FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_socket2.c

     /*      $NetBSD: uipc_socket2.c,v 1.142 2022/10/26 23:38:09 riastradh Exp $     */
     
     /*-
      * Copyright (c) 2008 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. 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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     * POSSIBILITY OF SUCH DAMAGE.
     */
    
    /*
     * Copyright (c) 1982, 1986, 1988, 1990, 1993
     *      The Regents of the University of California.  All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. 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.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)uipc_socket2.c      8.2 (Berkeley) 2/14/95
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: uipc_socket2.c,v 1.142 2022/10/26 23:38:09 riastradh Exp $");
    
    #ifdef _KERNEL_OPT
    #include "opt_ddb.h"
    #include "opt_inet.h"
    #include "opt_mbuftrace.h"
    #include "opt_sb_max.h"
    #endif
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/file.h>
    #include <sys/buf.h>
    #include <sys/mbuf.h>
    #include <sys/protosw.h>
    #include <sys/domain.h>
    #include <sys/poll.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/signalvar.h>
    #include <sys/kauth.h>
    #include <sys/pool.h>
    #include <sys/uidinfo.h>
    
    #ifdef DDB
    #include <sys/filedesc.h>
    #include <ddb/db_active.h>
    #endif
    
    /*
     * Primitive routines for operating on sockets and socket buffers.
     *
     * Connection life-cycle:
     *
     *      Normal sequence from the active (originating) side:
     *
     *      - soisconnecting() is called during processing of connect() call,
     *      - resulting in an eventual call to soisconnected() if/when the
    *        connection is established.
    *
    *      When the connection is torn down during processing of disconnect():
    *
    *      - soisdisconnecting() is called and,
    *      - soisdisconnected() is called when the connection to the peer
    *        is totally severed.
    *
    *      The semantics of these routines are such that connectionless protocols
    *      can call soisconnected() and soisdisconnected() only, bypassing the
    *      in-progress calls when setting up a ``connection'' takes no time.
    *
    *      From the passive side, a socket is created with two queues of sockets:
    *
    *      - so_q0 (0) for partial connections (i.e. connections in progress)
    *      - so_q (1) for connections already made and awaiting user acceptance.
    *
    *      As a protocol is preparing incoming connections, it creates a socket
    *      structure queued on so_q0 by calling sonewconn().  When the connection
    *      is established, soisconnected() is called, and transfers the
    *      socket structure to so_q, making it available to accept().
    *
    *      If a socket is closed with sockets on either so_q0 or so_q, these
    *      sockets are dropped.
    *
    * Locking rules and assumptions:
    *
    * o socket::so_lock can change on the fly.  The low level routines used
    *   to lock sockets are aware of this.  When so_lock is acquired, the
    *   routine locking must check to see if so_lock still points to the
    *   lock that was acquired.  If so_lock has changed in the meantime, the
    *   now irrelevant lock that was acquired must be dropped and the lock
    *   operation retried.  Although not proven here, this is completely safe
    *   on a multiprocessor system, even with relaxed memory ordering, given
    *   the next two rules:
    *
    * o In order to mutate so_lock, the lock pointed to by the current value
    *   of so_lock must be held: i.e., the socket must be held locked by the
    *   changing thread.  The thread must issue membar_release() to prevent
    *   memory accesses being reordered, and can set so_lock to the desired
    *   value.  If the lock pointed to by the new value of so_lock is not
    *   held by the changing thread, the socket must then be considered
    *   unlocked.
    *
    * o If so_lock is mutated, and the previous lock referred to by so_lock
    *   could still be visible to other threads in the system (e.g. via file
    *   descriptor or protocol-internal reference), then the old lock must
    *   remain valid until the socket and/or protocol control block has been
    *   torn down.
    *
    * o If a socket has a non-NULL so_head value (i.e. is in the process of
    *   connecting), then locking the socket must also lock the socket pointed
    *   to by so_head: their lock pointers must match.
    *
    * o If a socket has connections in progress (so_q, so_q0 not empty) then
    *   locking the socket must also lock the sockets attached to both queues.
    *   Again, their lock pointers must match.
    *
    * o Beyond the initial lock assignment in socreate(), assigning locks to
    *   sockets is the responsibility of the individual protocols / protocol
    *   domains.
    */
   
   static pool_cache_t     socket_cache;
   u_long                  sb_max = SB_MAX;/* maximum socket buffer size */
   static u_long           sb_max_adj;     /* adjusted sb_max */
   
   void
   soisconnecting(struct socket *so)
   {
   
           KASSERT(solocked(so));
   
           so->so_state &= ~(SS_ISCONNECTED|SS_ISDISCONNECTING);
           so->so_state |= SS_ISCONNECTING;
   }
   
   void
   soisconnected(struct socket *so)
   {
           struct socket   *head;
   
           head = so->so_head;
   
           KASSERT(solocked(so));
           KASSERT(head == NULL || solocked2(so, head));
   
           so->so_state &= ~(SS_ISCONNECTING | SS_ISDISCONNECTING);
           so->so_state |= SS_ISCONNECTED;
           if (head && so->so_onq == &head->so_q0) {
                   if ((so->so_options & SO_ACCEPTFILTER) == 0) {
                           /*
                            * Re-enqueue and wake up any waiters, e.g.
                            * processes blocking on accept().
                            */
                           soqremque(so, 0);
                           soqinsque(head, so, 1);
                           sorwakeup(head);
                           cv_broadcast(&head->so_cv);
                   } else {
                           so->so_upcall =
                               head->so_accf->so_accept_filter->accf_callback;
                           so->so_upcallarg = head->so_accf->so_accept_filter_arg;
                           so->so_rcv.sb_flags |= SB_UPCALL;
                           so->so_options &= ~SO_ACCEPTFILTER;
                           (*so->so_upcall)(so, so->so_upcallarg,
                                            POLLIN|POLLRDNORM, M_DONTWAIT);
                   }
           } else {
                   cv_broadcast(&so->so_cv);
                   sorwakeup(so);
                   sowwakeup(so);
           }
   }
   
   void
   soisdisconnecting(struct socket *so)
   {
   
           KASSERT(solocked(so));
   
           so->so_state &= ~SS_ISCONNECTING;
           so->so_state |= (SS_ISDISCONNECTING|SS_CANTRCVMORE|SS_CANTSENDMORE);
           cv_broadcast(&so->so_cv);
           sowwakeup(so);
           sorwakeup(so);
   }
   
   void
   soisdisconnected(struct socket *so)
   {
   
           KASSERT(solocked(so));
   
           so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
           so->so_state |= (SS_CANTRCVMORE|SS_CANTSENDMORE|SS_ISDISCONNECTED);
           cv_broadcast(&so->so_cv);
           sowwakeup(so);
           sorwakeup(so);
   }
   
   void
   soinit2(void)
   {
   
           socket_cache = pool_cache_init(sizeof(struct socket), 0, 0, 0,
               "socket", NULL, IPL_SOFTNET, NULL, NULL, NULL);
   }
   
