2 * SPDX-License-Identifier: BSD-4-Clause
4 * Copyright (c) 1996 John S. Dyson
5 * Copyright (c) 2012 Giovanni Trematerra
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice immediately at the beginning of the file, without modification,
13 * this list of conditions, and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Absolutely no warranty of function or purpose is made by the author
19 * 4. Modifications may be freely made to this file if the above conditions
24 * This file contains a high-performance replacement for the socket-based
25 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support
26 * all features of sockets, but does do everything that pipes normally
31 * This code has two modes of operation, a small write mode and a large
32 * write mode. The small write mode acts like conventional pipes with
33 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the
34 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT
35 * and PIPE_SIZE in size, the sending process pins the underlying pages in
36 * memory, and the receiving process copies directly from these pinned pages
37 * in the sending process.
39 * If the sending process receives a signal, it is possible that it will
40 * go away, and certainly its address space can change, because control
41 * is returned back to the user-mode side. In that case, the pipe code
42 * arranges to copy the buffer supplied by the user process, to a pageable
43 * kernel buffer, and the receiving process will grab the data from the
44 * pageable kernel buffer. Since signals don't happen all that often,
45 * the copy operation is normally eliminated.
47 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
48 * happen for small transfers so that the system will not spend all of
49 * its time context switching.
51 * In order to limit the resource use of pipes, two sysctls exist:
53 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
54 * address space available to us in pipe_map. This value is normally
55 * autotuned, but may also be loader tuned.
57 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
58 * memory in use by pipes.
60 * Based on how large pipekva is relative to maxpipekva, the following
64 * New pipes are given 16K of memory backing, pipes may dynamically
65 * grow to as large as 64K where needed.
67 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
68 * existing pipes may NOT grow.
70 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
71 * existing pipes will be shrunk down to 4K whenever possible.
73 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If
74 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
75 * resize which MUST occur for reverse-direction pipes when they are
78 * Additional information about the current state of pipes may be obtained
79 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
80 * and kern.ipc.piperesizefail.
82 * Locking rules: There are two locks present here: A mutex, used via
83 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via
84 * the flag, as mutexes can not persist over uiomove. The mutex
85 * exists only to guard access to the flag, and is not in itself a
86 * locking mechanism. Also note that there is only a single mutex for
87 * both directions of a pipe.
89 * As pipelock() may have to sleep before it can acquire the flag, it
90 * is important to reread all data after a call to pipelock(); everything
91 * in the structure may have changed.
94 #include <sys/cdefs.h>
95 __FBSDID("$FreeBSD$");
97 #include <sys/param.h>
98 #include <sys/systm.h>
100 #include <sys/fcntl.h>
101 #include <sys/file.h>
102 #include <sys/filedesc.h>
103 #include <sys/filio.h>
104 #include <sys/kernel.h>
105 #include <sys/lock.h>
106 #include <sys/mutex.h>
107 #include <sys/ttycom.h>
108 #include <sys/stat.h>
109 #include <sys/malloc.h>
110 #include <sys/poll.h>
111 #include <sys/selinfo.h>
112 #include <sys/signalvar.h>
113 #include <sys/syscallsubr.h>
114 #include <sys/sysctl.h>
115 #include <sys/sysproto.h>
116 #include <sys/pipe.h>
117 #include <sys/proc.h>
118 #include <sys/vnode.h>
120 #include <sys/user.h>
121 #include <sys/event.h>
123 #include <security/mac/mac_framework.h>
126 #include <vm/vm_param.h>
127 #include <vm/vm_object.h>
128 #include <vm/vm_kern.h>
129 #include <vm/vm_extern.h>
131 #include <vm/vm_map.h>
132 #include <vm/vm_page.h>
136 * Use this define if you want to disable *fancy* VM things. Expect an
137 * approx 30% decrease in transfer rate. This could be useful for
140 /* #define PIPE_NODIRECT */
142 #define PIPE_PEER(pipe) \
143 (((pipe)->pipe_type & PIPE_TYPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
146 * interfaces to the outside world
148 static fo_rdwr_t pipe_read;
149 static fo_rdwr_t pipe_write;
150 static fo_truncate_t pipe_truncate;
151 static fo_ioctl_t pipe_ioctl;
152 static fo_poll_t pipe_poll;
153 static fo_kqfilter_t pipe_kqfilter;
154 static fo_stat_t pipe_stat;
155 static fo_close_t pipe_close;
156 static fo_chmod_t pipe_chmod;
157 static fo_chown_t pipe_chown;
158 static fo_fill_kinfo_t pipe_fill_kinfo;
160 struct fileops pipeops = {
161 .fo_read = pipe_read,
162 .fo_write = pipe_write,
163 .fo_truncate = pipe_truncate,
164 .fo_ioctl = pipe_ioctl,
165 .fo_poll = pipe_poll,
166 .fo_kqfilter = pipe_kqfilter,
167 .fo_stat = pipe_stat,
168 .fo_close = pipe_close,
169 .fo_chmod = pipe_chmod,
170 .fo_chown = pipe_chown,
171 .fo_sendfile = invfo_sendfile,
172 .fo_fill_kinfo = pipe_fill_kinfo,
173 .fo_flags = DFLAG_PASSABLE
176 static void filt_pipedetach(struct knote *kn);
177 static void filt_pipedetach_notsup(struct knote *kn);
178 static int filt_pipenotsup(struct knote *kn, long hint);
179 static int filt_piperead(struct knote *kn, long hint);
180 static int filt_pipewrite(struct knote *kn, long hint);
182 static struct filterops pipe_nfiltops = {
184 .f_detach = filt_pipedetach_notsup,
185 .f_event = filt_pipenotsup
187 static struct filterops pipe_rfiltops = {
189 .f_detach = filt_pipedetach,
190 .f_event = filt_piperead
192 static struct filterops pipe_wfiltops = {
194 .f_detach = filt_pipedetach,
195 .f_event = filt_pipewrite
199 * Default pipe buffer size(s), this can be kind-of large now because pipe
200 * space is pageable. The pipe code will try to maintain locality of
201 * reference for performance reasons, so small amounts of outstanding I/O
202 * will not wipe the cache.
