Import 2.4.0-test2pre7

[davej-history.git] / net / sunrpc / svcsock.c

/*
 * linux/net/sunrpc/svcsock.c
 *
 * These are the RPC server socket internals.
 *
 * The server scheduling algorithm does not always distribute the load
 * evenly when servicing a single client. May need to modify the
 * svc_sock_enqueue procedure...
 *
 * TCP support is largely untested and may be a little slow. The problem
 * is that we currently do two separate recvfrom's, one for the 4-byte
 * record length, and the second for the actual record. This could possibly
 * be improved by always reading a minimum size of around 100 bytes and
 * tucking any superfluous bytes away in a temporary store. Still, that
 * leaves write requests out in the rain. An alternative may be to peek at
 * the first skb in the queue, and if it matches the next TCP sequence
 * number, to extract the record marker. Yuck.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/net.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/udp.h>
#include <linux/version.h>
#include <linux/unistd.h>
#include <linux/malloc.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/ip.h>
#include <asm/uaccess.h>

#include <linux/sunrpc/types.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/stats.h>

/* SMP locking strategy:
 *
 *      svc_sock->sk_lock and svc_serv->sv_lock protect their
 *      respective structures.
 *
 *      Antideadlock ordering is sk_lock --> sv_lock.
 */

#define RPCDBG_FACILITY RPCDBG_SVCSOCK


static struct svc_sock *svc_setup_socket(struct svc_serv *, struct socket *,
                                         int *errp, int pmap_reg);
static void             svc_udp_data_ready(struct sock *, int);
static int              svc_udp_recvfrom(struct svc_rqst *);
static int              svc_udp_sendto(struct svc_rqst *);


/*
 * Queue up an idle server thread.  Must have serv->sv_lock held.
 */
static inline void
svc_serv_enqueue(struct svc_serv *serv, struct svc_rqst *rqstp)
{
        rpc_append_list(&serv->sv_threads, rqstp);
}

/*
 * Dequeue an nfsd thread.  Must have serv->sv_lock held.
 */
static inline void
svc_serv_dequeue(struct svc_serv *serv, struct svc_rqst *rqstp)
{
        rpc_remove_list(&serv->sv_threads, rqstp);
}

/*
 * Release an skbuff after use
 */
static inline void
svc_release_skb(struct svc_rqst *rqstp)
{
        struct sk_buff *skb = rqstp->rq_skbuff;

        if (!skb)
                return;
        rqstp->rq_skbuff = NULL;

        dprintk("svc: service %p, releasing skb %p\n", rqstp, skb);
        skb_free_datagram(rqstp->rq_sock->sk_sk, skb);
}

/*
 * Queue up a socket with data pending. If there are idle nfsd
 * processes, wake 'em up.
 *
 * This must be called with svsk->sk_lock held.
 */
static void
svc_sock_enqueue(struct svc_sock *svsk)
{
        struct svc_serv *serv = svsk->sk_server;
        struct svc_rqst *rqstp;

        /* NOTE: Local BH is already disabled by our caller. */
        spin_lock(&serv->sv_lock);

        if (serv->sv_threads && serv->sv_sockets)
                printk(KERN_ERR
                        "svc_sock_enqueue: threads and sockets both waiting??\n");

        if (svsk->sk_busy) {
                /* Don't enqueue socket while daemon is receiving */
                dprintk("svc: socket %p busy, not enqueued\n", svsk->sk_sk);
                goto out_unlock;
        }

        /* Mark socket as busy. It will remain in this state until the
         * server has processed all pending data and put the socket back
         * on the idle list.
         */
        svsk->sk_busy = 1;

        if ((rqstp = serv->sv_threads) != NULL) {
                dprintk("svc: socket %p served by daemon %p\n",
                        svsk->sk_sk, rqstp);
                svc_serv_dequeue(serv, rqstp);
                if (rqstp->rq_sock)
                        printk(KERN_ERR 
                                "svc_sock_enqueue: server %p, rq_sock=%p!\n",
                                rqstp, rqstp->rq_sock);
                rqstp->rq_sock = svsk;
                svsk->sk_inuse++;
                wake_up(&rqstp->rq_wait);
        } else {
                dprintk("svc: socket %p put into queue\n", svsk->sk_sk);
                rpc_append_list(&serv->sv_sockets, svsk);
                svsk->sk_qued = 1;
        }

