FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_pipe.c
1 /* $NetBSD: sys_pipe.c,v 1.77 2006/11/01 10:17:59 yamt Exp $ */
2
3 /*-
4 * Copyright (c) 2003 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Paul Kranenburg.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the NetBSD
21 * Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 * contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39 /*
40 * Copyright (c) 1996 John S. Dyson
41 * All rights reserved.
42 *
43 * Redistribution and use in source and binary forms, with or without
44 * modification, are permitted provided that the following conditions
45 * are met:
46 * 1. Redistributions of source code must retain the above copyright
47 * notice immediately at the beginning of the file, without modification,
48 * this list of conditions, and the following disclaimer.
49 * 2. Redistributions in binary form must reproduce the above copyright
50 * notice, this list of conditions and the following disclaimer in the
51 * documentation and/or other materials provided with the distribution.
52 * 3. Absolutely no warranty of function or purpose is made by the author
53 * John S. Dyson.
54 * 4. Modifications may be freely made to this file if the above conditions
55 * are met.
56 *
57 * $FreeBSD: src/sys/kern/sys_pipe.c,v 1.95 2002/03/09 22:06:31 alfred Exp $
58 */
59
60 /*
61 * This file contains a high-performance replacement for the socket-based
62 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support
63 * all features of sockets, but does do everything that pipes normally
64 * do.
65 *
66 * Adaption for NetBSD UVM, including uvm_loan() based direct write, was
67 * written by Jaromir Dolecek.
68 */
69
70 /*
71 * This code has two modes of operation, a small write mode and a large
72 * write mode. The small write mode acts like conventional pipes with
73 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the
74 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT
75 * and PIPE_SIZE in size it is mapped read-only into the kernel address space
76 * using the UVM page loan facility from where the receiving process can copy
77 * the data directly from the pages in the sending process.
78 *
79 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
80 * happen for small transfers so that the system will not spend all of
81 * its time context switching. PIPE_SIZE is constrained by the
82 * amount of kernel virtual memory.
83 */
84
85 #include <sys/cdefs.h>
86 __KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.77 2006/11/01 10:17:59 yamt Exp $");
87
88 #include <sys/param.h>
89 #include <sys/systm.h>
90 #include <sys/proc.h>
91 #include <sys/fcntl.h>
92 #include <sys/file.h>
93 #include <sys/filedesc.h>
94 #include <sys/filio.h>
95 #include <sys/kernel.h>
96 #include <sys/ttycom.h>
97 #include <sys/stat.h>
98 #include <sys/malloc.h>
99 #include <sys/poll.h>
100 #include <sys/signalvar.h>
101 #include <sys/vnode.h>
102 #include <sys/uio.h>
103 #include <sys/lock.h>
104 #include <sys/select.h>
105 #include <sys/mount.h>
106 #include <sys/sa.h>
107 #include <sys/syscallargs.h>
108 #include <uvm/uvm.h>
109 #include <sys/sysctl.h>
110 #include <sys/kernel.h>
111 #include <sys/kauth.h>
112
113 #include <sys/pipe.h>
114
115 /*
116 * Use this define if you want to disable *fancy* VM things. Expect an
117 * approx 30% decrease in transfer rate.
118 */
119 /* #define PIPE_NODIRECT */
120
121 /*
122 * interfaces to the outside world
123 */
124 static int pipe_read(struct file *fp, off_t *offset, struct uio *uio,
125 kauth_cred_t cred, int flags);
126 static int pipe_write(struct file *fp, off_t *offset, struct uio *uio,
127 kauth_cred_t cred, int flags);
128 static int pipe_close(struct file *fp, struct lwp *l);
129 static int pipe_poll(struct file *fp, int events, struct lwp *l);
130 static int pipe_kqfilter(struct file *fp, struct knote *kn);
131 static int pipe_stat(struct file *fp, struct stat *sb, struct lwp *l);
132 static int pipe_ioctl(struct file *fp, u_long cmd, void *data,
133 struct lwp *l);
134
135 static const struct fileops pipeops = {
136 pipe_read, pipe_write, pipe_ioctl, fnullop_fcntl, pipe_poll,
137 pipe_stat, pipe_close, pipe_kqfilter
138 };
139
140 /*
141 * Default pipe buffer size(s), this can be kind-of large now because pipe
142 * space is pageable. The pipe code will try to maintain locality of
143 * reference for performance reasons, so small amounts of outstanding I/O
144 * will not wipe the cache.
145 */
146 #define MINPIPESIZE (PIPE_SIZE/3)
147 #define MAXPIPESIZE (2*PIPE_SIZE/3)
148
149 /*
150 * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
151 * is there so that on large systems, we don't exhaust it.
152 */
153 #define MAXPIPEKVA (8*1024*1024)
154 static int maxpipekva = MAXPIPEKVA;
155
156 /*
157 * Limit for direct transfers, we cannot, of course limit
158 * the amount of kva for pipes in general though.
159 */
160 #define LIMITPIPEKVA (16*1024*1024)
161 static int limitpipekva = LIMITPIPEKVA;
162
163 /*
164 * Limit the number of "big" pipes
165 */
166 #define LIMITBIGPIPES 32
167 static int maxbigpipes = LIMITBIGPIPES;
168 static int nbigpipe = 0;
169
170 /*
171 * Amount of KVA consumed by pipe buffers.
172 */
173 static int amountpipekva = 0;
174
175 MALLOC_DEFINE(M_PIPE, "pipe", "Pipe structures");
176
177 static void pipeclose(struct file *fp, struct pipe *pipe);
178 static void pipe_free_kmem(struct pipe *pipe);
179 static int pipe_create(struct pipe **pipep, int allockva);
180 static int pipelock(struct pipe *pipe, int catch);
181 static inline void pipeunlock(struct pipe *pipe);
182 static void pipeselwakeup(struct pipe *pipe, struct pipe *sigp, int code);
183 #ifndef PIPE_NODIRECT
184 static int pipe_direct_write(struct file *fp, struct pipe *wpipe,
185 struct uio *uio);
186 #endif
187 static int pipespace(struct pipe *pipe, int size);
188
189 #ifndef PIPE_NODIRECT
190 static int pipe_loan_alloc(struct pipe *, int);
191 static void pipe_loan_free(struct pipe *);
192 #endif /* PIPE_NODIRECT */
193
194 static POOL_INIT(pipe_pool, sizeof(struct pipe), 0, 0, 0, "pipepl",
195 &pool_allocator_nointr);
196
197 /*
198 * The pipe system call for the DTYPE_PIPE type of pipes
199 */
200
201 /* ARGSUSED */
202 int
203 sys_pipe(struct lwp *l, void *v, register_t *retval)
204 {
205 struct file *rf, *wf;
206 struct pipe *rpipe, *wpipe;
207 int fd, error;
208
209 rpipe = wpipe = NULL;
210 if (pipe_create(&rpipe, 1) || pipe_create(&wpipe, 0)) {
211 pipeclose(NULL, rpipe);
212 pipeclose(NULL, wpipe);
213 return (ENFILE);
214 }
215
216 /*
217 * Note: the file structure returned from falloc() is marked
218 * as 'larval' initially. Unless we mark it as 'mature' by
219 * FILE_SET_MATURE(), any attempt to do anything with it would
220 * return EBADF, including e.g. dup(2) or close(2). This avoids
221 * file descriptor races if we block in the second falloc().