204 #define MINPIPESIZE (PIPE_SIZE/3)
205 #define MAXPIPESIZE (2*PIPE_SIZE/3)
207 static long amountpipekva;
208 static int pipefragretry;
209 static int pipeallocfail;
210 static int piperesizefail;
211 static int piperesizeallowed = 1;
213 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
214 &maxpipekva, 0, "Pipe KVA limit");
215 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
216 &amountpipekva, 0, "Pipe KVA usage");
217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
218 &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
219 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
220 &pipeallocfail, 0, "Pipe allocation failures");
221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
222 &piperesizefail, 0, "Pipe resize failures");
223 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
224 &piperesizeallowed, 0, "Pipe resizing allowed");
226 static void pipeinit(void *dummy __unused);
227 static void pipeclose(struct pipe *cpipe);
228 static void pipe_free_kmem(struct pipe *cpipe);
229 static int pipe_create(struct pipe *pipe, bool backing);
230 static int pipe_paircreate(struct thread *td, struct pipepair **p_pp);
231 static __inline int pipelock(struct pipe *cpipe, int catch);
232 static __inline void pipeunlock(struct pipe *cpipe);
233 static void pipe_timestamp(struct timespec *tsp);
234 #ifndef PIPE_NODIRECT
235 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
236 static void pipe_destroy_write_buffer(struct pipe *wpipe);
237 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
238 static void pipe_clone_write_buffer(struct pipe *wpipe);
240 static int pipespace(struct pipe *cpipe, int size);
241 static int pipespace_new(struct pipe *cpipe, int size);
243 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags);
244 static int pipe_zone_init(void *mem, int size, int flags);
245 static void pipe_zone_fini(void *mem, int size);
247 static uma_zone_t pipe_zone;
248 static struct unrhdr64 pipeino_unr;
249 static dev_t pipedev_ino;
251 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
254 pipeinit(void *dummy __unused)
257 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
258 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
260 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
261 new_unrhdr64(&pipeino_unr, 1);
262 pipedev_ino = devfs_alloc_cdp_inode();
263 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
267 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
270 struct pipe *rpipe, *wpipe;
272 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
274 pp = (struct pipepair *)mem;
277 * We zero both pipe endpoints to make sure all the kmem pointers
278 * are NULL, flag fields are zero'd, etc. We timestamp both
279 * endpoints with the same time.
281 rpipe = &pp->pp_rpipe;
282 bzero(rpipe, sizeof(*rpipe));
283 pipe_timestamp(&rpipe->pipe_ctime);
284 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
286 wpipe = &pp->pp_wpipe;
287 bzero(wpipe, sizeof(*wpipe));
288 wpipe->pipe_ctime = rpipe->pipe_ctime;
289 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
291 rpipe->pipe_peer = wpipe;
292 rpipe->pipe_pair = pp;
293 wpipe->pipe_peer = rpipe;
294 wpipe->pipe_pair = pp;
297 * Mark both endpoints as present; they will later get free'd
298 * one at a time. When both are free'd, then the whole pair
301 rpipe->pipe_present = PIPE_ACTIVE;
302 wpipe->pipe_present = PIPE_ACTIVE;
305 * Eventually, the MAC Framework may initialize the label
306 * in ctor or init, but for now we do it elswhere to avoid
307 * blocking in ctor or init.
315 pipe_zone_init(void *mem, int size, int flags)
319 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
321 pp = (struct pipepair *)mem;
323 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW);
328 pipe_zone_fini(void *mem, int size)
332 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
334 pp = (struct pipepair *)mem;
336 mtx_destroy(&pp->pp_mtx);
340 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
343 struct pipe *rpipe, *wpipe;
346 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
349 * The MAC label is shared between the connected endpoints. As a
350 * result mac_pipe_init() and mac_pipe_create() are called once
351 * for the pair, and not on the endpoints.
354 mac_pipe_create(td->td_ucred, pp);
356 rpipe = &pp->pp_rpipe;
357 wpipe = &pp->pp_wpipe;
359 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
360 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
363 * Only the forward direction pipe is backed by big buffer by
366 error = pipe_create(rpipe, true);
369 error = pipe_create(wpipe, false);
372 * This cleanup leaves the pipe inode number for rpipe
373 * still allocated, but never used. We do not free
374 * inode numbers for opened pipes, which is required
375 * for correctness because numbers must be unique.