out_unlock:
        spin_unlock(&serv->sv_lock);
}

/*
 * Dequeue the first socket.  Must be called with the serv->sv_lock held.
 */
static inline struct svc_sock *
svc_sock_dequeue(struct svc_serv *serv)
{
        struct svc_sock *svsk;

        if ((svsk = serv->sv_sockets) != NULL)
                rpc_remove_list(&serv->sv_sockets, svsk);

        if (svsk) {
                dprintk("svc: socket %p dequeued, inuse=%d\n",
                        svsk->sk_sk, svsk->sk_inuse);
                svsk->sk_qued = 0;
        }

        return svsk;
}

/*
 * Having read count bytes from a socket, check whether it
 * needs to be re-enqueued.
 */
static inline void
svc_sock_received(struct svc_sock *svsk, int count)
{
        spin_lock_bh(&svsk->sk_lock);
        if ((svsk->sk_data -= count) < 0) {
                printk(KERN_NOTICE "svc: sk_data negative!\n");
                svsk->sk_data = 0;
        }
        svsk->sk_rqstp = NULL; /* XXX */
        svsk->sk_busy = 0;
        if (svsk->sk_conn || svsk->sk_data || svsk->sk_close) {
                dprintk("svc: socket %p re-enqueued after receive\n",
                                                svsk->sk_sk);
                svc_sock_enqueue(svsk);
        }
        spin_unlock_bh(&svsk->sk_lock);
}

/*
 * Dequeue a new connection.
 */
static inline void
svc_sock_accepted(struct svc_sock *svsk)
{
        spin_lock_bh(&svsk->sk_lock);
        svsk->sk_busy = 0;
        svsk->sk_conn--;
        if (svsk->sk_conn || svsk->sk_data || svsk->sk_close) {
                dprintk("svc: socket %p re-enqueued after accept\n",
                                                svsk->sk_sk);
                svc_sock_enqueue(svsk);
        }
        spin_unlock_bh(&svsk->sk_lock);
}

/*
 * Release a socket after use.
 */
static inline void
svc_sock_release(struct svc_rqst *rqstp)
{
        struct svc_sock *svsk = rqstp->rq_sock;

        if (!svsk)
                return;
        svc_release_skb(rqstp);
        rqstp->rq_sock = NULL;
        if (!--(svsk->sk_inuse) && svsk->sk_dead) {
                dprintk("svc: releasing dead socket\n");
                sock_release(svsk->sk_sock);
                kfree(svsk);
        }
}

/*
 * External function to wake up a server waiting for data
 */
void
svc_wake_up(struct svc_serv *serv)
{
        struct svc_rqst *rqstp;

        spin_lock_bh(&serv->sv_lock);
        if ((rqstp = serv->sv_threads) != NULL) {
                dprintk("svc: daemon %p woken up.\n", rqstp);
                /*
                svc_serv_dequeue(serv, rqstp);
                rqstp->rq_sock = NULL;
                 */
                wake_up(&rqstp->rq_wait);
        }
        spin_unlock_bh(&serv->sv_lock);
}

/*
 * Generic sendto routine
 */
static int
svc_sendto(struct svc_rqst *rqstp, struct iovec *iov, int nr)
{
        mm_segment_t    oldfs;
        struct socket   *sock = rqstp->rq_sock->sk_sock;
        struct msghdr   msg;
        int             i, buflen, len;

        for (i = buflen = 0; i < nr; i++)
                buflen += iov[i].iov_len;

        msg.msg_name    = &rqstp->rq_addr;
        msg.msg_namelen = sizeof(rqstp->rq_addr);
        msg.msg_iov     = iov;
        msg.msg_iovlen  = nr;
        msg.msg_control = NULL;
        msg.msg_controllen = 0;

        msg.msg_flags   = MSG_DONTWAIT;

        oldfs = get_fs(); set_fs(KERNEL_DS);
        len = sock_sendmsg(sock, &msg, buflen);
        set_fs(oldfs);

        dprintk("svc: socket %p sendto([%p %Zu... ], %d, %d) = %d\n",
                        rqstp->rq_sock, iov[0].iov_base, iov[0].iov_len, nr, buflen, len);

