2 * Copyright (c) 1996 John S. Dyson
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 immediately at the beginning of the file, without modification,
10 * this list of conditions, and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Absolutely no warranty of function or purpose is made by the author
16 * 4. Modifications may be freely made to this file if the above conditions
19 * $FreeBSD: src/sys/kern/sys_pipe.c,v 1.60.2.13 2002/08/05 15:05:15 des Exp $
20 * $DragonFly: src/sys/kern/sys_pipe.c,v 1.44 2006/12/28 21:24:01 dillon Exp $
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, it is fully mapped and wired into the kernel, and
36 * the receiving process can copy it directly from the pages in the sending
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. PIPE_SIZE is constrained by the
50 * amount of kernel virtual memory.
53 #include <sys/param.h>
54 #include <sys/systm.h>
55 #include <sys/kernel.h>
57 #include <sys/fcntl.h>
59 #include <sys/filedesc.h>
60 #include <sys/filio.h>
61 #include <sys/ttycom.h>
64 #include <sys/select.h>
65 #include <sys/signalvar.h>
66 #include <sys/sysproto.h>
68 #include <sys/vnode.h>
70 #include <sys/event.h>
71 #include <sys/globaldata.h>
72 #include <sys/module.h>
73 #include <sys/malloc.h>
74 #include <sys/sysctl.h>
75 #include <sys/socket.h>
78 #include <vm/vm_param.h>
80 #include <vm/vm_object.h>
81 #include <vm/vm_kern.h>
82 #include <vm/vm_extern.h>
84 #include <vm/vm_map.h>
85 #include <vm/vm_page.h>
86 #include <vm/vm_zone.h>
88 #include <sys/file2.h>
90 #include <machine/cpufunc.h>
93 * interfaces to the outside world
95 static int pipe_read (struct file *fp, struct uio *uio,
96 struct ucred *cred, int flags);
97 static int pipe_write (struct file *fp, struct uio *uio,
98 struct ucred *cred, int flags);
99 static int pipe_close (struct file *fp);
100 static int pipe_shutdown (struct file *fp, int how);
101 static int pipe_poll (struct file *fp, int events, struct ucred *cred);
102 static int pipe_kqfilter (struct file *fp, struct knote *kn);
103 static int pipe_stat (struct file *fp, struct stat *sb, struct ucred *cred);
104 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, struct ucred *cred);
106 static struct fileops pipeops = {
107 .fo_read = pipe_read,
108 .fo_write = pipe_write,
109 .fo_ioctl = pipe_ioctl,
110 .fo_poll = pipe_poll,
111 .fo_kqfilter = pipe_kqfilter,
112 .fo_stat = pipe_stat,
113 .fo_close = pipe_close,
114 .fo_shutdown = pipe_shutdown
117 static void filt_pipedetach(struct knote *kn);
118 static int filt_piperead(struct knote *kn, long hint);
119 static int filt_pipewrite(struct knote *kn, long hint);
121 static struct filterops pipe_rfiltops =
122 { 1, NULL, filt_pipedetach, filt_piperead };
123 static struct filterops pipe_wfiltops =
124 { 1, NULL, filt_pipedetach, filt_pipewrite };
126 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures");
129 * Default pipe buffer size(s), this can be kind-of large now because pipe
130 * space is pageable. The pipe code will try to maintain locality of
131 * reference for performance reasons, so small amounts of outstanding I/O
132 * will not wipe the cache.
134 #define MINPIPESIZE (PIPE_SIZE/3)
135 #define MAXPIPESIZE (2*PIPE_SIZE/3)
138 * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
139 * is there so that on large systems, we don't exhaust it.
141 #define MAXPIPEKVA (8*1024*1024)
144 * Limit for direct transfers, we cannot, of course limit
145 * the amount of kva for pipes in general though.
