recv.c

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/*
 * Copyright (c) 2006 Oracle.  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 "rds.h"

void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
          __be32 saddr)
{
    atomic_set(&inc->i_refcount, 1);
    INIT_LIST_HEAD(&inc->i_item);
    inc->i_conn = conn;
    inc->i_saddr = saddr;
    inc->i_rdma_cookie = 0;
}
EXPORT_SYMBOL_GPL(rds_inc_init);

static void rds_inc_addref(struct rds_incoming *inc)
{
    rdsdebug("addref inc %p ref %d\n", inc, atomic_read(&inc->i_refcount));
    atomic_inc(&inc->i_refcount);
}

void rds_inc_put(struct rds_incoming *inc)
{
    rdsdebug("put inc %p ref %d\n", inc, atomic_read(&inc->i_refcount));
    if (atomic_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;
    now_congested = rs->rs_rcv_bytes > rds_sk_rcvbuf(rs);

    rdsdebug("rs %p (%pI4:%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 */
}

/*
 * 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;
        }
    }
}

/*
 * 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, __be32 saddr, __be32 daddr,
               struct rds_incoming *inc, gfp_t gfp)
{
    struct rds_sock *rs = NULL;
    struct sock *sk;
    unsigned long flags;

    inc->i_conn = conn;
    inc->i_rx_jiffies = jiffies;

    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)conn->c_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) < conn->c_next_rx_seq &&
        (inc->i_hdr.h_flags & RDS_FLAG_RETRANSMITTED)) {
        rds_stats_inc(s_recv_drop_old_seq);
        goto out;
    }
    conn->c_next_rx_seq = be64_to_cpu(inc->i_hdr.h_sequence) + 1;

    if (rds_sysctl_ping_enable && inc->i_hdr.h_dport == 0) {
        rds_stats_inc(s_recv_ping);
        rds_send_pong(conn, inc->i_hdr.h_sport);
        goto out;
    }

    rs = rds_find_bound(daddr, inc->i_hdr.h_dport);
    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);
        rds_inc_addref(inc);
        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)
{
    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)
            return ret;
    }

    return 0;
}

int rds_recvmsg(struct kiocb *iocb, 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;
    struct sockaddr_in *sin;
    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);

    msg->msg_namelen = 0;

    if (msg_flags & MSG_OOB)
        goto out;

    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) {
                ret = -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 %pI4:%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_iov,
                                 size);
        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);
            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)) {
            ret = -EFAULT;
            goto out;
        }

        rds_stats_inc(s_recv_delivered);

        sin = (struct sockaddr_in *)msg->msg_name;
        if (sin) {
            sin->sin_family = AF_INET;
            sin->sin_port = inc->i_hdr.h_sport;
            sin->sin_addr.s_addr = inc->i_saddr;
            memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
            msg->msg_namelen = sizeof(*sin);
        }
        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);

    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;
    }

    rds_info_copy(iter, &minfo, sizeof(minfo));
}