svcsock.c

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/*
 * 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_xprt_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 <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/module.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/tcp.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/file.h>
#include <linux/freezer.h>
#include <net/sock.h>
#include <net/checksum.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/tcp.h>
#include <net/tcp_states.h>
#include <asm/uaccess.h>
#include <asm/ioctls.h>
#include <trace/events/skb.h>

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

#include "sunrpc.h"

#define RPCDBG_FACILITY RPCDBG_SVCXPRT


static struct svc_sock *svc_setup_socket(struct svc_serv *, struct socket *,
                     int flags);
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 *);
static void     svc_sock_detach(struct svc_xprt *);
static void     svc_tcp_sock_detach(struct svc_xprt *);
static void     svc_sock_free(struct svc_xprt *);

static struct svc_xprt *svc_create_socket(struct svc_serv *, int,
                      struct net *, struct sockaddr *,
                      int, int);
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int,
                         struct net *, struct sockaddr *,
                         int, int);
static void svc_bc_sock_free(struct svc_xprt *xprt);
#endif /* CONFIG_SUNRPC_BACKCHANNEL */

#ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct lock_class_key svc_key[2];
static struct lock_class_key svc_slock_key[2];

static void svc_reclassify_socket(struct socket *sock)
{
    struct sock *sk = sock->sk;
    BUG_ON(sock_owned_by_user(sk));
    switch (sk->sk_family) {
    case AF_INET:
        sock_lock_init_class_and_name(sk, "slock-AF_INET-NFSD",
                          &svc_slock_key[0],
                          "sk_xprt.xpt_lock-AF_INET-NFSD",
                          &svc_key[0]);
        break;

    case AF_INET6:
        sock_lock_init_class_and_name(sk, "slock-AF_INET6-NFSD",
                          &svc_slock_key[1],
                          "sk_xprt.xpt_lock-AF_INET6-NFSD",
                          &svc_key[1]);
        break;

    default:
        BUG();
    }
}
#else
static void svc_reclassify_socket(struct socket *sock)
{
}
#endif

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

    if (skb) {
        struct svc_sock *svsk =
            container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
        rqstp->rq_xprt_ctxt = NULL;

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

union svc_pktinfo_u {
    struct in_pktinfo pkti;
    struct in6_pktinfo pkti6;
};
#define SVC_PKTINFO_SPACE \
    CMSG_SPACE(sizeof(union svc_pktinfo_u))

static void svc_set_cmsg_data(struct svc_rqst *rqstp, struct cmsghdr *cmh)
{
    struct svc_sock *svsk =
        container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
    switch (svsk->sk_sk->sk_family) {
    case AF_INET: {
            struct in_pktinfo *pki = CMSG_DATA(cmh);

            cmh->cmsg_level = SOL_IP;
            cmh->cmsg_type = IP_PKTINFO;
            pki->ipi_ifindex = 0;
            pki->ipi_spec_dst.s_addr =
                 svc_daddr_in(rqstp)->sin_addr.s_addr;
            cmh->cmsg_len = CMSG_LEN(sizeof(*pki));
        }
        break;

    case AF_INET6: {
            struct in6_pktinfo *pki = CMSG_DATA(cmh);
            struct sockaddr_in6 *daddr = svc_daddr_in6(rqstp);

            cmh->cmsg_level = SOL_IPV6;
            cmh->cmsg_type = IPV6_PKTINFO;
            pki->ipi6_ifindex = daddr->sin6_scope_id;
            pki->ipi6_addr = daddr->sin6_addr;
            cmh->cmsg_len = CMSG_LEN(sizeof(*pki));
        }
        break;
    }
}

/*
 * send routine intended to be shared by the fore- and back-channel
 */
int svc_send_common(struct socket *sock, struct xdr_buf *xdr,
            struct page *headpage, unsigned long headoffset,
            struct page *tailpage, unsigned long tailoffset)
{
    int     result;
    int     size;
    struct page **ppage = xdr->pages;
    size_t      base = xdr->page_base;
    unsigned int    pglen = xdr->page_len;
    unsigned int    flags = MSG_MORE;
    int     slen;
    int     len = 0;

    slen = xdr->len;

    /* send head */
    if (slen == xdr->head[0].iov_len)
        flags = 0;
    len = kernel_sendpage(sock, headpage, headoffset,
                  xdr->head[0].iov_len, flags);
    if (len != xdr->head[0].iov_len)
        goto out;
    slen -= xdr->head[0].iov_len;
    if (slen == 0)
        goto out;

    /* send page data */
    size = PAGE_SIZE - base < pglen ? PAGE_SIZE - base : pglen;
    while (pglen > 0) {
        if (slen == size)
            flags = 0;
        result = kernel_sendpage(sock, *ppage, base, size, flags);
        if (result > 0)
            len += result;
        if (result != size)
            goto out;
        slen -= size;
        pglen -= size;
        size = PAGE_SIZE < pglen ? PAGE_SIZE : pglen;
        base = 0;
        ppage++;
    }

    /* send tail */
    if (xdr->tail[0].iov_len) {
        result = kernel_sendpage(sock, tailpage, tailoffset,
                   xdr->tail[0].iov_len, 0);
        if (result > 0)
            len += result;
    }

out:
    return len;
}


/*
 * Generic sendto routine
 */
static int svc_sendto(struct svc_rqst *rqstp, struct xdr_buf *xdr)
{
    struct svc_sock *svsk =
        container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
    struct socket   *sock = svsk->sk_sock;
    union {
        struct cmsghdr  hdr;
        long        all[SVC_PKTINFO_SPACE / sizeof(long)];
    } buffer;
    struct cmsghdr *cmh = &buffer.hdr;
    int     len = 0;
    unsigned long tailoff;
    unsigned long headoff;
    RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);

    if (rqstp->rq_prot == IPPROTO_UDP) {
        struct msghdr msg = {
            .msg_name   = &rqstp->rq_addr,
            .msg_namelen    = rqstp->rq_addrlen,
            .msg_control    = cmh,
            .msg_controllen = sizeof(buffer),
            .msg_flags  = MSG_MORE,
        };

        svc_set_cmsg_data(rqstp, cmh);