147 #define LIMITPIPEKVA (16*1024*1024)
150 * Limit the number of "big" pipes
152 #define LIMITBIGPIPES 32
153 #define PIPEQ_MAX_CACHE 16 /* per-cpu pipe structure cache */
155 static int pipe_maxbig = LIMITBIGPIPES;
156 static int pipe_maxcache = PIPEQ_MAX_CACHE;
157 static int pipe_nbig;
158 static int pipe_bcache_alloc;
159 static int pipe_bkmem_alloc;
160 static int pipe_dwrite_enable = 1; /* 0:copy, 1:kmem/sfbuf 2:force */
161 static int pipe_dwrite_sfbuf = 1; /* 0:kmem_map 1:sfbufs 2:sfbufs_dmap */
162 /* 3:sfbuf_dmap w/ forced invlpg */
164 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation");
165 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig,
166 CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated");
167 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache,
168 CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu");
169 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig,
170 CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes");
171 SYSCTL_INT(_kern_pipe, OID_AUTO, dwrite_enable,
172 CTLFLAG_RW, &pipe_dwrite_enable, 0, "1:enable/2:force direct writes");
173 SYSCTL_INT(_kern_pipe, OID_AUTO, dwrite_sfbuf,
174 CTLFLAG_RW, &pipe_dwrite_sfbuf, 0,
175 "(if dwrite_enable) 0:kmem 1:sfbuf 2:sfbuf_dmap 3:sfbuf_dmap_forceinvlpg");
176 #if !defined(NO_PIPE_SYSCTL_STATS)
177 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc,
178 CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache");
179 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc,
180 CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem");
183 static void pipeclose (struct pipe *cpipe);
184 static void pipe_free_kmem (struct pipe *cpipe);
185 static int pipe_create (struct pipe **cpipep);
186 static __inline int pipelock (struct pipe *cpipe, int catch);
187 static __inline void pipeunlock (struct pipe *cpipe);
188 static __inline void pipeselwakeup (struct pipe *cpipe);
189 #ifndef PIPE_NODIRECT
190 static int pipe_build_write_buffer (struct pipe *wpipe, struct uio *uio);
191 static int pipe_direct_write (struct pipe *wpipe, struct uio *uio);
192 static void pipe_clone_write_buffer (struct pipe *wpipe);
194 static int pipespace (struct pipe *cpipe, int size);
197 * The pipe system call for the DTYPE_PIPE type of pipes
199 * pipe_ARgs(int dummy)
204 sys_pipe(struct pipe_args *uap)
206 struct thread *td = curthread;
207 struct proc *p = td->td_proc;
208 struct file *rf, *wf;
209 struct pipe *rpipe, *wpipe;
214 rpipe = wpipe = NULL;
215 if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
221 rpipe->pipe_state |= PIPE_DIRECTOK;
222 wpipe->pipe_state |= PIPE_DIRECTOK;
225 * Select the direct-map features to use for this pipe. Since the
226 * sysctl's can change on the fly we record the settings when the
229 * Generally speaking the system will default to what we consider
230 * to be the best-balanced and most stable option. Right now this
231 * is SFBUF1. Modes 2 and 3 are considered experiemental at the
234 wpipe->pipe_feature = PIPE_COPY;
235 if (pipe_dwrite_enable) {
236 switch(pipe_dwrite_sfbuf) {
238 wpipe->pipe_feature = PIPE_KMEM;
241 wpipe->pipe_feature = PIPE_SFBUF1;
245 wpipe->pipe_feature = PIPE_SFBUF2;
249 rpipe->pipe_feature = wpipe->pipe_feature;
251 error = falloc(p, &rf, &fd1);
257 uap->sysmsg_fds[0] = fd1;
260 * Warning: once we've gotten past allocation of the fd for the
261 * read-side, we can only drop the read side via fdrop() in order
262 * to avoid races against processes which manage to dup() the read
263 * side while we are blocked trying to allocate the write side.
265 rf->f_type = DTYPE_PIPE;
266 rf->f_flag = FREAD | FWRITE;
267 rf->f_ops = &pipeops;
269 error = falloc(p, &wf, &fd2);
271 fsetfd(p, NULL, fd1);
273 /* rpipe has been closed by fdrop(). */
277 wf->f_type = DTYPE_PIPE;
278 wf->f_flag = FREAD | FWRITE;
279 wf->f_ops = &pipeops;
281 uap->sysmsg_fds[1] = fd2;
283 rpipe->pipe_peer = wpipe;
284 wpipe->pipe_peer = rpipe;
295 * Allocate kva for pipe circular buffer, the space is pageable
296 * This routine will 'realloc' the size of a pipe safely, if it fails
297 * it will retain the old buffer.
298 * If it fails it will return ENOMEM.
