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 1.41 2006/09/05 00:55:45 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, 1,
322 VM_PROT_ALL, VM_PROT_ALL, 0);
324 if (error != KERN_SUCCESS) {
325 vm_object_deallocate(object);
328 pipe_free_kmem(cpipe);
329 cpipe->pipe_buffer.object = object;
330 cpipe->pipe_buffer.buffer = buffer;
331 cpipe->pipe_buffer.size = size;
336 cpipe->pipe_buffer.in = 0;
337 cpipe->pipe_buffer.out = 0;
338 cpipe->pipe_buffer.cnt = 0;
343 * Initialize and allocate VM and memory for pipe, pulling the pipe from
344 * our per-cpu cache if possible. For now make sure it is sized for the
345 * smaller PIPE_SIZE default.
349 struct pipe **cpipep;
351 globaldata_t gd = mycpu;
355 if ((cpipe = gd->gd_pipeq) != NULL) {
356 gd->gd_pipeq = cpipe->pipe_peer;
358 cpipe->pipe_peer = NULL;
360 cpipe = kmalloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
363 if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
365 vfs_timestamp(&cpipe->pipe_ctime);
366 cpipe->pipe_atime = cpipe->pipe_ctime;
367 cpipe->pipe_mtime = cpipe->pipe_ctime;
373 * lock a pipe for I/O, blocking other access
376 pipelock(cpipe, 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
400 cpipe->pipe_state &= ~PIPE_LOCK;
401 if (cpipe->pipe_state & PIPE_LWANT) {
402 cpipe->pipe_state &= ~PIPE_LWANT;
412 if (cpipe->pipe_state & PIPE_SEL) {
413 cpipe->pipe_state &= ~PIPE_SEL;
414 selwakeup(&cpipe->pipe_sel);
416 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
417 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
418 KNOTE(&cpipe->pipe_sel.si_note, 0);
422 * MPALMOSTSAFE (acquires mplock)
425 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
434 rpipe = (struct pipe *) fp->f_data;
436 error = pipelock(rpipe, 1);
440 if (fflags & O_FBLOCKING)
442 else if (fflags & O_FNONBLOCKING)
444 else if (fp->f_flag & O_NONBLOCK)
449 while (uio->uio_resid) {
452 if (rpipe->pipe_buffer.cnt > 0) {
454 * normal pipe buffer receive
456 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
457 if (size > rpipe->pipe_buffer.cnt)
458 size = rpipe->pipe_buffer.cnt;
459 if (size > (u_int) uio->uio_resid)
460 size = (u_int) uio->uio_resid;
462 error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
467 rpipe->pipe_buffer.out += size;
468 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
469 rpipe->pipe_buffer.out = 0;
471 rpipe->pipe_buffer.cnt -= size;
474 * If there is no more to read in the pipe, reset
475 * its pointers to the beginning. This improves
478 if (rpipe->pipe_buffer.cnt == 0) {
479 rpipe->pipe_buffer.in = 0;
480 rpipe->pipe_buffer.out = 0;
483 #ifndef PIPE_NODIRECT
484 } else if (rpipe->pipe_kva &&
485 rpipe->pipe_feature == PIPE_KMEM &&
486 (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
490 * Direct copy using source-side kva mapping
492 size = rpipe->pipe_map.xio_bytes -
493 rpipe->pipe_buffer.out;
494 if (size > (u_int)uio->uio_resid)
495 size = (u_int)uio->uio_resid;
496 va = (caddr_t)rpipe->pipe_kva +
497 xio_kvaoffset(&rpipe->pipe_map, rpipe->pipe_buffer.out);
498 error = uiomove(va, size, uio);
502 rpipe->pipe_buffer.out += size;
503 if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
504 rpipe->pipe_state |= PIPE_DIRECTIP;
505 rpipe->pipe_state &= ~PIPE_DIRECTW;
506 /* reset out index for copy mode */
507 rpipe->pipe_buffer.out = 0;
510 } else if (rpipe->pipe_buffer.out != rpipe->pipe_map.xio_bytes &&
512 rpipe->pipe_feature == PIPE_SFBUF2 &&
513 (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
517 * Direct copy, bypassing a kernel buffer. We cannot
518 * mess with the direct-write buffer until
519 * PIPE_DIRECTIP is cleared. In order to prevent
520 * the pipe_write code from racing itself in
521 * direct_write, we set DIRECTIP when we clear
522 * DIRECTW after we have exhausted the buffer.
