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32 results

icmp.c

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  • recv.c 23.32 KiB
    /*
     * 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_rdma_cookie = 0;
    	inc->i_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_rdma_cookie = 0;
    	inc->i_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_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_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 = { 0 }; /* fill holes with zero */
    	unsigned int count = 0, max_messages = ~0U;
    	unsigned long flags;
    	LIST_HEAD(copy);
    	int err = 0;
    
    
    	/* 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_rdma_cookie) {
    		ret = put_cmsg(msg, SOL_RDS, RDS_CMSG_RDMA_DEST,
    				sizeof(inc->i_rdma_cookie), &inc->i_rdma_cookie);
    		if (ret)
    			goto out;
    	}
    
    	if ((inc->i_rx_tstamp != 0) &&
    	    sock_flag(rds_rs_to_sk(rs), SOCK_RCVTSTAMP)) {
    		struct __kernel_old_timeval tv = ns_to_kernel_old_timeval(inc->i_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;
    			goto out;
    		}
    		rds_recvmsg_zcookie(rs, msg);
    
    		rds_stats_inc(s_recv_delivered);
    
    		if (msg->msg_name) {
    			if (ipv6_addr_v4mapped(&inc->i_saddr)) {
    				sin = (struct sockaddr_in *)msg->msg_name;
    
    				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 = (struct sockaddr_in6 *)msg->msg_name;
    
    				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