        return len;
}

/*
 * Check input queue length
 */
static int
svc_recv_available(struct svc_sock *svsk)
{
        mm_segment_t    oldfs;
        struct socket   *sock = svsk->sk_sock;
        int             avail, err;

        oldfs = get_fs(); set_fs(KERNEL_DS);
        err = sock->ops->ioctl(sock, TIOCINQ, (unsigned long) &avail);
        set_fs(oldfs);

        return (err >= 0)? avail : err;
}

/*
 * Generic recvfrom routine.
 */
static int
svc_recvfrom(struct svc_rqst *rqstp, struct iovec *iov, int nr, int buflen)
{
        mm_segment_t    oldfs;
        struct msghdr   msg;
        struct socket   *sock;
        int             len, alen;

        rqstp->rq_addrlen = sizeof(rqstp->rq_addr);
        sock = rqstp->rq_sock->sk_sock;

        msg.msg_name    = &rqstp->rq_addr;
        msg.msg_namelen = sizeof(rqstp->rq_addr);
        msg.msg_iov     = iov;
        msg.msg_iovlen  = nr;
        msg.msg_control = NULL;
        msg.msg_controllen = 0;

        msg.msg_flags   = MSG_DONTWAIT;

        oldfs = get_fs(); set_fs(KERNEL_DS);
        len = sock_recvmsg(sock, &msg, buflen, MSG_DONTWAIT);
        set_fs(oldfs);

        /* sock_recvmsg doesn't fill in the name/namelen, so we must..
         * possibly we should cache this in the svc_sock structure
         * at accept time. FIXME
         */
        alen = sizeof(rqstp->rq_addr);
        sock->ops->getname(sock, (struct sockaddr *)&rqstp->rq_addr, &alen, 1);

        dprintk("svc: socket %p recvfrom(%p, %Zu) = %d\n",
                rqstp->rq_sock, iov[0].iov_base, iov[0].iov_len, len);

        return len;
}

/*
 * INET callback when data has been received on the socket.
 */
static void
svc_udp_data_ready(struct sock *sk, int count)
{
        struct svc_sock *svsk = (struct svc_sock *)(sk->user_data);

        if (!svsk)
                return;
        dprintk("svc: socket %p(inet %p), count=%d, busy=%d\n",
                svsk, sk, count, svsk->sk_busy);
        spin_lock_bh(&svsk->sk_lock);
        svsk->sk_data = 1;
        svc_sock_enqueue(svsk);
        spin_unlock_bh(&svsk->sk_lock);
}

/*
 * Receive a datagram from a UDP socket.
 */
static int
svc_udp_recvfrom(struct svc_rqst *rqstp)
{
        struct svc_sock *svsk = rqstp->rq_sock;
        struct svc_serv *serv = svsk->sk_server;
        struct sk_buff  *skb;
        u32             *data;
        int             err, len;

        svsk->sk_data = 0;
        while ((skb = skb_recv_datagram(svsk->sk_sk, 0, 1, &err)) == NULL) {
                svc_sock_received(svsk, 0);
                if (err == -EAGAIN)
                        return err;
                /* possibly an icmp error */
                dprintk("svc: recvfrom returned error %d\n", -err);
        }

        /* There may be more data */
        svsk->sk_data = 1;

        len  = skb->len - sizeof(struct udphdr);
        data = (u32 *) (skb->h.raw + sizeof(struct udphdr));

        rqstp->rq_skbuff      = skb;
        rqstp->rq_argbuf.base = data;
        rqstp->rq_argbuf.buf  = data;
        rqstp->rq_argbuf.len  = (len >> 2);
        /* rqstp->rq_resbuf      = rqstp->rq_defbuf; */
        rqstp->rq_prot        = IPPROTO_UDP;

        /* Get sender address */
        rqstp->rq_addr.sin_family = AF_INET;
        rqstp->rq_addr.sin_port = skb->h.uh->source;
        rqstp->rq_addr.sin_addr.s_addr = skb->nh.iph->saddr;

        if (serv->sv_stats)
                serv->sv_stats->netudpcnt++;