524 if (pipe_dwrite_sfbuf == 3)
525 rpipe->pipe_kvamask = 0;
526 pmap_qenter2(rpipe->pipe_kva, rpipe->pipe_map.xio_pages,
527 rpipe->pipe_map.xio_npages,
528 &rpipe->pipe_kvamask);
529 size = rpipe->pipe_map.xio_bytes -
530 rpipe->pipe_buffer.out;
531 if (size > (u_int)uio->uio_resid)
532 size = (u_int)uio->uio_resid;
533 va = (caddr_t)rpipe->pipe_kva + xio_kvaoffset(&rpipe->pipe_map, rpipe->pipe_buffer.out);
534 error = uiomove(va, size, uio);
538 rpipe->pipe_buffer.out += size;
539 if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
540 rpipe->pipe_state |= PIPE_DIRECTIP;
541 rpipe->pipe_state &= ~PIPE_DIRECTW;
542 /* reset out index for copy mode */
543 rpipe->pipe_buffer.out = 0;
546 } else if (rpipe->pipe_buffer.out != rpipe->pipe_map.xio_bytes &&
547 rpipe->pipe_feature == PIPE_SFBUF1 &&
548 (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
552 * Direct copy, bypassing a kernel buffer. We cannot
553 * mess with the direct-write buffer until
554 * PIPE_DIRECTIP is cleared. In order to prevent
555 * the pipe_write code from racing itself in
556 * direct_write, we set DIRECTIP when we clear
557 * DIRECTW after we have exhausted the buffer.
559 error = xio_uio_copy(&rpipe->pipe_map, rpipe->pipe_buffer.out, uio, &size);
563 rpipe->pipe_buffer.out += size;
564 if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
565 rpipe->pipe_state |= PIPE_DIRECTIP;
566 rpipe->pipe_state &= ~PIPE_DIRECTW;
567 /* reset out index for copy mode */
568 rpipe->pipe_buffer.out = 0;
574 * detect EOF condition
575 * read returns 0 on EOF, no need to set error
577 if (rpipe->pipe_state & PIPE_EOF)
581 * If the "write-side" has been blocked, wake it up now.
583 if (rpipe->pipe_state & PIPE_WANTW) {
584 rpipe->pipe_state &= ~PIPE_WANTW;
589 * Break if some data was read.
595 * Unlock the pipe buffer for our remaining
596 * processing. We will either break out with an
597 * error or we will sleep and relock to loop.
602 * Handle non-blocking mode operation or
603 * wait for more data.
608 rpipe->pipe_state |= PIPE_WANTR;
609 if ((error = tsleep(rpipe, PCATCH|PNORESCHED,
610 "piperd", 0)) == 0) {
611 error = pipelock(rpipe, 1);
621 vfs_timestamp(&rpipe->pipe_atime);
626 * PIPE_WANT processing only makes sense if pipe_busy is 0.
628 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
629 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
631 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
633 * Handle write blocking hysteresis.
635 if (rpipe->pipe_state & PIPE_WANTW) {
636 rpipe->pipe_state &= ~PIPE_WANTW;
641 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
642 pipeselwakeup(rpipe);
647 #ifndef PIPE_NODIRECT
649 * Map the sending processes' buffer into kernel space and wire it.
650 * This is similar to a physical write operation.