301 pipespace(struct pipe *cpipe, int size)
303 struct vm_object *object;
307 npages = round_page(size) / PAGE_SIZE;
308 object = cpipe->pipe_buffer.object;
311 * [re]create the object if necessary and reserve space for it
312 * in the kernel_map. The object and memory are pageable. On
313 * success, free the old resources before assigning the new
316 if (object == NULL || object->size != npages) {
317 object = vm_object_allocate(OBJT_DEFAULT, npages);
318 buffer = (caddr_t)vm_map_min(&kernel_map);
320 error = vm_map_find(&kernel_map, object, 0,
321 (vm_offset_t *)&buffer, size,
324 VM_PROT_ALL, VM_PROT_ALL,
327 if (error != KERN_SUCCESS) {
328 vm_object_deallocate(object);
331 pipe_free_kmem(cpipe);
332 cpipe->pipe_buffer.object = object;
333 cpipe->pipe_buffer.buffer = buffer;
334 cpipe->pipe_buffer.size = size;
339 cpipe->pipe_buffer.in = 0;
340 cpipe->pipe_buffer.out = 0;
341 cpipe->pipe_buffer.cnt = 0;
346 * Initialize and allocate VM and memory for pipe, pulling the pipe from
347 * our per-cpu cache if possible. For now make sure it is sized for the
348 * smaller PIPE_SIZE default.
351 pipe_create(struct pipe **cpipep)
353 globaldata_t gd = mycpu;
357 if ((cpipe = gd->gd_pipeq) != NULL) {
358 gd->gd_pipeq = cpipe->pipe_peer;
360 cpipe->pipe_peer = NULL;
362 cpipe = kmalloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
365 if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
367 vfs_timestamp(&cpipe->pipe_ctime);
368 cpipe->pipe_atime = cpipe->pipe_ctime;
369 cpipe->pipe_mtime = cpipe->pipe_ctime;
375 * lock a pipe for I/O, blocking other access
378 pipelock(struct pipe *cpipe, int catch)
382 while (cpipe->pipe_state & PIPE_LOCK) {
383 cpipe->pipe_state |= PIPE_LWANT;
384 error = tsleep(cpipe, (catch ? PCATCH : 0), "pipelk", 0);
388 cpipe->pipe_state |= PIPE_LOCK;
393 * unlock a pipe I/O lock
396 pipeunlock(struct pipe *cpipe)
399 cpipe->pipe_state &= ~PIPE_LOCK;
400 if (cpipe->pipe_state & PIPE_LWANT) {
401 cpipe->pipe_state &= ~PIPE_LWANT;
407 pipeselwakeup(struct pipe *cpipe)
410 if (cpipe->pipe_state & PIPE_SEL) {
411 cpipe->pipe_state &= ~PIPE_SEL;
412 selwakeup(&cpipe->pipe_sel);
414 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
415 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
416 KNOTE(&cpipe->pipe_sel.si_note, 0);
420 * MPALMOSTSAFE (acquires mplock)
423 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
432 rpipe = (struct pipe *) fp->f_data;
434 error = pipelock(rpipe, 1);
438 if (fflags & O_FBLOCKING)
440 else if (fflags & O_FNONBLOCKING)
442 else if (fp->f_flag & O_NONBLOCK)
447 while (uio->uio_resid) {
450 if (rpipe->pipe_buffer.cnt > 0) {
452 * normal pipe buffer receive
454 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
455 if (size > rpipe->pipe_buffer.cnt)
456 size = rpipe->pipe_buffer.cnt;
457 if (size > (u_int) uio->uio_resid)
458 size = (u_int) uio->uio_resid;
460 error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
465 rpipe->pipe_buffer.out += size;
466 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
467 rpipe->pipe_buffer.out = 0;
469 rpipe->pipe_buffer.cnt -= size;
472 * If there is no more to read in the pipe, reset
473 * its pointers to the beginning. This improves
476 if (rpipe->pipe_buffer.cnt == 0) {
477 rpipe->pipe_buffer.in = 0;
478 rpipe->pipe_buffer.out = 0;
481 #ifndef PIPE_NODIRECT
482 } else if (rpipe->pipe_kva &&
483 rpipe->pipe_feature == PIPE_KMEM &&
484 (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
488 * Direct copy using source-side kva mapping
490 size = rpipe->pipe_map.xio_bytes -
491 rpipe->pipe_buffer.out;
492 if (size > (u_int)uio->uio_resid)
493 size = (u_int)uio->uio_resid;
494 va = (caddr_t)rpipe->pipe_kva +
495 xio_kvaoffset(&rpipe->pipe_map, rpipe->pipe_buffer.out);
496 error = uiomove(va, size, uio);
500 rpipe->pipe_buffer.out += size;
501 if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
502 rpipe->pipe_state |= PIPE_DIRECTIP;
503 rpipe->pipe_state &= ~PIPE_DIRECTW;
504 /* reset out index for copy mode */
505 rpipe->pipe_buffer.out = 0;
508 } else if (rpipe->pipe_buffer.out != rpipe->pipe_map.xio_bytes &&
510 rpipe->pipe_feature == PIPE_SFBUF2 &&
511 (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
515 * Direct copy, bypassing a kernel buffer. We cannot
516 * mess with the direct-write buffer until
517 * PIPE_DIRECTIP is cleared. In order to prevent
518 * the pipe_write code from racing itself in
519 * direct_write, we set DIRECTIP when we clear
520 * DIRECTW after we have exhausted the buffer.