        /* One down, maybe more to go... */
        svsk->sk_sk->stamp = skb->stamp;
        svc_sock_received(svsk, 0);

        return len;
}

static int
svc_udp_sendto(struct svc_rqst *rqstp)
{
        struct svc_buf  *bufp = &rqstp->rq_resbuf;
        int             error;

        /* Set up the first element of the reply iovec.
         * Any other iovecs that may be in use have been taken
         * care of by the server implementation itself.
         */
        /* bufp->base = bufp->area; */
        bufp->iov[0].iov_base = bufp->base;
        bufp->iov[0].iov_len  = bufp->len << 2;

        error = svc_sendto(rqstp, bufp->iov, bufp->nriov);
        if (error == -ECONNREFUSED)
                /* ICMP error on earlier request. */
                error = svc_sendto(rqstp, bufp->iov, bufp->nriov);
        else if (error == -EAGAIN)
                /* Ignore and wait for re-xmit */
                error = 0;

        return error;
}

static int
svc_udp_init(struct svc_sock *svsk)
{
        svsk->sk_sk->data_ready = svc_udp_data_ready;
        svsk->sk_recvfrom = svc_udp_recvfrom;
        svsk->sk_sendto = svc_udp_sendto;

        return 0;
}

/*
 * A state change on a listening socket means there's a connection
 * pending.
 */
static void
svc_tcp_state_change1(struct sock *sk)
{
        struct svc_sock *svsk;

        dprintk("svc: socket %p TCP (listen) state change %d\n",
                        sk, sk->state);

        if  (sk->state != TCP_ESTABLISHED) {
                /* Aborted connection, SYN_RECV or whatever... */
                return;
        }
        if (!(svsk = (struct svc_sock *) sk->user_data)) {
                printk("svc: socket %p: no user data\n", sk);
                return;
        }
        spin_lock_bh(&svsk->sk_lock);
        svsk->sk_conn++;
        svc_sock_enqueue(svsk);
        spin_unlock_bh(&svsk->sk_lock);
}

/*
 * A state change on a connected socket means it's dying or dead.
 */
static void
svc_tcp_state_change2(struct sock *sk)
{
        struct svc_sock *svsk;

        dprintk("svc: socket %p TCP (connected) state change %d (svsk %p)\n",
                        sk, sk->state, sk->user_data);

        if (!(svsk = (struct svc_sock *) sk->user_data)) {
                printk("svc: socket %p: no user data\n", sk);
                return;
        }
        spin_lock_bh(&svsk->sk_lock);
        svsk->sk_close = 1;
        svc_sock_enqueue(svsk);
        spin_unlock_bh(&svsk->sk_lock);
}

static void
svc_tcp_data_ready(struct sock *sk, int count)
{
        struct svc_sock *       svsk;

        /* Disconnect signalled through data_ready?!? */
        if (sk->state != TCP_ESTABLISHED) {
                svc_tcp_state_change2(sk);
                return;
        }

        dprintk("svc: socket %p TCP data ready (svsk %p)\n",
                        sk, sk->user_data);
        if (!(svsk = (struct svc_sock *)(sk->user_data)))
                return;
        spin_lock_bh(&svsk->sk_lock);
        svsk->sk_data++;
        svc_sock_enqueue(svsk);
        spin_unlock_bh(&svsk->sk_lock);
}

/*
 * Accept a TCP connection
 */
static void
svc_tcp_accept(struct svc_sock *svsk)
{
        struct sockaddr_in sin;
        struct svc_serv *serv = svsk->sk_server;
        struct socket   *sock = svsk->sk_sock;
        struct socket   *newsock;
        struct proto_ops *ops;
        struct svc_sock *newsvsk;
        int             err, slen;

        dprintk("svc: tcp_accept %p sock %p\n", svsk, sock);
        if (!sock)
                return;

        if (!(newsock = sock_alloc())) {
                printk(KERN_WARNING "%s: no more sockets!\n", serv->sv_name);
                return;
        }
        dprintk("svc: tcp_accept %p allocated\n", newsock);

        newsock->type = sock->type;
        newsock->ops = ops = sock->ops;

        if ((err = ops->accept(sock, newsock, O_NONBLOCK)) < 0) {
                if (net_ratelimit())
                        printk(KERN_WARNING "%s: accept failed (err %d)!\n",
                                   serv->sv_name, -err);
                goto failed;            /* aborted connection or whatever */
        }

        slen = sizeof(sin);
        err = ops->getname(newsock, (struct sockaddr *) &sin, &slen, 1);
        if (err < 0) {
                if (net_ratelimit())
                        printk(KERN_WARNING "%s: peername failed (err %d)!\n",
                                   serv->sv_name, -err);
                goto failed;            /* aborted connection or whatever */
        }