653 pipe_build_write_buffer(wpipe, uio)
660 size = (u_int) uio->uio_iov->iov_len;
661 if (size > wpipe->pipe_buffer.size)
662 size = wpipe->pipe_buffer.size;
664 if (uio->uio_segflg == UIO_SYSSPACE) {
665 error = xio_init_kbuf(&wpipe->pipe_map, uio->uio_iov->iov_base,
668 error = xio_init_ubuf(&wpipe->pipe_map, uio->uio_iov->iov_base,
671 wpipe->pipe_buffer.out = 0;
676 * Create a kernel map for KMEM and SFBUF2 copy modes. SFBUF2 will
677 * map the pages on the target while KMEM maps the pages now.
679 switch(wpipe->pipe_feature) {
682 if (wpipe->pipe_kva == NULL) {
684 kmem_alloc_nofault(kernel_map, XIO_INTERNAL_SIZE);
685 wpipe->pipe_kvamask = 0;
687 if (wpipe->pipe_feature == PIPE_KMEM) {
688 pmap_qenter(wpipe->pipe_kva, wpipe->pipe_map.xio_pages,
689 wpipe->pipe_map.xio_npages);
697 * And update the uio data. The XIO might have loaded fewer bytes
698 * then requested so reload 'size'.
700 size = wpipe->pipe_map.xio_bytes;
701 uio->uio_iov->iov_len -= size;
702 uio->uio_iov->iov_base += size;
703 if (uio->uio_iov->iov_len == 0)
705 uio->uio_resid -= size;
706 uio->uio_offset += size;
711 * In the case of a signal, the writing process might go away. This
712 * code copies the data into the circular buffer so that the source
713 * pages can be freed without loss of data.
715 * Note that in direct mode pipe_buffer.out is used to track the
716 * XIO offset. We are converting the direct mode into buffered mode
717 * which changes the meaning of pipe_buffer.out.
720 pipe_clone_write_buffer(wpipe)
726 offset = wpipe->pipe_buffer.out;
727 size = wpipe->pipe_map.xio_bytes - offset;
729 KKASSERT(size <= wpipe->pipe_buffer.size);
731 wpipe->pipe_buffer.in = size;
732 wpipe->pipe_buffer.out = 0;
733 wpipe->pipe_buffer.cnt = size;
734 wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
736 xio_copy_xtok(&wpipe->pipe_map, offset, wpipe->pipe_buffer.buffer, size);
737 xio_release(&wpipe->pipe_map);
738 if (wpipe->pipe_kva) {
739 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
740 kmem_free(kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
741 wpipe->pipe_kva = NULL;
746 * This implements the pipe buffer write mechanism. Note that only
747 * a direct write OR a normal pipe write can be pending at any given time.
748 * If there are any characters in the pipe buffer, the direct write will
749 * be deferred until the receiving process grabs all of the bytes from
750 * the pipe buffer. Then the direct mapping write is set-up.
753 pipe_direct_write(wpipe, uio)
760 while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
761 if (wpipe->pipe_state & PIPE_WANTR) {
762 wpipe->pipe_state &= ~PIPE_WANTR;
765 wpipe->pipe_state |= PIPE_WANTW;
766 error = tsleep(wpipe, PCATCH, "pipdww", 0);
769 if (wpipe->pipe_state & PIPE_EOF) {
774 KKASSERT(wpipe->pipe_map.xio_bytes == 0);
775 if (wpipe->pipe_buffer.cnt > 0) {
776 if (wpipe->pipe_state & PIPE_WANTR) {
777 wpipe->pipe_state &= ~PIPE_WANTR;
781 wpipe->pipe_state |= PIPE_WANTW;
782 error = tsleep(wpipe, PCATCH, "pipdwc", 0);
785 if (wpipe->pipe_state & PIPE_EOF) {
793 * Build our direct-write buffer
795 wpipe->pipe_state |= PIPE_DIRECTW | PIPE_DIRECTIP;
796 error = pipe_build_write_buffer(wpipe, uio);
799 wpipe->pipe_state &= ~PIPE_DIRECTIP;
802 * Wait until the receiver has snarfed the data. Since we are likely
803 * going to sleep we optimize the case and yield synchronously,
804 * possibly avoiding the tsleep().
