = rds_rdma_make_cookie(
+					be32_to_cpu(buffer.rdma_dest.h_rdma_rkey),
+					be32_to_cpu(buffer.rdma_dest.h_rdma_offset));
+
+			break;
+		}
+	}
+}
+
+static void rds_recv_hs_exthdrs(struct rds_header *hdr,
+				struct rds_connection *conn)
+{
+	unsigned int pos = 0, type, len;
+	union {
+		struct rds_ext_header_version version;
+		u16 rds_npaths;
+		u32 rds_gen_num;
+	} buffer;
+	u32 new_peer_gen_num = 0;
+
+	while (1) {
+		len = sizeof(buffer);
+		type = rds_message_next_extension(hdr, &pos, &buffer, &len);
+		if (type == RDS_EXTHDR_NONE)
+			break;
+		/* Process extension header here */
+		switch (type) {
+		case RDS_EXTHDR_NPATHS:
+			conn->c_npaths = min_t(int, RDS_MPATH_WORKERS,
+					       be16_to_cpu(buffer.rds_npaths));
+			break;
+		case RDS_EXTHDR_GEN_NUM:
+			new_peer_gen_num = be32_to_cpu(buffer.rds_gen_num);
+			break;
+		default:
+			pr_warn_ratelimited("ignoring unknown exthdr type "
+					     "0x%x\n", type);
+		}
+	}
+	/* if RDS_EXTHDR_NPATHS was not found, default to a single-path */
+	conn->c_npaths = max_t(int, conn->c_npaths, 1);
+	conn->c_ping_triggered = 0;
+	rds_conn_peer_gen_update(conn, new_peer_gen_num);
+}
+
+/* rds_start_mprds() will synchronously start multiple paths when appropriate.
+ * The scheme is based on the following rules:
+ *
+ * 1. rds_sendmsg on first connect attempt sends the probe ping, with the
+ *    sender's npaths (s_npaths)
+ * 2. rcvr of probe-ping knows the mprds_paths = min(s_npaths, r_npaths). It
+ *    sends back a probe-pong with r_npaths. After that, if rcvr is the
+ *    smaller ip addr, it starts rds_conn_path_connect_if_down on all
+ *    mprds_paths.
+ * 3. sender gets woken up, and can move to rds_conn_path_connect_if_down.
+ *    If it is the smaller ipaddr, rds_conn_path_connect_if_down can be
+ *    called after reception of the probe-pong on all mprds_paths.
+ *    Otherwise (sender of probe-ping is not the smaller ip addr): just call
+ *    rds_conn_path_connect_if_down on the hashed path. (see rule 4)
+ * 4. rds_connect_worker must only trigger a connection if laddr < faddr.
+ * 5. sender may end up queuing the packet on the cp. will get sent out later.
+ *    when connection is completed.
+ */
+static void rds_start_mprds(struct rds_connection *conn)
+{
+	int i;
+	struct rds_conn_path *cp;
+
+	if (conn->c_npaths > 1 &&
+	    rds_addr_cmp(&conn->c_laddr, &conn->c_faddr) < 0) {
+		for (i = 0; i < conn->c_npaths; i++) {
+			cp = &conn->c_path[i];
+			rds_conn_path_connect_if_down(cp);
+		}
+	}
+}
+
+/*
+ * The transport must make sure that this is serialized against other
+ * rx and conn reset on this specific conn.
+ *
+ * We currently assert that only one fragmented message will be sent
+ * down a connection at a time.  This lets us reassemble in the conn
+ * instead of per-flow which means that we don't have to go digging through
+ * flows to tear down partial reassembly progress on conn failure and
+ * we save flow lookup and locking for each frag arrival.  It does mean
+ * that small messages will wait behind large ones.  Fragmenting at all
+ * is only to reduce the memory consumption of pre-posted buffers.
+ *
+ * The caller passes in saddr and daddr instead of us getting it from the
+ * conn.  This lets loopback, who only has one conn for both directions,
+ * tell us which roles the addrs in the conn are playing for this message.