        /* Ideally, we would want to reject connections from unauthorized
         * hosts here, but when we get encription, the IP of the host won't
         * tell us anything. For now just warn about unpriv connections.
         */
        if (ntohs(sin.sin_port) >= 1024) {
                if (net_ratelimit())
                        printk(KERN_WARNING
                                   "%s: connect from unprivileged port: %u.%u.%u.%u:%d\n",
                                   serv->sv_name, 
                                   NIPQUAD(sin.sin_addr.s_addr), ntohs(sin.sin_port));
        }

        dprintk("%s: connect from %u.%u.%u.%u:%04x\n", serv->sv_name,
                        NIPQUAD(sin.sin_addr.s_addr), ntohs(sin.sin_port));

        if (!(newsvsk = svc_setup_socket(serv, newsock, &err, 0)))
                goto failed;

        /* Precharge. Data may have arrived on the socket before we
         * installed the data_ready callback. 
         */
        spin_lock_bh(&newsvsk->sk_lock);
        newsvsk->sk_data = 1;
        newsvsk->sk_temp = 1;
        svc_sock_enqueue(newsvsk);
        spin_unlock_bh(&newsvsk->sk_lock);

        if (serv->sv_stats)
                serv->sv_stats->nettcpconn++;

        return;

failed:
        sock_release(newsock);
        return;
}

/*
 * Receive data from a TCP socket.
 */
static int
svc_tcp_recvfrom(struct svc_rqst *rqstp)
{
        struct svc_sock *svsk = rqstp->rq_sock;
        struct svc_serv *serv = svsk->sk_server;
        struct svc_buf  *bufp = &rqstp->rq_argbuf;
        int             len, ready, used;

        dprintk("svc: tcp_recv %p data %d conn %d close %d\n",
                        svsk, svsk->sk_data, svsk->sk_conn, svsk->sk_close);

        if (svsk->sk_close) {
                svc_delete_socket(svsk);
                return 0;
        }

        if (svsk->sk_conn) {
                svc_tcp_accept(svsk);
                svc_sock_accepted(svsk);
                return 0;
        }

        ready = svsk->sk_data;

        /* Receive data. If we haven't got the record length yet, get
         * the next four bytes. Otherwise try to gobble up as much as
         * possible up to the complete record length.
         */
        if (svsk->sk_tcplen < 4) {
                unsigned long   want = 4 - svsk->sk_tcplen;
                struct iovec    iov;

                iov.iov_base = ((char *) &svsk->sk_reclen) + svsk->sk_tcplen;
                iov.iov_len  = want;
                if ((len = svc_recvfrom(rqstp, &iov, 1, want)) < 0)
                        goto error;
                svsk->sk_tcplen += len;

                svsk->sk_reclen = ntohl(svsk->sk_reclen);
                if (!(svsk->sk_reclen & 0x80000000)) {
                        /* FIXME: technically, a record can be fragmented,
                         *  and non-terminal fragments will not have the top
                         *  bit set in the fragment length header.
                         *  But apparently no known nfs clients send fragmented
                         *  records. */
                        /* FIXME: shutdown socket */
                        printk(KERN_NOTICE "RPC: bad TCP reclen %08lx",
                               (unsigned long) svsk->sk_reclen);
                        return -EIO;
                }
                svsk->sk_reclen &= 0x7fffffff;
                dprintk("svc: TCP record, %d bytes\n", svsk->sk_reclen);
        }