222 */
223
224 error = falloc(l, &rf, &fd);
225 if (error)
226 goto free2;
227 retval[0] = fd;
228 rf->f_flag = FREAD;
229 rf->f_type = DTYPE_PIPE;
230 rf->f_data = (caddr_t)rpipe;
231 rf->f_ops = &pipeops;
232
233 error = falloc(l, &wf, &fd);
234 if (error)
235 goto free3;
236 retval[1] = fd;
237 wf->f_flag = FWRITE;
238 wf->f_type = DTYPE_PIPE;
239 wf->f_data = (caddr_t)wpipe;
240 wf->f_ops = &pipeops;
241
242 rpipe->pipe_peer = wpipe;
243 wpipe->pipe_peer = rpipe;
244
245 FILE_SET_MATURE(rf);
246 FILE_SET_MATURE(wf);
247 FILE_UNUSE(rf, l);
248 FILE_UNUSE(wf, l);
249 return (0);
250 free3:
251 FILE_UNUSE(rf, l);
252 ffree(rf);
253 fdremove(l->l_proc->p_fd, retval[0]);
254 free2:
255 pipeclose(NULL, wpipe);
256 pipeclose(NULL, rpipe);
257
258 return (error);
259 }
260
261 /*
262 * Allocate kva for pipe circular buffer, the space is pageable
263 * This routine will 'realloc' the size of a pipe safely, if it fails
264 * it will retain the old buffer.
265 * If it fails it will return ENOMEM.
266 */
267 static int
268 pipespace(struct pipe *pipe, int size)
269 {
270 caddr_t buffer;
271 /*
272 * Allocate pageable virtual address space. Physical memory is
273 * allocated on demand.
274 */
275 buffer = (caddr_t) uvm_km_alloc(kernel_map, round_page(size), 0,
276 UVM_KMF_PAGEABLE);
277 if (buffer == NULL)
278 return (ENOMEM);
279
280 /* free old resources if we're resizing */
281 pipe_free_kmem(pipe);
282 pipe->pipe_buffer.buffer = buffer;
283 pipe->pipe_buffer.size = size;
284 pipe->pipe_buffer.in = 0;
285 pipe->pipe_buffer.out = 0;
286 pipe->pipe_buffer.cnt = 0;
287 amountpipekva += pipe->pipe_buffer.size;
288 return (0);
289 }
290
291 /*
292 * Initialize and allocate VM and memory for pipe.
293 */
294 static int
295 pipe_create(struct pipe **pipep, int allockva)
296 {
297 struct pipe *pipe;
298 int error;
299
300 pipe = *pipep = pool_get(&pipe_pool, PR_WAITOK);
301
302 /* Initialize */
303 memset(pipe, 0, sizeof(struct pipe));
304 pipe->pipe_state = PIPE_SIGNALR;
305
306 getmicrotime(&pipe->pipe_ctime);
307 pipe->pipe_atime = pipe->pipe_ctime;
308 pipe->pipe_mtime = pipe->pipe_ctime;
309 simple_lock_init(&pipe->pipe_slock);
310
311 if (allockva && (error = pipespace(pipe, PIPE_SIZE)))
312 return (error);
313
314 return (0);
315 }
316
317
318 /*
319 * Lock a pipe for I/O, blocking other access
320 * Called with pipe spin lock held.
321 * Return with pipe spin lock released on success.
322 */
323 static int
324 pipelock(struct pipe *pipe, int catch)
325 {
326
327 LOCK_ASSERT(simple_lock_held(&pipe->pipe_slock));
328
329 while (pipe->pipe_state & PIPE_LOCKFL) {
330 int error;
331 const int pcatch = catch ? PCATCH : 0;
332
333 pipe->pipe_state |= PIPE_LWANT;
334 error = ltsleep(pipe, PSOCK | pcatch, "pipelk", 0,
335 &pipe->pipe_slock);
336 if (error != 0)
337 return error;
338 }
339
340 pipe->pipe_state |= PIPE_LOCKFL;
341 simple_unlock(&pipe->pipe_slock);
342
343 return 0;
344 }
345
346 /*
347 * unlock a pipe I/O lock
348 */
349 static inline void
350 pipeunlock(struct pipe *pipe)
351 {
352
353 KASSERT(pipe->pipe_state & PIPE_LOCKFL);
354
355 pipe->pipe_state &= ~PIPE_LOCKFL;
356 if (pipe->pipe_state & PIPE_LWANT) {
357 pipe->pipe_state &= ~PIPE_LWANT;
358 wakeup(pipe);
359 }
360 }
361
362 /*
363 * Select/poll wakup. This also sends SIGIO to peer connected to
364 * 'sigpipe' side of pipe.