   /*
    * sonewconn: accept a new connection.
    *
    * When an attempt at a new connection is noted on a socket which accepts
    * connections, sonewconn(9) is called.  If the connection is possible
    * (subject to space constraints, etc) then we allocate a new structure,
    * properly linked into the data structure of the original socket.
    *
    * => If 'soready' is true, then socket will become ready for accept() i.e.
    *    inserted into the so_q queue, SS_ISCONNECTED set and waiters awoken.
    * => May be called from soft-interrupt context.
    * => Listening socket should be locked.
    * => Returns the new socket locked.
    */
   struct socket *
   sonewconn(struct socket *head, bool soready)
   {
           struct socket *so;
           int soqueue, error;
   
           KASSERT(solocked(head));
   
           if (head->so_qlen + head->so_q0len > 3 * head->so_qlimit / 2) {
                   /*
                    * Listen queue overflow.  If there is an accept filter
                    * active, pass through the oldest cxn it's handling.
                    */
                   if (head->so_accf == NULL) {
                           return NULL;
                   } else {
                           struct socket *so2, *next;
   
                           /* Pass the oldest connection waiting in the
                              accept filter */
                           for (so2 = TAILQ_FIRST(&head->so_q0);
                                so2 != NULL; so2 = next) {
                                   next = TAILQ_NEXT(so2, so_qe);
                                   if (so2->so_upcall == NULL) {
                                           continue;
                                   }
                                   so2->so_upcall = NULL;
                                   so2->so_upcallarg = NULL;
                                   so2->so_options &= ~SO_ACCEPTFILTER;
                                   so2->so_rcv.sb_flags &= ~SB_UPCALL;
                                   soisconnected(so2);
                                   break;
                           }
   
                           /* If nothing was nudged out of the acept filter, bail
                            * out; otherwise proceed allocating the socket. */
                           if (so2 == NULL) {
                                   return NULL;
                           }
                   }
           }
           if ((head->so_options & SO_ACCEPTFILTER) != 0) {
                   soready = false;
           }
           soqueue = soready ? 1 : 0;
   
           if ((so = soget(false)) == NULL) {
                   return NULL;
           }
           so->so_type = head->so_type;
           so->so_options = head->so_options & ~SO_ACCEPTCONN;
           so->so_linger = head->so_linger;
           so->so_state = head->so_state | SS_NOFDREF;
           so->so_proto = head->so_proto;
           so->so_timeo = head->so_timeo;
           so->so_pgid = head->so_pgid;
           so->so_send = head->so_send;
           so->so_receive = head->so_receive;
           so->so_uidinfo = head->so_uidinfo;
           so->so_egid = head->so_egid;
           so->so_cpid = head->so_cpid;
   
           /*
            * Share the lock with the listening-socket, it may get unshared
            * once the connection is complete.
            *
            * so_lock is stable while we hold the socket locked, so no
            * need for atomic_load_* here.
            */
           mutex_obj_hold(head->so_lock);
           so->so_lock = head->so_lock;
   
           /*
            * Reserve the space for socket buffers.
            */
   #ifdef MBUFTRACE
           so->so_mowner = head->so_mowner;
           so->so_rcv.sb_mowner = head->so_rcv.sb_mowner;
           so->so_snd.sb_mowner = head->so_snd.sb_mowner;
   #endif
           if (soreserve(so, head->so_snd.sb_hiwat, head->so_rcv.sb_hiwat)) {
                   goto out;
           }
           so->so_snd.sb_lowat = head->so_snd.sb_lowat;
           so->so_rcv.sb_lowat = head->so_rcv.sb_lowat;
           so->so_rcv.sb_timeo = head->so_rcv.sb_timeo;
           so->so_snd.sb_timeo = head->so_snd.sb_timeo;
           so->so_rcv.sb_flags |= head->so_rcv.sb_flags & (SB_AUTOSIZE | SB_ASYNC);
           so->so_snd.sb_flags |= head->so_snd.sb_flags & (SB_AUTOSIZE | SB_ASYNC);
   
           /*
            * Finally, perform the protocol attach.  Note: a new socket
            * lock may be assigned at this point (if so, it will be held).
            */
           error = (*so->so_proto->pr_usrreqs->pr_attach)(so, 0);
           if (error) {
   out:
                   KASSERT(solocked(so));
                   KASSERT(so->so_accf == NULL);
                   soput(so);
   
                   /* Note: the listening socket shall stay locked. */
                   KASSERT(solocked(head));
                   return NULL;
           }
           KASSERT(solocked2(head, so));
   
           /*
            * Insert into the queue.  If ready, update the connection status
            * and wake up any waiters, e.g. processes blocking on accept().
            */
           soqinsque(head, so, soqueue);
           if (soready) {
                   so->so_state |= SS_ISCONNECTED;
                   sorwakeup(head);
                   cv_broadcast(&head->so_cv);
           }
           return so;
   }
   
   struct socket *
   soget(bool waitok)
   {
           struct socket *so;
   
           so = pool_cache_get(socket_cache, (waitok ? PR_WAITOK : PR_NOWAIT));
           if (__predict_false(so == NULL))
                   return (NULL);
           memset(so, 0, sizeof(*so));
           TAILQ_INIT(&so->so_q0);
           TAILQ_INIT(&so->so_q);
           cv_init(&so->so_cv, "socket");
           cv_init(&so->so_rcv.sb_cv, "netio");
           cv_init(&so->so_snd.sb_cv, "netio");
           selinit(&so->so_rcv.sb_sel);
           selinit(&so->so_snd.sb_sel);
           so->so_rcv.sb_so = so;
           so->so_snd.sb_so = so;
           return so;
   }
   
   void
   soput(struct socket *so)
   {
   
           KASSERT(!cv_has_waiters(&so->so_cv));
           KASSERT(!cv_has_waiters(&so->so_rcv.sb_cv));
           KASSERT(!cv_has_waiters(&so->so_snd.sb_cv));
           seldestroy(&so->so_rcv.sb_sel);
           seldestroy(&so->so_snd.sb_sel);
           mutex_obj_free(so->so_lock);
           cv_destroy(&so->so_cv);
           cv_destroy(&so->so_rcv.sb_cv);
           cv_destroy(&so->so_snd.sb_cv);
           pool_cache_put(socket_cache, so);
   }
   
   /*
    * soqinsque: insert socket of a new connection into the specified
    * accept queue of the listening socket (head).
    *
    *      q = 0: queue of partial connections
    *      q = 1: queue of incoming connections
    */
   void
   soqinsque(struct socket *head, struct socket *so, int q)
   {
           KASSERT(q == 0 || q == 1);
           KASSERT(solocked2(head, so));
           KASSERT(so->so_onq == NULL);
           KASSERT(so->so_head == NULL);
   
           so->so_head = head;
           if (q == 0) {
                   head->so_q0len++;
                   so->so_onq = &head->so_q0;
           } else {
                   head->so_qlen++;
                   so->so_onq = &head->so_q;
           }
           TAILQ_INSERT_TAIL(so->so_onq, so, so_qe);
   }
   