376 * But also it avoids any memory use by the unr
377 * allocator, so stashing away the transient inode
378 * number is reasonable.
380 pipe_free_kmem(rpipe);
384 rpipe->pipe_state |= PIPE_DIRECTOK;
385 wpipe->pipe_state |= PIPE_DIRECTOK;
389 knlist_destroy(&rpipe->pipe_sel.si_note);
390 knlist_destroy(&wpipe->pipe_sel.si_note);
392 mac_pipe_destroy(pp);
398 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
403 error = pipe_paircreate(td, &pp);
406 pp->pp_rpipe.pipe_type |= PIPE_TYPE_NAMED;
407 *ppipe = &pp->pp_rpipe;
412 pipe_dtor(struct pipe *dpipe)
416 peer = (dpipe->pipe_type & PIPE_TYPE_NAMED) != 0 ? dpipe->pipe_peer : NULL;
417 funsetown(&dpipe->pipe_sigio);
420 funsetown(&peer->pipe_sigio);
428 * This used to be vfs_timestamp but the higher precision is unnecessary and
429 * can very negatively affect performance in virtualized environments (e.g., on
430 * vms running on amd64 when using the rdtscp instruction).
433 pipe_timestamp(struct timespec *tsp)
440 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let
441 * the zone pick up the pieces via pipeclose().
444 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
445 struct filecaps *fcaps2)
447 struct file *rf, *wf;
448 struct pipe *rpipe, *wpipe;
450 int fd, fflags, error;
452 error = pipe_paircreate(td, &pp);
455 rpipe = &pp->pp_rpipe;
456 wpipe = &pp->pp_wpipe;
457 error = falloc_caps(td, &rf, &fd, flags, fcaps1);
463 /* An extra reference on `rf' has been held for us by falloc_caps(). */
466 fflags = FREAD | FWRITE;
467 if ((flags & O_NONBLOCK) != 0)
471 * Warning: once we've gotten past allocation of the fd for the
472 * read-side, we can only drop the read side via fdrop() in order
473 * to avoid races against processes which manage to dup() the read
474 * side while we are blocked trying to allocate the write side.
476 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
477 error = falloc_caps(td, &wf, &fd, flags, fcaps2);
479 fdclose(td, rf, fildes[0]);
481 /* rpipe has been closed by fdrop(). */
485 /* An extra reference on `wf' has been held for us by falloc_caps(). */
486 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
494 #ifdef COMPAT_FREEBSD10
497 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused)
502 error = kern_pipe(td, fildes, 0, NULL, NULL);
506 td->td_retval[0] = fildes[0];
507 td->td_retval[1] = fildes[1];
514 sys_pipe2(struct thread *td, struct pipe2_args *uap)
516 int error, fildes[2];
518 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
520 error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
523 error = copyout(fildes, uap->fildes, 2 * sizeof(int));
525 (void)kern_close(td, fildes[0]);
526 (void)kern_close(td, fildes[1]);
532 * Allocate kva for pipe circular buffer, the space is pageable
533 * This routine will 'realloc' the size of a pipe safely, if it fails
534 * it will retain the old buffer.
535 * If it fails it will return ENOMEM.
538 pipespace_new(struct pipe *cpipe, int size)
541 int error, cnt, firstseg;
542 static int curfail = 0;
543 static struct timeval lastfail;
545 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
546 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
547 ("pipespace: resize of direct writes not allowed"));
549 cnt = cpipe->pipe_buffer.cnt;
553 size = round_page(size);
554 buffer = (caddr_t) vm_map_min(pipe_map);
556 error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0,
557 VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
558 if (error != KERN_SUCCESS) {
559 if (cpipe->pipe_buffer.buffer == NULL &&
560 size > SMALL_PIPE_SIZE) {
561 size = SMALL_PIPE_SIZE;
565 if (cpipe->pipe_buffer.buffer == NULL) {
567 if (ppsratecheck(&lastfail, &curfail, 1))
568 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
575 /* copy data, then free old resources if we're resizing */
577 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
578 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
579 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
581 if ((cnt - firstseg) > 0)
582 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
583 cpipe->pipe_buffer.in);
585 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
589 pipe_free_kmem(cpipe);
590 cpipe->pipe_buffer.buffer = buffer;
591 cpipe->pipe_buffer.size = size;
592 cpipe->pipe_buffer.in = cnt;
593 cpipe->pipe_buffer.out = 0;
594 cpipe->pipe_buffer.cnt = cnt;
595 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
600 * Wrapper for pipespace_new() that performs locking assertions.