        if (sock_sendmsg(sock, &msg, 0) < 0)
            goto out;
    }

    tailoff = ((unsigned long)xdr->tail[0].iov_base) & (PAGE_SIZE-1);
    headoff = 0;
    len = svc_send_common(sock, xdr, rqstp->rq_respages[0], headoff,
                   rqstp->rq_respages[0], tailoff);

out:
    dprintk("svc: socket %p sendto([%p %Zu... ], %d) = %d (addr %s)\n",
        svsk, xdr->head[0].iov_base, xdr->head[0].iov_len,
        xdr->len, len, svc_print_addr(rqstp, buf, sizeof(buf)));

    return len;
}

/*
 * Report socket names for nfsdfs
 */
static int svc_one_sock_name(struct svc_sock *svsk, char *buf, int remaining)
{
    const struct sock *sk = svsk->sk_sk;
    const char *proto_name = sk->sk_protocol == IPPROTO_UDP ?
                            "udp" : "tcp";
    int len;

    switch (sk->sk_family) {
    case PF_INET:
        len = snprintf(buf, remaining, "ipv4 %s %pI4 %d\n",
                proto_name,
                &inet_sk(sk)->inet_rcv_saddr,
                inet_sk(sk)->inet_num);
        break;
    case PF_INET6:
        len = snprintf(buf, remaining, "ipv6 %s %pI6 %d\n",
                proto_name,
                &inet6_sk(sk)->rcv_saddr,
                inet_sk(sk)->inet_num);
        break;
    default:
        len = snprintf(buf, remaining, "*unknown-%d*\n",
                sk->sk_family);
    }

    if (len >= remaining) {
        *buf = '\0';
        return -ENAMETOOLONG;
    }
    return len;
}

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

    err = kernel_sock_ioctl(sock, TIOCINQ, (unsigned long) &avail);

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

/*
 * Generic recvfrom routine.
 */
static int svc_recvfrom(struct svc_rqst *rqstp, struct kvec *iov, int nr,
            int buflen)
{
    struct svc_sock *svsk =
        container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
    struct msghdr msg = {
        .msg_flags  = MSG_DONTWAIT,
    };
    int len;

    rqstp->rq_xprt_hlen = 0;

    len = kernel_recvmsg(svsk->sk_sock, &msg, iov, nr, buflen,
                msg.msg_flags);

    dprintk("svc: socket %p recvfrom(%p, %Zu) = %d\n",
        svsk, iov[0].iov_base, iov[0].iov_len, len);
    return len;
}

static int svc_partial_recvfrom(struct svc_rqst *rqstp,
                struct kvec *iov, int nr,
                int buflen, unsigned int base)
{
    size_t save_iovlen;
    void *save_iovbase;
    unsigned int i;
    int ret;

    if (base == 0)
        return svc_recvfrom(rqstp, iov, nr, buflen);

    for (i = 0; i < nr; i++) {
        if (iov[i].iov_len > base)
            break;
        base -= iov[i].iov_len;
    }
    save_iovlen = iov[i].iov_len;
    save_iovbase = iov[i].iov_base;
    iov[i].iov_len -= base;
    iov[i].iov_base += base;
    ret = svc_recvfrom(rqstp, &iov[i], nr - i, buflen);
    iov[i].iov_len = save_iovlen;
    iov[i].iov_base = save_iovbase;
    return ret;
}

/*
 * Set socket snd and rcv buffer lengths
 */
static void svc_sock_setbufsize(struct socket *sock, unsigned int snd,
                unsigned int rcv)
{
#if 0
    mm_segment_t    oldfs;
    oldfs = get_fs(); set_fs(KERNEL_DS);
    sock_setsockopt(sock, SOL_SOCKET, SO_SNDBUF,
            (char*)&snd, sizeof(snd));
    sock_setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
            (char*)&rcv, sizeof(rcv));
#else
    /* sock_setsockopt limits use to sysctl_?mem_max,
     * which isn't acceptable.  Until that is made conditional
     * on not having CAP_SYS_RESOURCE or similar, we go direct...
     * DaveM said I could!
     */
    lock_sock(sock->sk);
    sock->sk->sk_sndbuf = snd * 2;
    sock->sk->sk_rcvbuf = rcv * 2;
    sock->sk->sk_write_space(sock->sk);
    release_sock(sock->sk);
#endif
}
/*
 * 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->sk_user_data;
    wait_queue_head_t *wq = sk_sleep(sk);

    if (svsk) {
        dprintk("svc: socket %p(inet %p), count=%d, busy=%d\n",
            svsk, sk, count,
            test_bit(XPT_BUSY, &svsk->sk_xprt.xpt_flags));
        set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
        svc_xprt_enqueue(&svsk->sk_xprt);
    }
    if (wq && waitqueue_active(wq))
        wake_up_interruptible(wq);
}

/*
 * INET callback when space is newly available on the socket.
 */
static void svc_write_space(struct sock *sk)
{
    struct svc_sock *svsk = (struct svc_sock *)(sk->sk_user_data);
    wait_queue_head_t *wq = sk_sleep(sk);

    if (svsk) {
        dprintk("svc: socket %p(inet %p), write_space busy=%d\n",
            svsk, sk, test_bit(XPT_BUSY, &svsk->sk_xprt.xpt_flags));
        svc_xprt_enqueue(&svsk->sk_xprt);
    }

    if (wq && waitqueue_active(wq)) {
        dprintk("RPC svc_write_space: someone sleeping on %p\n",
               svsk);
        wake_up_interruptible(wq);
    }
}

static void svc_tcp_write_space(struct sock *sk)
{
    struct socket *sock = sk->sk_socket;

    if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk) && sock)
        clear_bit(SOCK_NOSPACE, &sock->flags);
    svc_write_space(sk);
}

/*
 * See net/ipv6/ip_sockglue.c : ip_cmsg_recv_pktinfo
 */
static int svc_udp_get_dest_address4(struct svc_rqst *rqstp,
                     struct cmsghdr *cmh)
{
    struct in_pktinfo *pki = CMSG_DATA(cmh);
    struct sockaddr_in *daddr = svc_daddr_in(rqstp);

    if (cmh->cmsg_type != IP_PKTINFO)
        return 0;

    daddr->sin_family = AF_INET;
    daddr->sin_addr.s_addr = pki->ipi_spec_dst.s_addr;
    return 1;
}

