2 * Copyright (c) 1996 John S. Dyson
3 * Copyright (c) 2012 Giovanni Trematerra
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice immediately at the beginning of the file, without modification,
11 * this list of conditions, and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Absolutely no warranty of function or purpose is made by the author
17 * 4. Modifications may be freely made to this file if the above conditions
22 * This file contains a high-performance replacement for the socket-based
23 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support
24 * all features of sockets, but does do everything that pipes normally
29 * This code has two modes of operation, a small write mode and a large
30 * write mode. The small write mode acts like conventional pipes with
31 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the
32 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT
33 * and PIPE_SIZE in size, the sending process pins the underlying pages in
34 * memory, and the receiving process copies directly from these pinned pages
35 * in the sending process.
37 * If the sending process receives a signal, it is possible that it will
38 * go away, and certainly its address space can change, because control
39 * is returned back to the user-mode side. In that case, the pipe code
40 * arranges to copy the buffer supplied by the user process, to a pageable
41 * kernel buffer, and the receiving process will grab the data from the
42 * pageable kernel buffer. Since signals don't happen all that often,
43 * the copy operation is normally eliminated.
45 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
46 * happen for small transfers so that the system will not spend all of
47 * its time context switching.
49 * In order to limit the resource use of pipes, two sysctls exist:
51 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
52 * address space available to us in pipe_map. This value is normally
53 * autotuned, but may also be loader tuned.
55 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
56 * memory in use by pipes.
58 * Based on how large pipekva is relative to maxpipekva, the following
62 * New pipes are given 16K of memory backing, pipes may dynamically
63 * grow to as large as 64K where needed.
65 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
66 * existing pipes may NOT grow.
68 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
69 * existing pipes will be shrunk down to 4K whenever possible.
71 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If
72 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
73 * resize which MUST occur for reverse-direction pipes when they are
76 * Additional information about the current state of pipes may be obtained
77 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
78 * and kern.ipc.piperesizefail.
80 * Locking rules: There are two locks present here: A mutex, used via
81 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via
82 * the flag, as mutexes can not persist over uiomove. The mutex
83 * exists only to guard access to the flag, and is not in itself a
84 * locking mechanism. Also note that there is only a single mutex for
85 * both directions of a pipe.
87 * As pipelock() may have to sleep before it can acquire the flag, it
88 * is important to reread all data after a call to pipelock(); everything
89 * in the structure may have changed.
92 #include <sys/cdefs.h>
93 __FBSDID("$FreeBSD$");
95 #include <sys/param.h>
96 #include <sys/systm.h>
98 #include <sys/fcntl.h>
100 #include <sys/filedesc.h>
101 #include <sys/filio.h>
102 #include <sys/kernel.h>
103 #include <sys/lock.h>
104 #include <sys/mutex.h>
105 #include <sys/ttycom.h>
106 #include <sys/stat.h>
107 #include <sys/malloc.h>
108 #include <sys/poll.h>
109 #include <sys/selinfo.h>
110 #include <sys/signalvar.h>
111 #include <sys/syscallsubr.h>
112 #include <sys/sysctl.h>
113 #include <sys/sysproto.h>
114 #include <sys/pipe.h>
115 #include <sys/proc.h>
116 #include <sys/vnode.h>
118 #include <sys/event.h>
120 #include <security/mac/mac_framework.h>
123 #include <vm/vm_param.h>
124 #include <vm/vm_object.h>
125 #include <vm/vm_kern.h>
126 #include <vm/vm_extern.h>
128 #include <vm/vm_map.h>
129 #include <vm/vm_page.h>
133 * Use this define if you want to disable *fancy* VM things. Expect an
134 * approx 30% decrease in transfer rate. This could be useful for
137 /* #define PIPE_NODIRECT */
139 #define PIPE_PEER(pipe) \
140 (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
143 * interfaces to the outside world
145 static fo_rdwr_t pipe_read;
146 static fo_rdwr_t pipe_write;
147 static fo_truncate_t pipe_truncate;
148 static fo_ioctl_t pipe_ioctl;
149 static fo_poll_t pipe_poll;
150 static fo_kqfilter_t pipe_kqfilter;
151 static fo_stat_t pipe_stat;
152 static fo_close_t pipe_close;
153 static fo_chmod_t pipe_chmod;
154 static fo_chown_t pipe_chown;
156 struct fileops pipeops = {
157 .fo_read = pipe_read,
158 .fo_write = pipe_write,
159 .fo_truncate = pipe_truncate,
160 .fo_ioctl = pipe_ioctl,
161 .fo_poll = pipe_poll,
162 .fo_kqfilter = pipe_kqfilter,
163 .fo_stat = pipe_stat,
164 .fo_close = pipe_close,
165 .fo_chmod = pipe_chmod,
166 .fo_chown = pipe_chown,
167 .fo_sendfile = invfo_sendfile,
168 .fo_flags = DFLAG_PASSABLE
171 static void filt_pipedetach(struct knote *kn);
172 static void filt_pipedetach_notsup(struct knote *kn);
173 static int filt_pipenotsup(struct knote *kn, long hint);
174 static int filt_piperead(struct knote *kn, long hint);
175 static int filt_pipewrite(struct knote *kn, long hint);
177 static struct filterops pipe_nfiltops = {
179 .f_detach = filt_pipedetach_notsup,
180 .f_event = filt_pipenotsup
182 static struct filterops pipe_rfiltops = {
184 .f_detach = filt_pipedetach,
185 .f_event = filt_piperead
187 static struct filterops pipe_wfiltops = {
189 .f_detach = filt_pipedetach,
190 .f_event = filt_pipewrite
194 * Default pipe buffer size(s), this can be kind-of large now because pipe
195 * space is pageable. The pipe code will try to maintain locality of
196 * reference for performance reasons, so small amounts of outstanding I/O
197 * will not wipe the cache.