+ */
+void rds_recv_incoming(struct rds_connection *conn, struct in6_addr *saddr,
+		       struct in6_addr *daddr,
+		       struct rds_incoming *inc, gfp_t gfp)
+{
+	struct rds_sock *rs = NULL;
+	struct sock *sk;
+	unsigned long flags;
+	struct rds_conn_path *cp;
+
+	inc->i_conn = conn;
+	inc->i_rx_jiffies = jiffies;
+	if (conn->c_trans->t_mp_capable)
+		cp = inc->i_conn_path;
+	else
+		cp = &conn->c_path[0];
+
+	rdsdebug("conn %p next %llu inc %p seq %llu len %u sport %u dport %u "
+		 "flags 0x%x rx_jiffies %lu\n", conn,
+		 (unsigned long long)cp->cp_next_rx_seq,
+		 inc,
+		 (unsigned long long)be64_to_cpu(inc->i_hdr.h_sequence),
+		 be32_to_cpu(inc->i_hdr.h_len),
+		 be16_to_cpu(inc->i_hdr.h_sport),
+		 be16_to_cpu(inc->i_hdr.h_dport),
+		 inc->i_hdr.h_flags,
+		 inc->i_rx_jiffies);
+
+	/*
+	 * Sequence numbers should only increase.  Messages get their
+	 * sequence number as they're queued in a sending conn.  They
+	 * can be dropped, though, if the sending socket is closed before
+	 * they hit the wire.  So sequence numbers can skip forward
+	 * under normal operation.  They can also drop back in the conn
+	 * failover case as previously sent messages are resent down the
+	 * new instance of a conn.  We drop those, otherwise we have
+	 * to assume that the next valid seq does not come after a
+	 * hole in the fragment stream.
+	 *
+	 * The headers don't give us a way to realize if fragments of
+	 * a message have been dropped.  We assume that frags that arrive
+	 * to a flow are part of the current message on the flow that is
+	 * being reassembled.  This means that senders can't drop messages
+	 * from the sending conn until all their frags are sent.
+	 *
+	 * XXX we could spend more on the wire to get more robust failure
+	 * detection, arguably worth it to avoid data corruption.
+	 */
+	if (be64_to_cpu(inc->i_hdr.h_sequence) < cp->cp_next_rx_seq &&
+	    (inc->i_hdr.h_flags & RDS_FLAG_RETRANSMITTED)) {
+		rds_stats_inc(s_recv_drop_old_seq);
+		goto out;
+	}
+	cp->cp_next_rx_seq = be64_to_cpu(inc->i_hdr.h_sequence) + 1;
+
+	if (rds_sysctl_ping_enable && inc->i_hdr.h_dport == 0) {
+		if (inc->i_hdr.h_sport == 0) {
+			rdsdebug("ignore ping with 0 sport from %pI6c\n",
+				 saddr);
+			goto out;
+		}
+		rds_stats_inc(s_recv_ping);
+		rds_send_pong(cp, inc->i_hdr.h_sport);
+		/* if this is a handshake ping, start multipath if necessary */
+		if (RDS_HS_PROBE(be16_to_cpu(inc->i_hdr.h_sport),
+				 be16_to_cpu(inc->i_hdr.h_dport))) {
+			rds_recv_hs_exthdrs(&inc->i_hdr, cp->cp_conn);
+			rds_start_mprds(cp->cp_conn);
+		}
+		goto out;
+	}
+
+	if (be16_to_cpu(inc->i_hdr.h_dport) ==  RDS_FLAG_PROBE_PORT &&
+	    inc->i_hdr.h_sport == 0) {
+		rds_recv_hs_exthdrs(&inc->i_hdr, cp->cp_conn);
+		/* if this is a handshake pong, start multipath if necessary */
+		rds_start_mprds(cp->cp_conn);
+		wake_up(&cp->cp_conn->c_hs_waitq);
+		goto out;
+	}
+
+	rs = rds_find_bound(daddr, inc->i_hdr.h_dport, conn->c_bound_if);
+	if (!rs) {
+		rds_stats_inc(s_recv_drop_no_sock);
+		goto out;
+	}
+
+	/* Process extension headers */
+	rds_recv_incoming_exthdrs(inc, rs);
+
+	/* We can be racing with rds_release() which marks the socket dead. */
+	sk = rds_rs_to_sk(rs);
+
+	/* serialize with rds_release -> sock_orphan */
+	write_lock_irqsave(&rs->rs_recv_lock, flags);
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		rdsdebug("adding inc %p to rs %p's recv queue\n", inc, rs);
+		rds_stats_inc(s_recv_queued);
+		rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
+				      be32_to_cpu(inc->i_hdr.h_len),
+				      inc->i_hdr.h_dport);
+		if (sock_flag(sk, SOCK_RCVTSTAMP))
+			inc->i_usercopy.rx_tstamp = ktime_get_real();
+		rds_inc_addref(inc);
+		inc->i_rx_lat_trace[RDS_MSG_RX_END] = local_clock();
+		list_add_tail(&inc->i_item, &rs->rs_recv_queue);
+		__rds_wake_sk_sleep(sk);
+	} else {
+		rds_stats_inc(s_recv_drop_dead_sock);
+	}
+	write_unlock_irqrestore(&rs->rs_recv_lock, flags);
+
+out:
+	if (rs)
+		rds_sock_put(rs);
+}
+EXPORT_SYMBOL_GPL(rds_recv_incoming);
+
+/*
+ * be very careful here.  This is being called as the condition in
+ * wait_event_*() needs to cope with being called many times.