   /*
    * soqremque: remove socket from the specified queue.
    *
    * => Returns true if socket was removed from the specified queue.
    * => False if socket was not removed (because it was in other queue).
    */
   bool
   soqremque(struct socket *so, int q)
   {
           struct socket *head = so->so_head;
   
           KASSERT(q == 0 || q == 1);
           KASSERT(solocked(so));
           KASSERT(so->so_onq != NULL);
           KASSERT(head != NULL);
   
           if (q == 0) {
                   if (so->so_onq != &head->so_q0)
                           return false;
                   head->so_q0len--;
           } else {
                   if (so->so_onq != &head->so_q)
                           return false;
                   head->so_qlen--;
           }
           KASSERT(solocked2(so, head));
           TAILQ_REMOVE(so->so_onq, so, so_qe);
           so->so_onq = NULL;
           so->so_head = NULL;
           return true;
   }
   
   /*
    * socantsendmore: indicates that no more data will be sent on the
    * socket; it would normally be applied to a socket when the user
    * informs the system that no more data is to be sent, by the protocol
    * code (in case pr_shutdown()).
    */
   void
   socantsendmore(struct socket *so)
   {
           KASSERT(solocked(so));
   
           so->so_state |= SS_CANTSENDMORE;
           sowwakeup(so);
   }
   
   /*
    * socantrcvmore(): indicates that no more data will be received and
    * will normally be applied to the socket by a protocol when it detects
    * that the peer will send no more data.  Data queued for reading in
    * the socket may yet be read.
    */
   void
   socantrcvmore(struct socket *so)
   {
           KASSERT(solocked(so));
   
           so->so_state |= SS_CANTRCVMORE;
           sorwakeup(so);
   }
   
   /*
    * soroverflow(): indicates that data was attempted to be sent
    * but the receiving buffer overflowed.
    */
   void
   soroverflow(struct socket *so)
   {
           KASSERT(solocked(so));
   
           so->so_rcv.sb_overflowed++;
           if (so->so_options & SO_RERROR)  {
                   so->so_rerror = ENOBUFS;
                   sorwakeup(so);
           }
   }
   
   /*
    * Wait for data to arrive at/drain from a socket buffer.
    */
   int
   sbwait(struct sockbuf *sb)
   {
           struct socket *so;
           kmutex_t *lock;
           int error;
   
           so = sb->sb_so;
   
           KASSERT(solocked(so));
   
           sb->sb_flags |= SB_NOTIFY;
           lock = so->so_lock;
           if ((sb->sb_flags & SB_NOINTR) != 0)
                   error = cv_timedwait(&sb->sb_cv, lock, sb->sb_timeo);
           else
                   error = cv_timedwait_sig(&sb->sb_cv, lock, sb->sb_timeo);
           if (__predict_false(lock != atomic_load_relaxed(&so->so_lock)))
                   solockretry(so, lock);
           return error;
   }
   
   /*
    * Wakeup processes waiting on a socket buffer.
    * Do asynchronous notification via SIGIO
    * if the socket buffer has the SB_ASYNC flag set.
    */
   void
   sowakeup(struct socket *so, struct sockbuf *sb, int code)
   {
           int band;
   
           KASSERT(solocked(so));
           KASSERT(sb->sb_so == so);
   
           switch (code) {
           case POLL_IN:
                   band = POLLIN|POLLRDNORM;
                   break;
   
           case POLL_OUT:
                   band = POLLOUT|POLLWRNORM;
                   break;
   
           case POLL_HUP:
                   band = POLLHUP;
                   break;
   
           default:
                   band = 0;
   #ifdef DIAGNOSTIC
                   printf("bad siginfo code %d in socket notification.\n", code);
   #endif 
                   break;
           }
   
           sb->sb_flags &= ~SB_NOTIFY;
           selnotify(&sb->sb_sel, band, NOTE_SUBMIT);
           cv_broadcast(&sb->sb_cv);
           if (sb->sb_flags & SB_ASYNC)
                   fownsignal(so->so_pgid, SIGIO, code, band, so);
           if (sb->sb_flags & SB_UPCALL)
                   (*so->so_upcall)(so, so->so_upcallarg, band, M_DONTWAIT);
   }
   
   /*
    * Reset a socket's lock pointer.  Wake all threads waiting on the
    * socket's condition variables so that they can restart their waits
    * using the new lock.  The existing lock must be held.
    *
    * Caller must have issued membar_release before this.
    */
   void
   solockreset(struct socket *so, kmutex_t *lock)
   {
   
           KASSERT(solocked(so));
   
           so->so_lock = lock;
           cv_broadcast(&so->so_snd.sb_cv);
           cv_broadcast(&so->so_rcv.sb_cv);
           cv_broadcast(&so->so_cv);
   }
   
   /*
    * Socket buffer (struct sockbuf) utility routines.
    *
    * Each socket contains two socket buffers: one for sending data and
    * one for receiving data.  Each buffer contains a queue of mbufs,
    * information about the number of mbufs and amount of data in the
    * queue, and other fields allowing poll() statements and notification
    * on data availability to be implemented.
    *
    * Data stored in a socket buffer is maintained as a list of records.
    * Each record is a list of mbufs chained together with the m_next
    * field.  Records are chained together with the m_nextpkt field. The upper
    * level routine soreceive() expects the following conventions to be
    * observed when placing information in the receive buffer:
    *
    * 1. If the protocol requires each message be preceded by the sender's
    *    name, then a record containing that name must be present before
    *    any associated data (mbuf's must be of type MT_SONAME).
    * 2. If the protocol supports the exchange of ``access rights'' (really
    *    just additional data associated with the message), and there are
    *    ``rights'' to be received, then a record containing this data
    *    should be present (mbuf's must be of type MT_CONTROL).
    * 3. If a name or rights record exists, then it must be followed by
    *    a data record, perhaps of zero length.
    *
    * Before using a new socket structure it is first necessary to reserve
    * buffer space to the socket, by calling sbreserve().  This should commit
    * some of the available buffer space in the system buffer pool for the
    * socket (currently, it does nothing but enforce limits).  The space
    * should be released by calling sbrelease() when the socket is destroyed.
    */
   
   int
   sb_max_set(u_long new_sbmax)
   {
           int s;
   
           if (new_sbmax < (16 * 1024))
                   return (EINVAL);
   
           s = splsoftnet();
           sb_max = new_sbmax;
           sb_max_adj = (u_quad_t)new_sbmax * MCLBYTES / (MSIZE + MCLBYTES);
           splx(s);
   
           return (0);
   }
   
   int
   soreserve(struct socket *so, u_long sndcc, u_long rcvcc)
   {
           KASSERT(so->so_pcb == NULL || solocked(so));
   