807 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
808 if (wpipe->pipe_state & PIPE_EOF) {
810 xio_release(&wpipe->pipe_map);
811 if (wpipe->pipe_kva) {
812 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
813 kmem_free(kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
814 wpipe->pipe_kva = NULL;
817 pipeselwakeup(wpipe);
821 if (wpipe->pipe_state & PIPE_WANTR) {
822 wpipe->pipe_state &= ~PIPE_WANTR;
825 pipeselwakeup(wpipe);
826 error = tsleep(wpipe, PCATCH|PNORESCHED, "pipdwt", 0);
829 if (wpipe->pipe_state & PIPE_DIRECTW) {
831 * this bit of trickery substitutes a kernel buffer for
832 * the process that might be going away.
834 pipe_clone_write_buffer(wpipe);
835 KKASSERT((wpipe->pipe_state & PIPE_DIRECTIP) == 0);
838 * note: The pipe_kva mapping is not qremove'd here. For
839 * legacy PIPE_KMEM mode this constitutes an improvement
840 * over the original FreeBSD-4 algorithm. For PIPE_SFBUF2
841 * mode the kva mapping must not be removed to get the
844 * For testing purposes we will give the original algorithm
845 * the benefit of the doubt 'what it could have been', and
846 * keep the optimization.
848 KKASSERT(wpipe->pipe_state & PIPE_DIRECTIP);
849 xio_release(&wpipe->pipe_map);
850 wpipe->pipe_state &= ~PIPE_DIRECTIP;
856 * Direct-write error, clear the direct write flags.
859 wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
863 * General error, wakeup the other side if it happens to be sleeping.
872 * MPALMOSTSAFE - acquires mplock
875 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
880 struct pipe *wpipe, *rpipe;
883 rpipe = (struct pipe *) fp->f_data;
884 wpipe = rpipe->pipe_peer;
887 * detect loss of pipe read side, issue SIGPIPE if lost.
889 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
895 if (fflags & O_FBLOCKING)
897 else if (fflags & O_FNONBLOCKING)
899 else if (fp->f_flag & O_NONBLOCK)
905 * If it is advantageous to resize the pipe buffer, do
908 if ((uio->uio_resid > PIPE_SIZE) &&
909 (pipe_nbig < pipe_maxbig) &&
910 (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) == 0 &&
911 (wpipe->pipe_buffer.size <= PIPE_SIZE) &&
912 (wpipe->pipe_buffer.cnt == 0)) {
914 if ((error = pipelock(wpipe,1)) == 0) {
915 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
922 * If an early error occured unbusy and return, waking up any pending
927 if ((wpipe->pipe_busy == 0) &&
928 (wpipe->pipe_state & PIPE_WANT)) {
929 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
936 KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone"));
938 orig_resid = uio->uio_resid;
940 while (uio->uio_resid) {
943 #ifndef PIPE_NODIRECT
945 * If the transfer is large, we can gain performance if
946 * we do process-to-process copies directly.
947 * If the write is non-blocking, we don't use the
948 * direct write mechanism.