199 #define MINPIPESIZE (PIPE_SIZE/3)
200 #define MAXPIPESIZE (2*PIPE_SIZE/3)
202 static long amountpipekva;
203 static int pipefragretry;
204 static int pipeallocfail;
205 static int piperesizefail;
206 static int piperesizeallowed = 1;
208 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN,
209 &maxpipekva, 0, "Pipe KVA limit");
210 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
211 &amountpipekva, 0, "Pipe KVA usage");
212 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
213 &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
214 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
215 &pipeallocfail, 0, "Pipe allocation failures");
216 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
217 &piperesizefail, 0, "Pipe resize failures");
218 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
219 &piperesizeallowed, 0, "Pipe resizing allowed");
221 static void pipeinit(void *dummy __unused);
222 static void pipeclose(struct pipe *cpipe);
223 static void pipe_free_kmem(struct pipe *cpipe);
224 static int pipe_create(struct pipe *pipe, int backing);
225 static int pipe_paircreate(struct thread *td, struct pipepair **p_pp);
226 static __inline int pipelock(struct pipe *cpipe, int catch);
227 static __inline void pipeunlock(struct pipe *cpipe);
228 #ifndef PIPE_NODIRECT
229 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
230 static void pipe_destroy_write_buffer(struct pipe *wpipe);
231 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
232 static void pipe_clone_write_buffer(struct pipe *wpipe);
234 static int pipespace(struct pipe *cpipe, int size);
235 static int pipespace_new(struct pipe *cpipe, int size);
237 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags);
238 static int pipe_zone_init(void *mem, int size, int flags);
239 static void pipe_zone_fini(void *mem, int size);
241 static uma_zone_t pipe_zone;
242 static struct unrhdr *pipeino_unr;
243 static dev_t pipedev_ino;
245 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
248 pipeinit(void *dummy __unused)
251 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
252 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
254 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
255 pipeino_unr = new_unrhdr(1, INT32_MAX, NULL);
256 KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized"));
257 pipedev_ino = devfs_alloc_cdp_inode();
258 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
262 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
265 struct pipe *rpipe, *wpipe;
267 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
269 pp = (struct pipepair *)mem;
272 * We zero both pipe endpoints to make sure all the kmem pointers
273 * are NULL, flag fields are zero'd, etc. We timestamp both
274 * endpoints with the same time.
276 rpipe = &pp->pp_rpipe;
277 bzero(rpipe, sizeof(*rpipe));
278 vfs_timestamp(&rpipe->pipe_ctime);
279 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
281 wpipe = &pp->pp_wpipe;
282 bzero(wpipe, sizeof(*wpipe));
283 wpipe->pipe_ctime = rpipe->pipe_ctime;
284 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
286 rpipe->pipe_peer = wpipe;
287 rpipe->pipe_pair = pp;
288 wpipe->pipe_peer = rpipe;
289 wpipe->pipe_pair = pp;
292 * Mark both endpoints as present; they will later get free'd
293 * one at a time. When both are free'd, then the whole pair
296 rpipe->pipe_present = PIPE_ACTIVE;
297 wpipe->pipe_present = PIPE_ACTIVE;
300 * Eventually, the MAC Framework may initialize the label
301 * in ctor or init, but for now we do it elswhere to avoid
302 * blocking in ctor or init.
310 pipe_zone_init(void *mem, int size, int flags)
314 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
316 pp = (struct pipepair *)mem;
318 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE);
323 pipe_zone_fini(void *mem, int size)
327 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
329 pp = (struct pipepair *)mem;
331 mtx_destroy(&pp->pp_mtx);
335 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
338 struct pipe *rpipe, *wpipe;
341 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
344 * The MAC label is shared between the connected endpoints. As a
345 * result mac_pipe_init() and mac_pipe_create() are called once
346 * for the pair, and not on the endpoints.