           /*
            * there's at least one application (a configure script of screen)
            * which expects a fifo is writable even if it has "some" bytes
            * in its buffer.
            * so we want to make sure (hiwat - lowat) >= (some bytes).
            *
            * PIPE_BUF here is an arbitrary value chosen as (some bytes) above.
            * we expect it's large enough for such applications.
            */
           u_long  lowat = MAX(sock_loan_thresh, MCLBYTES);
           u_long  hiwat = lowat + PIPE_BUF;
   
           if (sndcc < hiwat)
                   sndcc = hiwat;
           if (sbreserve(&so->so_snd, sndcc, so) == 0)
                   goto bad;
           if (sbreserve(&so->so_rcv, rcvcc, so) == 0)
                   goto bad2;
           if (so->so_rcv.sb_lowat == 0)
                   so->so_rcv.sb_lowat = 1;
           if (so->so_snd.sb_lowat == 0)
                   so->so_snd.sb_lowat = lowat;
           if (so->so_snd.sb_lowat > so->so_snd.sb_hiwat)
                   so->so_snd.sb_lowat = so->so_snd.sb_hiwat;
           return (0);
    bad2:
           sbrelease(&so->so_snd, so);
    bad:
           return (ENOBUFS);
   }
   
   /*
    * Allot mbufs to a sockbuf.
    * Attempt to scale mbmax so that mbcnt doesn't become limiting
    * if buffering efficiency is near the normal case.
    */
   int
   sbreserve(struct sockbuf *sb, u_long cc, struct socket *so)
   {
           struct lwp *l = curlwp; /* XXX */
           rlim_t maxcc;
           struct uidinfo *uidinfo;
   
           KASSERT(so->so_pcb == NULL || solocked(so));
           KASSERT(sb->sb_so == so);
           KASSERT(sb_max_adj != 0);
   
           if (cc == 0 || cc > sb_max_adj)
                   return (0);
   
           maxcc = l->l_proc->p_rlimit[RLIMIT_SBSIZE].rlim_cur;
   
           uidinfo = so->so_uidinfo;
           if (!chgsbsize(uidinfo, &sb->sb_hiwat, cc, maxcc))
                   return 0;
           sb->sb_mbmax = uimin(cc * 2, sb_max);
           if (sb->sb_lowat > sb->sb_hiwat)
                   sb->sb_lowat = sb->sb_hiwat;
   
           return (1);
   }
   
   /*
    * Free mbufs held by a socket, and reserved mbuf space.  We do not assert
    * that the socket is held locked here: see sorflush().
    */
   void
   sbrelease(struct sockbuf *sb, struct socket *so)
   {
   
           KASSERT(sb->sb_so == so);
   
           sbflush(sb);
           (void)chgsbsize(so->so_uidinfo, &sb->sb_hiwat, 0, RLIM_INFINITY);
           sb->sb_mbmax = 0;
   }
   
   /*
    * Routines to add and remove
    * data from an mbuf queue.
    *
    * The routines sbappend() or sbappendrecord() are normally called to
    * append new mbufs to a socket buffer, after checking that adequate
    * space is available, comparing the function sbspace() with the amount
    * of data to be added.  sbappendrecord() differs from sbappend() in
    * that data supplied is treated as the beginning of a new record.
    * To place a sender's address, optional access rights, and data in a
    * socket receive buffer, sbappendaddr() should be used.  To place
    * access rights and data in a socket receive buffer, sbappendrights()
    * should be used.  In either case, the new data begins a new record.
    * Note that unlike sbappend() and sbappendrecord(), these routines check
    * for the caller that there will be enough space to store the data.
    * Each fails if there is not enough space, or if it cannot find mbufs
    * to store additional information in.
    *
    * Reliable protocols may use the socket send buffer to hold data
    * awaiting acknowledgement.  Data is normally copied from a socket
    * send buffer in a protocol with m_copym for output to a peer,
    * and then removing the data from the socket buffer with sbdrop()
    * or sbdroprecord() when the data is acknowledged by the peer.
    */
   
   #ifdef SOCKBUF_DEBUG
   void
   sblastrecordchk(struct sockbuf *sb, const char *where)
   {
           struct mbuf *m = sb->sb_mb;
   
           KASSERT(solocked(sb->sb_so));
   
           while (m && m->m_nextpkt)
                   m = m->m_nextpkt;
   
           if (m != sb->sb_lastrecord) {
                   printf("sblastrecordchk: sb_mb %p sb_lastrecord %p last %p\n",
                       sb->sb_mb, sb->sb_lastrecord, m);
                   printf("packet chain:\n");
                   for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt)
                           printf("\t%p\n", m);
                   panic("sblastrecordchk from %s", where);
           }
   }
   
   void
   sblastmbufchk(struct sockbuf *sb, const char *where)
   {
           struct mbuf *m = sb->sb_mb;
           struct mbuf *n;
   
           KASSERT(solocked(sb->sb_so));
   
           while (m && m->m_nextpkt)
                   m = m->m_nextpkt;
   
           while (m && m->m_next)
                   m = m->m_next;
   
           if (m != sb->sb_mbtail) {
                   printf("sblastmbufchk: sb_mb %p sb_mbtail %p last %p\n",
                       sb->sb_mb, sb->sb_mbtail, m);
                   printf("packet tree:\n");
                   for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt) {
                           printf("\t");
                           for (n = m; n != NULL; n = n->m_next)
                                   printf("%p ", n);
                           printf("\n");
                   }
                   panic("sblastmbufchk from %s", where);
           }
   }
   #endif /* SOCKBUF_DEBUG */
   
   /*
    * Link a chain of records onto a socket buffer
    */
   #define SBLINKRECORDCHAIN(sb, m0, mlast)                                \
   do {                                                                    \
           if ((sb)->sb_lastrecord != NULL)                                \
                   (sb)->sb_lastrecord->m_nextpkt = (m0);                  \
           else                                                            \
                   (sb)->sb_mb = (m0);                                     \
           (sb)->sb_lastrecord = (mlast);                                  \
   } while (/*CONSTCOND*/0)
   
   
   #define SBLINKRECORD(sb, m0)                                            \
       SBLINKRECORDCHAIN(sb, m0, m0)
   
   /*
    * Append mbuf chain m to the last record in the
    * socket buffer sb.  The additional space associated
    * the mbuf chain is recorded in sb.  Empty mbufs are
    * discarded and mbufs are compacted where possible.
    */
   void
   sbappend(struct sockbuf *sb, struct mbuf *m)
   {
           struct mbuf     *n;
   
           KASSERT(solocked(sb->sb_so));
   
           if (m == NULL)
                   return;
   
   #ifdef MBUFTRACE
           m_claimm(m, sb->sb_mowner);
   #endif
   
           SBLASTRECORDCHK(sb, "sbappend 1");
   
           if ((n = sb->sb_lastrecord) != NULL) {
                   /*
                    * XXX Would like to simply use sb_mbtail here, but
                    * XXX I need to verify that I won't miss an EOR that
                    * XXX way.
                    */
                   do {
                           if (n->m_flags & M_EOR) {
                                   sbappendrecord(sb, m); /* XXXXXX!!!! */
                                   return;
                           }
                   } while (n->m_next && (n = n->m_next));
           } else {
                   /*
                    * If this is the first record in the socket buffer, it's
                    * also the last record.
                    */
                   sb->sb_lastrecord = m;
           }
           sbcompress(sb, m, n);
           SBLASTRECORDCHK(sb, "sbappend 2");
   }
   