603 pipespace(struct pipe *cpipe, int size)
606 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
607 ("Unlocked pipe passed to pipespace"));
608 return (pipespace_new(cpipe, size));
612 * lock a pipe for I/O, blocking other access
615 pipelock(struct pipe *cpipe, int catch)
619 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
624 while (cpipe->pipe_state & PIPE_LOCKFL) {
625 KASSERT(cpipe->pipe_waiters >= 0,
626 ("%s: bad waiter count %d", __func__,
627 cpipe->pipe_waiters));
628 cpipe->pipe_waiters++;
629 error = msleep(cpipe, PIPE_MTX(cpipe),
631 cpipe->pipe_waiters--;
635 cpipe->pipe_state |= PIPE_LOCKFL;
640 * unlock a pipe I/O lock
643 pipeunlock(struct pipe *cpipe)
646 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
647 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
648 ("Unlocked pipe passed to pipeunlock"));
649 KASSERT(cpipe->pipe_waiters >= 0,
650 ("%s: bad waiter count %d", __func__,
651 cpipe->pipe_waiters));
652 cpipe->pipe_state &= ~PIPE_LOCKFL;
653 if (cpipe->pipe_waiters > 0) {
659 pipeselwakeup(struct pipe *cpipe)
662 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
663 if (cpipe->pipe_state & PIPE_SEL) {
664 selwakeuppri(&cpipe->pipe_sel, PSOCK);
665 if (!SEL_WAITING(&cpipe->pipe_sel))
666 cpipe->pipe_state &= ~PIPE_SEL;
668 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
669 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
670 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
674 * Initialize and allocate VM and memory for pipe. The structure
675 * will start out zero'd from the ctor, so we just manage the kmem.
678 pipe_create(struct pipe *pipe, bool large_backing)
682 error = pipespace_new(pipe, !large_backing || amountpipekva >
683 maxpipekva / 2 ? SMALL_PIPE_SIZE : PIPE_SIZE);
685 pipe->pipe_ino = alloc_unr64(&pipeino_unr);
691 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
692 int flags, struct thread *td)
702 error = pipelock(rpipe, 1);
707 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
711 if (amountpipekva > (3 * maxpipekva) / 4) {
712 if ((rpipe->pipe_state & PIPE_DIRECTW) == 0 &&
713 rpipe->pipe_buffer.size > SMALL_PIPE_SIZE &&
714 rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE &&
715 piperesizeallowed == 1) {
717 pipespace(rpipe, SMALL_PIPE_SIZE);
722 while (uio->uio_resid) {
724 * normal pipe buffer receive
726 if (rpipe->pipe_buffer.cnt > 0) {
727 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
728 if (size > rpipe->pipe_buffer.cnt)
729 size = rpipe->pipe_buffer.cnt;
730 if (size > uio->uio_resid)
731 size = uio->uio_resid;
735 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
741 rpipe->pipe_buffer.out += size;
742 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
743 rpipe->pipe_buffer.out = 0;
745 rpipe->pipe_buffer.cnt -= size;
748 * If there is no more to read in the pipe, reset
749 * its pointers to the beginning. This improves
752 if (rpipe->pipe_buffer.cnt == 0) {
753 rpipe->pipe_buffer.in = 0;
754 rpipe->pipe_buffer.out = 0;
757 #ifndef PIPE_NODIRECT
759 * Direct copy, bypassing a kernel buffer.
761 } else if ((size = rpipe->pipe_pages.cnt) != 0) {
762 if (size > uio->uio_resid)
763 size = (u_int) uio->uio_resid;
765 error = uiomove_fromphys(rpipe->pipe_pages.ms,
766 rpipe->pipe_pages.pos, size, uio);
771 rpipe->pipe_pages.pos += size;
772 rpipe->pipe_pages.cnt -= size;
773 if (rpipe->pipe_pages.cnt == 0) {
774 rpipe->pipe_state &= ~PIPE_WANTW;
780 * detect EOF condition
781 * read returns 0 on EOF, no need to set error
783 if (rpipe->pipe_state & PIPE_EOF)
787 * If the "write-side" has been blocked, wake it up now.
789 if (rpipe->pipe_state & PIPE_WANTW) {
790 rpipe->pipe_state &= ~PIPE_WANTW;
795 * Break if some data was read.
801 * Unlock the pipe buffer for our remaining processing.
802 * We will either break out with an error or we will
803 * sleep and relock to loop.
808 * Handle non-blocking mode operation or
809 * wait for more data.
811 if (fp->f_flag & FNONBLOCK) {
814 rpipe->pipe_state |= PIPE_WANTR;
815 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
818 error = pipelock(rpipe, 1);
829 /* XXX: should probably do this before getting any locks. */
831 pipe_timestamp(&rpipe->pipe_atime);
836 * PIPE_WANT processing only makes sense if pipe_busy is 0.
838 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
839 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
841 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
843 * Handle write blocking hysteresis.
845 if (rpipe->pipe_state & PIPE_WANTW) {
846 rpipe->pipe_state &= ~PIPE_WANTW;
852 * Only wake up writers if there was actually something read.
853 * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs.
856 rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF)
857 pipeselwakeup(rpipe);
863 #ifndef PIPE_NODIRECT
865 * Map the sending processes' buffer into kernel space and wire it.
866 * This is similar to a physical write operation.