+ */
+static int rds_next_incoming(struct rds_sock *rs, struct rds_incoming **inc)
+{
+	unsigned long flags;
+
+	if (!*inc) {
+		read_lock_irqsave(&rs->rs_recv_lock, flags);
+		if (!list_empty(&rs->rs_recv_queue)) {
+			*inc = list_entry(rs->rs_recv_queue.next,
+					  struct rds_incoming,
+					  i_item);
+			rds_inc_addref(*inc);
+		}
+		read_unlock_irqrestore(&rs->rs_recv_lock, flags);
+	}
+
+	return *inc != NULL;
+}
+
+static int rds_still_queued(struct rds_sock *rs, struct rds_incoming *inc,
+			    int drop)
+{
+	struct sock *sk = rds_rs_to_sk(rs);
+	int ret = 0;
+	unsigned long flags;
+
+	write_lock_irqsave(&rs->rs_recv_lock, flags);
+	if (!list_empty(&inc->i_item)) {
+		ret = 1;
+		if (drop) {
+			/* XXX make sure this i_conn is reliable */
+			rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
+					      -be32_to_cpu(inc->i_hdr.h_len),
+					      inc->i_hdr.h_dport);
+			list_del_init(&inc->i_item);
+			rds_inc_put(inc);
+		}
+	}
+	write_unlock_irqrestore(&rs->rs_recv_lock, flags);
+
+	rdsdebug("inc %p rs %p still %d dropped %d\n", inc, rs, ret, drop);
+	return ret;
+}
+
+/*
+ * Pull errors off the error queue.
+ * If msghdr is NULL, we will just purge the error queue.
+ */
+int rds_notify_queue_get(struct rds_sock *rs, struct msghdr *msghdr)
+{
+	struct rds_notifier *notifier;
+	struct rds_rdma_notify cmsg;
+	unsigned int count = 0, max_messages = ~0U;
+	unsigned long flags;
+	LIST_HEAD(copy);
+	int err = 0;
+
+	memset(&cmsg, 0, sizeof(cmsg));	/* fill holes with zero */
+
+	/* put_cmsg copies to user space and thus may sleep. We can't do this
+	 * with rs_lock held, so first grab as many notifications as we can stuff
+	 * in the user provided cmsg buffer. We don't try to copy more, to avoid
+	 * losing notifications - except when the buffer is so small that it wouldn't
+	 * even hold a single notification. Then we give him as much of this single
+	 * msg as we can squeeze in, and set MSG_CTRUNC.