365 */
366 static void
367 pipeselwakeup(struct pipe *selp, struct pipe *sigp, int code)
368 {
369 int band;
370
371 selnotify(&selp->pipe_sel, NOTE_SUBMIT);
372
373 if (sigp == NULL || (sigp->pipe_state & PIPE_ASYNC) == 0)
374 return;
375
376 switch (code) {
377 case POLL_IN:
378 band = POLLIN|POLLRDNORM;
379 break;
380 case POLL_OUT:
381 band = POLLOUT|POLLWRNORM;
382 break;
383 case POLL_HUP:
384 band = POLLHUP;
385 break;
386 #if POLL_HUP != POLL_ERR
387 case POLL_ERR:
388 band = POLLERR;
389 break;
390 #endif
391 default:
392 band = 0;
393 #ifdef DIAGNOSTIC
394 printf("bad siginfo code %d in pipe notification.\n", code);
395 #endif
396 break;
397 }
398
399 fownsignal(sigp->pipe_pgid, SIGIO, code, band, selp);
400 }
401
402 /* ARGSUSED */
403 static int
404 pipe_read(struct file *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
405 int flags)
406 {
407 struct pipe *rpipe = (struct pipe *) fp->f_data;
408 struct pipebuf *bp = &rpipe->pipe_buffer;
409 int error;
410 size_t nread = 0;
411 size_t size;
412 size_t ocnt;
413
414 PIPE_LOCK(rpipe);
415 ++rpipe->pipe_busy;
416 ocnt = bp->cnt;
417
418 again:
419 error = pipelock(rpipe, 1);
420 if (error)
421 goto unlocked_error;
422
423 while (uio->uio_resid) {
424 /*
425 * normal pipe buffer receive
426 */
427 if (bp->cnt > 0) {
428 size = bp->size - bp->out;
429 if (size > bp->cnt)
430 size = bp->cnt;
431 if (size > uio->uio_resid)
432 size = uio->uio_resid;
433
434 error = uiomove(&bp->buffer[bp->out], size, uio);
435 if (error)
436 break;
437
438 bp->out += size;
439 if (bp->out >= bp->size)
440 bp->out = 0;
441
442 bp->cnt -= size;
443
444 /*
445 * If there is no more to read in the pipe, reset
446 * its pointers to the beginning. This improves
447 * cache hit stats.
448 */
449 if (bp->cnt == 0) {
450 bp->in = 0;
451 bp->out = 0;
452 }
453 nread += size;
454 #ifndef PIPE_NODIRECT
455 } else if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) {
456 /*
457 * Direct copy, bypassing a kernel buffer.
458 */
459 caddr_t va;
460
461 KASSERT(rpipe->pipe_state & PIPE_DIRECTW);
462
463 size = rpipe->pipe_map.cnt;
464 if (size > uio->uio_resid)
465 size = uio->uio_resid;
466
467 va = (caddr_t) rpipe->pipe_map.kva +
468 rpipe->pipe_map.pos;
469 error = uiomove(va, size, uio);
470 if (error)
471 break;
472 nread += size;
473 rpipe->pipe_map.pos += size;
474 rpipe->pipe_map.cnt -= size;
475 if (rpipe->pipe_map.cnt == 0) {
476 PIPE_LOCK(rpipe);
477 rpipe->pipe_state &= ~PIPE_DIRECTR;
478 wakeup(rpipe);
479 PIPE_UNLOCK(rpipe);
480 }
481 #endif
482 } else {
483 /*
484 * Break if some data was read.
485 */
486 if (nread > 0)
487 break;
488
489 PIPE_LOCK(rpipe);
490
491 /*
492 * detect EOF condition
493 * read returns 0 on EOF, no need to set error
494 */
495 if (rpipe->pipe_state & PIPE_EOF) {
496 PIPE_UNLOCK(rpipe);
497 break;
498 }
499
500 /*
501 * don't block on non-blocking I/O
502 */
503 if (fp->f_flag & FNONBLOCK) {
504 PIPE_UNLOCK(rpipe);
505 error = EAGAIN;
506 break;
507 }
508
509 /*
510 * Unlock the pipe buffer for our remaining processing.
511 * We will either break out with an error or we will
512 * sleep and relock to loop.
513 */
514 pipeunlock(rpipe);
515
516 /*
517 * The PIPE_DIRECTR flag is not under the control
518 * of the long-term lock (see pipe_direct_write()),
519 * so re-check now while holding the spin lock.
520 */
521 if ((rpipe->pipe_state & PIPE_DIRECTR) != 0)
522 goto again;
523
524 /*
525 * We want to read more, wake up select/poll.
526 */
527 pipeselwakeup(rpipe, rpipe->pipe_peer, POLL_IN);
528
529 /*
530 * If the "write-side" is blocked, wake it up now.
531 */
532 if (rpipe->pipe_state & PIPE_WANTW) {
533 rpipe->pipe_state &= ~PIPE_WANTW;
534 wakeup(rpipe);
535 }
536
537 /* Now wait until the pipe is filled */
538 rpipe->pipe_state |= PIPE_WANTR;
539 error = ltsleep(rpipe, PSOCK | PCATCH,
540 "piperd", 0, &rpipe->pipe_slock);
541 if (error != 0)
542 goto unlocked_error;
543 goto again;
544 }
545 }
546
547 if (error == 0)
548 getmicrotime(&rpipe->pipe_atime);
549
550 PIPE_LOCK(rpipe);
551 pipeunlock(rpipe);
552
553 unlocked_error:
554 --rpipe->pipe_busy;
555
556 /*
557 * PIPE_WANTCLOSE processing only makes sense if pipe_busy is 0.
558 */
559 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANTCLOSE)) {
560 rpipe->pipe_state &= ~(PIPE_WANTCLOSE|PIPE_WANTW);
561 wakeup(rpipe);
562 } else if (bp->cnt < MINPIPESIZE) {
563 /*
564 * Handle write blocking hysteresis.
565 */
566 if (rpipe->pipe_state & PIPE_WANTW) {
567 rpipe->pipe_state &= ~PIPE_WANTW;
568 wakeup(rpipe);
569 }
570 }
571
572 /*
573 * If anything was read off the buffer, signal to the writer it's
574 * possible to write more data. Also send signal if we are here for the
575 * first time after last write.
576 */
577 if ((bp->size - bp->cnt) >= PIPE_BUF
578 && (ocnt != bp->cnt || (rpipe->pipe_state & PIPE_SIGNALR))) {
579 pipeselwakeup(rpipe, rpipe->pipe_peer, POLL_OUT);
580 rpipe->pipe_state &= ~PIPE_SIGNALR;
581 }
582
583 PIPE_UNLOCK(rpipe);
584 return (error);
585 }
586
587 #ifndef PIPE_NODIRECT
588 /*
589 * Allocate structure for loan transfer.
590 */
591 static int
592 pipe_loan_alloc(struct pipe *wpipe, int npages)
593 {
594 vsize_t len;
595
596 len = (vsize_t)npages << PAGE_SHIFT;
597 wpipe->pipe_map.kva = uvm_km_alloc(kernel_map, len, 0,
598 UVM_KMF_VAONLY | UVM_KMF_WAITVA);
599 if (wpipe->pipe_map.kva == 0)
600 return (ENOMEM);
601
602 amountpipekva += len;
603 wpipe->pipe_map.npages = npages;
604 wpipe->pipe_map.pgs = malloc(npages * sizeof(struct vm_page *), M_PIPE,
605 M_WAITOK);
606 return (0);
607 }
608
609 /*
610 * Free resources allocated for loan transfer.