869 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio)
874 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
875 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
876 ("%s: PIPE_DIRECTW set on %p", __func__, wpipe));
877 KASSERT(wpipe->pipe_pages.cnt == 0,
878 ("%s: pipe map for %p contains residual data", __func__, wpipe));
880 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
881 size = wpipe->pipe_buffer.size;
883 size = uio->uio_iov->iov_len;
885 wpipe->pipe_state |= PIPE_DIRECTW;
887 i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
888 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
889 wpipe->pipe_pages.ms, PIPENPAGES);
892 wpipe->pipe_state &= ~PIPE_DIRECTW;
896 wpipe->pipe_pages.npages = i;
897 wpipe->pipe_pages.pos =
898 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
899 wpipe->pipe_pages.cnt = size;
901 uio->uio_iov->iov_len -= size;
902 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
903 if (uio->uio_iov->iov_len == 0)
905 uio->uio_resid -= size;
906 uio->uio_offset += size;
911 * Unwire the process buffer.
914 pipe_destroy_write_buffer(struct pipe *wpipe)
917 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
918 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
919 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
920 KASSERT(wpipe->pipe_pages.cnt == 0,
921 ("%s: pipe map for %p contains residual data", __func__, wpipe));
923 wpipe->pipe_state &= ~PIPE_DIRECTW;
924 vm_page_unhold_pages(wpipe->pipe_pages.ms, wpipe->pipe_pages.npages);
925 wpipe->pipe_pages.npages = 0;
929 * In the case of a signal, the writing process might go away. This
930 * code copies the data into the circular buffer so that the source
931 * pages can be freed without loss of data.
934 pipe_clone_write_buffer(struct pipe *wpipe)
941 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
942 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
943 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
945 size = wpipe->pipe_pages.cnt;
946 pos = wpipe->pipe_pages.pos;
947 wpipe->pipe_pages.cnt = 0;
949 wpipe->pipe_buffer.in = size;
950 wpipe->pipe_buffer.out = 0;
951 wpipe->pipe_buffer.cnt = size;
954 iov.iov_base = wpipe->pipe_buffer.buffer;
959 uio.uio_resid = size;
960 uio.uio_segflg = UIO_SYSSPACE;
961 uio.uio_rw = UIO_READ;
962 uio.uio_td = curthread;
963 uiomove_fromphys(wpipe->pipe_pages.ms, pos, size, &uio);
965 pipe_destroy_write_buffer(wpipe);
969 * This implements the pipe buffer write mechanism. Note that only
970 * a direct write OR a normal pipe write can be pending at any given time.
971 * If there are any characters in the pipe buffer, the direct write will
972 * be deferred until the receiving process grabs all of the bytes from
973 * the pipe buffer. Then the direct mapping write is set-up.
976 pipe_direct_write(struct pipe *wpipe, struct uio *uio)
981 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
982 if ((wpipe->pipe_state & PIPE_EOF) != 0) {
986 if (wpipe->pipe_state & PIPE_DIRECTW) {
987 if (wpipe->pipe_state & PIPE_WANTR) {
988 wpipe->pipe_state &= ~PIPE_WANTR;
991 pipeselwakeup(wpipe);
992 wpipe->pipe_state |= PIPE_WANTW;
994 error = msleep(wpipe, PIPE_MTX(wpipe),
995 PRIBIO | PCATCH, "pipdww", 0);
1001 if (wpipe->pipe_buffer.cnt > 0) {
1002 if (wpipe->pipe_state & PIPE_WANTR) {
1003 wpipe->pipe_state &= ~PIPE_WANTR;
1006 pipeselwakeup(wpipe);
1007 wpipe->pipe_state |= PIPE_WANTW;
1009 error = msleep(wpipe, PIPE_MTX(wpipe),
1010 PRIBIO | PCATCH, "pipdwc", 0);
1017 error = pipe_build_write_buffer(wpipe, uio);
1022 while (wpipe->pipe_pages.cnt != 0 &&
1023 (wpipe->pipe_state & PIPE_EOF) == 0) {
1024 if (wpipe->pipe_state & PIPE_WANTR) {
1025 wpipe->pipe_state &= ~PIPE_WANTR;
1028 pipeselwakeup(wpipe);
1029 wpipe->pipe_state |= PIPE_WANTW;
1031 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
1038 if ((wpipe->pipe_state & PIPE_EOF) != 0) {
1039 wpipe->pipe_pages.cnt = 0;
1040 pipe_destroy_write_buffer(wpipe);
1041 pipeselwakeup(wpipe);
1043 } else if (error == EINTR || error == ERESTART) {
1044 pipe_clone_write_buffer(wpipe);
1046 pipe_destroy_write_buffer(wpipe);
1048 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
1049 ("pipe %p leaked PIPE_DIRECTW", wpipe));
1059 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
1060 int flags, struct thread *td)
1062 struct pipe *wpipe, *rpipe;
1064 int desiredsize, error;
1067 wpipe = PIPE_PEER(rpipe);
1069 error = pipelock(wpipe, 1);
1075 * detect loss of pipe read side, issue SIGPIPE if lost.