+	 */
+	if (msghdr) {
+		max_messages = msghdr->msg_controllen / CMSG_SPACE(sizeof(cmsg));
+		if (!max_messages)
+			max_messages = 1;
+	}
+
+	spin_lock_irqsave(&rs->rs_lock, flags);
+	while (!list_empty(&rs->rs_notify_queue) && count < max_messages) {
+		notifier = list_entry(rs->rs_notify_queue.next,
+				struct rds_notifier, n_list);
+		list_move(&notifier->n_list, &copy);
+		count++;
+	}
+	spin_unlock_irqrestore(&rs->rs_lock, flags);
+
+	if (!count)
+		return 0;
+
+	while (!list_empty(&copy)) {
+		notifier = list_entry(copy.next, struct rds_notifier, n_list);
+
+		if (msghdr) {
+			cmsg.user_token = notifier->n_user_token;
+			cmsg.status = notifier->n_status;
+
+			err = put_cmsg(msghdr, SOL_RDS, RDS_CMSG_RDMA_STATUS,
+				       sizeof(cmsg), &cmsg);
+			if (err)
+				break;
+		}
+
+		list_del_init(&notifier->n_list);
+		kfree(notifier);
+	}
+
+	/* If we bailed out because of an error in put_cmsg,
+	 * we may be left with one or more notifications that we
+	 * didn't process. Return them to the head of the list. */
+	if (!list_empty(&copy)) {
+		spin_lock_irqsave(&rs->rs_lock, flags);
+		list_splice(&copy, &rs->rs_notify_queue);
+		spin_unlock_irqrestore(&rs->rs_lock, flags);
+	}
+
+	return err;
+}
+
+/*
+ * Queue a congestion notification
+ */
+static int rds_notify_cong(struct rds_sock *rs, struct msghdr *msghdr)
+{
+	uint64_t notify = rs->rs_cong_notify;
+	unsigned long flags;
+	int err;
+
+	err = put_cmsg(msghdr, SOL_RDS, RDS_CMSG_CONG_UPDATE,
+			sizeof(notify), &notify);
+	if (err)
+		return err;
+
+	spin_lock_irqsave(&rs->rs_lock, flags);
+	rs->rs_cong_notify &= ~notify;
+	spin_unlock_irqrestore(&rs->rs_lock, flags);
+
+	return 0;
+}
+
+/*
+ * Receive any control messages.
+ */
+static int rds_cmsg_recv(struct rds_incoming *inc, struct msghdr *msg,
+			 struct rds_sock *rs)
+{
+	int ret = 0;
+
+	if (inc->i_usercopy.rdma_cookie) {
+		ret = put_cmsg(msg, SOL_RDS, RDS_CMSG_RDMA_DEST,
+				sizeof(inc->i_usercopy.rdma_cookie),
+				&inc->i_usercopy.rdma_cookie);
+		if (ret)
+			goto out;
+	}
+
+	if ((inc->i_usercopy.rx_tstamp != 0) &&
+	    sock_flag(rds_rs_to_sk(rs), SOCK_RCVTSTAMP)) {
+		struct __kernel_old_timeval tv =
+			ns_to_kernel_old_timeval(inc->i_usercopy.rx_tstamp);
+
+		if (!sock_flag(rds_rs_to_sk(rs), SOCK_TSTAMP_NEW)) {
+			ret = put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_OLD,
+				       sizeof(tv), &tv);
+		} else {
+			struct __kernel_sock_timeval sk_tv;
+
+			sk_tv.tv_sec = tv.tv_sec;
+			sk_tv.tv_usec = tv.tv_usec;
+
+			ret = put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_NEW,
+				       sizeof(sk_tv), &sk_tv);
+		}
+
+		if (ret)
+			goto out;
+	}
+
+	if (rs->rs_rx_traces) {
+		struct rds_cmsg_rx_trace t;
+		int i, j;
+
+		memset(&t, 0, sizeof(t));
+		inc->i_rx_lat_trace[RDS_MSG_RX_CMSG] = local_clock();
+		t.rx_traces =  rs->rs_rx_traces;
+		for (i = 0; i < rs->rs_rx_traces; i++) {
+			j = rs->rs_rx_trace[i];
+			t.rx_trace_pos[i] = j;
+			t.rx_trace[i] = inc->i_rx_lat_trace[j + 1] -
+					  inc->i_rx_lat_trace[j];
+		}
+