950 * The direct write mechanism will detect the reader going
953 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT ||
954 pipe_dwrite_enable > 1) &&
956 pipe_dwrite_enable) {
957 error = pipe_direct_write( wpipe, uio);
965 * Pipe buffered writes cannot be coincidental with
966 * direct writes. We wait until the currently executing
967 * direct write is completed before we start filling the
968 * pipe buffer. We break out if a signal occurs or the
972 while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
973 if (wpipe->pipe_state & PIPE_WANTR) {
974 wpipe->pipe_state &= ~PIPE_WANTR;
977 error = tsleep(wpipe, PCATCH, "pipbww", 0);
978 if (wpipe->pipe_state & PIPE_EOF)
983 if (wpipe->pipe_state & PIPE_EOF) {
988 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
990 /* Writes of size <= PIPE_BUF must be atomic. */
991 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
995 * Write to fill, read size handles write hysteresis. Also
996 * additional restrictions can cause select-based non-blocking
1000 if ((error = pipelock(wpipe,1)) == 0) {
1001 int size; /* Transfer size */
1002 int segsize; /* first segment to transfer */
1005 * It is possible for a direct write to
1006 * slip in on us... handle it here...
1008 if (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
1013 * If a process blocked in uiomove, our
1014 * value for space might be bad.
1016 * XXX will we be ok if the reader has gone
1019 if (space > wpipe->pipe_buffer.size -
1020 wpipe->pipe_buffer.cnt) {
1026 * Transfer size is minimum of uio transfer
1027 * and free space in pipe buffer.
1029 if (space > uio->uio_resid)
1030 size = uio->uio_resid;
1034 * First segment to transfer is minimum of
1035 * transfer size and contiguous space in
1036 * pipe buffer. If first segment to transfer
1037 * is less than the transfer size, we've got
1038 * a wraparound in the buffer.
1040 segsize = wpipe->pipe_buffer.size -
1041 wpipe->pipe_buffer.in;
1045 /* Transfer first segment */
1047 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1050 if (error == 0 && segsize < size) {
1052 * Transfer remaining part now, to
1053 * support atomic writes. Wraparound
1056 if (wpipe->pipe_buffer.in + segsize !=
1057 wpipe->pipe_buffer.size)
1058 panic("Expected pipe buffer wraparound disappeared");
1060 error = uiomove(&wpipe->pipe_buffer.buffer[0],
1061 size - segsize, uio);
1064 wpipe->pipe_buffer.in += size;
1065 if (wpipe->pipe_buffer.in >=
1066 wpipe->pipe_buffer.size) {
1067 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
1068 panic("Expected wraparound bad");
1069 wpipe->pipe_buffer.in = size - segsize;
1072 wpipe->pipe_buffer.cnt += size;
1073 if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
1074 panic("Pipe buffer overflow");
1084 * If the "read-side" has been blocked, wake it up now
1085 * and yield to let it drain synchronously rather
1088 if (wpipe->pipe_state & PIPE_WANTR) {
1089 wpipe->pipe_state &= ~PIPE_WANTR;
1094 * don't block on non-blocking I/O
1102 * We have no more space and have something to offer,
1103 * wake up select/poll.
1105 pipeselwakeup(wpipe);
1107 wpipe->pipe_state |= PIPE_WANTW;
1108 error = tsleep(wpipe, PCATCH|PNORESCHED, "pipewr", 0);
1112 * If read side wants to go away, we just issue a signal
1115 if (wpipe->pipe_state & PIPE_EOF) {
1124 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1125 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1127 } else if (wpipe->pipe_buffer.cnt > 0) {
1129 * If we have put any characters in the buffer, we wake up
1132 if (wpipe->pipe_state & PIPE_WANTR) {
1133 wpipe->pipe_state &= ~PIPE_WANTR;
1139 * Don't return EPIPE if I/O was successful
1141 if ((wpipe->pipe_buffer.cnt == 0) &&
1142 (uio->uio_resid == 0) &&
1148 vfs_timestamp(&wpipe->pipe_mtime);
1151 * We have something to offer,
1152 * wake up select/poll.
1154 if (wpipe->pipe_buffer.cnt)
1155 pipeselwakeup(wpipe);
1161 * MPALMOSTSAFE - acquires mplock
1163 * we implement a very minimal set of ioctls for compatibility with sockets.