/*
 * See net/ipv6/datagram.c : datagram_recv_ctl
 */
static int svc_udp_get_dest_address6(struct svc_rqst *rqstp,
                     struct cmsghdr *cmh)
{
    struct in6_pktinfo *pki = CMSG_DATA(cmh);
    struct sockaddr_in6 *daddr = svc_daddr_in6(rqstp);

    if (cmh->cmsg_type != IPV6_PKTINFO)
        return 0;

    daddr->sin6_family = AF_INET6;
    daddr->sin6_addr = pki->ipi6_addr;
    daddr->sin6_scope_id = pki->ipi6_ifindex;
    return 1;
}

/*
 * Copy the UDP datagram's destination address to the rqstp structure.
 * The 'destination' address in this case is the address to which the
 * peer sent the datagram, i.e. our local address. For multihomed
 * hosts, this can change from msg to msg. Note that only the IP
 * address changes, the port number should remain the same.
 */
static int svc_udp_get_dest_address(struct svc_rqst *rqstp,
                    struct cmsghdr *cmh)
{
    switch (cmh->cmsg_level) {
    case SOL_IP:
        return svc_udp_get_dest_address4(rqstp, cmh);
    case SOL_IPV6:
        return svc_udp_get_dest_address6(rqstp, cmh);
    }

    return 0;
}

/*
 * Receive a datagram from a UDP socket.
 */
static int svc_udp_recvfrom(struct svc_rqst *rqstp)
{
    struct svc_sock *svsk =
        container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
    struct svc_serv *serv = svsk->sk_xprt.xpt_server;
    struct sk_buff  *skb;
    union {
        struct cmsghdr  hdr;
        long        all[SVC_PKTINFO_SPACE / sizeof(long)];
    } buffer;
    struct cmsghdr *cmh = &buffer.hdr;
    struct msghdr msg = {
        .msg_name = svc_addr(rqstp),
        .msg_control = cmh,
        .msg_controllen = sizeof(buffer),
        .msg_flags = MSG_DONTWAIT,
    };
    size_t len;
    int err;

    if (test_and_clear_bit(XPT_CHNGBUF, &svsk->sk_xprt.xpt_flags))
        /* udp sockets need large rcvbuf as all pending
         * requests are still in that buffer.  sndbuf must
         * also be large enough that there is enough space
         * for one reply per thread.  We count all threads
         * rather than threads in a particular pool, which
         * provides an upper bound on the number of threads
         * which will access the socket.
         */
        svc_sock_setbufsize(svsk->sk_sock,
                (serv->sv_nrthreads+3) * serv->sv_max_mesg,
                (serv->sv_nrthreads+3) * serv->sv_max_mesg);

    clear_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
    skb = NULL;
    err = kernel_recvmsg(svsk->sk_sock, &msg, NULL,
                 0, 0, MSG_PEEK | MSG_DONTWAIT);
    if (err >= 0)
        skb = skb_recv_datagram(svsk->sk_sk, 0, 1, &err);

    if (skb == NULL) {
        if (err != -EAGAIN) {
            /* possibly an icmp error */
            dprintk("svc: recvfrom returned error %d\n", -err);
            set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
        }
        return 0;
    }
    len = svc_addr_len(svc_addr(rqstp));
    rqstp->rq_addrlen = len;
    if (skb->tstamp.tv64 == 0) {
        skb->tstamp = ktime_get_real();
        /* Don't enable netstamp, sunrpc doesn't
           need that much accuracy */
    }
    svsk->sk_sk->sk_stamp = skb->tstamp;
    set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags); /* there may be more data... */

    len  = skb->len - sizeof(struct udphdr);
    rqstp->rq_arg.len = len;

    rqstp->rq_prot = IPPROTO_UDP;

    if (!svc_udp_get_dest_address(rqstp, cmh)) {
        net_warn_ratelimited("svc: received unknown control message %d/%d; dropping RPC reply datagram\n",
                     cmh->cmsg_level, cmh->cmsg_type);
        goto out_free;
    }
    rqstp->rq_daddrlen = svc_addr_len(svc_daddr(rqstp));

    if (skb_is_nonlinear(skb)) {
        /* we have to copy */
        local_bh_disable();
        if (csum_partial_copy_to_xdr(&rqstp->rq_arg, skb)) {
            local_bh_enable();
            /* checksum error */
            goto out_free;
        }
        local_bh_enable();
        skb_free_datagram_locked(svsk->sk_sk, skb);
    } else {
        /* we can use it in-place */
        rqstp->rq_arg.head[0].iov_base = skb->data +
            sizeof(struct udphdr);
        rqstp->rq_arg.head[0].iov_len = len;
        if (skb_checksum_complete(skb))
            goto out_free;
        rqstp->rq_xprt_ctxt = skb;
    }

    rqstp->rq_arg.page_base = 0;
    if (len <= rqstp->rq_arg.head[0].iov_len) {
        rqstp->rq_arg.head[0].iov_len = len;
        rqstp->rq_arg.page_len = 0;
        rqstp->rq_respages = rqstp->rq_pages+1;
    } else {
        rqstp->rq_arg.page_len = len - rqstp->rq_arg.head[0].iov_len;
        rqstp->rq_respages = rqstp->rq_pages + 1 +
            DIV_ROUND_UP(rqstp->rq_arg.page_len, PAGE_SIZE);
    }

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

    return len;
out_free:
    trace_kfree_skb(skb, svc_udp_recvfrom);
    skb_free_datagram_locked(svsk->sk_sk, skb);
    return 0;
}

static int
svc_udp_sendto(struct svc_rqst *rqstp)
{
    int     error;

    error = svc_sendto(rqstp, &rqstp->rq_res);
    if (error == -ECONNREFUSED)
        /* ICMP error on earlier request. */
        error = svc_sendto(rqstp, &rqstp->rq_res);

    return error;
}

static void svc_udp_prep_reply_hdr(struct svc_rqst *rqstp)
{
}

static int svc_udp_has_wspace(struct svc_xprt *xprt)
{
    struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
    struct svc_serv *serv = xprt->xpt_server;
    unsigned long required;