611 */
612 static void
613 pipe_loan_free(struct pipe *wpipe)
614 {
615 vsize_t len;
616
617 len = (vsize_t)wpipe->pipe_map.npages << PAGE_SHIFT;
618 uvm_km_free(kernel_map, wpipe->pipe_map.kva, len, UVM_KMF_VAONLY);
619 wpipe->pipe_map.kva = 0;
620 amountpipekva -= len;
621 free(wpipe->pipe_map.pgs, M_PIPE);
622 wpipe->pipe_map.pgs = NULL;
623 }
624
625 /*
626 * NetBSD direct write, using uvm_loan() mechanism.
627 * This implements the pipe buffer write mechanism. Note that only
628 * a direct write OR a normal pipe write can be pending at any given time.
629 * If there are any characters in the pipe buffer, the direct write will
630 * be deferred until the receiving process grabs all of the bytes from
631 * the pipe buffer. Then the direct mapping write is set-up.
632 *
633 * Called with the long-term pipe lock held.
634 */
635 static int
636 pipe_direct_write(struct file *fp, struct pipe *wpipe, struct uio *uio)
637 {
638 int error, npages, j;
639 struct vm_page **pgs;
640 vaddr_t bbase, kva, base, bend;
641 vsize_t blen, bcnt;
642 voff_t bpos;
643
644 KASSERT(wpipe->pipe_map.cnt == 0);
645
646 /*
647 * Handle first PIPE_CHUNK_SIZE bytes of buffer. Deal with buffers
648 * not aligned to PAGE_SIZE.
649 */
650 bbase = (vaddr_t)uio->uio_iov->iov_base;
651 base = trunc_page(bbase);
652 bend = round_page(bbase + uio->uio_iov->iov_len);
653 blen = bend - base;
654 bpos = bbase - base;
655
656 if (blen > PIPE_DIRECT_CHUNK) {
657 blen = PIPE_DIRECT_CHUNK;
658 bend = base + blen;
659 bcnt = PIPE_DIRECT_CHUNK - bpos;
660 } else {
661 bcnt = uio->uio_iov->iov_len;
662 }
663 npages = blen >> PAGE_SHIFT;
664
665 /*
666 * Free the old kva if we need more pages than we have
667 * allocated.
668 */
669 if (wpipe->pipe_map.kva != 0 && npages > wpipe->pipe_map.npages)
670 pipe_loan_free(wpipe);
671
672 /* Allocate new kva. */
673 if (wpipe->pipe_map.kva == 0) {
674 error = pipe_loan_alloc(wpipe, npages);
675 if (error)
676 return (error);
677 }
678
679 /* Loan the write buffer memory from writer process */
680 pgs = wpipe->pipe_map.pgs;
681 error = uvm_loan(&uio->uio_vmspace->vm_map, base, blen,
682 pgs, UVM_LOAN_TOPAGE);
683 if (error) {
684 pipe_loan_free(wpipe);
685 return (ENOMEM); /* so that caller fallback to ordinary write */
686 }
687
688 /* Enter the loaned pages to kva */
689 kva = wpipe->pipe_map.kva;
690 for (j = 0; j < npages; j++, kva += PAGE_SIZE) {
691 pmap_kenter_pa(kva, VM_PAGE_TO_PHYS(pgs[j]), VM_PROT_READ);
692 }
693 pmap_update(pmap_kernel());
694
695 /* Now we can put the pipe in direct write mode */
696 wpipe->pipe_map.pos = bpos;
697 wpipe->pipe_map.cnt = bcnt;
698 wpipe->pipe_state |= PIPE_DIRECTW;
699
700 /*
701 * But before we can let someone do a direct read,
702 * we have to wait until the pipe is drained.
703 */
704
705 /* Relase the pipe lock while we wait */
706 PIPE_LOCK(wpipe);
707 pipeunlock(wpipe);
708
709 while (error == 0 && wpipe->pipe_buffer.cnt > 0) {
710 if (wpipe->pipe_state & PIPE_WANTR) {
711 wpipe->pipe_state &= ~PIPE_WANTR;
712 wakeup(wpipe);
713 }
714
715 wpipe->pipe_state |= PIPE_WANTW;
716 error = ltsleep(wpipe, PSOCK | PCATCH, "pipdwc", 0,
717 &wpipe->pipe_slock);
718 if (error == 0 && wpipe->pipe_state & PIPE_EOF)
719 error = EPIPE;
720 }
721
722 /* Pipe is drained; next read will off the direct buffer */
723 wpipe->pipe_state |= PIPE_DIRECTR;
724
725 /* Wait until the reader is done */
726 while (error == 0 && (wpipe->pipe_state & PIPE_DIRECTR)) {
727 if (wpipe->pipe_state & PIPE_WANTR) {
728 wpipe->pipe_state &= ~PIPE_WANTR;
729 wakeup(wpipe);
730 }
731 pipeselwakeup(wpipe, wpipe, POLL_IN);
732 error = ltsleep(wpipe, PSOCK | PCATCH, "pipdwt", 0,
733 &wpipe->pipe_slock);
734 if (error == 0 && wpipe->pipe_state & PIPE_EOF)
735 error = EPIPE;
736 }
737
738 /* Take pipe out of direct write mode */
739 wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTR);
740
741 /* Acquire the pipe lock and cleanup */
742 (void)pipelock(wpipe, 0);
743 if (pgs != NULL) {
744 pmap_kremove(wpipe->pipe_map.kva, blen);
745 uvm_unloan(pgs, npages, UVM_LOAN_TOPAGE);
746 }
747 if (error || amountpipekva > maxpipekva)
748 pipe_loan_free(wpipe);
749
750 if (error) {
751 pipeselwakeup(wpipe, wpipe, POLL_ERR);
752
753 /*
754 * If nothing was read from what we offered, return error
755 * straight on. Otherwise update uio resid first. Caller
756 * will deal with the error condition, returning short
757 * write, error, or restarting the write(2) as appropriate.