349 mac_pipe_create(td->td_ucred, pp);
351 rpipe = &pp->pp_rpipe;
352 wpipe = &pp->pp_wpipe;
354 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
355 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
357 /* Only the forward direction pipe is backed by default */
358 if ((error = pipe_create(rpipe, 1)) != 0 ||
359 (error = pipe_create(wpipe, 0)) != 0) {
365 rpipe->pipe_state |= PIPE_DIRECTOK;
366 wpipe->pipe_state |= PIPE_DIRECTOK;
371 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
376 error = pipe_paircreate(td, &pp);
379 pp->pp_rpipe.pipe_state |= PIPE_NAMED;
380 *ppipe = &pp->pp_rpipe;
385 pipe_dtor(struct pipe *dpipe)
389 ino = dpipe->pipe_ino;
390 funsetown(&dpipe->pipe_sigio);
392 if (dpipe->pipe_state & PIPE_NAMED) {
393 dpipe = dpipe->pipe_peer;
394 funsetown(&dpipe->pipe_sigio);
397 if (ino != 0 && ino != (ino_t)-1)
398 free_unr(pipeino_unr, ino);
402 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let
403 * the zone pick up the pieces via pipeclose().
406 kern_pipe(struct thread *td, int fildes[2])
409 return (kern_pipe2(td, fildes, 0));
413 kern_pipe2(struct thread *td, int fildes[2], int flags)
415 struct filedesc *fdp;
416 struct file *rf, *wf;
417 struct pipe *rpipe, *wpipe;
419 int fd, fflags, error;
421 fdp = td->td_proc->p_fd;
422 error = pipe_paircreate(td, &pp);
425 rpipe = &pp->pp_rpipe;
426 wpipe = &pp->pp_wpipe;
427 error = falloc(td, &rf, &fd, flags);
433 /* An extra reference on `rf' has been held for us by falloc(). */
436 fflags = FREAD | FWRITE;
437 if ((flags & O_NONBLOCK) != 0)
441 * Warning: once we've gotten past allocation of the fd for the
442 * read-side, we can only drop the read side via fdrop() in order
443 * to avoid races against processes which manage to dup() the read
444 * side while we are blocked trying to allocate the write side.
446 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
447 error = falloc(td, &wf, &fd, flags);
449 fdclose(fdp, rf, fildes[0], td);
451 /* rpipe has been closed by fdrop(). */
455 /* An extra reference on `wf' has been held for us by falloc(). */
456 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
466 sys_pipe(struct thread *td, struct pipe_args *uap)
471 error = kern_pipe(td, fildes);
475 td->td_retval[0] = fildes[0];
476 td->td_retval[1] = fildes[1];
482 sys_pipe2(struct thread *td, struct pipe2_args *uap)
484 int error, fildes[2];
486 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
488 error = kern_pipe2(td, fildes, uap->flags);
491 error = copyout(fildes, uap->fildes, 2 * sizeof(int));
493 (void)kern_close(td, fildes[0]);
494 (void)kern_close(td, fildes[1]);
500 * Allocate kva for pipe circular buffer, the space is pageable
501 * This routine will 'realloc' the size of a pipe safely, if it fails
502 * it will retain the old buffer.
503 * If it fails it will return ENOMEM.
506 pipespace_new(cpipe, size)
511 int error, cnt, firstseg;
512 static int curfail = 0;
513 static struct timeval lastfail;
515 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
516 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
517 ("pipespace: resize of direct writes not allowed"));
519 cnt = cpipe->pipe_buffer.cnt;
523 size = round_page(size);
524 buffer = (caddr_t) vm_map_min(pipe_map);
526 error = vm_map_find(pipe_map, NULL, 0,
527 (vm_offset_t *) &buffer, size, 0, VMFS_ANY_SPACE,
528 VM_PROT_ALL, VM_PROT_ALL, 0);
529 if (error != KERN_SUCCESS) {
530 if ((cpipe->pipe_buffer.buffer == NULL) &&
531 (size > SMALL_PIPE_SIZE)) {
532 size = SMALL_PIPE_SIZE;
536 if (cpipe->pipe_buffer.buffer == NULL) {
538 if (ppsratecheck(&lastfail, &curfail, 1))
539 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
546 /* copy data, then free old resources if we're resizing */
548 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
549 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
550 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
552 if ((cnt - firstseg) > 0)
553 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
554 cpipe->pipe_buffer.in);
556 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
560 pipe_free_kmem(cpipe);
561 cpipe->pipe_buffer.buffer = buffer;
562 cpipe->pipe_buffer.size = size;
563 cpipe->pipe_buffer.in = cnt;
564 cpipe->pipe_buffer.out = 0;
565 cpipe->pipe_buffer.cnt = cnt;
566 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
571 * Wrapper for pipespace_new() that performs locking assertions.
