2 * Copyright (c) 1982, 1986, 1988, 1990, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * @(#)uipc_socket2.c 8.1 (Berkeley) 6/10/93
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include "opt_param.h"
37 #include <sys/param.h>
38 #include <sys/aio.h> /* for aio_swake proto */
39 #include <sys/kernel.h>
42 #include <sys/mutex.h>
44 #include <sys/protosw.h>
45 #include <sys/resourcevar.h>
46 #include <sys/signalvar.h>
47 #include <sys/socket.h>
48 #include <sys/socketvar.h>
49 #include <sys/sysctl.h>
52 * Function pointer set by the AIO routines so that the socket buffer code
53 * can call back into the AIO module if it is loaded.
55 void (*aio_swake)(struct socket *, struct sockbuf *);
58 * Primitive routines for operating on socket buffers
61 u_long sb_max = SB_MAX;
62 static u_long sb_max_adj =
63 SB_MAX * MCLBYTES / (MSIZE + MCLBYTES); /* adjusted sb_max */
65 static u_long sb_efficiency = 8; /* parameter for sbreserve() */
67 static void sbdrop_internal(struct sockbuf *sb, int len);
68 static void sbflush_internal(struct sockbuf *sb);
69 static void sbrelease_internal(struct sockbuf *sb, struct socket *so);
72 * Socantsendmore indicates that no more data will be sent on the socket; it
73 * would normally be applied to a socket when the user informs the system
74 * that no more data is to be sent, by the protocol code (in case
75 * PRU_SHUTDOWN). Socantrcvmore indicates that no more data will be
76 * received, and will normally be applied to the socket by a protocol when it
77 * detects that the peer will send no more data. Data queued for reading in
78 * the socket may yet be read.
81 socantsendmore_locked(struct socket *so)
84 SOCKBUF_LOCK_ASSERT(&so->so_snd);
86 so->so_snd.sb_state |= SBS_CANTSENDMORE;
88 mtx_assert(SOCKBUF_MTX(&so->so_snd), MA_NOTOWNED);
92 socantsendmore(struct socket *so)
95 SOCKBUF_LOCK(&so->so_snd);
96 socantsendmore_locked(so);
97 mtx_assert(SOCKBUF_MTX(&so->so_snd), MA_NOTOWNED);
101 socantrcvmore_locked(struct socket *so)
104 SOCKBUF_LOCK_ASSERT(&so->so_rcv);
106 so->so_rcv.sb_state |= SBS_CANTRCVMORE;
107 sorwakeup_locked(so);
108 mtx_assert(SOCKBUF_MTX(&so->so_rcv), MA_NOTOWNED);
112 socantrcvmore(struct socket *so)
115 SOCKBUF_LOCK(&so->so_rcv);
116 socantrcvmore_locked(so);
117 mtx_assert(SOCKBUF_MTX(&so->so_rcv), MA_NOTOWNED);
121 * Wait for data to arrive at/drain from a socket buffer.
124 sbwait(struct sockbuf *sb)
127 SOCKBUF_LOCK_ASSERT(sb);
129 sb->sb_flags |= SB_WAIT;
130 return (msleep(&sb->sb_cc, &sb->sb_mtx,
131 (sb->sb_flags & SB_NOINTR) ? PSOCK : PSOCK | PCATCH, "sbwait",
136 * Lock a sockbuf already known to be locked; return any error returned from
140 sb_lock(struct sockbuf *sb)
144 SOCKBUF_LOCK_ASSERT(sb);
146 while (sb->sb_flags & SB_LOCK) {
147 sb->sb_flags |= SB_WANT;
148 error = msleep(&sb->sb_flags, &sb->sb_mtx,
149 (sb->sb_flags & SB_NOINTR) ? PSOCK : PSOCK|PCATCH,
154 sb->sb_flags |= SB_LOCK;
159 * Wakeup processes waiting on a socket buffer. Do asynchronous notification
160 * via SIGIO if the socket has the SS_ASYNC flag set.