758 */
759 if (wpipe->pipe_map.cnt == bcnt) {
760 wpipe->pipe_map.cnt = 0;
761 wakeup(wpipe);
762 return (error);
763 }
764
765 bcnt -= wpipe->pipe_map.cnt;
766 }
767
768 uio->uio_resid -= bcnt;
769 /* uio_offset not updated, not set/used for write(2) */
770 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + bcnt;
771 uio->uio_iov->iov_len -= bcnt;
772 if (uio->uio_iov->iov_len == 0) {
773 uio->uio_iov++;
774 uio->uio_iovcnt--;
775 }
776
777 wpipe->pipe_map.cnt = 0;
778 return (error);
779 }
780 #endif /* !PIPE_NODIRECT */
781
782 static int
783 pipe_write(struct file *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
784 int flags)
785 {
786 struct pipe *wpipe, *rpipe;
787 struct pipebuf *bp;
788 int error;
789
790 /* We want to write to our peer */
791 rpipe = (struct pipe *) fp->f_data;
792
793 retry:
794 error = 0;
795 PIPE_LOCK(rpipe);
796 wpipe = rpipe->pipe_peer;
797
798 /*
799 * Detect loss of pipe read side, issue SIGPIPE if lost.
800 */
801 if (wpipe == NULL)
802 error = EPIPE;
803 else if (simple_lock_try(&wpipe->pipe_slock) == 0) {
804 /* Deal with race for peer */
805 PIPE_UNLOCK(rpipe);
806 goto retry;
807 } else if ((wpipe->pipe_state & PIPE_EOF) != 0) {
808 PIPE_UNLOCK(wpipe);
809 error = EPIPE;
810 }
811
812 PIPE_UNLOCK(rpipe);
813 if (error != 0)
814 return (error);
815
816 ++wpipe->pipe_busy;
817
818 /* Aquire the long-term pipe lock */
819 if ((error = pipelock(wpipe,1)) != 0) {
820 --wpipe->pipe_busy;
821 if (wpipe->pipe_busy == 0
822 && (wpipe->pipe_state & PIPE_WANTCLOSE)) {
823 wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR);
824 wakeup(wpipe);
825 }
826 PIPE_UNLOCK(wpipe);
827 return (error);
828 }
829
830 bp = &wpipe->pipe_buffer;
831
832 /*
833 * If it is advantageous to resize the pipe buffer, do so.
834 */
835 if ((uio->uio_resid > PIPE_SIZE) &&
836 (nbigpipe < maxbigpipes) &&
837 #ifndef PIPE_NODIRECT
838 (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
839 #endif
840 (bp->size <= PIPE_SIZE) && (bp->cnt == 0)) {
841
842 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
843 nbigpipe++;
844 }
845
846 while (uio->uio_resid) {
847 size_t space;
848
849 #ifndef PIPE_NODIRECT
850 /*
851 * Pipe buffered writes cannot be coincidental with
852 * direct writes. Also, only one direct write can be
853 * in progress at any one time. We wait until the currently
854 * executing direct write is completed before continuing.
855 *
856 * We break out if a signal occurs or the reader goes away.
857 */
858 while (error == 0 && wpipe->pipe_state & PIPE_DIRECTW) {
859 PIPE_LOCK(wpipe);
860 if (wpipe->pipe_state & PIPE_WANTR) {
861 wpipe->pipe_state &= ~PIPE_WANTR;
862 wakeup(wpipe);
863 }
864 pipeunlock(wpipe);
865 error = ltsleep(wpipe, PSOCK | PCATCH,
866 "pipbww", 0, &wpipe->pipe_slock);
867
868 (void)pipelock(wpipe, 0);
869 if (wpipe->pipe_state & PIPE_EOF)
870 error = EPIPE;
871 }
872 if (error)
873 break;
874
875 /*
876 * If the transfer is large, we can gain performance if
877 * we do process-to-process copies directly.
878 * If the write is non-blocking, we don't use the
879 * direct write mechanism.
880 *
881 * The direct write mechanism will detect the reader going
882 * away on us.
883 */
884 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
885 (fp->f_flag & FNONBLOCK) == 0 &&
886 (wpipe->pipe_map.kva || (amountpipekva < limitpipekva))) {
887 error = pipe_direct_write(fp, wpipe, uio);
888
889 /*
890 * Break out if error occurred, unless it's ENOMEM.
891 * ENOMEM means we failed to allocate some resources
892 * for direct write, so we just fallback to ordinary
893 * write. If the direct write was successful,
894 * process rest of data via ordinary write.
895 */
896 if (error == 0)
897 continue;
898
899 if (error != ENOMEM)
900 break;
901 }
902 #endif /* PIPE_NODIRECT */
903
904 space = bp->size - bp->cnt;
905
906 /* Writes of size <= PIPE_BUF must be atomic. */
907 if ((space < uio->uio_resid) && (uio->uio_resid <= PIPE_BUF))
908 space = 0;
909
910 if (space > 0) {
911 int size; /* Transfer size */
912 int segsize; /* first segment to transfer */
913
914 /*
915 * Transfer size is minimum of uio transfer
916 * and free space in pipe buffer.
917 */
918 if (space > uio->uio_resid)
919 size = uio->uio_resid;
920 else
921 size = space;
922 /*
923 * First segment to transfer is minimum of
924 * transfer size and contiguous space in
925 * pipe buffer. If first segment to transfer
926 * is less than the transfer size, we've got
927 * a wraparound in the buffer.
928 */
929 segsize = bp->size - bp->in;
930 if (segsize > size)
931 segsize = size;
932
933 /* Transfer first segment */
934 error = uiomove(&bp->buffer[bp->in], segsize, uio);
935
936 if (error == 0 && segsize < size) {
937 /*
938 * Transfer remaining part now, to
939 * support atomic writes. Wraparound
940 * happened.
941 */
942 #ifdef DEBUG
943 if (bp->in + segsize != bp->size)
944 panic("Expected pipe buffer wraparound disappeared");
945 #endif
946
947 error = uiomove(&bp->buffer[0],
948 size - segsize, uio);
949 }
950 if (error)
951 break;
952
953 bp->in += size;
954 if (bp->in >= bp->size) {
955 #ifdef DEBUG
956 if (bp->in != size - segsize + bp->size)
957 panic("Expected wraparound bad");
958 #endif
959 bp->in = size - segsize;
960 }
961
962 bp->cnt += size;
963 #ifdef DEBUG
964 if (bp->cnt > bp->size)
965 panic("Pipe buffer overflow");
966 #endif
967 } else {
968 /*
969 * If the "read-side" has been blocked, wake it up now.