        /* Check whether enough data is available */
        len = svc_recv_available(svsk);
        if (len < 0)
                goto error;

        if (len < svsk->sk_reclen) {
                /* FIXME: if sk_reclen > window-size, then we will
                 * never be able to receive the record, so should
                 * shutdown the connection
                 */
                dprintk("svc: incomplete TCP record (%d of %d)\n",
                        len, svsk->sk_reclen);
                svc_sock_received(svsk, ready);
                return -EAGAIN; /* record not complete */
        }
        /* if we think there is only one more record to read, but
         * it is bigger than we expect, then two records must have arrived
         * together, so pretend we aren't using the record.. */
        if (len > svsk->sk_reclen && ready == 1)
                used = 0;
        else    used = 1;

        /* Frob argbuf */
        bufp->iov[0].iov_base += 4;
        bufp->iov[0].iov_len  -= 4;

        /* Now receive data */
        len = svc_recvfrom(rqstp, bufp->iov, bufp->nriov, svsk->sk_reclen);
        if (len < 0)
                goto error;

        dprintk("svc: TCP complete record (%d bytes)\n", len);

        /* Position reply write pointer immediately after
         * record length */
        rqstp->rq_resbuf.buf += 1;
        rqstp->rq_resbuf.len  = 1;

        rqstp->rq_skbuff      = 0;
        rqstp->rq_argbuf.buf += 1;
        rqstp->rq_argbuf.len  = (len >> 2);
        rqstp->rq_prot        = IPPROTO_TCP;

        /* Reset TCP read info */
        svsk->sk_reclen = 0;
        svsk->sk_tcplen = 0;

        svc_sock_received(svsk, used);
        if (serv->sv_stats)
                serv->sv_stats->nettcpcnt++;

        return len;

error:
        if (len == -EAGAIN) {
                dprintk("RPC: TCP recvfrom got EAGAIN\n");
                svc_sock_received(svsk, ready); /* Clear data ready */
        } else {
                printk(KERN_NOTICE "%s: recvfrom returned errno %d\n",
                                        svsk->sk_server->sv_name, -len);
                svc_sock_received(svsk, 0);
        }

        return len;
}

/*
 * Send out data on TCP socket.
 * FIXME: Make the sendto call non-blocking in order not to hang
 * a daemon on a dead client. Requires write queue maintenance.
 */
static int
svc_tcp_sendto(struct svc_rqst *rqstp)
{
        struct svc_buf  *bufp = &rqstp->rq_resbuf;
        int sent;

        /* Set up the first element of the reply iovec.
         * Any other iovecs that may be in use have been taken
         * care of by the server implementation itself.
         */
        bufp->iov[0].iov_base = bufp->base;
        bufp->iov[0].iov_len  = bufp->len << 2;
        bufp->base[0] = htonl(0x80000000|((bufp->len << 2) - 4));

        sent = svc_sendto(rqstp, bufp->iov, bufp->nriov);
        if (sent != bufp->len<<2) {
                printk(KERN_NOTICE "rpc-srv/tcp: %s: sent only %d bytes of %d - should shutdown socket\n",
                       rqstp->rq_sock->sk_server->sv_name,
                       sent, bufp->len << 2);
                /* FIXME: should shutdown the socket, or allocate more memort
                 * or wait and try again or something.  Otherwise
                 * client will get confused
                 */
        }
        return sent;
}

static int
svc_tcp_init(struct svc_sock *svsk)
{
        struct sock     *sk = svsk->sk_sk;

        svsk->sk_recvfrom = svc_tcp_recvfrom;
        svsk->sk_sendto = svc_tcp_sendto;

        if (sk->state == TCP_LISTEN) {
                dprintk("setting up TCP socket for listening\n");
                sk->state_change = svc_tcp_state_change1;
        } else {
                dprintk("setting up TCP socket for reading\n");
                sk->state_change = svc_tcp_state_change2;
                sk->data_ready = svc_tcp_data_ready;

                svsk->sk_reclen = 0;
                svsk->sk_tcplen = 0;
        }

        return 0;
}

/*
 * Receive the next request on any socket.
 */
int
svc_recv(struct svc_serv *serv, struct svc_rqst *rqstp, long timeout)
{
        struct svc_sock         *svsk;
        int                     len;
        DECLARE_WAITQUEUE(wait, current);

        dprintk("svc: server %p waiting for data (to = %ld)\n",
                rqstp, timeout);

        if (rqstp->rq_sock)
                printk(KERN_ERR 
                        "svc_recv: service %p, socket not NULL!\n",
                         rqstp);
        if (waitqueue_active(&rqstp->rq_wait))
                printk(KERN_ERR 
                        "svc_recv: service %p, wait queue active!\n",
                         rqstp);