522 if (pipe_dwrite_sfbuf == 3)
523 rpipe->pipe_kvamask = 0;
524 pmap_qenter2(rpipe->pipe_kva, rpipe->pipe_map.xio_pages,
525 rpipe->pipe_map.xio_npages,
526 &rpipe->pipe_kvamask);
527 size = rpipe->pipe_map.xio_bytes -
528 rpipe->pipe_buffer.out;
529 if (size > (u_int)uio->uio_resid)
530 size = (u_int)uio->uio_resid;
531 va = (caddr_t)rpipe->pipe_kva + xio_kvaoffset(&rpipe->pipe_map, rpipe->pipe_buffer.out);
532 error = uiomove(va, size, uio);
536 rpipe->pipe_buffer.out += size;
537 if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
538 rpipe->pipe_state |= PIPE_DIRECTIP;
539 rpipe->pipe_state &= ~PIPE_DIRECTW;
540 /* reset out index for copy mode */
541 rpipe->pipe_buffer.out = 0;
544 } else if (rpipe->pipe_buffer.out != rpipe->pipe_map.xio_bytes &&
545 rpipe->pipe_feature == PIPE_SFBUF1 &&
546 (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
550 * Direct copy, bypassing a kernel buffer. We cannot
551 * mess with the direct-write buffer until
552 * PIPE_DIRECTIP is cleared. In order to prevent
553 * the pipe_write code from racing itself in
554 * direct_write, we set DIRECTIP when we clear
555 * DIRECTW after we have exhausted the buffer.
557 error = xio_uio_copy(&rpipe->pipe_map, rpipe->pipe_buffer.out, uio, &size);
561 rpipe->pipe_buffer.out += size;
562 if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
563 rpipe->pipe_state |= PIPE_DIRECTIP;
564 rpipe->pipe_state &= ~PIPE_DIRECTW;
565 /* reset out index for copy mode */
566 rpipe->pipe_buffer.out = 0;
572 * detect EOF condition
573 * read returns 0 on EOF, no need to set error
575 if (rpipe->pipe_state & PIPE_EOF)
579 * If the "write-side" has been blocked, wake it up now.
581 if (rpipe->pipe_state & PIPE_WANTW) {
582 rpipe->pipe_state &= ~PIPE_WANTW;
587 * Break if some data was read.
593 * Unlock the pipe buffer for our remaining
594 * processing. We will either break out with an
595 * error or we will sleep and relock to loop.
600 * Handle non-blocking mode operation or
601 * wait for more data.
606 rpipe->pipe_state |= PIPE_WANTR;
607 if ((error = tsleep(rpipe, PCATCH|PNORESCHED,
608 "piperd", 0)) == 0) {
609 error = pipelock(rpipe, 1);
619 vfs_timestamp(&rpipe->pipe_atime);
624 * PIPE_WANT processing only makes sense if pipe_busy is 0.
626 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
627 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
629 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
631 * Handle write blocking hysteresis.
633 if (rpipe->pipe_state & PIPE_WANTW) {
634 rpipe->pipe_state &= ~PIPE_WANTW;
639 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
640 pipeselwakeup(rpipe);
645 #ifndef PIPE_NODIRECT
647 * Map the sending processes' buffer into kernel space and wire it.
648 * This is similar to a physical write operation.
651 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio)
656 size = (u_int) uio->uio_iov->iov_len;
657 if (size > wpipe->pipe_buffer.size)
658 size = wpipe->pipe_buffer.size;
660 if (uio->uio_segflg == UIO_SYSSPACE) {
661 error = xio_init_kbuf(&wpipe->pipe_map, uio->uio_iov->iov_base,
664 error = xio_init_ubuf(&wpipe->pipe_map, uio->uio_iov->iov_base,
667 wpipe->pipe_buffer.out = 0;
672 * Create a kernel map for KMEM and SFBUF2 copy modes. SFBUF2 will
673 * map the pages on the target while KMEM maps the pages now.
675 switch(wpipe->pipe_feature) {
678 if (wpipe->pipe_kva == NULL) {
680 kmem_alloc_nofault(&kernel_map, XIO_INTERNAL_SIZE);
681 wpipe->pipe_kvamask = 0;
683 if (wpipe->pipe_feature == PIPE_KMEM) {
684 pmap_qenter(wpipe->pipe_kva, wpipe->pipe_map.xio_pages,
685 wpipe->pipe_map.xio_npages);
693 * And update the uio data. The XIO might have loaded fewer bytes
694 * then requested so reload 'size'.