162 * Called with the socket buffer lock held; will release the lock by the end
163 * of the function. This allows the caller to acquire the socket buffer lock
164 * while testing for the need for various sorts of wakeup and hold it through
165 * to the point where it's no longer required. We currently hold the lock
166 * through calls out to other subsystems (with the exception of kqueue), and
167 * then release it to avoid lock order issues. It's not clear that's
171 sowakeup(struct socket *so, struct sockbuf *sb)
174 SOCKBUF_LOCK_ASSERT(sb);
176 selwakeuppri(&sb->sb_sel, PSOCK);
177 sb->sb_flags &= ~SB_SEL;
178 if (sb->sb_flags & SB_WAIT) {
179 sb->sb_flags &= ~SB_WAIT;
182 KNOTE_LOCKED(&sb->sb_sel.si_note, 0);
184 if ((so->so_state & SS_ASYNC) && so->so_sigio != NULL)
185 pgsigio(&so->so_sigio, SIGIO, 0);
186 if (sb->sb_flags & SB_UPCALL)
187 (*so->so_upcall)(so, so->so_upcallarg, M_DONTWAIT);
188 if (sb->sb_flags & SB_AIO)
190 mtx_assert(SOCKBUF_MTX(sb), MA_NOTOWNED);
194 * Socket buffer (struct sockbuf) utility routines.
196 * Each socket contains two socket buffers: one for sending data and one for
197 * receiving data. Each buffer contains a queue of mbufs, information about
198 * the number of mbufs and amount of data in the queue, and other fields
199 * allowing select() statements and notification on data availability to be
202 * Data stored in a socket buffer is maintained as a list of records. Each
203 * record is a list of mbufs chained together with the m_next field. Records
204 * are chained together with the m_nextpkt field. The upper level routine
205 * soreceive() expects the following conventions to be observed when placing
206 * information in the receive buffer:
208 * 1. If the protocol requires each message be preceded by the sender's name,
209 * then a record containing that name must be present before any
210 * associated data (mbuf's must be of type MT_SONAME).
211 * 2. If the protocol supports the exchange of ``access rights'' (really just
212 * additional data associated with the message), and there are ``rights''
213 * to be received, then a record containing this data should be present
214 * (mbuf's must be of type MT_RIGHTS).
215 * 3. If a name or rights record exists, then it must be followed by a data
216 * record, perhaps of zero length.
218 * Before using a new socket structure it is first necessary to reserve
219 * buffer space to the socket, by calling sbreserve(). This should commit
220 * some of the available buffer space in the system buffer pool for the
221 * socket (currently, it does nothing but enforce limits). The space should
222 * be released by calling sbrelease() when the socket is destroyed.
225 soreserve(struct socket *so, u_long sndcc, u_long rcvcc)
227 struct thread *td = curthread;
229 SOCKBUF_LOCK(&so->so_snd);
230 SOCKBUF_LOCK(&so->so_rcv);
231 if (sbreserve_locked(&so->so_snd, sndcc, so, td) == 0)
233 if (sbreserve_locked(&so->so_rcv, rcvcc, so, td) == 0)
235 if (so->so_rcv.sb_lowat == 0)
236 so->so_rcv.sb_lowat = 1;
237 if (so->so_snd.sb_lowat == 0)
238 so->so_snd.sb_lowat = MCLBYTES;
239 if (so->so_snd.sb_lowat > so->so_snd.sb_hiwat)
240 so->so_snd.sb_lowat = so->so_snd.sb_hiwat;
241 SOCKBUF_UNLOCK(&so->so_rcv);
242 SOCKBUF_UNLOCK(&so->so_snd);
245 sbrelease_locked(&so->so_snd, so);
247 SOCKBUF_UNLOCK(&so->so_rcv);
248 SOCKBUF_UNLOCK(&so->so_snd);
253 sysctl_handle_sb_max(SYSCTL_HANDLER_ARGS)
256 u_long tmp_sb_max = sb_max;
258 error = sysctl_handle_long(oidp, &tmp_sb_max, arg2, req);
259 if (error || !req->newptr)
261 if (tmp_sb_max < MSIZE + MCLBYTES)
264 sb_max_adj = (u_quad_t)sb_max * MCLBYTES / (MSIZE + MCLBYTES);
269 * Allot mbufs to a sockbuf. Attempt to scale mbmax so that mbcnt doesn't
270 * become limiting if buffering efficiency is near the normal case.