again:
        /* Initialize the buffers */
        rqstp->rq_argbuf = rqstp->rq_defbuf;
        rqstp->rq_resbuf = rqstp->rq_defbuf;

        if (signalled())
                return -EINTR;

        spin_lock_bh(&serv->sv_lock);
        if ((svsk = svc_sock_dequeue(serv)) != NULL) {
                rqstp->rq_sock = svsk;
                svsk->sk_inuse++;
        } else {
                /* No data pending. Go to sleep */
                svc_serv_enqueue(serv, rqstp);

                /*
                 * We have to be able to interrupt this wait
                 * to bring down the daemons ...
                 */
                set_current_state(TASK_INTERRUPTIBLE);
                add_wait_queue(&rqstp->rq_wait, &wait);
                spin_unlock_bh(&serv->sv_lock);

                schedule_timeout(timeout);

                spin_lock_bh(&serv->sv_lock);
                remove_wait_queue(&rqstp->rq_wait, &wait);

                if (!(svsk = rqstp->rq_sock)) {
                        svc_serv_dequeue(serv, rqstp);
                        spin_unlock_bh(&serv->sv_lock);
                        dprintk("svc: server %p, no data yet\n", rqstp);
                        return signalled()? -EINTR : -EAGAIN;
                }
        }
        spin_unlock_bh(&serv->sv_lock);

        dprintk("svc: server %p, socket %p, inuse=%d\n",
                 rqstp, svsk, svsk->sk_inuse);
        len = svsk->sk_recvfrom(rqstp);
        dprintk("svc: got len=%d\n", len);

        /* No data, incomplete (TCP) read, or accept() */
        if (len == 0 || len == -EAGAIN) {
                svc_sock_release(rqstp);
                goto again;
        }

        rqstp->rq_secure  = ntohs(rqstp->rq_addr.sin_port) < 1024;
        rqstp->rq_userset = 0;
        rqstp->rq_verfed  = 0;

        svc_getlong(&rqstp->rq_argbuf, rqstp->rq_xid);
        svc_putlong(&rqstp->rq_resbuf, rqstp->rq_xid);

        /* Assume that the reply consists of a single buffer. */
        rqstp->rq_resbuf.nriov = 1;

        if (serv->sv_stats)
                serv->sv_stats->netcnt++;
        return len;
}

/* 
 * Drop request
 */
void
svc_drop(struct svc_rqst *rqstp)
{
        dprintk("svc: socket %p dropped request\n", rqstp->rq_sock);
        svc_sock_release(rqstp);
}

/*
 * Return reply to client.
 */
int
svc_send(struct svc_rqst *rqstp)
{
        struct svc_sock *svsk;
        int             len;

        if ((svsk = rqstp->rq_sock) == NULL) {
                printk(KERN_WARNING "NULL socket pointer in %s:%d\n",
                                __FILE__, __LINE__);
                return -EFAULT;
        }

        /* release the receive skb before sending the reply */
        svc_release_skb(rqstp);

        len = svsk->sk_sendto(rqstp);
        svc_sock_release(rqstp);

        if (len == -ECONNREFUSED || len == -ENOTCONN || len == -EAGAIN)
                return 0;
        return len;
}

/*
 * Initialize socket for RPC use and create svc_sock struct
 * XXX: May want to setsockopt SO_SNDBUF and SO_RCVBUF.
 */
static struct svc_sock *
svc_setup_socket(struct svc_serv *serv, struct socket *sock,
                                        int *errp, int pmap_register)
{
        struct svc_sock *svsk;
        struct sock     *inet;

        dprintk("svc: svc_setup_socket %p\n", sock);
        if (!(svsk = kmalloc(sizeof(*svsk), GFP_KERNEL))) {
                *errp = -ENOMEM;
                return NULL;
        }
        memset(svsk, 0, sizeof(*svsk));

        inet = sock->sk;
        inet->user_data = svsk;
        svsk->sk_sock = sock;
        svsk->sk_sk = inet;
        svsk->sk_ostate = inet->state_change;
        svsk->sk_odata = inet->data_ready;
        svsk->sk_server = serv;
        spin_lock_init(&svsk->sk_lock);