696 size = wpipe->pipe_map.xio_bytes;
697 uio->uio_iov->iov_len -= size;
698 uio->uio_iov->iov_base += size;
699 if (uio->uio_iov->iov_len == 0)
701 uio->uio_resid -= size;
702 uio->uio_offset += size;
707 * In the case of a signal, the writing process might go away. This
708 * code copies the data into the circular buffer so that the source
709 * pages can be freed without loss of data.
711 * Note that in direct mode pipe_buffer.out is used to track the
712 * XIO offset. We are converting the direct mode into buffered mode
713 * which changes the meaning of pipe_buffer.out.
716 pipe_clone_write_buffer(struct pipe *wpipe)
721 offset = wpipe->pipe_buffer.out;
722 size = wpipe->pipe_map.xio_bytes - offset;
724 KKASSERT(size <= wpipe->pipe_buffer.size);
726 wpipe->pipe_buffer.in = size;
727 wpipe->pipe_buffer.out = 0;
728 wpipe->pipe_buffer.cnt = size;
729 wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
731 xio_copy_xtok(&wpipe->pipe_map, offset, wpipe->pipe_buffer.buffer, size);
732 xio_release(&wpipe->pipe_map);
733 if (wpipe->pipe_kva) {
734 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
735 kmem_free(&kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
736 wpipe->pipe_kva = NULL;
741 * This implements the pipe buffer write mechanism. Note that only
742 * a direct write OR a normal pipe write can be pending at any given time.
743 * If there are any characters in the pipe buffer, the direct write will
744 * be deferred until the receiving process grabs all of the bytes from
745 * the pipe buffer. Then the direct mapping write is set-up.
748 pipe_direct_write(struct pipe *wpipe, struct uio *uio)
753 while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
754 if (wpipe->pipe_state & PIPE_WANTR) {
755 wpipe->pipe_state &= ~PIPE_WANTR;
758 wpipe->pipe_state |= PIPE_WANTW;
759 error = tsleep(wpipe, PCATCH, "pipdww", 0);
762 if (wpipe->pipe_state & PIPE_EOF) {
767 KKASSERT(wpipe->pipe_map.xio_bytes == 0);
768 if (wpipe->pipe_buffer.cnt > 0) {
769 if (wpipe->pipe_state & PIPE_WANTR) {
770 wpipe->pipe_state &= ~PIPE_WANTR;
774 wpipe->pipe_state |= PIPE_WANTW;
775 error = tsleep(wpipe, PCATCH, "pipdwc", 0);
778 if (wpipe->pipe_state & PIPE_EOF) {
786 * Build our direct-write buffer
788 wpipe->pipe_state |= PIPE_DIRECTW | PIPE_DIRECTIP;
789 error = pipe_build_write_buffer(wpipe, uio);
792 wpipe->pipe_state &= ~PIPE_DIRECTIP;
795 * Wait until the receiver has snarfed the data. Since we are likely
796 * going to sleep we optimize the case and yield synchronously,
797 * possibly avoiding the tsleep().
800 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
801 if (wpipe->pipe_state & PIPE_EOF) {
803 xio_release(&wpipe->pipe_map);
804 if (wpipe->pipe_kva) {
805 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
806 kmem_free(&kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
807 wpipe->pipe_kva = NULL;
810 pipeselwakeup(wpipe);
814 if (wpipe->pipe_state & PIPE_WANTR) {
815 wpipe->pipe_state &= ~PIPE_WANTR;
818 pipeselwakeup(wpipe);
819 error = tsleep(wpipe, PCATCH|PNORESCHED, "pipdwt", 0);
822 if (wpipe->pipe_state & PIPE_DIRECTW) {
824 * this bit of trickery substitutes a kernel buffer for
825 * the process that might be going away.
827 pipe_clone_write_buffer(wpipe);
828 KKASSERT((wpipe->pipe_state & PIPE_DIRECTIP) == 0);
831 * note: The pipe_kva mapping is not qremove'd here. For
832 * legacy PIPE_KMEM mode this constitutes an improvement
833 * over the original FreeBSD-4 algorithm. For PIPE_SFBUF2
834 * mode the kva mapping must not be removed to get the
837 * For testing purposes we will give the original algorithm
838 * the benefit of the doubt 'what it could have been', and
839 * keep the optimization.