    /*
     * Set the SOCK_NOSPACE flag before checking the available
     * sock space.
     */
    set_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
    required = atomic_read(&svsk->sk_xprt.xpt_reserved) + serv->sv_max_mesg;
    if (required*2 > sock_wspace(svsk->sk_sk))
        return 0;
    clear_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
    return 1;
}

static struct svc_xprt *svc_udp_accept(struct svc_xprt *xprt)
{
    BUG();
    return NULL;
}

static struct svc_xprt *svc_udp_create(struct svc_serv *serv,
                       struct net *net,
                       struct sockaddr *sa, int salen,
                       int flags)
{
    return svc_create_socket(serv, IPPROTO_UDP, net, sa, salen, flags);
}

static struct svc_xprt_ops svc_udp_ops = {
    .xpo_create = svc_udp_create,
    .xpo_recvfrom = svc_udp_recvfrom,
    .xpo_sendto = svc_udp_sendto,
    .xpo_release_rqst = svc_release_skb,
    .xpo_detach = svc_sock_detach,
    .xpo_free = svc_sock_free,
    .xpo_prep_reply_hdr = svc_udp_prep_reply_hdr,
    .xpo_has_wspace = svc_udp_has_wspace,
    .xpo_accept = svc_udp_accept,
};

static struct svc_xprt_class svc_udp_class = {
    .xcl_name = "udp",
    .xcl_owner = THIS_MODULE,
    .xcl_ops = &svc_udp_ops,
    .xcl_max_payload = RPCSVC_MAXPAYLOAD_UDP,
};

static void svc_udp_init(struct svc_sock *svsk, struct svc_serv *serv)
{
    int err, level, optname, one = 1;

    svc_xprt_init(sock_net(svsk->sk_sock->sk), &svc_udp_class,
              &svsk->sk_xprt, serv);
    clear_bit(XPT_CACHE_AUTH, &svsk->sk_xprt.xpt_flags);
    svsk->sk_sk->sk_data_ready = svc_udp_data_ready;
    svsk->sk_sk->sk_write_space = svc_write_space;

    /* initialise setting must have enough space to
     * receive and respond to one request.
     * svc_udp_recvfrom will re-adjust if necessary
     */
    svc_sock_setbufsize(svsk->sk_sock,
                3 * svsk->sk_xprt.xpt_server->sv_max_mesg,
                3 * svsk->sk_xprt.xpt_server->sv_max_mesg);

    /* data might have come in before data_ready set up */
    set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
    set_bit(XPT_CHNGBUF, &svsk->sk_xprt.xpt_flags);

    /* make sure we get destination address info */
    switch (svsk->sk_sk->sk_family) {
    case AF_INET:
        level = SOL_IP;
        optname = IP_PKTINFO;
        break;
    case AF_INET6:
        level = SOL_IPV6;
        optname = IPV6_RECVPKTINFO;
        break;
    default:
        BUG();
    }
    err = kernel_setsockopt(svsk->sk_sock, level, optname,
                    (char *)&one, sizeof(one));
    dprintk("svc: kernel_setsockopt returned %d\n", err);
}

/*
 * A data_ready event on a listening socket means there's a connection
 * pending. Do not use state_change as a substitute for it.
 */
static void svc_tcp_listen_data_ready(struct sock *sk, int count_unused)
{
    struct svc_sock *svsk = (struct svc_sock *)sk->sk_user_data;
    wait_queue_head_t *wq;

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

    /*
     * This callback may called twice when a new connection
     * is established as a child socket inherits everything
     * from a parent LISTEN socket.
     * 1) data_ready method of the parent socket will be called
     *    when one of child sockets become ESTABLISHED.
     * 2) data_ready method of the child socket may be called
     *    when it receives data before the socket is accepted.
     * In case of 2, we should ignore it silently.
     */
    if (sk->sk_state == TCP_LISTEN) {
        if (svsk) {
            set_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);
            svc_xprt_enqueue(&svsk->sk_xprt);
        } else
            printk("svc: socket %p: no user data\n", sk);
    }

    wq = sk_sleep(sk);
    if (wq && waitqueue_active(wq))
        wake_up_interruptible_all(wq);
}

/*
 * A state change on a connected socket means it's dying or dead.
 */
static void svc_tcp_state_change(struct sock *sk)
{
    struct svc_sock *svsk = (struct svc_sock *)sk->sk_user_data;
    wait_queue_head_t *wq = sk_sleep(sk);

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

    if (!svsk)
        printk("svc: socket %p: no user data\n", sk);
    else {
        set_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags);
        svc_xprt_enqueue(&svsk->sk_xprt);
    }
    if (wq && waitqueue_active(wq))
        wake_up_interruptible_all(wq);
}

static void svc_tcp_data_ready(struct sock *sk, int count)
{
    struct svc_sock *svsk = (struct svc_sock *)sk->sk_user_data;
    wait_queue_head_t *wq = sk_sleep(sk);

    dprintk("svc: socket %p TCP data ready (svsk %p)\n",
        sk, sk->sk_user_data);
    if (svsk) {
        set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
        svc_xprt_enqueue(&svsk->sk_xprt);
    }
    if (wq && waitqueue_active(wq))
        wake_up_interruptible(wq);
}

/*
 * Accept a TCP connection
 */
static struct svc_xprt *svc_tcp_accept(struct svc_xprt *xprt)
{
    struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
    struct sockaddr_storage addr;
    struct sockaddr *sin = (struct sockaddr *) &addr;
    struct svc_serv *serv = svsk->sk_xprt.xpt_server;
    struct socket   *sock = svsk->sk_sock;
    struct socket   *newsock;
    struct svc_sock *newsvsk;
    int     err, slen;
    RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);

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

    clear_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);
    err = kernel_accept(sock, &newsock, O_NONBLOCK);
    if (err < 0) {
        if (err == -ENOMEM)
            printk(KERN_WARNING "%s: no more sockets!\n",
                   serv->sv_name);
        else if (err != -EAGAIN)
            net_warn_ratelimited("%s: accept failed (err %d)!\n",
                         serv->sv_name, -err);
        return NULL;
    }
    set_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);

    err = kernel_getpeername(newsock, sin, &slen);
    if (err < 0) {
        net_warn_ratelimited("%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 encryption, the IP of the host won't
     * tell us anything.  For now just warn about unpriv connections.
     */
    if (!svc_port_is_privileged(sin)) {
        dprintk(KERN_WARNING
            "%s: connect from unprivileged port: %s\n",
            serv->sv_name,
            __svc_print_addr(sin, buf, sizeof(buf)));
    }
    dprintk("%s: connect from %s\n", serv->sv_name,
        __svc_print_addr(sin, buf, sizeof(buf)));