   /*
    * This version of sbappend() should only be used when the caller
    * absolutely knows that there will never be more than one record
    * in the socket buffer, that is, a stream protocol (such as TCP).
    */
   void
   sbappendstream(struct sockbuf *sb, struct mbuf *m)
   {
   
           KASSERT(solocked(sb->sb_so));
           KDASSERT(m->m_nextpkt == NULL);
           KASSERT(sb->sb_mb == sb->sb_lastrecord);
   
           SBLASTMBUFCHK(sb, __func__);
   
   #ifdef MBUFTRACE
           m_claimm(m, sb->sb_mowner);
   #endif
   
           sbcompress(sb, m, sb->sb_mbtail);
   
           sb->sb_lastrecord = sb->sb_mb;
           SBLASTRECORDCHK(sb, __func__);
   }
   
   #ifdef SOCKBUF_DEBUG
   void
   sbcheck(struct sockbuf *sb)
   {
           struct mbuf     *m, *m2;
           u_long          len, mbcnt;
   
           KASSERT(solocked(sb->sb_so));
   
           len = 0;
           mbcnt = 0;
           for (m = sb->sb_mb; m; m = m->m_nextpkt) {
                   for (m2 = m; m2 != NULL; m2 = m2->m_next) {
                           len += m2->m_len;
                           mbcnt += MSIZE;
                           if (m2->m_flags & M_EXT)
                                   mbcnt += m2->m_ext.ext_size;
                           if (m2->m_nextpkt != NULL)
                                   panic("sbcheck nextpkt");
                   }
           }
           if (len != sb->sb_cc || mbcnt != sb->sb_mbcnt) {
                   printf("cc %lu != %lu || mbcnt %lu != %lu\n", len, sb->sb_cc,
                       mbcnt, sb->sb_mbcnt);
                   panic("sbcheck");
           }
   }
   #endif
   
   /*
    * As above, except the mbuf chain
    * begins a new record.
    */
   void
   sbappendrecord(struct sockbuf *sb, struct mbuf *m0)
   {
           struct mbuf     *m;
   
           KASSERT(solocked(sb->sb_so));
   
           if (m0 == NULL)
                   return;
   
   #ifdef MBUFTRACE
           m_claimm(m0, sb->sb_mowner);
   #endif
           /*
            * Put the first mbuf on the queue.
            * Note this permits zero length records.
            */
           sballoc(sb, m0);
           SBLASTRECORDCHK(sb, "sbappendrecord 1");
           SBLINKRECORD(sb, m0);
           m = m0->m_next;
           m0->m_next = 0;
           if (m && (m0->m_flags & M_EOR)) {
                   m0->m_flags &= ~M_EOR;
                   m->m_flags |= M_EOR;
           }
           sbcompress(sb, m, m0);
           SBLASTRECORDCHK(sb, "sbappendrecord 2");
   }
   
   /*
    * As above except that OOB data
    * is inserted at the beginning of the sockbuf,
    * but after any other OOB data.
    */
   void
   sbinsertoob(struct sockbuf *sb, struct mbuf *m0)
   {
           struct mbuf     *m, **mp;
   
           KASSERT(solocked(sb->sb_so));
   
           if (m0 == NULL)
                   return;
   
           SBLASTRECORDCHK(sb, "sbinsertoob 1");
   
           for (mp = &sb->sb_mb; (m = *mp) != NULL; mp = &((*mp)->m_nextpkt)) {
               again:
                   switch (m->m_type) {
   
                   case MT_OOBDATA:
                           continue;               /* WANT next train */
   
                   case MT_CONTROL:
                           if ((m = m->m_next) != NULL)
                                   goto again;     /* inspect THIS train further */
                   }
                   break;
           }
           /*
            * Put the first mbuf on the queue.
            * Note this permits zero length records.
            */
           sballoc(sb, m0);
          m0->m_nextpkt = *mp;
          if (*mp == NULL) {
                  /* m0 is actually the new tail */
                  sb->sb_lastrecord = m0;
          }
          *mp = m0;
          m = m0->m_next;
          m0->m_next = 0;
          if (m && (m0->m_flags & M_EOR)) {
                  m0->m_flags &= ~M_EOR;
                  m->m_flags |= M_EOR;
          }
          sbcompress(sb, m, m0);
          SBLASTRECORDCHK(sb, "sbinsertoob 2");
  }
  
  /*
   * Append address and data, and optionally, control (ancillary) data
   * to the receive queue of a socket.  If present,
   * m0 must include a packet header with total length.
   * Returns 0 if no space in sockbuf or insufficient mbufs.
   */
  int
  sbappendaddr(struct sockbuf *sb, const struct sockaddr *asa, struct mbuf *m0,
          struct mbuf *control)
  {
          struct mbuf     *m, *n, *nlast;
          int             space, len;
  
          KASSERT(solocked(sb->sb_so));
  
          space = asa->sa_len;
  
          if (m0 != NULL) {
                  if ((m0->m_flags & M_PKTHDR) == 0)
                          panic("sbappendaddr");
                  space += m0->m_pkthdr.len;
  #ifdef MBUFTRACE
                  m_claimm(m0, sb->sb_mowner);
  #endif
          }
          for (n = control; n; n = n->m_next) {
                  space += n->m_len;
                  MCLAIM(n, sb->sb_mowner);
                  if (n->m_next == NULL)  /* keep pointer to last control buf */
                          break;
          }
          if (space > sbspace(sb))
                  return (0);
          m = m_get(M_DONTWAIT, MT_SONAME);
          if (m == NULL)
                  return (0);
          MCLAIM(m, sb->sb_mowner);
          /*
           * XXX avoid 'comparison always true' warning which isn't easily
           * avoided.
           */
          len = asa->sa_len;
          if (len > MLEN) {
                  MEXTMALLOC(m, asa->sa_len, M_NOWAIT);
                  if ((m->m_flags & M_EXT) == 0) {
                          m_free(m);
                          return (0);
                  }
          }
          m->m_len = asa->sa_len;
          memcpy(mtod(m, void *), asa, asa->sa_len);
          if (n)
                  n->m_next = m0;         /* concatenate data to control */
          else
                  control = m0;
          m->m_next = control;
  