841 KKASSERT(wpipe->pipe_state & PIPE_DIRECTIP);
842 xio_release(&wpipe->pipe_map);
843 wpipe->pipe_state &= ~PIPE_DIRECTIP;
849 * Direct-write error, clear the direct write flags.
852 wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
856 * General error, wakeup the other side if it happens to be sleeping.
865 * MPALMOSTSAFE - acquires mplock
868 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
873 struct pipe *wpipe, *rpipe;
876 rpipe = (struct pipe *) fp->f_data;
877 wpipe = rpipe->pipe_peer;
880 * detect loss of pipe read side, issue SIGPIPE if lost.
882 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
888 if (fflags & O_FBLOCKING)
890 else if (fflags & O_FNONBLOCKING)
892 else if (fp->f_flag & O_NONBLOCK)
898 * If it is advantageous to resize the pipe buffer, do
901 if ((uio->uio_resid > PIPE_SIZE) &&
902 (pipe_nbig < pipe_maxbig) &&
903 (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) == 0 &&
904 (wpipe->pipe_buffer.size <= PIPE_SIZE) &&
905 (wpipe->pipe_buffer.cnt == 0)) {
907 if ((error = pipelock(wpipe,1)) == 0) {
908 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
915 * If an early error occured unbusy and return, waking up any pending
920 if ((wpipe->pipe_busy == 0) &&
921 (wpipe->pipe_state & PIPE_WANT)) {
922 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
929 KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone"));
931 orig_resid = uio->uio_resid;
933 while (uio->uio_resid) {
936 #ifndef PIPE_NODIRECT
938 * If the transfer is large, we can gain performance if
939 * we do process-to-process copies directly.
940 * If the write is non-blocking, we don't use the
941 * direct write mechanism.
943 * The direct write mechanism will detect the reader going
946 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT ||
947 pipe_dwrite_enable > 1) &&
949 pipe_dwrite_enable) {
950 error = pipe_direct_write( wpipe, uio);
958 * Pipe buffered writes cannot be coincidental with
959 * direct writes. We wait until the currently executing
960 * direct write is completed before we start filling the
961 * pipe buffer. We break out if a signal occurs or the
965 while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
966 if (wpipe->pipe_state & PIPE_WANTR) {
967 wpipe->pipe_state &= ~PIPE_WANTR;
970 error = tsleep(wpipe, PCATCH, "pipbww", 0);
971 if (wpipe->pipe_state & PIPE_EOF)
976 if (wpipe->pipe_state & PIPE_EOF) {
981 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
983 /* Writes of size <= PIPE_BUF must be atomic. */
984 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
988 * Write to fill, read size handles write hysteresis. Also
989 * additional restrictions can cause select-based non-blocking
993 if ((error = pipelock(wpipe,1)) == 0) {
994 int size; /* Transfer size */
995 int segsize; /* first segment to transfer */
998 * It is possible for a direct write to
999 * slip in on us... handle it here...
1001 if (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
1006 * If a process blocked in uiomove, our
1007 * value for space might be bad.
1009 * XXX will we be ok if the reader has gone
1012 if (space > wpipe->pipe_buffer.size -
1013 wpipe->pipe_buffer.cnt) {
1019 * Transfer size is minimum of uio transfer
1020 * and free space in pipe buffer.
1022 if (space > uio->uio_resid)
1023 size = uio->uio_resid;
1027 * First segment to transfer is minimum of
1028 * transfer size and contiguous space in
1029 * pipe buffer. If first segment to transfer
1030 * is less than the transfer size, we've got
1031 * a wraparound in the buffer.
1033 segsize = wpipe->pipe_buffer.size -
1034 wpipe->pipe_buffer.in;
1038 /* Transfer first segment */
1040 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1043 if (error == 0 && segsize < size) {
1045 * Transfer remaining part now, to
1046 * support atomic writes. Wraparound
1049 if (wpipe->pipe_buffer.in + segsize !=
1050 wpipe->pipe_buffer.size)
1051 panic("Expected pipe buffer wraparound disappeared");
1053 error = uiomove(&wpipe->pipe_buffer.buffer[0],
1054 size - segsize, uio);
1057 wpipe->pipe_buffer.in += size;
1058 if (wpipe->pipe_buffer.in >=
1059 wpipe->pipe_buffer.size) {
1060 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
1061 panic("Expected wraparound bad");
1062 wpipe->pipe_buffer.in = size - segsize;
1065 wpipe->pipe_buffer.cnt += size;
1066 if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
1067 panic("Pipe buffer overflow");
1077 * If the "read-side" has been blocked, wake it up now
1078 * and yield to let it drain synchronously rather
1081 if (wpipe->pipe_state & PIPE_WANTR) {
1082 wpipe->pipe_state &= ~PIPE_WANTR;
1087 * don't block on non-blocking I/O
1095 * We have no more space and have something to offer,
1096 * wake up select/poll.