    /* make sure that a write doesn't block forever when
     * low on memory
     */
    newsock->sk->sk_sndtimeo = HZ*30;

    newsvsk = svc_setup_socket(serv, newsock,
                 (SVC_SOCK_ANONYMOUS | SVC_SOCK_TEMPORARY));
    if (IS_ERR(newsvsk))
        goto failed;
    svc_xprt_set_remote(&newsvsk->sk_xprt, sin, slen);
    err = kernel_getsockname(newsock, sin, &slen);
    if (unlikely(err < 0)) {
        dprintk("svc_tcp_accept: kernel_getsockname error %d\n", -err);
        slen = offsetof(struct sockaddr, sa_data);
    }
    svc_xprt_set_local(&newsvsk->sk_xprt, sin, slen);

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

    return &newsvsk->sk_xprt;

failed:
    sock_release(newsock);
    return NULL;
}

static unsigned int svc_tcp_restore_pages(struct svc_sock *svsk, struct svc_rqst *rqstp)
{
    unsigned int i, len, npages;

    if (svsk->sk_tcplen <= sizeof(rpc_fraghdr))
        return 0;
    len = svsk->sk_tcplen - sizeof(rpc_fraghdr);
    npages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
    for (i = 0; i < npages; i++) {
        if (rqstp->rq_pages[i] != NULL)
            put_page(rqstp->rq_pages[i]);
        BUG_ON(svsk->sk_pages[i] == NULL);
        rqstp->rq_pages[i] = svsk->sk_pages[i];
        svsk->sk_pages[i] = NULL;
    }
    rqstp->rq_arg.head[0].iov_base = page_address(rqstp->rq_pages[0]);
    return len;
}

static void svc_tcp_save_pages(struct svc_sock *svsk, struct svc_rqst *rqstp)
{
    unsigned int i, len, npages;

    if (svsk->sk_tcplen <= sizeof(rpc_fraghdr))
        return;
    len = svsk->sk_tcplen - sizeof(rpc_fraghdr);
    npages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
    for (i = 0; i < npages; i++) {
        svsk->sk_pages[i] = rqstp->rq_pages[i];
        rqstp->rq_pages[i] = NULL;
    }
}

static void svc_tcp_clear_pages(struct svc_sock *svsk)
{
    unsigned int i, len, npages;

    if (svsk->sk_tcplen <= sizeof(rpc_fraghdr))
        goto out;
    len = svsk->sk_tcplen - sizeof(rpc_fraghdr);
    npages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
    for (i = 0; i < npages; i++) {
        BUG_ON(svsk->sk_pages[i] == NULL);
        put_page(svsk->sk_pages[i]);
        svsk->sk_pages[i] = NULL;
    }
out:
    svsk->sk_tcplen = 0;
}

/*
 * Receive data.
 * If we haven't gotten the record length yet, get the next four bytes.
 * Otherwise try to gobble up as much as possible up to the complete
 * record length.
 */
static int svc_tcp_recv_record(struct svc_sock *svsk, struct svc_rqst *rqstp)
{
    struct svc_serv *serv = svsk->sk_xprt.xpt_server;
    unsigned int want;
    int len;

    clear_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

    if (svsk->sk_tcplen < sizeof(rpc_fraghdr)) {
        struct kvec iov;

        want = sizeof(rpc_fraghdr) - svsk->sk_tcplen;
        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;

        if (len < want) {
            dprintk("svc: short recvfrom while reading record "
                "length (%d of %d)\n", len, want);
            return -EAGAIN;
        }

        svsk->sk_reclen = ntohl(svsk->sk_reclen);
        if (!(svsk->sk_reclen & RPC_LAST_STREAM_FRAGMENT)) {
            /* 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. */
            net_notice_ratelimited("RPC: multiple fragments per record not supported\n");
            goto err_delete;
        }

        svsk->sk_reclen &= RPC_FRAGMENT_SIZE_MASK;
        dprintk("svc: TCP record, %d bytes\n", svsk->sk_reclen);
        if (svsk->sk_reclen > serv->sv_max_mesg) {
            net_notice_ratelimited("RPC: fragment too large: 0x%08lx\n",
                           (unsigned long)svsk->sk_reclen);
            goto err_delete;
        }
    }

    if (svsk->sk_reclen < 8)
        goto err_delete; /* client is nuts. */

    len = svsk->sk_reclen;

    return len;
error:
    dprintk("RPC: TCP recv_record got %d\n", len);
    return len;
err_delete:
    set_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags);
    return -EAGAIN;
}

static int receive_cb_reply(struct svc_sock *svsk, struct svc_rqst *rqstp)
{
    struct rpc_xprt *bc_xprt = svsk->sk_xprt.xpt_bc_xprt;
    struct rpc_rqst *req = NULL;
    struct kvec *src, *dst;
    __be32 *p = (__be32 *)rqstp->rq_arg.head[0].iov_base;
    __be32 xid;
    __be32 calldir;

    xid = *p++;
    calldir = *p;

    if (bc_xprt)
        req = xprt_lookup_rqst(bc_xprt, xid);

    if (!req) {
        printk(KERN_NOTICE
            "%s: Got unrecognized reply: "
            "calldir 0x%x xpt_bc_xprt %p xid %08x\n",
            __func__, ntohl(calldir),
            bc_xprt, xid);
        return -EAGAIN;
    }

    memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
    /*
     * XXX!: cheating for now!  Only copying HEAD.
     * But we know this is good enough for now (in fact, for any
     * callback reply in the forseeable future).
     */
    dst = &req->rq_private_buf.head[0];
    src = &rqstp->rq_arg.head[0];
    if (dst->iov_len < src->iov_len)
        return -EAGAIN; /* whatever; just giving up. */
    memcpy(dst->iov_base, src->iov_base, src->iov_len);
    xprt_complete_rqst(req->rq_task, svsk->sk_reclen);
    rqstp->rq_arg.len = 0;
    return 0;
}

static int copy_pages_to_kvecs(struct kvec *vec, struct page **pages, int len)
{
    int i = 0;
    int t = 0;

    while (t < len) {
        vec[i].iov_base = page_address(pages[i]);
        vec[i].iov_len = PAGE_SIZE;
        i++;
        t += PAGE_SIZE;
    }
    return i;
}