+		ret = put_cmsg(msg, SOL_RDS, RDS_CMSG_RXPATH_LATENCY,
+			       sizeof(t), &t);
+		if (ret)
+			goto out;
+	}
+
+out:
+	return ret;
+}
+
+static bool rds_recvmsg_zcookie(struct rds_sock *rs, struct msghdr *msg)
+{
+	struct rds_msg_zcopy_queue *q = &rs->rs_zcookie_queue;
+	struct rds_msg_zcopy_info *info = NULL;
+	struct rds_zcopy_cookies *done;
+	unsigned long flags;
+
+	if (!msg->msg_control)
+		return false;
+
+	if (!sock_flag(rds_rs_to_sk(rs), SOCK_ZEROCOPY) ||
+	    msg->msg_controllen < CMSG_SPACE(sizeof(*done)))
+		return false;
+
+	spin_lock_irqsave(&q->lock, flags);
+	if (!list_empty(&q->zcookie_head)) {
+		info = list_entry(q->zcookie_head.next,
+				  struct rds_msg_zcopy_info, rs_zcookie_next);
+		list_del(&info->rs_zcookie_next);
+	}
+	spin_unlock_irqrestore(&q->lock, flags);
+	if (!info)
+		return false;
+	done = &info->zcookies;
+	if (put_cmsg(msg, SOL_RDS, RDS_CMSG_ZCOPY_COMPLETION, sizeof(*done),
+		     done)) {
+		spin_lock_irqsave(&q->lock, flags);
+		list_add(&info->rs_zcookie_next, &q->zcookie_head);
+		spin_unlock_irqrestore(&q->lock, flags);
+		return false;
+	}
+	kfree(info);
+	return true;
+}
+
+int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
+		int msg_flags)
+{
+	struct sock *sk = sock->sk;
+	struct rds_sock *rs = rds_sk_to_rs(sk);
+	long timeo;
+	int ret = 0, nonblock = msg_flags & MSG_DONTWAIT;
+	DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
+	DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
+	struct rds_incoming *inc = NULL;
+
+	/* udp_recvmsg()->sock_recvtimeo() gets away without locking too.. */
+	timeo = sock_rcvtimeo(sk, nonblock);
+
+	rdsdebug("size %zu flags 0x%x timeo %ld\n", size, msg_flags, timeo);
+
+	if (msg_flags & MSG_OOB)
+		goto out;
+	if (msg_flags & MSG_ERRQUEUE)
+		return sock_recv_errqueue(sk, msg, size, SOL_IP, IP_RECVERR);
+
+	while (1) {
+		/* If there are pending notifications, do those - and nothing else */
+		if (!list_empty(&rs->rs_notify_queue)) {
+			ret = rds_notify_queue_get(rs, msg);
+			break;
+		}
+
+		if (rs->rs_cong_notify) {
+			ret = rds_notify_cong(rs, msg);
+			break;
+		}
+
+		if (!rds_next_incoming(rs, &inc)) {
+			if (nonblock) {
+				bool reaped = rds_recvmsg_zcookie(rs, msg);
+
+				ret = reaped ?  0 : -EAGAIN;
+				break;
+			}
+
+			timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
+					(!list_empty(&rs->rs_notify_queue) ||
+					 rs->rs_cong_notify ||
+					 rds_next_incoming(rs, &inc)), timeo);
+			rdsdebug("recvmsg woke inc %p timeo %ld\n", inc,
+				 timeo);
+			if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
+				continue;
+
+			ret = timeo;
+			if (ret == 0)
+				ret = -ETIMEDOUT;
+			break;
+		}
+
+		rdsdebug("copying inc %p from %pI6c:%u to user\n", inc,
+			 &inc->i_conn->c_faddr,
+			 ntohs(inc->i_hdr.h_sport));
+		ret = inc->i_conn->c_trans->inc_copy_to_user(inc, &msg->msg_iter);
+		if (ret < 0)
+			break;
+
+		/*
+		 * if the message we just copied isn't at the head of the
+		 * recv queue then someone else raced us to return it, try
+		 * to get the next message.