1077 if (wpipe->pipe_present != PIPE_ACTIVE ||
1078 (wpipe->pipe_state & PIPE_EOF)) {
1084 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1093 /* Choose a larger size if it's advantageous */
1094 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1095 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1096 if (piperesizeallowed != 1)
1098 if (amountpipekva > maxpipekva / 2)
1100 if (desiredsize == BIG_PIPE_SIZE)
1102 desiredsize = desiredsize * 2;
1105 /* Choose a smaller size if we're in a OOM situation */
1106 if (amountpipekva > (3 * maxpipekva) / 4 &&
1107 wpipe->pipe_buffer.size > SMALL_PIPE_SIZE &&
1108 wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE &&
1109 piperesizeallowed == 1)
1110 desiredsize = SMALL_PIPE_SIZE;
1112 /* Resize if the above determined that a new size was necessary */
1113 if (desiredsize != wpipe->pipe_buffer.size &&
1114 (wpipe->pipe_state & PIPE_DIRECTW) == 0) {
1116 pipespace(wpipe, desiredsize);
1119 MPASS(wpipe->pipe_buffer.size != 0);
1121 orig_resid = uio->uio_resid;
1123 while (uio->uio_resid) {
1126 if (wpipe->pipe_state & PIPE_EOF) {
1130 #ifndef PIPE_NODIRECT
1132 * If the transfer is large, we can gain performance if
1133 * we do process-to-process copies directly.
1134 * If the write is non-blocking, we don't use the
1135 * direct write mechanism.
1137 * The direct write mechanism will detect the reader going
1140 if (uio->uio_segflg == UIO_USERSPACE &&
1141 uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1142 wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1143 (fp->f_flag & FNONBLOCK) == 0) {
1144 error = pipe_direct_write(wpipe, uio);
1152 * Pipe buffered writes cannot be coincidental with
1153 * direct writes. We wait until the currently executing
1154 * direct write is completed before we start filling the
1155 * pipe buffer. We break out if a signal occurs or the
1158 if (wpipe->pipe_pages.cnt != 0) {
1159 if (wpipe->pipe_state & PIPE_WANTR) {
1160 wpipe->pipe_state &= ~PIPE_WANTR;
1163 pipeselwakeup(wpipe);
1164 wpipe->pipe_state |= PIPE_WANTW;
1166 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1174 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1176 /* Writes of size <= PIPE_BUF must be atomic. */
1177 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1181 int size; /* Transfer size */
1182 int segsize; /* first segment to transfer */
1185 * Transfer size is minimum of uio transfer
1186 * and free space in pipe buffer.
1188 if (space > uio->uio_resid)
1189 size = uio->uio_resid;
1193 * First segment to transfer is minimum of
1194 * transfer size and contiguous space in
1195 * pipe buffer. If first segment to transfer
1196 * is less than the transfer size, we've got
1197 * a wraparound in the buffer.
1199 segsize = wpipe->pipe_buffer.size -
1200 wpipe->pipe_buffer.in;
1204 /* Transfer first segment */
1207 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1211 if (error == 0 && segsize < size) {
1212 KASSERT(wpipe->pipe_buffer.in + segsize ==
1213 wpipe->pipe_buffer.size,
1214 ("Pipe buffer wraparound disappeared"));
1216 * Transfer remaining part now, to
1217 * support atomic writes. Wraparound
1223 &wpipe->pipe_buffer.buffer[0],
1224 size - segsize, uio);
1228 wpipe->pipe_buffer.in += size;
1229 if (wpipe->pipe_buffer.in >=
1230 wpipe->pipe_buffer.size) {
1231 KASSERT(wpipe->pipe_buffer.in ==
1233 wpipe->pipe_buffer.size,
1234 ("Expected wraparound bad"));
1235 wpipe->pipe_buffer.in = size - segsize;
1238 wpipe->pipe_buffer.cnt += size;
1239 KASSERT(wpipe->pipe_buffer.cnt <=
1240 wpipe->pipe_buffer.size,
1241 ("Pipe buffer overflow"));
1248 * If the "read-side" has been blocked, wake it up now.
1250 if (wpipe->pipe_state & PIPE_WANTR) {
1251 wpipe->pipe_state &= ~PIPE_WANTR;
1256 * don't block on non-blocking I/O
1258 if (fp->f_flag & FNONBLOCK) {
1264 * We have no more space and have something to offer,
1265 * wake up select/poll.
1267 pipeselwakeup(wpipe);
1269 wpipe->pipe_state |= PIPE_WANTW;
1271 error = msleep(wpipe, PIPE_MTX(rpipe),
1272 PRIBIO | PCATCH, "pipewr", 0);
1282 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1283 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1285 } else if (wpipe->pipe_buffer.cnt > 0) {
1287 * If we have put any characters in the buffer, we wake up
1290 if (wpipe->pipe_state & PIPE_WANTR) {
1291 wpipe->pipe_state &= ~PIPE_WANTR;
1297 * Don't return EPIPE if any byte was written.
1298 * EINTR and other interrupts are handled by generic I/O layer.
1299 * Do not pretend that I/O succeeded for obvious user error
1302 if (uio->uio_resid != orig_resid && error == EPIPE)
1306 pipe_timestamp(&wpipe->pipe_mtime);
1309 * We have something to offer,
1310 * wake up select/poll.