/*
 * Receive data from a TCP socket.
 */
static int svc_tcp_recvfrom(struct svc_rqst *rqstp)
{
    struct svc_sock *svsk =
        container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
    struct svc_serv *serv = svsk->sk_xprt.xpt_server;
    int     len;
    struct kvec *vec;
    unsigned int want, base;
    __be32 *p;
    __be32 calldir;
    int pnum;

    dprintk("svc: tcp_recv %p data %d conn %d close %d\n",
        svsk, test_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags),
        test_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags),
        test_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags));

    len = svc_tcp_recv_record(svsk, rqstp);
    if (len < 0)
        goto error;

    base = svc_tcp_restore_pages(svsk, rqstp);
    want = svsk->sk_reclen - base;

    vec = rqstp->rq_vec;

    pnum = copy_pages_to_kvecs(&vec[0], &rqstp->rq_pages[0],
                        svsk->sk_reclen);

    rqstp->rq_respages = &rqstp->rq_pages[pnum];

    /* Now receive data */
    len = svc_partial_recvfrom(rqstp, vec, pnum, want, base);
    if (len >= 0)
        svsk->sk_tcplen += len;
    if (len != want) {
        svc_tcp_save_pages(svsk, rqstp);
        if (len < 0 && len != -EAGAIN)
            goto err_other;
        dprintk("svc: incomplete TCP record (%d of %d)\n",
            svsk->sk_tcplen, svsk->sk_reclen);
        goto err_noclose;
    }

    rqstp->rq_arg.len = svsk->sk_reclen;
    rqstp->rq_arg.page_base = 0;
    if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len) {
        rqstp->rq_arg.head[0].iov_len = rqstp->rq_arg.len;
        rqstp->rq_arg.page_len = 0;
    } else
        rqstp->rq_arg.page_len = rqstp->rq_arg.len - rqstp->rq_arg.head[0].iov_len;

    rqstp->rq_xprt_ctxt   = NULL;
    rqstp->rq_prot        = IPPROTO_TCP;

    p = (__be32 *)rqstp->rq_arg.head[0].iov_base;
    calldir = p[1];
    if (calldir)
        len = receive_cb_reply(svsk, rqstp);

    /* Reset TCP read info */
    svsk->sk_reclen = 0;
    svsk->sk_tcplen = 0;
    /* If we have more data, signal svc_xprt_enqueue() to try again */
    if (svc_recv_available(svsk) > sizeof(rpc_fraghdr))
        set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

    if (len < 0)
        goto error;

    svc_xprt_copy_addrs(rqstp, &svsk->sk_xprt);
    if (serv->sv_stats)
        serv->sv_stats->nettcpcnt++;

    dprintk("svc: TCP complete record (%d bytes)\n", rqstp->rq_arg.len);
    return rqstp->rq_arg.len;

error:
    if (len != -EAGAIN)
        goto err_other;
    dprintk("RPC: TCP recvfrom got EAGAIN\n");
    return 0;
err_other:
    printk(KERN_NOTICE "%s: recvfrom returned errno %d\n",
           svsk->sk_xprt.xpt_server->sv_name, -len);
    set_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags);
err_noclose:
    return 0;   /* record not complete */
}

/*
 * Send out data on TCP socket.
 */
static int svc_tcp_sendto(struct svc_rqst *rqstp)
{
    struct xdr_buf  *xbufp = &rqstp->rq_res;
    int sent;
    __be32 reclen;

    /* Set up the first element of the reply kvec.
     * Any other kvecs that may be in use have been taken
     * care of by the server implementation itself.
     */
    reclen = htonl(0x80000000|((xbufp->len ) - 4));
    memcpy(xbufp->head[0].iov_base, &reclen, 4);

    sent = svc_sendto(rqstp, &rqstp->rq_res);
    if (sent != xbufp->len) {
        printk(KERN_NOTICE
               "rpc-srv/tcp: %s: %s %d when sending %d bytes "
               "- shutting down socket\n",
               rqstp->rq_xprt->xpt_server->sv_name,
               (sent<0)?"got error":"sent only",
               sent, xbufp->len);
        set_bit(XPT_CLOSE, &rqstp->rq_xprt->xpt_flags);
        svc_xprt_enqueue(rqstp->rq_xprt);
        sent = -EAGAIN;
    }
    return sent;
}

/*
 * Setup response header. TCP has a 4B record length field.
 */
static void svc_tcp_prep_reply_hdr(struct svc_rqst *rqstp)
{
    struct kvec *resv = &rqstp->rq_res.head[0];

    /* tcp needs a space for the record length... */
    svc_putnl(resv, 0);
}

static int svc_tcp_has_wspace(struct svc_xprt *xprt)
{
    struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
    struct svc_serv *serv = svsk->sk_xprt.xpt_server;
    int required;

    if (test_bit(XPT_LISTENER, &xprt->xpt_flags))
        return 1;
    required = atomic_read(&xprt->xpt_reserved) + serv->sv_max_mesg;
    if (sk_stream_wspace(svsk->sk_sk) >= required)
        return 1;
    set_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
    return 0;
}

static struct svc_xprt *svc_tcp_create(struct svc_serv *serv,
                       struct net *net,
                       struct sockaddr *sa, int salen,
                       int flags)
{
    return svc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags);
}