        /* Initialize the socket */
        if (sock->type == SOCK_DGRAM)
                *errp = svc_udp_init(svsk);
        else
                *errp = svc_tcp_init(svsk);
if (svsk->sk_sk == NULL)
        printk(KERN_WARNING "svsk->sk_sk == NULL after svc_prot_init!\n");

        /* Register socket with portmapper */
        if (*errp >= 0 && pmap_register)
                *errp = svc_register(serv, inet->protocol, ntohs(inet->sport));

        if (*errp < 0) {
                inet->user_data = NULL;
                kfree(svsk);
                return NULL;
        }

        spin_lock_bh(&serv->sv_lock);
        svsk->sk_list = serv->sv_allsocks;
        serv->sv_allsocks = svsk;
        spin_unlock_bh(&serv->sv_lock);

        dprintk("svc: svc_setup_socket created %p (inet %p)\n",
                                svsk, svsk->sk_sk);
        return svsk;
}

/*
 * Create socket for RPC service.
 */
static int
svc_create_socket(struct svc_serv *serv, int protocol, struct sockaddr_in *sin)
{
        struct svc_sock *svsk;
        struct socket   *sock;
        int             error;
        int             type;

        dprintk("svc: svc_create_socket(%s, %d, %u.%u.%u.%u:%d)\n",
                                serv->sv_program->pg_name, protocol,
                                NIPQUAD(sin->sin_addr.s_addr),
                                ntohs(sin->sin_port));

        if (protocol != IPPROTO_UDP && protocol != IPPROTO_TCP) {
                printk(KERN_WARNING "svc: only UDP and TCP "
                                "sockets supported\n");
                return -EINVAL;
        }
        type = (protocol == IPPROTO_UDP)? SOCK_DGRAM : SOCK_STREAM;

        if ((error = sock_create(PF_INET, type, protocol, &sock)) < 0)
                return error;

        if (sin != NULL) {
                error = sock->ops->bind(sock, (struct sockaddr *) sin,
                                                sizeof(*sin));
                if (error < 0)
                        goto bummer;
        }

        if (protocol == IPPROTO_TCP) {
                if ((error = sock->ops->listen(sock, 5)) < 0)
                        goto bummer;
        }

        if ((svsk = svc_setup_socket(serv, sock, &error, 1)) != NULL)
                return 0;

bummer:
        dprintk("svc: svc_create_socket error = %d\n", -error);
        sock_release(sock);
        return error;
}

/*
 * Remove a dead socket
 */
void
svc_delete_socket(struct svc_sock *svsk)
{
        struct svc_sock **rsk;
        struct svc_serv *serv;
        struct sock     *sk;

        dprintk("svc: svc_delete_socket(%p)\n", svsk);

        serv = svsk->sk_server;
        sk = svsk->sk_sk;

        sk->state_change = svsk->sk_ostate;
        sk->data_ready = svsk->sk_odata;

        spin_lock_bh(&serv->sv_lock);

        for (rsk = &serv->sv_allsocks; *rsk; rsk = &(*rsk)->sk_list) {
                if (*rsk == svsk)
                        break;
        }
        if (!*rsk) {
                spin_unlock_bh(&serv->sv_lock);
                return;
        }
        *rsk = svsk->sk_list;
        if (svsk->sk_qued)
                rpc_remove_list(&serv->sv_sockets, svsk);

        spin_unlock_bh(&serv->sv_lock);

        svsk->sk_dead = 1;

        if (!svsk->sk_inuse) {
                sock_release(svsk->sk_sock);
                kfree(svsk);
        } else {
                printk(KERN_NOTICE "svc: server socket destroy delayed\n");
                /* svsk->sk_server = NULL; */
        }
}

/*
 * Make a socket for nfsd and lockd
 */
int
svc_makesock(struct svc_serv *serv, int protocol, unsigned short port)
{
        struct sockaddr_in      sin;

        dprintk("svc: creating socket proto = %d\n", protocol);
        sin.sin_family      = AF_INET;
        sin.sin_addr.s_addr = INADDR_ANY;
        sin.sin_port        = htons(port);
        return svc_create_socket(serv, protocol, &sin);
}