          SBLASTRECORDCHK(sb, "sbappendaddr 1");
  
          for (n = m; n->m_next != NULL; n = n->m_next)
                  sballoc(sb, n);
          sballoc(sb, n);
          nlast = n;
          SBLINKRECORD(sb, m);
  
          sb->sb_mbtail = nlast;
          SBLASTMBUFCHK(sb, "sbappendaddr");
          SBLASTRECORDCHK(sb, "sbappendaddr 2");
  
          return (1);
  }
  
  /*
   * Helper for sbappendchainaddr: prepend a struct sockaddr* to
   * an mbuf chain.
   */
  static inline struct mbuf *
  m_prepend_sockaddr(struct sockbuf *sb, struct mbuf *m0,
                     const struct sockaddr *asa)
  {
          struct mbuf *m;
          const int salen = asa->sa_len;
  
          KASSERT(solocked(sb->sb_so));
  
          /* only the first in each chain need be a pkthdr */
          m = m_gethdr(M_DONTWAIT, MT_SONAME);
          if (m == NULL)
                  return NULL;
          MCLAIM(m, sb->sb_mowner);
  #ifdef notyet
          if (salen > MHLEN) {
                  MEXTMALLOC(m, salen, M_NOWAIT);
                  if ((m->m_flags & M_EXT) == 0) {
                          m_free(m);
                          return NULL;
                  }
          }
  #else
          KASSERT(salen <= MHLEN);
  #endif
          m->m_len = salen;
          memcpy(mtod(m, void *), asa, salen);
          m->m_next = m0;
          m->m_pkthdr.len = salen + m0->m_pkthdr.len;
  
          return m;
  }
  
  int
  sbappendaddrchain(struct sockbuf *sb, const struct sockaddr *asa,
                    struct mbuf *m0, int sbprio)
  {
          struct mbuf *m, *n, *n0, *nlast;
          int error;
  
          KASSERT(solocked(sb->sb_so));
  
          /*
           * XXX sbprio reserved for encoding priority of this* request:
           *  SB_PRIO_NONE --> honour normal sb limits
           *  SB_PRIO_ONESHOT_OVERFLOW --> if socket has any space,
           *      take whole chain. Intended for large requests
           *      that should be delivered atomically (all, or none).
           * SB_PRIO_OVERDRAFT -- allow a small (2*MLEN) overflow
           *       over normal socket limits, for messages indicating
           *       buffer overflow in earlier normal/lower-priority messages
           * SB_PRIO_BESTEFFORT -->  ignore limits entirely.
           *       Intended for  kernel-generated messages only.
           *        Up to generator to avoid total mbuf resource exhaustion.
           */
          (void)sbprio;
  
          if (m0 && (m0->m_flags & M_PKTHDR) == 0)
                  panic("sbappendaddrchain");
  
  #ifdef notyet
          space = sbspace(sb);
  
          /*
           * Enforce SB_PRIO_* limits as described above.
           */
  #endif
  
          n0 = NULL;
          nlast = NULL;
          for (m = m0; m; m = m->m_nextpkt) {
                  struct mbuf *np;
  
  #ifdef MBUFTRACE
                  m_claimm(m, sb->sb_mowner);
  #endif
  
                  /* Prepend sockaddr to this record (m) of input chain m0 */
                  n = m_prepend_sockaddr(sb, m, asa);
                  if (n == NULL) {
                          error = ENOBUFS;
                          goto bad;
                  }
  
                  /* Append record (asa+m) to end of new chain n0 */
                  if (n0 == NULL) {
                          n0 = n;
                  } else {
                          nlast->m_nextpkt = n;
                  }
                  /* Keep track of last record on new chain */
                  nlast = n;
  
                  for (np = n; np; np = np->m_next)
                          sballoc(sb, np);
          }
  
          SBLASTRECORDCHK(sb, "sbappendaddrchain 1");
  
          /* Drop the entire chain of (asa+m) records onto the socket */
          SBLINKRECORDCHAIN(sb, n0, nlast);
  
          SBLASTRECORDCHK(sb, "sbappendaddrchain 2");
  
          for (m = nlast; m->m_next; m = m->m_next)
                  ;
          sb->sb_mbtail = m;
          SBLASTMBUFCHK(sb, "sbappendaddrchain");
  
          return (1);
  
  bad:
          /*
           * On error, free the prepended addreseses. For consistency
           * with sbappendaddr(), leave it to our caller to free
           * the input record chain passed to us as m0.
           */
          while ((n = n0) != NULL) {
                  struct mbuf *np;
  
                  /* Undo the sballoc() of this record */
                  for (np = n; np; np = np->m_next)
                          sbfree(sb, np);
  
                  n0 = n->m_nextpkt;      /* iterate at next prepended address */
                  np = m_free(n);         /* free prepended address (not data) */
          }
          return error;
  }
  
  
  int
  sbappendcontrol(struct sockbuf *sb, struct mbuf *m0, struct mbuf *control)
  {
          struct mbuf     *m, *mlast, *n;
          int             space;
  
          KASSERT(solocked(sb->sb_so));
  
          space = 0;
          if (control == NULL)
                  panic("sbappendcontrol");
          for (m = control; ; m = m->m_next) {
                  space += m->m_len;
                  MCLAIM(m, sb->sb_mowner);
                  if (m->m_next == NULL)
                          break;
          }
          n = m;                  /* save pointer to last control buffer */
          for (m = m0; m; m = m->m_next) {
                  MCLAIM(m, sb->sb_mowner);
                  space += m->m_len;
          }
          if (space > sbspace(sb))
                  return (0);
          n->m_next = m0;                 /* concatenate data to control */
  
          SBLASTRECORDCHK(sb, "sbappendcontrol 1");
  
          for (m = control; m->m_next != NULL; m = m->m_next)
                  sballoc(sb, m);
          sballoc(sb, m);
          mlast = m;
          SBLINKRECORD(sb, control);
  
          sb->sb_mbtail = mlast;
          SBLASTMBUFCHK(sb, "sbappendcontrol");
          SBLASTRECORDCHK(sb, "sbappendcontrol 2");
  
          return (1);
  }
  
  /*
   * Compress mbuf chain m into the socket
   * buffer sb following mbuf n.  If n
   * is null, the buffer is presumed empty.
   */
  void
  sbcompress(struct sockbuf *sb, struct mbuf *m, struct mbuf *n)
  {
          int             eor;
          struct mbuf     *o;
  
          KASSERT(solocked(sb->sb_so));
  
          eor = 0;
          while (m) {
                  eor |= m->m_flags & M_EOR;
                  if (m->m_len == 0 &&
                      (eor == 0 ||
                       (((o = m->m_next) || (o = n)) &&
                        o->m_type == m->m_type))) {
                          if (sb->sb_lastrecord == m)
                                  sb->sb_lastrecord = m->m_next;
                          m = m_free(m);
                          continue;
                  }
                  if (n && (n->m_flags & M_EOR) == 0 &&
                      /* M_TRAILINGSPACE() checks buffer writeability */
                      m->m_len <= MCLBYTES / 4 && /* XXX Don't copy too much */
                      m->m_len <= M_TRAILINGSPACE(n) &&
                      n->m_type == m->m_type) {
                          memcpy(mtod(n, char *) + n->m_len, mtod(m, void *),
                              (unsigned)m->m_len);
                          n->m_len += m->m_len;
                          sb->sb_cc += m->m_len;
                          m = m_free(m);
                          continue;
                  }
                  if (n)
                          n->m_next = m;
                  else
                          sb->sb_mb = m;
                  sb->sb_mbtail = m;
                  sballoc(sb, m);
                  n = m;
                  m->m_flags &= ~M_EOR;
                  m = m->m_next;
                  n->m_next = 0;
          }
          if (eor) {
                  if (n)
                          n->m_flags |= eor;
                  else
                          printf("semi-panic: sbcompress\n");
          }
          SBLASTMBUFCHK(sb, __func__);
  }
  