273 sbreserve_locked(struct sockbuf *sb, u_long cc, struct socket *so,
278 SOCKBUF_LOCK_ASSERT(sb);
281 * td will only be NULL when we're in an interrupt (e.g. in
284 * XXXRW: This comment needs updating, as might the code.
289 PROC_LOCK(td->td_proc);
290 sbsize_limit = lim_cur(td->td_proc, RLIMIT_SBSIZE);
291 PROC_UNLOCK(td->td_proc);
293 sbsize_limit = RLIM_INFINITY;
294 if (!chgsbsize(so->so_cred->cr_uidinfo, &sb->sb_hiwat, cc,
297 sb->sb_mbmax = min(cc * sb_efficiency, sb_max);
298 if (sb->sb_lowat > sb->sb_hiwat)
299 sb->sb_lowat = sb->sb_hiwat;
304 sbreserve(struct sockbuf *sb, u_long cc, struct socket *so,
310 error = sbreserve_locked(sb, cc, so, td);
316 * Free mbufs held by a socket, and reserved mbuf space.
319 sbrelease_internal(struct sockbuf *sb, struct socket *so)
322 sbflush_internal(sb);
323 (void)chgsbsize(so->so_cred->cr_uidinfo, &sb->sb_hiwat, 0,
329 sbrelease_locked(struct sockbuf *sb, struct socket *so)
332 SOCKBUF_LOCK_ASSERT(sb);
334 sbrelease_internal(sb, so);
338 sbrelease(struct sockbuf *sb, struct socket *so)
342 sbrelease_locked(sb, so);
347 sbdestroy(struct sockbuf *sb, struct socket *so)
350 sbrelease_internal(sb, so);
355 * Routines to add and remove data from an mbuf queue.
357 * The routines sbappend() or sbappendrecord() are normally called to append
358 * new mbufs to a socket buffer, after checking that adequate space is
359 * available, comparing the function sbspace() with the amount of data to be
360 * added. sbappendrecord() differs from sbappend() in that data supplied is
361 * treated as the beginning of a new record. To place a sender's address,
362 * optional access rights, and data in a socket receive buffer,
363 * sbappendaddr() should be used. To place access rights and data in a
364 * socket receive buffer, sbappendrights() should be used. In either case,
365 * the new data begins a new record. Note that unlike sbappend() and
366 * sbappendrecord(), these routines check for the caller that there will be
367 * enough space to store the data. Each fails if there is not enough space,
368 * or if it cannot find mbufs to store additional information in.
370 * Reliable protocols may use the socket send buffer to hold data awaiting
371 * acknowledgement. Data is normally copied from a socket send buffer in a
372 * protocol with m_copy for output to a peer, and then removing the data from
373 * the socket buffer with sbdrop() or sbdroprecord() when the data is
374 * acknowledged by the peer.