1098 pipeselwakeup(wpipe);
1100 wpipe->pipe_state |= PIPE_WANTW;
1101 error = tsleep(wpipe, PCATCH|PNORESCHED, "pipewr", 0);
1105 * If read side wants to go away, we just issue a signal
1108 if (wpipe->pipe_state & PIPE_EOF) {
1117 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1118 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1120 } else if (wpipe->pipe_buffer.cnt > 0) {
1122 * If we have put any characters in the buffer, we wake up
1125 if (wpipe->pipe_state & PIPE_WANTR) {
1126 wpipe->pipe_state &= ~PIPE_WANTR;
1132 * Don't return EPIPE if I/O was successful
1134 if ((wpipe->pipe_buffer.cnt == 0) &&
1135 (uio->uio_resid == 0) &&
1141 vfs_timestamp(&wpipe->pipe_mtime);
1144 * We have something to offer,
1145 * wake up select/poll.
1147 if (wpipe->pipe_buffer.cnt)
1148 pipeselwakeup(wpipe);
1154 * MPALMOSTSAFE - acquires mplock
1156 * we implement a very minimal set of ioctls for compatibility with sockets.
1159 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct ucred *cred)
1165 mpipe = (struct pipe *)fp->f_data;
1170 mpipe->pipe_state |= PIPE_ASYNC;
1172 mpipe->pipe_state &= ~PIPE_ASYNC;
1177 if (mpipe->pipe_state & PIPE_DIRECTW) {
1178 *(int *)data = mpipe->pipe_map.xio_bytes -
1179 mpipe->pipe_buffer.out;
1181 *(int *)data = mpipe->pipe_buffer.cnt;
1186 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1189 *(int *)data = fgetown(mpipe->pipe_sigio);
1193 /* This is deprecated, FIOSETOWN should be used instead. */
1194 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1198 /* This is deprecated, FIOGETOWN should be used instead. */
1199 *(int *)data = -fgetown(mpipe->pipe_sigio);
1211 * MPALMOSTSAFE - acquires mplock
1214 pipe_poll(struct file *fp, int events, struct ucred *cred)
1221 rpipe = (struct pipe *)fp->f_data;
1222 wpipe = rpipe->pipe_peer;
1223 if (events & (POLLIN | POLLRDNORM))
1224 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1225 (rpipe->pipe_buffer.cnt > 0) ||
1226 (rpipe->pipe_state & PIPE_EOF))
1227 revents |= events & (POLLIN | POLLRDNORM);
1229 if (events & (POLLOUT | POLLWRNORM))
1230 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) ||
1231 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1232 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1233 revents |= events & (POLLOUT | POLLWRNORM);
1235 if ((rpipe->pipe_state & PIPE_EOF) ||
1237 (wpipe->pipe_state & PIPE_EOF))
1241 if (events & (POLLIN | POLLRDNORM)) {
1242 selrecord(curthread, &rpipe->pipe_sel);
1243 rpipe->pipe_state |= PIPE_SEL;
1246 if (events & (POLLOUT | POLLWRNORM)) {
1247 selrecord(curthread, &wpipe->pipe_sel);
1248 wpipe->pipe_state |= PIPE_SEL;
1256 * MPALMOSTSAFE - acquires mplock
1259 pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred)
1264 pipe = (struct pipe *)fp->f_data;
1266 bzero((caddr_t)ub, sizeof(*ub));
1267 ub->st_mode = S_IFIFO;
1268 ub->st_blksize = pipe->pipe_buffer.size;
1269 ub->st_size = pipe->pipe_buffer.cnt;
1270 if (ub->st_size == 0 && (pipe->pipe_state & PIPE_DIRECTW)) {
1271 ub->st_size = pipe->pipe_map.xio_bytes -
1272 pipe->pipe_buffer.out;
1274 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1275 ub->st_atimespec = pipe->pipe_atime;
1276 ub->st_mtimespec = pipe->pipe_mtime;
1277 ub->st_ctimespec = pipe->pipe_ctime;
1279 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1281 * XXX (st_dev, st_ino) should be unique.
1288 * MPALMOSTSAFE - acquires mplock
1291 pipe_close(struct file *fp)
1293 struct pipe *cpipe = (struct pipe *)fp->f_data;
1296 fp->f_ops = &badfileops;
1298 funsetown(cpipe->pipe_sigio);
1305 * Shutdown one or both directions of a full-duplex pipe.