574 pipespace(cpipe, size)
579 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
580 ("Unlocked pipe passed to pipespace"));
581 return (pipespace_new(cpipe, size));
585 * lock a pipe for I/O, blocking other access
588 pipelock(cpipe, catch)
594 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
595 while (cpipe->pipe_state & PIPE_LOCKFL) {
596 cpipe->pipe_state |= PIPE_LWANT;
597 error = msleep(cpipe, PIPE_MTX(cpipe),
598 catch ? (PRIBIO | PCATCH) : PRIBIO,
603 cpipe->pipe_state |= PIPE_LOCKFL;
608 * unlock a pipe I/O lock
615 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
616 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
617 ("Unlocked pipe passed to pipeunlock"));
618 cpipe->pipe_state &= ~PIPE_LOCKFL;
619 if (cpipe->pipe_state & PIPE_LWANT) {
620 cpipe->pipe_state &= ~PIPE_LWANT;
630 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
631 if (cpipe->pipe_state & PIPE_SEL) {
632 selwakeuppri(&cpipe->pipe_sel, PSOCK);
633 if (!SEL_WAITING(&cpipe->pipe_sel))
634 cpipe->pipe_state &= ~PIPE_SEL;
636 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
637 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
638 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
642 * Initialize and allocate VM and memory for pipe. The structure
643 * will start out zero'd from the ctor, so we just manage the kmem.
646 pipe_create(pipe, backing)
653 if (amountpipekva > maxpipekva / 2)
654 error = pipespace_new(pipe, SMALL_PIPE_SIZE);
656 error = pipespace_new(pipe, PIPE_SIZE);
658 /* If we're not backing this pipe, no need to do anything. */
667 pipe_read(fp, uio, active_cred, flags, td)
670 struct ucred *active_cred;
682 error = pipelock(rpipe, 1);
687 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
691 if (amountpipekva > (3 * maxpipekva) / 4) {
692 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
693 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
694 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
695 (piperesizeallowed == 1)) {
697 pipespace(rpipe, SMALL_PIPE_SIZE);
702 while (uio->uio_resid) {
704 * normal pipe buffer receive
706 if (rpipe->pipe_buffer.cnt > 0) {
707 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
708 if (size > rpipe->pipe_buffer.cnt)
709 size = rpipe->pipe_buffer.cnt;
710 if (size > uio->uio_resid)
711 size = uio->uio_resid;
715 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
721 rpipe->pipe_buffer.out += size;
722 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
723 rpipe->pipe_buffer.out = 0;
725 rpipe->pipe_buffer.cnt -= size;
728 * If there is no more to read in the pipe, reset
729 * its pointers to the beginning. This improves
732 if (rpipe->pipe_buffer.cnt == 0) {
733 rpipe->pipe_buffer.in = 0;
734 rpipe->pipe_buffer.out = 0;
737 #ifndef PIPE_NODIRECT
739 * Direct copy, bypassing a kernel buffer.
741 } else if ((size = rpipe->pipe_map.cnt) &&
742 (rpipe->pipe_state & PIPE_DIRECTW)) {
743 if (size > uio->uio_resid)
744 size = (u_int) uio->uio_resid;
747 error = uiomove_fromphys(rpipe->pipe_map.ms,
748 rpipe->pipe_map.pos, size, uio);
753 rpipe->pipe_map.pos += size;
754 rpipe->pipe_map.cnt -= size;
755 if (rpipe->pipe_map.cnt == 0) {
756 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW);
762 * detect EOF condition
763 * read returns 0 on EOF, no need to set error
765 if (rpipe->pipe_state & PIPE_EOF)
769 * If the "write-side" has been blocked, wake it up now.
771 if (rpipe->pipe_state & PIPE_WANTW) {
772 rpipe->pipe_state &= ~PIPE_WANTW;
777 * Break if some data was read.
783 * Unlock the pipe buffer for our remaining processing.
784 * We will either break out with an error or we will
785 * sleep and relock to loop.
790 * Handle non-blocking mode operation or
791 * wait for more data.
793 if (fp->f_flag & FNONBLOCK) {
796 rpipe->pipe_state |= PIPE_WANTR;
797 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
800 error = pipelock(rpipe, 1);
811 /* XXX: should probably do this before getting any locks. */
813 vfs_timestamp(&rpipe->pipe_atime);
818 * PIPE_WANT processing only makes sense if pipe_busy is 0.
820 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
821 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
823 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
825 * Handle write blocking hysteresis.
827 if (rpipe->pipe_state & PIPE_WANTW) {
828 rpipe->pipe_state &= ~PIPE_WANTW;
833 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
834 pipeselwakeup(rpipe);
840 #ifndef PIPE_NODIRECT
842 * Map the sending processes' buffer into kernel space and wire it.
843 * This is similar to a physical write operation.