+		 */
+		if (!rds_still_queued(rs, inc, !(msg_flags & MSG_PEEK))) {
+			rds_inc_put(inc);
+			inc = NULL;
+			rds_stats_inc(s_recv_deliver_raced);
+			iov_iter_revert(&msg->msg_iter, ret);
+			continue;
+		}
+
+		if (ret < be32_to_cpu(inc->i_hdr.h_len)) {
+			if (msg_flags & MSG_TRUNC)
+				ret = be32_to_cpu(inc->i_hdr.h_len);
+			msg->msg_flags |= MSG_TRUNC;
+		}
+
+		if (rds_cmsg_recv(inc, msg, rs)) {
+			ret = -EFAULT;
+			break;
+		}
+		rds_recvmsg_zcookie(rs, msg);
+
+		rds_stats_inc(s_recv_delivered);
+
+		if (msg->msg_name) {
+			if (ipv6_addr_v4mapped(&inc->i_saddr)) {
+				sin->sin_family = AF_INET;
+				sin->sin_port = inc->i_hdr.h_sport;
+				sin->sin_addr.s_addr =
+				    inc->i_saddr.s6_addr32[3];
+				memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
+				msg->msg_namelen = sizeof(*sin);
+			} else {
+				sin6->sin6_family = AF_INET6;
+				sin6->sin6_port = inc->i_hdr.h_sport;
+				sin6->sin6_addr = inc->i_saddr;
+				sin6->sin6_flowinfo = 0;
+				sin6->sin6_scope_id = rs->rs_bound_scope_id;
+				msg->msg_namelen = sizeof(*sin6);
+			}
+		}
+		break;
+	}
+
+	if (inc)
+		rds_inc_put(inc);
+
+out:
+	return ret;
+}
+
+/*
+ * The socket is being shut down and we're asked to drop messages that were
+ * queued for recvmsg.  The caller has unbound the socket so the receive path
+ * won't queue any more incoming fragments or messages on the socket.
+ */
+void rds_clear_recv_queue(struct rds_sock *rs)
+{
+	struct sock *sk = rds_rs_to_sk(rs);
+	struct rds_incoming *inc, *tmp;
+	unsigned long flags;
+
+	write_lock_irqsave(&rs->rs_recv_lock, flags);
+	list_for_each_entry_safe(inc, tmp, &rs->rs_recv_queue, i_item) {
+		rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
+				      -be32_to_cpu(inc->i_hdr.h_len),
+				      inc->i_hdr.h_dport);
+		list_del_init(&inc->i_item);
+		rds_inc_put(inc);
+	}
+	write_unlock_irqrestore(&rs->rs_recv_lock, flags);
+}
+
+/*
+ * inc->i_saddr isn't used here because it is only set in the receive
+ * path.
+ */
+void rds_inc_info_copy(struct rds_incoming *inc,
+		       struct rds_info_iterator *iter,
+		       __be32 saddr, __be32 daddr, int flip)
+{
+	struct rds_info_message minfo;
+
+	minfo.seq = be64_to_cpu(inc->i_hdr.h_sequence);
+	minfo.len = be32_to_cpu(inc->i_hdr.h_len);
+	minfo.tos = inc->i_conn->c_tos;
+
+	if (flip) {
+		minfo.laddr = daddr;
+		minfo.faddr = saddr;
+		minfo.lport = inc->i_hdr.h_dport;
+		minfo.fport = inc->i_hdr.h_sport;
+	} else {
+		minfo.laddr = saddr;
+		minfo.faddr = daddr;
+		minfo.lport = inc->i_hdr.h_sport;
+		minfo.fport = inc->i_hdr.h_dport;
+	}
+
+	minfo.flags = 0;
+
+	rds_info_copy(iter, &minfo, sizeof(minfo));
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+void rds6_inc_info_copy(struct rds_incoming *inc,
+			struct rds_info_iterator *iter,
+			struct in6_addr *saddr, struct in6_addr *daddr,
+			int flip)
+{
+	struct rds6_info_message minfo6;
+
+	minfo6.seq = be64_to_cpu(inc->i_hdr.h_sequence);
+	minfo6.len = be32_to_cpu(inc->i_hdr.h_len);
+	minfo6.tos = inc->i_conn->c_tos;
+
+	if (flip) {
+		minfo6.laddr = *daddr;
+		minfo6.faddr = *saddr;
+		minfo6.lport = inc->i_hdr.h_dport;
+		minfo6.fport = inc->i_hdr.h_sport;
+	} else {
+		minfo6.laddr = *saddr;
+		minfo6.faddr = *daddr;
+		minfo6.lport = inc->i_hdr.h_sport;
+		minfo6.fport = inc->i_hdr.h_dport;
+	}
+
+	minfo6.flags = 0;
+
+	rds_info_copy(iter, &minfo6, sizeof(minfo6));
+}
+#endif