#if defined(CONFIG_SUNRPC_BACKCHANNEL)
static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int,
                         struct net *, struct sockaddr *,
                         int, int);
static void svc_bc_sock_free(struct svc_xprt *xprt);

static struct svc_xprt *svc_bc_tcp_create(struct svc_serv *serv,
                       struct net *net,
                       struct sockaddr *sa, int salen,
                       int flags)
{
    return svc_bc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags);
}

static void svc_bc_tcp_sock_detach(struct svc_xprt *xprt)
{
}

static struct svc_xprt_ops svc_tcp_bc_ops = {
    .xpo_create = svc_bc_tcp_create,
    .xpo_detach = svc_bc_tcp_sock_detach,
    .xpo_free = svc_bc_sock_free,
    .xpo_prep_reply_hdr = svc_tcp_prep_reply_hdr,
};

static struct svc_xprt_class svc_tcp_bc_class = {
    .xcl_name = "tcp-bc",
    .xcl_owner = THIS_MODULE,
    .xcl_ops = &svc_tcp_bc_ops,
    .xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP,
};

static void svc_init_bc_xprt_sock(void)
{
    svc_reg_xprt_class(&svc_tcp_bc_class);
}

static void svc_cleanup_bc_xprt_sock(void)
{
    svc_unreg_xprt_class(&svc_tcp_bc_class);
}
#else /* CONFIG_SUNRPC_BACKCHANNEL */
static void svc_init_bc_xprt_sock(void)
{
}

static void svc_cleanup_bc_xprt_sock(void)
{
}
#endif /* CONFIG_SUNRPC_BACKCHANNEL */

static struct svc_xprt_ops svc_tcp_ops = {
    .xpo_create = svc_tcp_create,
    .xpo_recvfrom = svc_tcp_recvfrom,
    .xpo_sendto = svc_tcp_sendto,
    .xpo_release_rqst = svc_release_skb,
    .xpo_detach = svc_tcp_sock_detach,
    .xpo_free = svc_sock_free,
    .xpo_prep_reply_hdr = svc_tcp_prep_reply_hdr,
    .xpo_has_wspace = svc_tcp_has_wspace,
    .xpo_accept = svc_tcp_accept,
};

static struct svc_xprt_class svc_tcp_class = {
    .xcl_name = "tcp",
    .xcl_owner = THIS_MODULE,
    .xcl_ops = &svc_tcp_ops,
    .xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP,
};

void svc_init_xprt_sock(void)
{
    svc_reg_xprt_class(&svc_tcp_class);
    svc_reg_xprt_class(&svc_udp_class);
    svc_init_bc_xprt_sock();
}

void svc_cleanup_xprt_sock(void)
{
    svc_unreg_xprt_class(&svc_tcp_class);
    svc_unreg_xprt_class(&svc_udp_class);
    svc_cleanup_bc_xprt_sock();
}

static void svc_tcp_init(struct svc_sock *svsk, struct svc_serv *serv)
{
    struct sock *sk = svsk->sk_sk;

    svc_xprt_init(sock_net(svsk->sk_sock->sk), &svc_tcp_class,
              &svsk->sk_xprt, serv);
    set_bit(XPT_CACHE_AUTH, &svsk->sk_xprt.xpt_flags);
    if (sk->sk_state == TCP_LISTEN) {
        dprintk("setting up TCP socket for listening\n");
        set_bit(XPT_LISTENER, &svsk->sk_xprt.xpt_flags);
        sk->sk_data_ready = svc_tcp_listen_data_ready;
        set_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);
    } else {
        dprintk("setting up TCP socket for reading\n");
        sk->sk_state_change = svc_tcp_state_change;
        sk->sk_data_ready = svc_tcp_data_ready;
        sk->sk_write_space = svc_tcp_write_space;

        svsk->sk_reclen = 0;
        svsk->sk_tcplen = 0;
        memset(&svsk->sk_pages[0], 0, sizeof(svsk->sk_pages));

        tcp_sk(sk)->nonagle |= TCP_NAGLE_OFF;

        set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
        if (sk->sk_state != TCP_ESTABLISHED)
            set_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags);
    }
}

void svc_sock_update_bufs(struct svc_serv *serv)
{
    /*
     * The number of server threads has changed. Update
     * rcvbuf and sndbuf accordingly on all sockets
     */
    struct svc_sock *svsk;

    spin_lock_bh(&serv->sv_lock);
    list_for_each_entry(svsk, &serv->sv_permsocks, sk_xprt.xpt_list)
        set_bit(XPT_CHNGBUF, &svsk->sk_xprt.xpt_flags);
    spin_unlock_bh(&serv->sv_lock);
}
EXPORT_SYMBOL_GPL(svc_sock_update_bufs);

/*
 * 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 flags)
{
    struct svc_sock *svsk;
    struct sock *inet;
    int     pmap_register = !(flags & SVC_SOCK_ANONYMOUS);
    int     err = 0;

    dprintk("svc: svc_setup_socket %p\n", sock);
    svsk = kzalloc(sizeof(*svsk), GFP_KERNEL);
    if (!svsk)
        return ERR_PTR(-ENOMEM);

    inet = sock->sk;

    /* Register socket with portmapper */
    if (pmap_register)
        err = svc_register(serv, sock_net(sock->sk), inet->sk_family,
                     inet->sk_protocol,
                     ntohs(inet_sk(inet)->inet_sport));

    if (err < 0) {
        kfree(svsk);
        return ERR_PTR(err);
    }

    inet->sk_user_data = svsk;
    svsk->sk_sock = sock;
    svsk->sk_sk = inet;
    svsk->sk_ostate = inet->sk_state_change;
    svsk->sk_odata = inet->sk_data_ready;
    svsk->sk_owspace = inet->sk_write_space;

    /* Initialize the socket */
    if (sock->type == SOCK_DGRAM)
        svc_udp_init(svsk, serv);
    else {
        /* initialise setting must have enough space to
         * receive and respond to one request.
         */
        svc_sock_setbufsize(svsk->sk_sock, 4 * serv->sv_max_mesg,
                    4 * serv->sv_max_mesg);
        svc_tcp_init(svsk, serv);
    }