1312 if (wpipe->pipe_buffer.cnt)
1313 pipeselwakeup(wpipe);
1322 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred,
1329 if (cpipe->pipe_type & PIPE_TYPE_NAMED)
1330 error = vnops.fo_truncate(fp, length, active_cred, td);
1332 error = invfo_truncate(fp, length, active_cred, td);
1337 * we implement a very minimal set of ioctls for compatibility with sockets.
1340 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred,
1343 struct pipe *mpipe = fp->f_data;
1349 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1363 mpipe->pipe_state |= PIPE_ASYNC;
1365 mpipe->pipe_state &= ~PIPE_ASYNC;
1370 if (!(fp->f_flag & FREAD)) {
1375 if (mpipe->pipe_pages.cnt != 0)
1376 *(int *)data = mpipe->pipe_pages.cnt;
1378 *(int *)data = mpipe->pipe_buffer.cnt;
1383 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1387 *(int *)data = fgetown(&mpipe->pipe_sigio);
1390 /* This is deprecated, FIOSETOWN should be used instead. */
1393 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1396 /* This is deprecated, FIOGETOWN should be used instead. */
1398 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1411 pipe_poll(struct file *fp, int events, struct ucred *active_cred,
1416 int levents, revents;
1423 wpipe = PIPE_PEER(rpipe);
1426 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1430 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1431 if (rpipe->pipe_pages.cnt > 0 || rpipe->pipe_buffer.cnt > 0)
1432 revents |= events & (POLLIN | POLLRDNORM);
1434 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1435 if (wpipe->pipe_present != PIPE_ACTIVE ||
1436 (wpipe->pipe_state & PIPE_EOF) ||
1437 ((wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
1438 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1439 wpipe->pipe_buffer.size == 0)))
1440 revents |= events & (POLLOUT | POLLWRNORM);
1443 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1444 if (rpipe->pipe_type & PIPE_TYPE_NAMED && fp->f_flag & FREAD && levents &&
1445 fp->f_pipegen == rpipe->pipe_wgen)
1446 events |= POLLINIGNEOF;
1448 if ((events & POLLINIGNEOF) == 0) {
1449 if (rpipe->pipe_state & PIPE_EOF) {
1450 if (fp->f_flag & FREAD)
1451 revents |= (events & (POLLIN | POLLRDNORM));
1452 if (wpipe->pipe_present != PIPE_ACTIVE ||
1453 (wpipe->pipe_state & PIPE_EOF))
1460 * Add ourselves regardless of eventmask as we have to return
1461 * POLLHUP even if it was not asked for.
1463 if ((fp->f_flag & FREAD) != 0) {
1464 selrecord(td, &rpipe->pipe_sel);
1465 if (SEL_WAITING(&rpipe->pipe_sel))
1466 rpipe->pipe_state |= PIPE_SEL;
1469 if ((fp->f_flag & FWRITE) != 0) {
1470 selrecord(td, &wpipe->pipe_sel);
1471 if (SEL_WAITING(&wpipe->pipe_sel))
1472 wpipe->pipe_state |= PIPE_SEL;
1484 * We shouldn't need locks here as we're doing a read and this should
1485 * be a natural race.
1488 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred,
1498 if (mac_pipe_check_stat_enabled()) {
1500 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1508 /* For named pipes ask the underlying filesystem. */
1509 if (pipe->pipe_type & PIPE_TYPE_NAMED) {
1510 return (vnops.fo_stat(fp, ub, active_cred, td));
1513 bzero(ub, sizeof(*ub));
1514 ub->st_mode = S_IFIFO;
1515 ub->st_blksize = PAGE_SIZE;
1516 if (pipe->pipe_pages.cnt != 0)
1517 ub->st_size = pipe->pipe_pages.cnt;
1519 ub->st_size = pipe->pipe_buffer.cnt;
1520 ub->st_blocks = howmany(ub->st_size, ub->st_blksize);
1521 ub->st_atim = pipe->pipe_atime;
1522 ub->st_mtim = pipe->pipe_mtime;
1523 ub->st_ctim = pipe->pipe_ctime;
1524 ub->st_uid = fp->f_cred->cr_uid;
1525 ub->st_gid = fp->f_cred->cr_gid;
1526 ub->st_dev = pipedev_ino;
1527 ub->st_ino = pipe->pipe_ino;
1529 * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1536 pipe_close(struct file *fp, struct thread *td)
1539 if (fp->f_vnode != NULL)
1540 return vnops.fo_close(fp, td);
1541 fp->f_ops = &badfileops;
1542 pipe_dtor(fp->f_data);
1548 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1554 if (cpipe->pipe_type & PIPE_TYPE_NAMED)
1555 error = vn_chmod(fp, mode, active_cred, td);
1557 error = invfo_chmod(fp, mode, active_cred, td);
1562 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1569 if (cpipe->pipe_type & PIPE_TYPE_NAMED)
1570 error = vn_chown(fp, uid, gid, active_cred, td);
1572 error = invfo_chown(fp, uid, gid, active_cred, td);
1577 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1581 if (fp->f_type == DTYPE_FIFO)
1582 return (vn_fill_kinfo(fp, kif, fdp));
1583 kif->kf_type = KF_TYPE_PIPE;
1585 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
1586 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
1587 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
1592 pipe_free_kmem(struct pipe *cpipe)
1595 KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1596 ("pipe_free_kmem: pipe mutex locked"));
1598 if (cpipe->pipe_buffer.buffer != NULL) {
1599 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1600 vm_map_remove(pipe_map,
1601 (vm_offset_t)cpipe->pipe_buffer.buffer,
1602 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1603 cpipe->pipe_buffer.buffer = NULL;
1605 #ifndef PIPE_NODIRECT
1607 cpipe->pipe_pages.cnt = 0;
1608 cpipe->pipe_pages.pos = 0;
1609 cpipe->pipe_pages.npages = 0;
1618 pipeclose(struct pipe *cpipe)
1620 struct pipepair *pp;
1623 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1627 pp = cpipe->pipe_pair;
1630 * If the other side is blocked, wake it up saying that
1631 * we want to close it down.