378 sblastrecordchk(struct sockbuf *sb, const char *file, int line)
380 struct mbuf *m = sb->sb_mb;
382 SOCKBUF_LOCK_ASSERT(sb);
384 while (m && m->m_nextpkt)
387 if (m != sb->sb_lastrecord) {
388 printf("%s: sb_mb %p sb_lastrecord %p last %p\n",
389 __func__, sb->sb_mb, sb->sb_lastrecord, m);
390 printf("packet chain:\n");
391 for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt)
393 panic("%s from %s:%u", __func__, file, line);
398 sblastmbufchk(struct sockbuf *sb, const char *file, int line)
400 struct mbuf *m = sb->sb_mb;
403 SOCKBUF_LOCK_ASSERT(sb);
405 while (m && m->m_nextpkt)
408 while (m && m->m_next)
411 if (m != sb->sb_mbtail) {
412 printf("%s: sb_mb %p sb_mbtail %p last %p\n",
413 __func__, sb->sb_mb, sb->sb_mbtail, m);
414 printf("packet tree:\n");
415 for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt) {
417 for (n = m; n != NULL; n = n->m_next)
421 panic("%s from %s:%u", __func__, file, line);
424 #endif /* SOCKBUF_DEBUG */
426 #define SBLINKRECORD(sb, m0) do { \
427 SOCKBUF_LOCK_ASSERT(sb); \
428 if ((sb)->sb_lastrecord != NULL) \
429 (sb)->sb_lastrecord->m_nextpkt = (m0); \
431 (sb)->sb_mb = (m0); \
432 (sb)->sb_lastrecord = (m0); \
433 } while (/*CONSTCOND*/0)
436 * Append mbuf chain m to the last record in the socket buffer sb. The
437 * additional space associated the mbuf chain is recorded in sb. Empty mbufs
438 * are discarded and mbufs are compacted where possible.
441 sbappend_locked(struct sockbuf *sb, struct mbuf *m)
445 SOCKBUF_LOCK_ASSERT(sb);
456 if (n->m_flags & M_EOR) {
457 sbappendrecord_locked(sb, m); /* XXXXXX!!!! */
460 } while (n->m_next && (n = n->m_next));
463 * XXX Would like to simply use sb_mbtail here, but
464 * XXX I need to verify that I won't miss an EOR that
467 if ((n = sb->sb_lastrecord) != NULL) {
469 if (n->m_flags & M_EOR) {
470 sbappendrecord_locked(sb, m); /* XXXXXX!!!! */
473 } while (n->m_next && (n = n->m_next));
476 * If this is the first record in the socket buffer,
477 * it's also the last record.
479 sb->sb_lastrecord = m;
482 sbcompress(sb, m, n);
487 * Append mbuf chain m to the last record in the socket buffer sb. The
488 * additional space associated the mbuf chain is recorded in sb. Empty mbufs
489 * are discarded and mbufs are compacted where possible.
492 sbappend(struct sockbuf *sb, struct mbuf *m)
496 sbappend_locked(sb, m);
501 * This version of sbappend() should only be used when the caller absolutely
502 * knows that there will never be more than one record in the socket buffer,
503 * that is, a stream protocol (such as TCP).
506 sbappendstream_locked(struct sockbuf *sb, struct mbuf *m)
508 SOCKBUF_LOCK_ASSERT(sb);
510 KASSERT(m->m_nextpkt == NULL,("sbappendstream 0"));
511 KASSERT(sb->sb_mb == sb->sb_lastrecord,("sbappendstream 1"));
515 sbcompress(sb, m, sb->sb_mbtail);
517 sb->sb_lastrecord = sb->sb_mb;
522 * This version of sbappend() should only be used when the caller absolutely
523 * knows that there will never be more than one record in the socket buffer,
524 * that is, a stream protocol (such as TCP).
527 sbappendstream(struct sockbuf *sb, struct mbuf *m)
531 sbappendstream_locked(sb, m);
537 sbcheck(struct sockbuf *sb)
541 u_long len = 0, mbcnt = 0;
543 SOCKBUF_LOCK_ASSERT(sb);
545 for (m = sb->sb_mb; m; m = n) {
547 for (; m; m = m->m_next) {
550 if (m->m_flags & M_EXT) /*XXX*/ /* pretty sure this is bogus */
551 mbcnt += m->m_ext.ext_size;
554 if (len != sb->sb_cc || mbcnt != sb->sb_mbcnt) {
555 printf("cc %ld != %u || mbcnt %ld != %u\n", len, sb->sb_cc,
556 mbcnt, sb->sb_mbcnt);
563 * As above, except the mbuf chain begins a new record.