970 */
971 PIPE_LOCK(wpipe);
972 if (wpipe->pipe_state & PIPE_WANTR) {
973 wpipe->pipe_state &= ~PIPE_WANTR;
974 wakeup(wpipe);
975 }
976 PIPE_UNLOCK(wpipe);
977
978 /*
979 * don't block on non-blocking I/O
980 */
981 if (fp->f_flag & FNONBLOCK) {
982 error = EAGAIN;
983 break;
984 }
985
986 /*
987 * We have no more space and have something to offer,
988 * wake up select/poll.
989 */
990 if (bp->cnt)
991 pipeselwakeup(wpipe, wpipe, POLL_OUT);
992
993 PIPE_LOCK(wpipe);
994 pipeunlock(wpipe);
995 wpipe->pipe_state |= PIPE_WANTW;
996 error = ltsleep(wpipe, PSOCK | PCATCH, "pipewr", 0,
997 &wpipe->pipe_slock);
998 (void)pipelock(wpipe, 0);
999 if (error != 0)
1000 break;
1001 /*
1002 * If read side wants to go away, we just issue a signal
1003 * to ourselves.
1004 */
1005 if (wpipe->pipe_state & PIPE_EOF) {
1006 error = EPIPE;
1007 break;
1008 }
1009 }
1010 }
1011
1012 PIPE_LOCK(wpipe);
1013 --wpipe->pipe_busy;
1014 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANTCLOSE)) {
1015 wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR);
1016 wakeup(wpipe);
1017 } else if (bp->cnt > 0) {
1018 /*
1019 * If we have put any characters in the buffer, we wake up
1020 * the reader.
1021 */
1022 if (wpipe->pipe_state & PIPE_WANTR) {
1023 wpipe->pipe_state &= ~PIPE_WANTR;
1024 wakeup(wpipe);
1025 }
1026 }
1027
1028 /*
1029 * Don't return EPIPE if I/O was successful
1030 */
1031 if (error == EPIPE && bp->cnt == 0 && uio->uio_resid == 0)
1032 error = 0;
1033
1034 if (error == 0)
1035 getmicrotime(&wpipe->pipe_mtime);
1036
1037 /*
1038 * We have something to offer, wake up select/poll.
1039 * wpipe->pipe_map.cnt is always 0 in this point (direct write
1040 * is only done synchronously), so check only wpipe->pipe_buffer.cnt
1041 */
1042 if (bp->cnt)
1043 pipeselwakeup(wpipe, wpipe, POLL_OUT);
1044
1045 /*
1046 * Arrange for next read(2) to do a signal.
1047 */
1048 wpipe->pipe_state |= PIPE_SIGNALR;
1049
1050 pipeunlock(wpipe);
1051 PIPE_UNLOCK(wpipe);
1052 return (error);
1053 }
1054
1055 /*
1056 * we implement a very minimal set of ioctls for compatibility with sockets.
1057 */
1058 int
1059 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct lwp *l)
1060 {
1061 struct pipe *pipe = (struct pipe *)fp->f_data;
1062 struct proc *p = l->l_proc;
1063
1064 switch (cmd) {
1065
1066 case FIONBIO:
1067 return (0);
1068
1069 case FIOASYNC:
1070 PIPE_LOCK(pipe);
1071 if (*(int *)data) {
1072 pipe->pipe_state |= PIPE_ASYNC;
1073 } else {
1074 pipe->pipe_state &= ~PIPE_ASYNC;
1075 }
1076 PIPE_UNLOCK(pipe);
1077 return (0);
1078
1079 case FIONREAD:
1080 PIPE_LOCK(pipe);
1081 #ifndef PIPE_NODIRECT
1082 if (pipe->pipe_state & PIPE_DIRECTW)
1083 *(int *)data = pipe->pipe_map.cnt;
1084 else
1085 #endif
1086 *(int *)data = pipe->pipe_buffer.cnt;
1087 PIPE_UNLOCK(pipe);
1088 return (0);
1089
1090 case FIONWRITE:
1091 /* Look at other side */
1092 pipe = pipe->pipe_peer;
1093 PIPE_LOCK(pipe);
1094 #ifndef PIPE_NODIRECT
1095 if (pipe->pipe_state & PIPE_DIRECTW)
1096 *(int *)data = pipe->pipe_map.cnt;
1097 else
1098 #endif
1099 *(int *)data = pipe->pipe_buffer.cnt;
1100 PIPE_UNLOCK(pipe);
1101 return (0);
1102
1103 case FIONSPACE:
1104 /* Look at other side */
1105 pipe = pipe->pipe_peer;
1106 PIPE_LOCK(pipe);
1107 #ifndef PIPE_NODIRECT
1108 /*
1109 * If we're in direct-mode, we don't really have a
1110 * send queue, and any other write will block. Thus
1111 * zero seems like the best answer.
