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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * 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

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