  /*
   * Free all mbufs in a sockbuf.
   * Check that all resources are reclaimed.
   */
  void
  sbflush(struct sockbuf *sb)
  {
  
          KASSERT(solocked(sb->sb_so));
          KASSERT((sb->sb_flags & SB_LOCK) == 0);
  
          while (sb->sb_mbcnt)
                  sbdrop(sb, (int)sb->sb_cc);
  
          KASSERT(sb->sb_cc == 0);
          KASSERT(sb->sb_mb == NULL);
          KASSERT(sb->sb_mbtail == NULL);
          KASSERT(sb->sb_lastrecord == NULL);
  }
  
  /*
   * Drop data from (the front of) a sockbuf.
   */
  void
  sbdrop(struct sockbuf *sb, int len)
  {
          struct mbuf     *m, *next;
  
          KASSERT(solocked(sb->sb_so));
  
          next = (m = sb->sb_mb) ? m->m_nextpkt : NULL;
          while (len > 0) {
                  if (m == NULL) {
                          if (next == NULL)
                                  panic("sbdrop(%p,%d): cc=%lu",
                                      sb, len, sb->sb_cc);
                          m = next;
                          next = m->m_nextpkt;
                          continue;
                  }
                  if (m->m_len > len) {
                          m->m_len -= len;
                          m->m_data += len;
                          sb->sb_cc -= len;
                          break;
                  }
                  len -= m->m_len;
                  sbfree(sb, m);
                  m = m_free(m);
          }
          while (m && m->m_len == 0) {
                  sbfree(sb, m);
                  m = m_free(m);
          }
          if (m) {
                  sb->sb_mb = m;
                  m->m_nextpkt = next;
          } else
                  sb->sb_mb = next;
          /*
           * First part is an inline SB_EMPTY_FIXUP().  Second part
           * makes sure sb_lastrecord is up-to-date if we dropped
           * part of the last record.
           */
          m = sb->sb_mb;
          if (m == NULL) {
                  sb->sb_mbtail = NULL;
                  sb->sb_lastrecord = NULL;
          } else if (m->m_nextpkt == NULL)
                  sb->sb_lastrecord = m;
  }
  
  /*
   * Drop a record off the front of a sockbuf
   * and move the next record to the front.
   */
  void
  sbdroprecord(struct sockbuf *sb)
  {
          struct mbuf     *m, *mn;
  
          KASSERT(solocked(sb->sb_so));
  
          m = sb->sb_mb;
          if (m) {
                  sb->sb_mb = m->m_nextpkt;
                  do {
                          sbfree(sb, m);
                          mn = m_free(m);
                  } while ((m = mn) != NULL);
          }
          SB_EMPTY_FIXUP(sb);
  }
  
  /*
   * Create a "control" mbuf containing the specified data
   * with the specified type for presentation on a socket buffer.
   */
  struct mbuf *
  sbcreatecontrol1(void **p, int size, int type, int level, int flags)
  {
          struct cmsghdr  *cp;
          struct mbuf     *m;
          int space = CMSG_SPACE(size);
  
          if ((flags & M_DONTWAIT) && space > MCLBYTES) {
                  printf("%s: message too large %d\n", __func__, space);
                  return NULL;
          }
  
          if ((m = m_get(flags, MT_CONTROL)) == NULL)
                  return NULL;
          if (space > MLEN) {
                  if (space > MCLBYTES)
                          MEXTMALLOC(m, space, M_WAITOK);
                  else
                          MCLGET(m, flags);
                  if ((m->m_flags & M_EXT) == 0) {
                          m_free(m);
                          return NULL;
                  }
          }
          cp = mtod(m, struct cmsghdr *);
          *p = CMSG_DATA(cp);
          m->m_len = space;
          cp->cmsg_len = CMSG_LEN(size);
          cp->cmsg_level = level;
          cp->cmsg_type = type;
  
          memset(cp + 1, 0, CMSG_LEN(0) - sizeof(*cp));
          memset((uint8_t *)*p + size, 0, CMSG_ALIGN(size) - size);
  
          return m;
  }
  
  struct mbuf *
  sbcreatecontrol(void *p, int size, int type, int level)
  {
          struct mbuf *m;
          void *v;
  
          m = sbcreatecontrol1(&v, size, type, level, M_DONTWAIT);
          if (m == NULL)
                  return NULL;
          memcpy(v, p, size);
          return m;
  }
  
  void
  solockretry(struct socket *so, kmutex_t *lock)
  {
  
          while (lock != atomic_load_relaxed(&so->so_lock)) {
                  mutex_exit(lock);
                  lock = atomic_load_consume(&so->so_lock);
                  mutex_enter(lock);
          }
  }
  
  bool
  solocked(const struct socket *so)
  {
  
          /*
           * Used only for diagnostic assertions, so so_lock should be
           * stable at this point, hence on need for atomic_load_*.
           */
          return mutex_owned(so->so_lock);
  }
  
  bool
  solocked2(const struct socket *so1, const struct socket *so2)
  {
          const kmutex_t *lock;
  
          /*
           * Used only for diagnostic assertions, so so_lock should be
           * stable at this point, hence on need for atomic_load_*.
           */
          lock = so1->so_lock;
          if (lock != so2->so_lock)
                  return false;
          return mutex_owned(lock);
  }
  
  /*
   * sosetlock: assign a default lock to a new socket.
   */
  void
  sosetlock(struct socket *so)
  {
          if (so->so_lock == NULL) {
                  kmutex_t *lock = softnet_lock;
  
                  so->so_lock = lock;
                  mutex_obj_hold(lock);
                  mutex_enter(lock);
          }
          KASSERT(solocked(so));
  }
  
  /*
   * Set lock on sockbuf sb; sleep if lock is already held.
   * Unless SB_NOINTR is set on sockbuf, sleep is interruptible.
   * Returns error without lock if sleep is interrupted.
   */
  int
  sblock(struct sockbuf *sb, int wf)
  {
          struct socket *so;
          kmutex_t *lock;
          int error;
  