1112 */
1113 if (pipe->pipe_state & PIPE_DIRECTW)
1114 *(int *)data = 0;
1115 else
1116 #endif
1117 *(int *)data = pipe->pipe_buffer.size -
1118 pipe->pipe_buffer.cnt;
1119 PIPE_UNLOCK(pipe);
1120 return (0);
1121
1122 case TIOCSPGRP:
1123 case FIOSETOWN:
1124 return fsetown(p, &pipe->pipe_pgid, cmd, data);
1125
1126 case TIOCGPGRP:
1127 case FIOGETOWN:
1128 return fgetown(p, pipe->pipe_pgid, cmd, data);
1129
1130 }
1131 return (EPASSTHROUGH);
1132 }
1133
1134 int
1135 pipe_poll(struct file *fp, int events, struct lwp *l)
1136 {
1137 struct pipe *rpipe = (struct pipe *)fp->f_data;
1138 struct pipe *wpipe;
1139 int eof = 0;
1140 int revents = 0;
1141
1142 retry:
1143 PIPE_LOCK(rpipe);
1144 wpipe = rpipe->pipe_peer;
1145 if (wpipe != NULL && simple_lock_try(&wpipe->pipe_slock) == 0) {
1146 /* Deal with race for peer */
1147 PIPE_UNLOCK(rpipe);
1148 goto retry;
1149 }
1150
1151 if (events & (POLLIN | POLLRDNORM))
1152 if ((rpipe->pipe_buffer.cnt > 0) ||
1153 #ifndef PIPE_NODIRECT
1154 (rpipe->pipe_state & PIPE_DIRECTR) ||
1155 #endif
1156 (rpipe->pipe_state & PIPE_EOF))
1157 revents |= events & (POLLIN | POLLRDNORM);
1158
1159 eof |= (rpipe->pipe_state & PIPE_EOF);
1160 PIPE_UNLOCK(rpipe);
1161
1162 if (wpipe == NULL)
1163 revents |= events & (POLLOUT | POLLWRNORM);
1164 else {
1165 if (events & (POLLOUT | POLLWRNORM))
1166 if ((wpipe->pipe_state & PIPE_EOF) || (
1167 #ifndef PIPE_NODIRECT
1168 (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
1169 #endif
1170 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1171 revents |= events & (POLLOUT | POLLWRNORM);
1172
1173 eof |= (wpipe->pipe_state & PIPE_EOF);
1174 PIPE_UNLOCK(wpipe);
1175 }
1176
1177 if (wpipe == NULL || eof)
1178 revents |= POLLHUP;
1179
1180 if (revents == 0) {
1181 if (events & (POLLIN | POLLRDNORM))
1182 selrecord(l, &rpipe->pipe_sel);
1183
1184 if (events & (POLLOUT | POLLWRNORM))
1185 selrecord(l, &wpipe->pipe_sel);
1186 }
1187
1188 return (revents);
1189 }
1190
1191 static int
1192 pipe_stat(struct file *fp, struct stat *ub, struct lwp *l)
1193 {
1194 struct pipe *pipe = (struct pipe *)fp->f_data;
1195
1196 memset((caddr_t)ub, 0, sizeof(*ub));
1197 ub->st_mode = S_IFIFO | S_IRUSR | S_IWUSR;
1198 ub->st_blksize = pipe->pipe_buffer.size;
1199 if (ub->st_blksize == 0 && pipe->pipe_peer)
1200 ub->st_blksize = pipe->pipe_peer->pipe_buffer.size;
1201 ub->st_size = pipe->pipe_buffer.cnt;
1202 ub->st_blocks = (ub->st_size) ? 1 : 0;
1203 TIMEVAL_TO_TIMESPEC(&pipe->pipe_atime, &ub->st_atimespec);
1204 TIMEVAL_TO_TIMESPEC(&pipe->pipe_mtime, &ub->st_mtimespec);
1205 TIMEVAL_TO_TIMESPEC(&pipe->pipe_ctime, &ub->st_ctimespec);
1206 ub->st_uid = kauth_cred_geteuid(fp->f_cred);
1207 ub->st_gid = kauth_cred_getegid(fp->f_cred);
1208 /*
1209 * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen.
1210 * XXX (st_dev, st_ino) should be unique.
1211 */
1212 return (0);
1213 }
1214
1215 /* ARGSUSED */
1216 static int
1217 pipe_close(struct file *fp, struct lwp *l)
1218 {
1219 struct pipe *pipe = (struct pipe *)fp->f_data;
1220
1221 fp->f_data = NULL;
1222 pipeclose(fp, pipe);
1223 return (0);
1224 }
1225
1226 static void
1227 pipe_free_kmem(struct pipe *pipe)
1228 {
1229
1230 if (pipe->pipe_buffer.buffer != NULL) {
1231 if (pipe->pipe_buffer.size > PIPE_SIZE)
1232 --nbigpipe;
1233 amountpipekva -= pipe->pipe_buffer.size;
1234 uvm_km_free(kernel_map,
1235 (vaddr_t)pipe->pipe_buffer.buffer,
1236 pipe->pipe_buffer.size, UVM_KMF_PAGEABLE);
1237 pipe->pipe_buffer.buffer = NULL;
1238 }
1239 #ifndef PIPE_NODIRECT
1240 if (pipe->pipe_map.kva != 0) {
1241 pipe_loan_free(pipe);
1242 pipe->pipe_map.cnt = 0;
1243 pipe->pipe_map.kva = 0;
1244 pipe->pipe_map.pos = 0;
1245 pipe->pipe_map.npages = 0;
1246 }
1247 #endif /* !PIPE_NODIRECT */
1248 }
1249
1250 /*
1251 * shutdown the pipe
1252 */
1253 static void
1254 pipeclose(struct file *fp, struct pipe *pipe)
1255 {
1256 struct pipe *ppipe;
1257
1258 if (pipe == NULL)
1259 return;
1260
1261 retry:
1262 PIPE_LOCK(pipe);
1263
1264 pipeselwakeup(pipe, pipe, POLL_HUP);
1265
1266 /*
1267 * If the other side is blocked, wake it up saying that
1268 * we want to close it down.
1269 */
1270 pipe->pipe_state |= PIPE_EOF;
1271 while (pipe->pipe_busy) {
1272 wakeup(pipe);
1273 pipe->pipe_state |= PIPE_WANTCLOSE;
1274 ltsleep(pipe, PSOCK, "pipecl", 0, &pipe->pipe_slock);
1275 }
1276
1277 /*
1278 * Disconnect from peer
1279 */
1280 if ((ppipe = pipe->pipe_peer) != NULL) {
1281 /* Deal with race for peer */
1282 if (simple_lock_try(&ppipe->pipe_slock) == 0) {
1283 PIPE_UNLOCK(pipe);
1284 goto retry;
1285 }
1286 pipeselwakeup(ppipe, ppipe, POLL_HUP);
1287
1288 ppipe->pipe_state |= PIPE_EOF;
1289 wakeup(ppipe);
1290 ppipe->pipe_peer = NULL;
1291 PIPE_UNLOCK(ppipe);
1292 }
1293
1294 KASSERT((pipe->pipe_state & PIPE_LOCKFL) == 0);
1295
1296 PIPE_UNLOCK(pipe);
1297
1298 /*
1299 * free resources
1300 */
1301 pipe_free_kmem(pipe);
1302 pool_put(&pipe_pool, pipe);
1303 }
1304
1305 static void
1306 filt_pipedetach(struct knote *kn)