1633 cpipe->pipe_state |= PIPE_EOF;
1634 while (cpipe->pipe_busy) {
1636 cpipe->pipe_state |= PIPE_WANT;
1638 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1642 pipeselwakeup(cpipe);
1645 * Disconnect from peer, if any.
1647 ppipe = cpipe->pipe_peer;
1648 if (ppipe->pipe_present == PIPE_ACTIVE) {
1649 ppipe->pipe_state |= PIPE_EOF;
1651 pipeselwakeup(ppipe);
1655 * Mark this endpoint as free. Release kmem resources. We
1656 * don't mark this endpoint as unused until we've finished
1657 * doing that, or the pipe might disappear out from under
1661 pipe_free_kmem(cpipe);
1663 cpipe->pipe_present = PIPE_CLOSING;
1667 * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1668 * PIPE_FINALIZED, that allows other end to free the
1669 * pipe_pair, only after the knotes are completely dismantled.
1671 knlist_clear(&cpipe->pipe_sel.si_note, 1);
1672 cpipe->pipe_present = PIPE_FINALIZED;
1673 seldrain(&cpipe->pipe_sel);
1674 knlist_destroy(&cpipe->pipe_sel.si_note);
1677 * If both endpoints are now closed, release the memory for the
1678 * pipe pair. If not, unlock.
1680 if (ppipe->pipe_present == PIPE_FINALIZED) {
1683 mac_pipe_destroy(pp);
1685 uma_zfree(pipe_zone, cpipe->pipe_pair);
1692 pipe_kqfilter(struct file *fp, struct knote *kn)
1697 * If a filter is requested that is not supported by this file
1698 * descriptor, don't return an error, but also don't ever generate an
1701 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1702 kn->kn_fop = &pipe_nfiltops;
1705 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1706 kn->kn_fop = &pipe_nfiltops;
1711 switch (kn->kn_filter) {
1713 kn->kn_fop = &pipe_rfiltops;
1716 kn->kn_fop = &pipe_wfiltops;
1717 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1718 /* other end of pipe has been closed */
1722 cpipe = PIPE_PEER(cpipe);
1729 kn->kn_hook = cpipe;
1730 knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1736 filt_pipedetach(struct knote *kn)
1738 struct pipe *cpipe = kn->kn_hook;
1741 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1747 filt_piperead(struct knote *kn, long hint)
1749 struct file *fp = kn->kn_fp;
1750 struct pipe *rpipe = kn->kn_hook;
1752 PIPE_LOCK_ASSERT(rpipe, MA_OWNED);
1753 kn->kn_data = rpipe->pipe_buffer.cnt;
1754 if (kn->kn_data == 0)
1755 kn->kn_data = rpipe->pipe_pages.cnt;
1757 if ((rpipe->pipe_state & PIPE_EOF) != 0 &&
1758 ((rpipe->pipe_type & PIPE_TYPE_NAMED) == 0 ||
1759 fp->f_pipegen != rpipe->pipe_wgen)) {
1760 kn->kn_flags |= EV_EOF;
1763 kn->kn_flags &= ~EV_EOF;
1764 return (kn->kn_data > 0);
1769 filt_pipewrite(struct knote *kn, long hint)
1771 struct pipe *wpipe = kn->kn_hook;
1774 * If this end of the pipe is closed, the knote was removed from the
1775 * knlist and the list lock (i.e., the pipe lock) is therefore not held.
1777 if (wpipe->pipe_present == PIPE_ACTIVE ||
1778 (wpipe->pipe_type & PIPE_TYPE_NAMED) != 0) {
1779 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1781 if (wpipe->pipe_state & PIPE_DIRECTW) {
1783 } else if (wpipe->pipe_buffer.size > 0) {
1784 kn->kn_data = wpipe->pipe_buffer.size -
1785 wpipe->pipe_buffer.cnt;
1787 kn->kn_data = PIPE_BUF;
1791 if (wpipe->pipe_present != PIPE_ACTIVE ||
1792 (wpipe->pipe_state & PIPE_EOF)) {
1793 kn->kn_flags |= EV_EOF;
1796 kn->kn_flags &= ~EV_EOF;
1797 return (kn->kn_data >= PIPE_BUF);
1801 filt_pipedetach_notsup(struct knote *kn)
1807 filt_pipenotsup(struct knote *kn, long hint)