566 sbappendrecord_locked(struct sockbuf *sb, struct mbuf *m0)
570 SOCKBUF_LOCK_ASSERT(sb);
579 * Put the first mbuf on the queue. Note this permits zero length
584 SBLINKRECORD(sb, m0);
591 if (m && (m0->m_flags & M_EOR)) {
592 m0->m_flags &= ~M_EOR;
595 sbcompress(sb, m, m0);
599 * As above, except the mbuf chain begins a new record.
602 sbappendrecord(struct sockbuf *sb, struct mbuf *m0)
606 sbappendrecord_locked(sb, m0);
611 * Append address and data, and optionally, control (ancillary) data to the
612 * receive queue of a socket. If present, m0 must include a packet header
613 * with total length. Returns 0 if no space in sockbuf or insufficient
617 sbappendaddr_locked(struct sockbuf *sb, const struct sockaddr *asa,
618 struct mbuf *m0, struct mbuf *control)
620 struct mbuf *m, *n, *nlast;
621 int space = asa->sa_len;
623 SOCKBUF_LOCK_ASSERT(sb);
625 if (m0 && (m0->m_flags & M_PKTHDR) == 0)
626 panic("sbappendaddr_locked");
628 space += m0->m_pkthdr.len;
629 space += m_length(control, &n);
631 if (space > sbspace(sb))
634 if (asa->sa_len > MLEN)
637 MGET(m, M_DONTWAIT, MT_SONAME);
640 m->m_len = asa->sa_len;
641 bcopy(asa, mtod(m, caddr_t), asa->sa_len);
643 n->m_next = m0; /* concatenate data to control */
647 for (n = m; n->m_next != NULL; n = n->m_next)
653 sb->sb_mbtail = nlast;
661 * Append address and data, and optionally, control (ancillary) data to the
662 * receive queue of a socket. If present, m0 must include a packet header
663 * with total length. Returns 0 if no space in sockbuf or insufficient
667 sbappendaddr(struct sockbuf *sb, const struct sockaddr *asa,
668 struct mbuf *m0, struct mbuf *control)
673 retval = sbappendaddr_locked(sb, asa, m0, control);
679 sbappendcontrol_locked(struct sockbuf *sb, struct mbuf *m0,
680 struct mbuf *control)
682 struct mbuf *m, *n, *mlast;
685 SOCKBUF_LOCK_ASSERT(sb);
688 panic("sbappendcontrol_locked");
689 space = m_length(control, &n) + m_length(m0, NULL);
691 if (space > sbspace(sb))
693 n->m_next = m0; /* concatenate data to control */
697 for (m = control; m->m_next; m = m->m_next)
701 SBLINKRECORD(sb, control);
703 sb->sb_mbtail = mlast;
711 sbappendcontrol(struct sockbuf *sb, struct mbuf *m0, struct mbuf *control)
716 retval = sbappendcontrol_locked(sb, m0, control);
722 * Append the data in mbuf chain (m) into the socket buffer sb following mbuf
723 * (n). If (n) is NULL, the buffer is presumed empty.
725 * When the data is compressed, mbufs in the chain may be handled in one of
728 * (1) The mbuf may simply be dropped, if it contributes nothing (no data, no
729 * record boundary, and no change in data type).
731 * (2) The mbuf may be coalesced -- i.e., data in the mbuf may be copied into
732 * an mbuf already in the socket buffer. This can occur if an
733 * appropriate mbuf exists, there is room, and no merging of data types
736 * (3) The mbuf may be appended to the end of the existing mbuf chain.