1307 * MPALMOSTSAFE - acquires mplock
1310 pipe_shutdown(struct file *fp, int how)
1317 rpipe = (struct pipe *)fp->f_data;
1323 rpipe->pipe_state |= PIPE_EOF;
1324 pipeselwakeup(rpipe);
1325 if (rpipe->pipe_busy)
1333 if (rpipe && (wpipe = rpipe->pipe_peer) != NULL) {
1334 wpipe->pipe_state |= PIPE_EOF;
1335 pipeselwakeup(wpipe);
1336 if (wpipe->pipe_busy)
1346 pipe_free_kmem(struct pipe *cpipe)
1348 if (cpipe->pipe_buffer.buffer != NULL) {
1349 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1351 kmem_free(&kernel_map,
1352 (vm_offset_t)cpipe->pipe_buffer.buffer,
1353 cpipe->pipe_buffer.size);
1354 cpipe->pipe_buffer.buffer = NULL;
1355 cpipe->pipe_buffer.object = NULL;
1357 #ifndef PIPE_NODIRECT
1358 KKASSERT(cpipe->pipe_map.xio_bytes == 0 &&
1359 cpipe->pipe_map.xio_offset == 0 &&
1360 cpipe->pipe_map.xio_npages == 0);
1368 pipeclose(struct pipe *cpipe)
1376 pipeselwakeup(cpipe);
1379 * If the other side is blocked, wake it up saying that
1380 * we want to close it down.
1382 while (cpipe->pipe_busy) {
1384 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
1385 tsleep(cpipe, 0, "pipecl", 0);
1389 * Disconnect from peer
1391 if ((ppipe = cpipe->pipe_peer) != NULL) {
1392 pipeselwakeup(ppipe);
1394 ppipe->pipe_state |= PIPE_EOF;
1396 KNOTE(&ppipe->pipe_sel.si_note, 0);
1397 ppipe->pipe_peer = NULL;
1400 if (cpipe->pipe_kva) {
1401 pmap_qremove(cpipe->pipe_kva, XIO_INTERNAL_PAGES);
1402 kmem_free(&kernel_map, cpipe->pipe_kva, XIO_INTERNAL_SIZE);
1403 cpipe->pipe_kva = NULL;
1407 * free or cache resources
1410 if (gd->gd_pipeqcount >= pipe_maxcache ||
1411 cpipe->pipe_buffer.size != PIPE_SIZE
1413 pipe_free_kmem(cpipe);
1414 kfree(cpipe, M_PIPE);
1416 KKASSERT(cpipe->pipe_map.xio_npages == 0 &&
1417 cpipe->pipe_map.xio_bytes == 0 &&
1418 cpipe->pipe_map.xio_offset == 0);
1419 cpipe->pipe_state = 0;
1420 cpipe->pipe_busy = 0;
1421 cpipe->pipe_peer = gd->gd_pipeq;
1422 gd->gd_pipeq = cpipe;
1423 ++gd->gd_pipeqcount;
1428 * MPALMOSTSAFE - acquires mplock
1431 pipe_kqfilter(struct file *fp, struct knote *kn)
1436 cpipe = (struct pipe *)kn->kn_fp->f_data;
1438 switch (kn->kn_filter) {
1440 kn->kn_fop = &pipe_rfiltops;
1443 kn->kn_fop = &pipe_wfiltops;
1444 cpipe = cpipe->pipe_peer;
1445 if (cpipe == NULL) {
1446 /* other end of pipe has been closed */
1454 kn->kn_hook = (caddr_t)cpipe;
1456 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1462 filt_pipedetach(struct knote *kn)
1464 struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1466 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1471 filt_piperead(struct knote *kn, long hint)
1473 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1474 struct pipe *wpipe = rpipe->pipe_peer;
1476 kn->kn_data = rpipe->pipe_buffer.cnt;
1477 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) {
1478 kn->kn_data = rpipe->pipe_map.xio_bytes -
1479 rpipe->pipe_buffer.out;
1482 if ((rpipe->pipe_state & PIPE_EOF) ||
1483 (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1484 kn->kn_flags |= EV_EOF;
1487 return (kn->kn_data > 0);
1492 filt_pipewrite(struct knote *kn, long hint)
1494 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1495 struct pipe *wpipe = rpipe->pipe_peer;
1497 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1499 kn->kn_flags |= EV_EOF;
1502 kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1503 if (wpipe->pipe_state & PIPE_DIRECTW)
1506 return (kn->kn_data >= PIPE_BUF);