846 pipe_build_write_buffer(wpipe, uio)
853 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
854 KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
855 ("Clone attempt on non-direct write pipe!"));
857 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
858 size = wpipe->pipe_buffer.size;
860 size = uio->uio_iov->iov_len;
862 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
863 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
864 wpipe->pipe_map.ms, PIPENPAGES)) < 0)
868 * set up the control block
870 wpipe->pipe_map.npages = i;
871 wpipe->pipe_map.pos =
872 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
873 wpipe->pipe_map.cnt = size;
876 * and update the uio data
879 uio->uio_iov->iov_len -= size;
880 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
881 if (uio->uio_iov->iov_len == 0)
883 uio->uio_resid -= size;
884 uio->uio_offset += size;
889 * unmap and unwire the process buffer
892 pipe_destroy_write_buffer(wpipe)
896 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
897 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
898 wpipe->pipe_map.npages = 0;
902 * In the case of a signal, the writing process might go away. This
903 * code copies the data into the circular buffer so that the source
904 * pages can be freed without loss of data.
907 pipe_clone_write_buffer(wpipe)
915 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
916 size = wpipe->pipe_map.cnt;
917 pos = wpipe->pipe_map.pos;
919 wpipe->pipe_buffer.in = size;
920 wpipe->pipe_buffer.out = 0;
921 wpipe->pipe_buffer.cnt = size;
922 wpipe->pipe_state &= ~PIPE_DIRECTW;
925 iov.iov_base = wpipe->pipe_buffer.buffer;
930 uio.uio_resid = size;
931 uio.uio_segflg = UIO_SYSSPACE;
932 uio.uio_rw = UIO_READ;
933 uio.uio_td = curthread;
934 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
936 pipe_destroy_write_buffer(wpipe);
940 * This implements the pipe buffer write mechanism. Note that only
941 * a direct write OR a normal pipe write can be pending at any given time.
942 * If there are any characters in the pipe buffer, the direct write will
943 * be deferred until the receiving process grabs all of the bytes from
944 * the pipe buffer. Then the direct mapping write is set-up.
947 pipe_direct_write(wpipe, uio)
954 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
955 error = pipelock(wpipe, 1);
956 if (wpipe->pipe_state & PIPE_EOF)
962 while (wpipe->pipe_state & PIPE_DIRECTW) {
963 if (wpipe->pipe_state & PIPE_WANTR) {
964 wpipe->pipe_state &= ~PIPE_WANTR;
967 pipeselwakeup(wpipe);
968 wpipe->pipe_state |= PIPE_WANTW;
970 error = msleep(wpipe, PIPE_MTX(wpipe),
971 PRIBIO | PCATCH, "pipdww", 0);
977 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */
978 if (wpipe->pipe_buffer.cnt > 0) {
979 if (wpipe->pipe_state & PIPE_WANTR) {
980 wpipe->pipe_state &= ~PIPE_WANTR;
983 pipeselwakeup(wpipe);
984 wpipe->pipe_state |= PIPE_WANTW;
986 error = msleep(wpipe, PIPE_MTX(wpipe),
987 PRIBIO | PCATCH, "pipdwc", 0);
994 wpipe->pipe_state |= PIPE_DIRECTW;
997 error = pipe_build_write_buffer(wpipe, uio);
1000 wpipe->pipe_state &= ~PIPE_DIRECTW;
1006 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
1007 if (wpipe->pipe_state & PIPE_EOF) {
1008 pipe_destroy_write_buffer(wpipe);
1009 pipeselwakeup(wpipe);
1014 if (wpipe->pipe_state & PIPE_WANTR) {
1015 wpipe->pipe_state &= ~PIPE_WANTR;
1018 pipeselwakeup(wpipe);
1019 wpipe->pipe_state |= PIPE_WANTW;
1021 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
1026 if (wpipe->pipe_state & PIPE_EOF)
1028 if (wpipe->pipe_state & PIPE_DIRECTW) {
1030 * this bit of trickery substitutes a kernel buffer for
1031 * the process that might be going away.
1033 pipe_clone_write_buffer(wpipe);
1035 pipe_destroy_write_buffer(wpipe);
1047 pipe_write(fp, uio, active_cred, flags, td)
1050 struct ucred *active_cred;
1057 struct pipe *wpipe, *rpipe;
1060 wpipe = PIPE_PEER(rpipe);
1062 error = pipelock(wpipe, 1);
1068 * detect loss of pipe read side, issue SIGPIPE if lost.