738 * If any of the new mbufs is marked as M_EOR, mark the last mbuf appended as
742 sbcompress(struct sockbuf *sb, struct mbuf *m, struct mbuf *n)
747 SOCKBUF_LOCK_ASSERT(sb);
750 eor |= m->m_flags & M_EOR;
753 (((o = m->m_next) || (o = n)) &&
754 o->m_type == m->m_type))) {
755 if (sb->sb_lastrecord == m)
756 sb->sb_lastrecord = m->m_next;
760 if (n && (n->m_flags & M_EOR) == 0 &&
762 m->m_len <= MCLBYTES / 4 && /* XXX: Don't copy too much */
763 m->m_len <= M_TRAILINGSPACE(n) &&
764 n->m_type == m->m_type) {
765 bcopy(mtod(m, caddr_t), mtod(n, caddr_t) + n->m_len,
767 n->m_len += m->m_len;
768 sb->sb_cc += m->m_len;
769 if (m->m_type != MT_DATA && m->m_type != MT_OOBDATA)
770 /* XXX: Probably don't need.*/
771 sb->sb_ctl += m->m_len;
782 m->m_flags &= ~M_EOR;
787 KASSERT(n != NULL, ("sbcompress: eor && n == NULL"));
794 * Free all mbufs in a sockbuf. Check that all resources are reclaimed.
797 sbflush_internal(struct sockbuf *sb)
800 if (sb->sb_flags & SB_LOCK)
801 panic("sbflush_internal: locked");
802 while (sb->sb_mbcnt) {
804 * Don't call sbdrop(sb, 0) if the leading mbuf is non-empty:
805 * we would loop forever. Panic instead.
807 if (!sb->sb_cc && (sb->sb_mb == NULL || sb->sb_mb->m_len))
809 sbdrop_internal(sb, (int)sb->sb_cc);
811 if (sb->sb_cc || sb->sb_mb || sb->sb_mbcnt)
812 panic("sbflush_internal: cc %u || mb %p || mbcnt %u",
813 sb->sb_cc, (void *)sb->sb_mb, sb->sb_mbcnt);
817 sbflush_locked(struct sockbuf *sb)
820 SOCKBUF_LOCK_ASSERT(sb);
821 sbflush_internal(sb);
825 sbflush(struct sockbuf *sb)
834 * Drop data from (the front of) a sockbuf.
837 sbdrop_internal(struct sockbuf *sb, int len)
842 next = (m = sb->sb_mb) ? m->m_nextpkt : 0;
851 if (m->m_len > len) {
855 if (m->m_type != MT_DATA && m->m_type != MT_OOBDATA)
863 while (m && m->m_len == 0) {
873 * First part is an inline SB_EMPTY_FIXUP(). Second part makes sure
874 * sb_lastrecord is up-to-date if we dropped part of the last record.
878 sb->sb_mbtail = NULL;
879 sb->sb_lastrecord = NULL;
880 } else if (m->m_nextpkt == NULL) {
881 sb->sb_lastrecord = m;
886 * Drop data from (the front of) a sockbuf.
889 sbdrop_locked(struct sockbuf *sb, int len)
892 SOCKBUF_LOCK_ASSERT(sb);
894 sbdrop_internal(sb, len);
898 sbdrop(struct sockbuf *sb, int len)
902 sbdrop_locked(sb, len);
907 * Drop a record off the front of a sockbuf and move the next record to the
911 sbdroprecord_locked(struct sockbuf *sb)
915 SOCKBUF_LOCK_ASSERT(sb);
919 sb->sb_mb = m->m_nextpkt;
929 * Drop a record off the front of a sockbuf and move the next record to the
933 sbdroprecord(struct sockbuf *sb)
937 sbdroprecord_locked(sb);
941 /* This takes the place of kern.maxsockbuf, which moved to kern.ipc. */
943 SYSCTL_INT(_kern, KERN_DUMMY, dummy, CTLFLAG_RW, &dummy, 0, "");
944 SYSCTL_OID(_kern_ipc, KIPC_MAXSOCKBUF, maxsockbuf, CTLTYPE_ULONG|CTLFLAG_RW,
945 &sb_max, 0, sysctl_handle_sb_max, "LU", "Maximum socket buffer size");
946 SYSCTL_ULONG(_kern_ipc, KIPC_SOCKBUF_WASTE, sockbuf_waste_factor, CTLFLAG_RW,
947 &sb_efficiency, 0, "");