1166 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct ucred *cred)
1172 mpipe = (struct pipe *)fp->f_data;
1177 mpipe->pipe_state |= PIPE_ASYNC;
1179 mpipe->pipe_state &= ~PIPE_ASYNC;
1184 if (mpipe->pipe_state & PIPE_DIRECTW) {
1185 *(int *)data = mpipe->pipe_map.xio_bytes -
1186 mpipe->pipe_buffer.out;
1188 *(int *)data = mpipe->pipe_buffer.cnt;
1193 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1196 *(int *)data = fgetown(mpipe->pipe_sigio);
1200 /* This is deprecated, FIOSETOWN should be used instead. */
1201 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1205 /* This is deprecated, FIOGETOWN should be used instead. */
1206 *(int *)data = -fgetown(mpipe->pipe_sigio);
1218 * MPALMOSTSAFE - acquires mplock
1221 pipe_poll(struct file *fp, int events, struct ucred *cred)
1228 rpipe = (struct pipe *)fp->f_data;
1229 wpipe = rpipe->pipe_peer;
1230 if (events & (POLLIN | POLLRDNORM))
1231 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1232 (rpipe->pipe_buffer.cnt > 0) ||
1233 (rpipe->pipe_state & PIPE_EOF))
1234 revents |= events & (POLLIN | POLLRDNORM);
1236 if (events & (POLLOUT | POLLWRNORM))
1237 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) ||
1238 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1239 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1240 revents |= events & (POLLOUT | POLLWRNORM);
1242 if ((rpipe->pipe_state & PIPE_EOF) ||
1244 (wpipe->pipe_state & PIPE_EOF))
1248 if (events & (POLLIN | POLLRDNORM)) {
1249 selrecord(curthread, &rpipe->pipe_sel);
1250 rpipe->pipe_state |= PIPE_SEL;
1253 if (events & (POLLOUT | POLLWRNORM)) {
1254 selrecord(curthread, &wpipe->pipe_sel);
1255 wpipe->pipe_state |= PIPE_SEL;
1263 * MPALMOSTSAFE - acquires mplock
1266 pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred)
1271 pipe = (struct pipe *)fp->f_data;
1273 bzero((caddr_t)ub, sizeof(*ub));
1274 ub->st_mode = S_IFIFO;
1275 ub->st_blksize = pipe->pipe_buffer.size;
1276 ub->st_size = pipe->pipe_buffer.cnt;
1277 if (ub->st_size == 0 && (pipe->pipe_state & PIPE_DIRECTW)) {
1278 ub->st_size = pipe->pipe_map.xio_bytes -
1279 pipe->pipe_buffer.out;
1281 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1282 ub->st_atimespec = pipe->pipe_atime;
1283 ub->st_mtimespec = pipe->pipe_mtime;
1284 ub->st_ctimespec = pipe->pipe_ctime;
1286 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1288 * XXX (st_dev, st_ino) should be unique.
1295 * MPALMOSTSAFE - acquires mplock
1298 pipe_close(struct file *fp)
1300 struct pipe *cpipe = (struct pipe *)fp->f_data;
1303 fp->f_ops = &badfileops;
1305 funsetown(cpipe->pipe_sigio);
1312 * Shutdown one or both directions of a full-duplex pipe.