1070 if (wpipe->pipe_present != PIPE_ACTIVE ||
1071 (wpipe->pipe_state & PIPE_EOF)) {
1077 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1086 /* Choose a larger size if it's advantageous */
1087 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1088 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1089 if (piperesizeallowed != 1)
1091 if (amountpipekva > maxpipekva / 2)
1093 if (desiredsize == BIG_PIPE_SIZE)
1095 desiredsize = desiredsize * 2;
1098 /* Choose a smaller size if we're in a OOM situation */
1099 if ((amountpipekva > (3 * maxpipekva) / 4) &&
1100 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1101 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1102 (piperesizeallowed == 1))
1103 desiredsize = SMALL_PIPE_SIZE;
1105 /* Resize if the above determined that a new size was necessary */
1106 if ((desiredsize != wpipe->pipe_buffer.size) &&
1107 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1109 pipespace(wpipe, desiredsize);
1112 if (wpipe->pipe_buffer.size == 0) {
1114 * This can only happen for reverse direction use of pipes
1115 * in a complete OOM situation.
1126 orig_resid = uio->uio_resid;
1128 while (uio->uio_resid) {
1132 if (wpipe->pipe_state & PIPE_EOF) {
1137 #ifndef PIPE_NODIRECT
1139 * If the transfer is large, we can gain performance if
1140 * we do process-to-process copies directly.
1141 * If the write is non-blocking, we don't use the
1142 * direct write mechanism.
1144 * The direct write mechanism will detect the reader going
1147 if (uio->uio_segflg == UIO_USERSPACE &&
1148 uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1149 wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1150 (fp->f_flag & FNONBLOCK) == 0) {
1152 error = pipe_direct_write(wpipe, uio);
1160 * Pipe buffered writes cannot be coincidental with
1161 * direct writes. We wait until the currently executing
1162 * direct write is completed before we start filling the
1163 * pipe buffer. We break out if a signal occurs or the
1166 if (wpipe->pipe_state & PIPE_DIRECTW) {
1167 if (wpipe->pipe_state & PIPE_WANTR) {
1168 wpipe->pipe_state &= ~PIPE_WANTR;
1171 pipeselwakeup(wpipe);
1172 wpipe->pipe_state |= PIPE_WANTW;
1174 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1182 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1184 /* Writes of size <= PIPE_BUF must be atomic. */
1185 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1189 int size; /* Transfer size */
1190 int segsize; /* first segment to transfer */
1193 * Transfer size is minimum of uio transfer
1194 * and free space in pipe buffer.
1196 if (space > uio->uio_resid)
1197 size = uio->uio_resid;
1201 * First segment to transfer is minimum of
1202 * transfer size and contiguous space in
1203 * pipe buffer. If first segment to transfer
1204 * is less than the transfer size, we've got
1205 * a wraparound in the buffer.
1207 segsize = wpipe->pipe_buffer.size -
1208 wpipe->pipe_buffer.in;
1212 /* Transfer first segment */
1215 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1219 if (error == 0 && segsize < size) {
1220 KASSERT(wpipe->pipe_buffer.in + segsize ==
1221 wpipe->pipe_buffer.size,
1222 ("Pipe buffer wraparound disappeared"));
1224 * Transfer remaining part now, to
1225 * support atomic writes. Wraparound
1231 &wpipe->pipe_buffer.buffer[0],
1232 size - segsize, uio);
1236 wpipe->pipe_buffer.in += size;
1237 if (wpipe->pipe_buffer.in >=
1238 wpipe->pipe_buffer.size) {
1239 KASSERT(wpipe->pipe_buffer.in ==
1241 wpipe->pipe_buffer.size,
1242 ("Expected wraparound bad"));
1243 wpipe->pipe_buffer.in = size - segsize;
1246 wpipe->pipe_buffer.cnt += size;
1247 KASSERT(wpipe->pipe_buffer.cnt <=
1248 wpipe->pipe_buffer.size,
1249 ("Pipe buffer overflow"));
1256 * If the "read-side" has been blocked, wake it up now.
1258 if (wpipe->pipe_state & PIPE_WANTR) {
1259 wpipe->pipe_state &= ~PIPE_WANTR;
1264 * don't block on non-blocking I/O
1266 if (fp->f_flag & FNONBLOCK) {
1273 * We have no more space and have something to offer,
1274 * wake up select/poll.
1276 pipeselwakeup(wpipe);
1278 wpipe->pipe_state |= PIPE_WANTW;
1280 error = msleep(wpipe, PIPE_MTX(rpipe),
1281 PRIBIO | PCATCH, "pipewr", 0);
1290 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1291 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1293 } else if (wpipe->pipe_buffer.cnt > 0) {
1295 * If we have put any characters in the buffer, we wake up
1298 if (wpipe->pipe_state & PIPE_WANTR) {
1299 wpipe->pipe_state &= ~PIPE_WANTR;
1305 * Don't return EPIPE if I/O was successful
1307 if ((wpipe->pipe_buffer.cnt == 0) &&
1308 (uio->uio_resid == 0) &&
1314 vfs_timestamp(&wpipe->pipe_mtime);
1317 * We have something to offer,
1318 * wake up select/poll.