          KASSERT(solocked(sb->sb_so));
  
          for (;;) {
                  if (__predict_true((sb->sb_flags & SB_LOCK) == 0)) {
                          sb->sb_flags |= SB_LOCK;
                          return 0;
                  }
                  if (wf != M_WAITOK)
                          return EWOULDBLOCK;
                  so = sb->sb_so;
                  lock = so->so_lock;
                  if ((sb->sb_flags & SB_NOINTR) != 0) {
                          cv_wait(&so->so_cv, lock);
                          error = 0;
                  } else
                          error = cv_wait_sig(&so->so_cv, lock);
                  if (__predict_false(lock != atomic_load_relaxed(&so->so_lock)))
                          solockretry(so, lock);
                  if (error != 0)
                          return error;
          }
  }
  
  void
  sbunlock(struct sockbuf *sb)
  {
          struct socket *so;
  
          so = sb->sb_so;
  
          KASSERT(solocked(so));
          KASSERT((sb->sb_flags & SB_LOCK) != 0);
  
          sb->sb_flags &= ~SB_LOCK;
          cv_broadcast(&so->so_cv);
  }
  
  int
  sowait(struct socket *so, bool catch_p, int timo)
  {
          kmutex_t *lock;
          int error;
  
          KASSERT(solocked(so));
          KASSERT(catch_p || timo != 0);
  
          lock = so->so_lock;
          if (catch_p)
                  error = cv_timedwait_sig(&so->so_cv, lock, timo);
          else
                  error = cv_timedwait(&so->so_cv, lock, timo);
          if (__predict_false(lock != atomic_load_relaxed(&so->so_lock)))
                  solockretry(so, lock);
          return error;
  }
  
  #ifdef DDB
  
  /*
   * Currently, sofindproc() is used only from DDB. It could be used from others
   * by using db_mutex_enter()
   */
  
  static inline int
  db_mutex_enter(kmutex_t *mtx)
  {
          int rv;
  
          if (!db_active) {
                  mutex_enter(mtx);
                  rv = 1;
          } else
                  rv = mutex_tryenter(mtx);
  
          return rv;
  }
  
  int
  sofindproc(struct socket *so, int all, void (*pr)(const char *, ...))
  {
          proc_t *p;
          filedesc_t *fdp;
          fdtab_t *dt;
          fdfile_t *ff;
          file_t *fp = NULL;
          int found = 0;
          int i, t;
  
          if (so == NULL)
                  return 0;
  
          t = db_mutex_enter(&proc_lock);
          if (!t) {
                  pr("could not acquire proc_lock mutex\n");
                  return 0;
          }
          PROCLIST_FOREACH(p, &allproc) {
                  if (p->p_stat == SIDL)
                          continue;
                  fdp = p->p_fd;
                  t = db_mutex_enter(&fdp->fd_lock);
                  if (!t) {
                          pr("could not acquire fd_lock mutex\n");
                          continue;
                  }
                  dt = atomic_load_consume(&fdp->fd_dt);
                  for (i = 0; i < dt->dt_nfiles; i++) {
                          ff = dt->dt_ff[i];
                          if (ff == NULL)
                                  continue;
  
                          fp = atomic_load_consume(&ff->ff_file);
                          if (fp == NULL)
                                  continue;
  
                          t = db_mutex_enter(&fp->f_lock);
                          if (!t) {
                                  pr("could not acquire f_lock mutex\n");
                                  continue;
                          }
                          if ((struct socket *)fp->f_data != so) {
                                  mutex_exit(&fp->f_lock);
                                  continue;
                          }
                          found++;
                          if (pr)
                                  pr("socket %p: owner %s(pid=%d)\n",
                                      so, p->p_comm, p->p_pid);
                          mutex_exit(&fp->f_lock);
                          if (all == 0)
                                  break;
                  }
                  mutex_exit(&fdp->fd_lock);
                  if (all == 0 && found != 0)
                          break;
          }
          mutex_exit(&proc_lock);
  
          return found;
  }
  
  void
  socket_print(const char *modif, void (*pr)(const char *, ...))
  {
          file_t *fp;
          struct socket *so;
          struct sockbuf *sb_snd, *sb_rcv;
          struct mbuf *m_rec, *m;
          bool opt_v = false;
          bool opt_m = false;
          bool opt_a = false;
          bool opt_p = false;
          int nrecs, nmbufs;
          char ch;
          const char *family;
  
          while ( (ch = *(modif++)) != '\0') {
                  switch (ch) {
                  case 'v':
                          opt_v = true;
                          break;
                  case 'm':
                          opt_m = true;
                          break;
                  case 'a':
                          opt_a = true;
                          break;
                  case 'p':
                          opt_p = true;
                          break;
                  }
          }
          if (opt_v == false && pr)
                  (pr)("Ignore empty sockets. use /v to print all.\n");
          if (opt_p == true && pr)
                  (pr)("Don't search owner process.\n");
  
          LIST_FOREACH(fp, &filehead, f_list) {
                  if (fp->f_type != DTYPE_SOCKET)
                          continue;
                  so = (struct socket *)fp->f_data;
                  if (so == NULL)
                          continue;
  
                  if (so->so_proto->pr_domain->dom_family == AF_INET)
                          family = "INET";
  #ifdef INET6
                  else if (so->so_proto->pr_domain->dom_family == AF_INET6)
                          family = "INET6";
  #endif
                  else if (so->so_proto->pr_domain->dom_family == pseudo_AF_KEY)
                          family = "KEY";
                  else if (so->so_proto->pr_domain->dom_family == AF_ROUTE)
                          family = "ROUTE";
                  else
                          continue;
  
                  sb_snd = &so->so_snd;
                  sb_rcv = &so->so_rcv;
  
                  if (opt_v != true &&
                      sb_snd->sb_cc == 0 && sb_rcv->sb_cc == 0)
                          continue;
  
                  pr("---SOCKET %p: type %s\n", so, family);
                  if (opt_p != true)
                          sofindproc(so, opt_a == true ? 1 : 0, pr);
                  pr("Send Buffer Bytes: %d [bytes]\n", sb_snd->sb_cc);
                  pr("Send Buffer mbufs:\n");
                  m_rec = m = sb_snd->sb_mb;
                  nrecs = 0;
                  nmbufs = 0;
                  while (m_rec) {
                          nrecs++;
                          if (opt_m == true)
                                  pr(" mbuf chain %p\n", m_rec);
                          while (m) {
                                  nmbufs++;
                                  m = m->m_next;
                          }
                          m_rec = m = m_rec->m_nextpkt;
                  }
                  pr(" Total %d records, %d mbufs.\n", nrecs, nmbufs);
  
                  pr("Recv Buffer Usage: %d [bytes]\n", sb_rcv->sb_cc);
                  pr("Recv Buffer mbufs:\n");
                  m_rec = m = sb_rcv->sb_mb;
                  nrecs = 0;
                  nmbufs = 0;
                  while (m_rec) {
                          nrecs++;
                          if (opt_m == true)
                                  pr(" mbuf chain %p\n", m_rec);
                          while (m) {
                                  nmbufs++;
                                  m = m->m_next;
                          }
                          m_rec = m = m_rec->m_nextpkt;
                  }
                  pr(" Total %d records, %d mbufs.\n", nrecs, nmbufs);
          }
  }
  #endif /* DDB */

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