1314 * MPALMOSTSAFE - acquires mplock
1317 pipe_shutdown(struct file *fp, int how)
1324 rpipe = (struct pipe *)fp->f_data;
1330 rpipe->pipe_state |= PIPE_EOF;
1331 pipeselwakeup(rpipe);
1332 if (rpipe->pipe_busy)
1340 if (rpipe && (wpipe = rpipe->pipe_peer) != NULL) {
1341 wpipe->pipe_state |= PIPE_EOF;
1342 pipeselwakeup(wpipe);
1343 if (wpipe->pipe_busy)
1353 pipe_free_kmem(struct pipe *cpipe)
1355 if (cpipe->pipe_buffer.buffer != NULL) {
1356 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1358 kmem_free(kernel_map,
1359 (vm_offset_t)cpipe->pipe_buffer.buffer,
1360 cpipe->pipe_buffer.size);
1361 cpipe->pipe_buffer.buffer = NULL;
1362 cpipe->pipe_buffer.object = NULL;
1364 #ifndef PIPE_NODIRECT
1365 KKASSERT(cpipe->pipe_map.xio_bytes == 0 &&
1366 cpipe->pipe_map.xio_offset == 0 &&
1367 cpipe->pipe_map.xio_npages == 0);
1375 pipeclose(struct pipe *cpipe)
1383 pipeselwakeup(cpipe);
1386 * If the other side is blocked, wake it up saying that
1387 * we want to close it down.
1389 while (cpipe->pipe_busy) {
1391 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
1392 tsleep(cpipe, 0, "pipecl", 0);
1396 * Disconnect from peer
1398 if ((ppipe = cpipe->pipe_peer) != NULL) {
1399 pipeselwakeup(ppipe);
1401 ppipe->pipe_state |= PIPE_EOF;
1403 KNOTE(&ppipe->pipe_sel.si_note, 0);
1404 ppipe->pipe_peer = NULL;
1407 if (cpipe->pipe_kva) {
1408 pmap_qremove(cpipe->pipe_kva, XIO_INTERNAL_PAGES);
1409 kmem_free(kernel_map, cpipe->pipe_kva, XIO_INTERNAL_SIZE);
1410 cpipe->pipe_kva = NULL;
1414 * free or cache resources
1417 if (gd->gd_pipeqcount >= pipe_maxcache ||
1418 cpipe->pipe_buffer.size != PIPE_SIZE
1420 pipe_free_kmem(cpipe);
1421 kfree(cpipe, M_PIPE);
1423 KKASSERT(cpipe->pipe_map.xio_npages == 0 &&
1424 cpipe->pipe_map.xio_bytes == 0 &&
1425 cpipe->pipe_map.xio_offset == 0);
1426 cpipe->pipe_state = 0;
1427 cpipe->pipe_busy = 0;
1428 cpipe->pipe_peer = gd->gd_pipeq;
1429 gd->gd_pipeq = cpipe;
1430 ++gd->gd_pipeqcount;
1435 * MPALMOSTSAFE - acquires mplock
1438 pipe_kqfilter(struct file *fp, struct knote *kn)
1443 cpipe = (struct pipe *)kn->kn_fp->f_data;
1445 switch (kn->kn_filter) {
1447 kn->kn_fop = &pipe_rfiltops;
1450 kn->kn_fop = &pipe_wfiltops;
1451 cpipe = cpipe->pipe_peer;
1452 if (cpipe == NULL) {
1453 /* other end of pipe has been closed */
1461 kn->kn_hook = (caddr_t)cpipe;
1463 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1469 filt_pipedetach(struct knote *kn)
1471 struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1473 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1478 filt_piperead(struct knote *kn, long hint)
1480 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1481 struct pipe *wpipe = rpipe->pipe_peer;
1483 kn->kn_data = rpipe->pipe_buffer.cnt;
1484 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) {
1485 kn->kn_data = rpipe->pipe_map.xio_bytes -
1486 rpipe->pipe_buffer.out;
1489 if ((rpipe->pipe_state & PIPE_EOF) ||
1490 (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1491 kn->kn_flags |= EV_EOF;
1494 return (kn->kn_data > 0);
1499 filt_pipewrite(struct knote *kn, long hint)
1501 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1502 struct pipe *wpipe = rpipe->pipe_peer;
1504 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1506 kn->kn_flags |= EV_EOF;
1509 kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1510 if (wpipe->pipe_state & PIPE_DIRECTW)
1513 return (kn->kn_data >= PIPE_BUF);