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

    return svsk;
}

int svc_addsock(struct svc_serv *serv, const int fd, char *name_return,
        const size_t len)
{
    int err = 0;
    struct socket *so = sockfd_lookup(fd, &err);
    struct svc_sock *svsk = NULL;
    struct sockaddr_storage addr;
    struct sockaddr *sin = (struct sockaddr *)&addr;
    int salen;

    if (!so)
        return err;
    err = -EAFNOSUPPORT;
    if ((so->sk->sk_family != PF_INET) && (so->sk->sk_family != PF_INET6))
        goto out;
    err =  -EPROTONOSUPPORT;
    if (so->sk->sk_protocol != IPPROTO_TCP &&
        so->sk->sk_protocol != IPPROTO_UDP)
        goto out;
    err = -EISCONN;
    if (so->state > SS_UNCONNECTED)
        goto out;
    err = -ENOENT;
    if (!try_module_get(THIS_MODULE))
        goto out;
    svsk = svc_setup_socket(serv, so, SVC_SOCK_DEFAULTS);
    if (IS_ERR(svsk)) {
        module_put(THIS_MODULE);
        err = PTR_ERR(svsk);
        goto out;
    }
    if (kernel_getsockname(svsk->sk_sock, sin, &salen) == 0)
        svc_xprt_set_local(&svsk->sk_xprt, sin, salen);
    svc_add_new_perm_xprt(serv, &svsk->sk_xprt);
    return svc_one_sock_name(svsk, name_return, len);
out:
    sockfd_put(so);
    return err;
}
EXPORT_SYMBOL_GPL(svc_addsock);

/*
 * Create socket for RPC service.
 */
static struct svc_xprt *svc_create_socket(struct svc_serv *serv,
                      int protocol,
                      struct net *net,
                      struct sockaddr *sin, int len,
                      int flags)
{
    struct svc_sock *svsk;
    struct socket   *sock;
    int     error;
    int     type;
    struct sockaddr_storage addr;
    struct sockaddr *newsin = (struct sockaddr *)&addr;
    int     newlen;
    int     family;
    int     val;
    RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);

    dprintk("svc: svc_create_socket(%s, %d, %s)\n",
            serv->sv_program->pg_name, protocol,
            __svc_print_addr(sin, buf, sizeof(buf)));

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

    type = (protocol == IPPROTO_UDP)? SOCK_DGRAM : SOCK_STREAM;
    switch (sin->sa_family) {
    case AF_INET6:
        family = PF_INET6;
        break;
    case AF_INET:
        family = PF_INET;
        break;
    default:
        return ERR_PTR(-EINVAL);
    }

    error = __sock_create(net, family, type, protocol, &sock, 1);
    if (error < 0)
        return ERR_PTR(error);

    svc_reclassify_socket(sock);

    /*
     * If this is an PF_INET6 listener, we want to avoid
     * getting requests from IPv4 remotes.  Those should
     * be shunted to a PF_INET listener via rpcbind.
     */
    val = 1;
    if (family == PF_INET6)
        kernel_setsockopt(sock, SOL_IPV6, IPV6_V6ONLY,
                    (char *)&val, sizeof(val));

    if (type == SOCK_STREAM)
        sock->sk->sk_reuse = SK_CAN_REUSE; /* allow address reuse */
    error = kernel_bind(sock, sin, len);
    if (error < 0)
        goto bummer;

    newlen = len;
    error = kernel_getsockname(sock, newsin, &newlen);
    if (error < 0)
        goto bummer;

    if (protocol == IPPROTO_TCP) {
        if ((error = kernel_listen(sock, 64)) < 0)
            goto bummer;
    }

    svsk = svc_setup_socket(serv, sock, flags);
    if (IS_ERR(svsk)) {
        error = PTR_ERR(svsk);
        goto bummer;
    }
    svc_xprt_set_local(&svsk->sk_xprt, newsin, newlen);
    return (struct svc_xprt *)svsk;
bummer:
    dprintk("svc: svc_create_socket error = %d\n", -error);
    sock_release(sock);
    return ERR_PTR(error);
}

/*
 * Detach the svc_sock from the socket so that no
 * more callbacks occur.
 */
static void svc_sock_detach(struct svc_xprt *xprt)
{
    struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
    struct sock *sk = svsk->sk_sk;
    wait_queue_head_t *wq;

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

    /* put back the old socket callbacks */
    sk->sk_state_change = svsk->sk_ostate;
    sk->sk_data_ready = svsk->sk_odata;
    sk->sk_write_space = svsk->sk_owspace;

    wq = sk_sleep(sk);
    if (wq && waitqueue_active(wq))
        wake_up_interruptible(wq);
}

/*
 * Disconnect the socket, and reset the callbacks
 */
static void svc_tcp_sock_detach(struct svc_xprt *xprt)
{
    struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);

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

    svc_sock_detach(xprt);

    if (!test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
        svc_tcp_clear_pages(svsk);
        kernel_sock_shutdown(svsk->sk_sock, SHUT_RDWR);
    }
}

/*
 * Free the svc_sock's socket resources and the svc_sock itself.
 */
static void svc_sock_free(struct svc_xprt *xprt)
{
    struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
    dprintk("svc: svc_sock_free(%p)\n", svsk);

    if (svsk->sk_sock->file)
        sockfd_put(svsk->sk_sock);
    else
        sock_release(svsk->sk_sock);
    kfree(svsk);
}

#if defined(CONFIG_SUNRPC_BACKCHANNEL)
/*
 * Create a back channel svc_xprt which shares the fore channel socket.
 */
static struct svc_xprt *svc_bc_create_socket(struct svc_serv *serv,
                         int protocol,
                         struct net *net,
                         struct sockaddr *sin, int len,
                         int flags)
{
    struct svc_sock *svsk;
    struct svc_xprt *xprt;

    if (protocol != IPPROTO_TCP) {
        printk(KERN_WARNING "svc: only TCP sockets"
            " supported on shared back channel\n");
        return ERR_PTR(-EINVAL);
    }

    svsk = kzalloc(sizeof(*svsk), GFP_KERNEL);
    if (!svsk)
        return ERR_PTR(-ENOMEM);

    xprt = &svsk->sk_xprt;
    svc_xprt_init(net, &svc_tcp_bc_class, xprt, serv);

    serv->sv_bc_xprt = xprt;

    return xprt;
}

/*
 * Free a back channel svc_sock.
 */
static void svc_bc_sock_free(struct svc_xprt *xprt)
{
    if (xprt)
        kfree(container_of(xprt, struct svc_sock, sk_xprt));
}
#endif /* CONFIG_SUNRPC_BACKCHANNEL */