1320 if (wpipe->pipe_buffer.cnt)
1321 pipeselwakeup(wpipe);
1330 pipe_truncate(fp, length, active_cred, td)
1333 struct ucred *active_cred;
1337 /* For named pipes call the vnode operation. */
1338 if (fp->f_vnode != NULL)
1339 return (vnops.fo_truncate(fp, length, active_cred, td));
1344 * we implement a very minimal set of ioctls for compatibility with sockets.
1347 pipe_ioctl(fp, cmd, data, active_cred, td)
1351 struct ucred *active_cred;
1354 struct pipe *mpipe = fp->f_data;
1360 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1375 mpipe->pipe_state |= PIPE_ASYNC;
1377 mpipe->pipe_state &= ~PIPE_ASYNC;
1382 if (!(fp->f_flag & FREAD)) {
1387 if (mpipe->pipe_state & PIPE_DIRECTW)
1388 *(int *)data = mpipe->pipe_map.cnt;
1390 *(int *)data = mpipe->pipe_buffer.cnt;
1395 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1399 *(int *)data = fgetown(&mpipe->pipe_sigio);
1402 /* This is deprecated, FIOSETOWN should be used instead. */
1405 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1408 /* This is deprecated, FIOGETOWN should be used instead. */
1410 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1423 pipe_poll(fp, events, active_cred, td)
1426 struct ucred *active_cred;
1431 int levents, revents;
1438 wpipe = PIPE_PEER(rpipe);
1441 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1445 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1446 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1447 (rpipe->pipe_buffer.cnt > 0))
1448 revents |= events & (POLLIN | POLLRDNORM);
1450 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1451 if (wpipe->pipe_present != PIPE_ACTIVE ||
1452 (wpipe->pipe_state & PIPE_EOF) ||
1453 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1454 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1455 wpipe->pipe_buffer.size == 0)))
1456 revents |= events & (POLLOUT | POLLWRNORM);
1459 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1460 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
1461 fp->f_seqcount == rpipe->pipe_wgen)
1462 events |= POLLINIGNEOF;
1464 if ((events & POLLINIGNEOF) == 0) {
1465 if (rpipe->pipe_state & PIPE_EOF) {
1466 revents |= (events & (POLLIN | POLLRDNORM));
1467 if (wpipe->pipe_present != PIPE_ACTIVE ||
1468 (wpipe->pipe_state & PIPE_EOF))
1474 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) {
1475 selrecord(td, &rpipe->pipe_sel);
1476 if (SEL_WAITING(&rpipe->pipe_sel))
1477 rpipe->pipe_state |= PIPE_SEL;
1480 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) {
1481 selrecord(td, &wpipe->pipe_sel);
1482 if (SEL_WAITING(&wpipe->pipe_sel))
1483 wpipe->pipe_state |= PIPE_SEL;
1495 * We shouldn't need locks here as we're doing a read and this should
1496 * be a natural race.
1499 pipe_stat(fp, ub, active_cred, td)
1502 struct ucred *active_cred;
1514 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1521 /* For named pipes ask the underlying filesystem. */
1522 if (pipe->pipe_state & PIPE_NAMED) {
1524 return (vnops.fo_stat(fp, ub, active_cred, td));
1528 * Lazily allocate an inode number for the pipe. Most pipe
1529 * users do not call fstat(2) on the pipe, which means that
1530 * postponing the inode allocation until it is must be
1531 * returned to userland is useful. If alloc_unr failed,
1532 * assign st_ino zero instead of returning an error.
1533 * Special pipe_ino values:
1534 * -1 - not yet initialized;
1535 * 0 - alloc_unr failed, return 0 as st_ino forever.