1307 {
1308 struct pipe *pipe = (struct pipe *)kn->kn_fp->f_data;
1309
1310 switch(kn->kn_filter) {
1311 case EVFILT_WRITE:
1312 /* need the peer structure, not our own */
1313 pipe = pipe->pipe_peer;
1314 /* XXXSMP: race for peer */
1315
1316 /* if reader end already closed, just return */
1317 if (pipe == NULL)
1318 return;
1319
1320 break;
1321 default:
1322 /* nothing to do */
1323 break;
1324 }
1325
1326 #ifdef DIAGNOSTIC
1327 if (kn->kn_hook != pipe)
1328 panic("filt_pipedetach: inconsistent knote");
1329 #endif
1330
1331 PIPE_LOCK(pipe);
1332 SLIST_REMOVE(&pipe->pipe_sel.sel_klist, kn, knote, kn_selnext);
1333 PIPE_UNLOCK(pipe);
1334 }
1335
1336 /*ARGSUSED*/
1337 static int
1338 filt_piperead(struct knote *kn, long hint)
1339 {
1340 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1341 struct pipe *wpipe = rpipe->pipe_peer;
1342
1343 if ((hint & NOTE_SUBMIT) == 0)
1344 PIPE_LOCK(rpipe);
1345 kn->kn_data = rpipe->pipe_buffer.cnt;
1346 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1347 kn->kn_data = rpipe->pipe_map.cnt;
1348
1349 /* XXXSMP: race for peer */
1350 if ((rpipe->pipe_state & PIPE_EOF) ||
1351 (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1352 kn->kn_flags |= EV_EOF;
1353 if ((hint & NOTE_SUBMIT) == 0)
1354 PIPE_UNLOCK(rpipe);
1355 return (1);
1356 }
1357 if ((hint & NOTE_SUBMIT) == 0)
1358 PIPE_UNLOCK(rpipe);
1359 return (kn->kn_data > 0);
1360 }
1361
1362 /*ARGSUSED*/
1363 static int
1364 filt_pipewrite(struct knote *kn, long hint)
1365 {
1366 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1367 struct pipe *wpipe = rpipe->pipe_peer;
1368
1369 if ((hint & NOTE_SUBMIT) == 0)
1370 PIPE_LOCK(rpipe);
1371 /* XXXSMP: race for peer */
1372 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1373 kn->kn_data = 0;
1374 kn->kn_flags |= EV_EOF;
1375 if ((hint & NOTE_SUBMIT) == 0)
1376 PIPE_UNLOCK(rpipe);
1377 return (1);
1378 }
1379 kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1380 if (wpipe->pipe_state & PIPE_DIRECTW)
1381 kn->kn_data = 0;
1382
1383 if ((hint & NOTE_SUBMIT) == 0)
1384 PIPE_UNLOCK(rpipe);
1385 return (kn->kn_data >= PIPE_BUF);
1386 }
1387
1388 static const struct filterops pipe_rfiltops =
1389 { 1, NULL, filt_pipedetach, filt_piperead };
1390 static const struct filterops pipe_wfiltops =
1391 { 1, NULL, filt_pipedetach, filt_pipewrite };
1392
1393 /*ARGSUSED*/
1394 static int
1395 pipe_kqfilter(struct file *fp, struct knote *kn)
1396 {
1397 struct pipe *pipe;
1398
1399 pipe = (struct pipe *)kn->kn_fp->f_data;
1400 switch (kn->kn_filter) {
1401 case EVFILT_READ:
1402 kn->kn_fop = &pipe_rfiltops;
1403 break;
1404 case EVFILT_WRITE:
1405 kn->kn_fop = &pipe_wfiltops;
1406 /* XXXSMP: race for peer */
1407 pipe = pipe->pipe_peer;
1408 if (pipe == NULL) {
1409 /* other end of pipe has been closed */
1410 return (EBADF);
1411 }
1412 break;
1413 default:
1414 return (1);
1415 }
1416 kn->kn_hook = pipe;
1417
1418 PIPE_LOCK(pipe);
1419 SLIST_INSERT_HEAD(&pipe->pipe_sel.sel_klist, kn, kn_selnext);
1420 PIPE_UNLOCK(pipe);
1421 return (0);
1422 }
1423
1424 /*
1425 * Handle pipe sysctls.
1426 */
1427 SYSCTL_SETUP(sysctl_kern_pipe_setup, "sysctl kern.pipe subtree setup")
1428 {
1429
1430 sysctl_createv(clog, 0, NULL, NULL,
1431 CTLFLAG_PERMANENT,
1432 CTLTYPE_NODE, "kern", NULL,
1433 NULL, 0, NULL, 0,
1434 CTL_KERN, CTL_EOL);
1435 sysctl_createv(clog, 0, NULL, NULL,
1436 CTLFLAG_PERMANENT,
1437 CTLTYPE_NODE, "pipe",
1438 SYSCTL_DESCR("Pipe settings"),
1439 NULL, 0, NULL, 0,
1440 CTL_KERN, KERN_PIPE, CTL_EOL);
1441
1442 sysctl_createv(clog, 0, NULL, NULL,
1443 CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1444 CTLTYPE_INT, "maxkvasz",
1445 SYSCTL_DESCR("Maximum amount of kernel memory to be "
1446 "used for pipes"),
1447 NULL, 0, &maxpipekva, 0,
1448 CTL_KERN, KERN_PIPE, KERN_PIPE_MAXKVASZ, CTL_EOL);
1449 sysctl_createv(clog, 0, NULL, NULL,
1450 CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1451 CTLTYPE_INT, "maxloankvasz",
1452 SYSCTL_DESCR("Limit for direct transfers via page loan"),
1453 NULL, 0, &limitpipekva, 0,
1454 CTL_KERN, KERN_PIPE, KERN_PIPE_LIMITKVA, CTL_EOL);
1455 sysctl_createv(clog, 0, NULL, NULL,
1456 CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1457 CTLTYPE_INT, "maxbigpipes",
1458 SYSCTL_DESCR("Maximum number of \"big\" pipes"),
1459 NULL, 0, &maxbigpipes, 0,
1460 CTL_KERN, KERN_PIPE, KERN_PIPE_MAXBIGPIPES, CTL_EOL);
1461 sysctl_createv(clog, 0, NULL, NULL,
1462 CTLFLAG_PERMANENT,
1463 CTLTYPE_INT, "nbigpipes",
1464 SYSCTL_DESCR("Number of \"big\" pipes"),
1465 NULL, 0, &nbigpipe, 0,
1466 CTL_KERN, KERN_PIPE, KERN_PIPE_NBIGPIPES, CTL_EOL);
1467 sysctl_createv(clog, 0, NULL, NULL,
1468 CTLFLAG_PERMANENT,
1469 CTLTYPE_INT, "kvasize",
1470 SYSCTL_DESCR("Amount of kernel memory consumed by pipe "
1471 "buffers"),
1472 NULL, 0, &amountpipekva, 0,
1473 CTL_KERN, KERN_PIPE, KERN_PIPE_KVASIZE, CTL_EOL);
1474 }
Cache object: 479077884af7b08c2e4b0f0667a3ef3e
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