1537 if (pipe->pipe_ino == (ino_t)-1) {
1538 new_unr = alloc_unr(pipeino_unr);
1540 pipe->pipe_ino = new_unr;
1546 bzero(ub, sizeof(*ub));
1547 ub->st_mode = S_IFIFO;
1548 ub->st_blksize = PAGE_SIZE;
1549 if (pipe->pipe_state & PIPE_DIRECTW)
1550 ub->st_size = pipe->pipe_map.cnt;
1552 ub->st_size = pipe->pipe_buffer.cnt;
1553 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1554 ub->st_atim = pipe->pipe_atime;
1555 ub->st_mtim = pipe->pipe_mtime;
1556 ub->st_ctim = pipe->pipe_ctime;
1557 ub->st_uid = fp->f_cred->cr_uid;
1558 ub->st_gid = fp->f_cred->cr_gid;
1559 ub->st_dev = pipedev_ino;
1560 ub->st_ino = pipe->pipe_ino;
1562 * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1574 if (fp->f_vnode != NULL)
1575 return vnops.fo_close(fp, td);
1576 fp->f_ops = &badfileops;
1577 pipe_dtor(fp->f_data);
1583 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1589 if (cpipe->pipe_state & PIPE_NAMED)
1590 error = vn_chmod(fp, mode, active_cred, td);
1592 error = invfo_chmod(fp, mode, active_cred, td);
1597 pipe_chown(fp, uid, gid, active_cred, td)
1601 struct ucred *active_cred;
1608 if (cpipe->pipe_state & PIPE_NAMED)
1609 error = vn_chown(fp, uid, gid, active_cred, td);
1611 error = invfo_chown(fp, uid, gid, active_cred, td);
1616 pipe_free_kmem(cpipe)
1620 KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1621 ("pipe_free_kmem: pipe mutex locked"));
1623 if (cpipe->pipe_buffer.buffer != NULL) {
1624 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1625 vm_map_remove(pipe_map,
1626 (vm_offset_t)cpipe->pipe_buffer.buffer,
1627 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1628 cpipe->pipe_buffer.buffer = NULL;
1630 #ifndef PIPE_NODIRECT
1632 cpipe->pipe_map.cnt = 0;
1633 cpipe->pipe_map.pos = 0;
1634 cpipe->pipe_map.npages = 0;
1646 struct pipepair *pp;
1649 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1653 pp = cpipe->pipe_pair;
1655 pipeselwakeup(cpipe);
1658 * If the other side is blocked, wake it up saying that
1659 * we want to close it down.
1661 cpipe->pipe_state |= PIPE_EOF;
1662 while (cpipe->pipe_busy) {
1664 cpipe->pipe_state |= PIPE_WANT;
1666 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1672 * Disconnect from peer, if any.
1674 ppipe = cpipe->pipe_peer;
1675 if (ppipe->pipe_present == PIPE_ACTIVE) {
1676 pipeselwakeup(ppipe);
1678 ppipe->pipe_state |= PIPE_EOF;
1680 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1684 * Mark this endpoint as free. Release kmem resources. We
1685 * don't mark this endpoint as unused until we've finished
1686 * doing that, or the pipe might disappear out from under
1690 pipe_free_kmem(cpipe);
1692 cpipe->pipe_present = PIPE_CLOSING;
1696 * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1697 * PIPE_FINALIZED, that allows other end to free the
1698 * pipe_pair, only after the knotes are completely dismantled.
1700 knlist_clear(&cpipe->pipe_sel.si_note, 1);
1701 cpipe->pipe_present = PIPE_FINALIZED;
1702 seldrain(&cpipe->pipe_sel);
1703 knlist_destroy(&cpipe->pipe_sel.si_note);
1706 * If both endpoints are now closed, release the memory for the
1707 * pipe pair. If not, unlock.
1709 if (ppipe->pipe_present == PIPE_FINALIZED) {
1712 mac_pipe_destroy(pp);
1714 uma_zfree(pipe_zone, cpipe->pipe_pair);
1721 pipe_kqfilter(struct file *fp, struct knote *kn)
1726 * If a filter is requested that is not supported by this file
1727 * descriptor, don't return an error, but also don't ever generate an
1730 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1731 kn->kn_fop = &pipe_nfiltops;
1734 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1735 kn->kn_fop = &pipe_nfiltops;
1740 switch (kn->kn_filter) {
1742 kn->kn_fop = &pipe_rfiltops;
1745 kn->kn_fop = &pipe_wfiltops;
1746 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1747 /* other end of pipe has been closed */
1751 cpipe = PIPE_PEER(cpipe);
1758 kn->kn_hook = cpipe;
1759 knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1765 filt_pipedetach(struct knote *kn)
1767 struct pipe *cpipe = kn->kn_hook;
1770 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1776 filt_piperead(struct knote *kn, long hint)
1778 struct pipe *rpipe = kn->kn_hook;
1779 struct pipe *wpipe = rpipe->pipe_peer;
1783 kn->kn_data = rpipe->pipe_buffer.cnt;
1784 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1785 kn->kn_data = rpipe->pipe_map.cnt;
1787 if ((rpipe->pipe_state & PIPE_EOF) ||
1788 wpipe->pipe_present != PIPE_ACTIVE ||
1789 (wpipe->pipe_state & PIPE_EOF)) {
1790 kn->kn_flags |= EV_EOF;
1794 ret = kn->kn_data > 0;
1801 filt_pipewrite(struct knote *kn, long hint)
1805 wpipe = kn->kn_hook;
1807 if (wpipe->pipe_present != PIPE_ACTIVE ||
1808 (wpipe->pipe_state & PIPE_EOF)) {
1810 kn->kn_flags |= EV_EOF;
1814 kn->kn_data = (wpipe->pipe_buffer.size > 0) ?
1815 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF;
1816 if (wpipe->pipe_state & PIPE_DIRECTW)
1820 return (kn->kn_data >= PIPE_BUF);
1824 filt_pipedetach_notsup(struct knote *kn)
1830 filt_pipenotsup(struct knote *kn, long hint)