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kernel - kqueue - major refactoring
[dragonfly.git] / sys / kern / sys_pipe.c
blob9203d13f51e2fcb83892eacd0d1e048e870e111f
1 /*
2 * Copyright (c) 1996 John S. Dyson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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
15 * John S. Dyson.
16 * 4. Modifications may be freely made to this file if the above conditions
17 * are met.
18 *
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 1.50 2008/09/09 04:06:13 dillon Exp $
21 */
22
23 /*
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
27 * do.
28 */
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
32 #include <sys/proc.h>
33 #include <sys/fcntl.h>
34 #include <sys/file.h>
35 #include <sys/filedesc.h>
36 #include <sys/filio.h>
37 #include <sys/ttycom.h>
38 #include <sys/stat.h>
39 #include <sys/poll.h>
40 #include <sys/select.h>
41 #include <sys/signalvar.h>
42 #include <sys/sysproto.h>
43 #include <sys/pipe.h>
44 #include <sys/vnode.h>
45 #include <sys/uio.h>
46 #include <sys/event.h>
47 #include <sys/globaldata.h>
48 #include <sys/module.h>
49 #include <sys/malloc.h>
50 #include <sys/sysctl.h>
51 #include <sys/socket.h>
52
53 #include <vm/vm.h>
54 #include <vm/vm_param.h>
55 #include <sys/lock.h>
56 #include <vm/vm_object.h>
57 #include <vm/vm_kern.h>
58 #include <vm/vm_extern.h>
59 #include <vm/pmap.h>
60 #include <vm/vm_map.h>
61 #include <vm/vm_page.h>
62 #include <vm/vm_zone.h>
63
64 #include <sys/file2.h>
65 #include <sys/signal2.h>
66 #include <sys/mplock2.h>
67
68 #include <machine/cpufunc.h>
69
70 /*
71 * interfaces to the outside world
72 */
73 static int pipe_read (struct file *fp, struct uio *uio,
74 struct ucred *cred, int flags);
75 static int pipe_write (struct file *fp, struct uio *uio,
76 struct ucred *cred, int flags);
77 static int pipe_close (struct file *fp);
78 static int pipe_shutdown (struct file *fp, int how);
79 static int pipe_poll (struct file *fp, int events, struct ucred *cred);
80 static int pipe_kqfilter (struct file *fp, struct knote *kn);
81 static int pipe_stat (struct file *fp, struct stat *sb, struct ucred *cred);
82 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data,
83 struct ucred *cred, struct sysmsg *msg);
84
85 static struct fileops pipeops = {
86 .fo_read = pipe_read,
87 .fo_write = pipe_write,
88 .fo_ioctl = pipe_ioctl,
89 .fo_poll = pipe_poll,
90 .fo_kqfilter = pipe_kqfilter,
91 .fo_stat = pipe_stat,
92 .fo_close = pipe_close,
93 .fo_shutdown = pipe_shutdown
94 };
95
96 static void filt_pipedetach(struct knote *kn);
97 static int filt_piperead(struct knote *kn, long hint);
98 static int filt_pipewrite(struct knote *kn, long hint);
99
100 static struct filterops pipe_rfiltops =
101 { 1, NULL, filt_pipedetach, filt_piperead };
102 static struct filterops pipe_wfiltops =
103 { 1, NULL, filt_pipedetach, filt_pipewrite };
104
105 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures");
106
107 /*
108 * Default pipe buffer size(s), this can be kind-of large now because pipe
109 * space is pageable. The pipe code will try to maintain locality of
110 * reference for performance reasons, so small amounts of outstanding I/O
111 * will not wipe the cache.
112 */
113 #define MINPIPESIZE (PIPE_SIZE/3)
114 #define MAXPIPESIZE (2*PIPE_SIZE/3)
115
116 /*
117 * Limit the number of "big" pipes
118 */
119 #define LIMITBIGPIPES 64
120 #define PIPEQ_MAX_CACHE 16 /* per-cpu pipe structure cache */
121
122 static int pipe_maxbig = LIMITBIGPIPES;
123 static int pipe_maxcache = PIPEQ_MAX_CACHE;
124 static int pipe_bigcount;
125 static int pipe_nbig;
126 static int pipe_bcache_alloc;
127 static int pipe_bkmem_alloc;
128 static int pipe_rblocked_count;
129 static int pipe_wblocked_count;
130
131 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation");
132 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig,
133 CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated");
134 SYSCTL_INT(_kern_pipe, OID_AUTO, bigcount,
135 CTLFLAG_RW, &pipe_bigcount, 0, "number of times pipe expanded");
136 SYSCTL_INT(_kern_pipe, OID_AUTO, rblocked,
137 CTLFLAG_RW, &pipe_rblocked_count, 0, "number of times pipe expanded");
138 SYSCTL_INT(_kern_pipe, OID_AUTO, wblocked,
139 CTLFLAG_RW, &pipe_wblocked_count, 0, "number of times pipe expanded");
140 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache,
141 CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu");
142 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig,
143 CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes");
144 #ifdef SMP
145 static int pipe_delay = 5000; /* 5uS default */
146 SYSCTL_INT(_kern_pipe, OID_AUTO, delay,
147 CTLFLAG_RW, &pipe_delay, 0, "SMP delay optimization in ns");
148 static int pipe_mpsafe = 1;
149 SYSCTL_INT(_kern_pipe, OID_AUTO, mpsafe,
150 CTLFLAG_RW, &pipe_mpsafe, 0, "");
151 #endif
152 #if !defined(NO_PIPE_SYSCTL_STATS)
153 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc,
154 CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache");
155 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc,
156 CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem");
157 #endif
158
159 static void pipeclose (struct pipe *cpipe);
160 static void pipe_free_kmem (struct pipe *cpipe);
161 static int pipe_create (struct pipe **cpipep);
162 static __inline void pipeselwakeup (struct pipe *cpipe);
163 static int pipespace (struct pipe *cpipe, int size);
164
165 static __inline int
166 pipeseltest(struct pipe *cpipe)
167 {
168 return ((cpipe->pipe_state & PIPE_SEL) ||
169 ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) ||
170 SLIST_FIRST(&cpipe->pipe_sel.si_note));
171 }
172
173 static __inline void
174 pipeselwakeup(struct pipe *cpipe)
175 {
176 if (cpipe->pipe_state & PIPE_SEL) {
177 get_mplock();
178 cpipe->pipe_state &= ~PIPE_SEL;
179 selwakeup(&cpipe->pipe_sel);
180 rel_mplock();
181 }
182 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) {
183 get_mplock();
184 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
185 rel_mplock();
186 }
187 if (SLIST_FIRST(&cpipe->pipe_sel.si_note)) {
188 get_mplock();
189 KNOTE(&cpipe->pipe_sel.si_note, 0);
190 rel_mplock();
191 }
192 }
193
194 /*
195 * These routines are called before and after a UIO. The UIO
196 * may block, causing our held tokens to be lost temporarily.
197 *
198 * We use these routines to serialize reads against other reads
199 * and writes against other writes.
200 *
201 * The read token is held on entry so *ipp does not race.
202 */
203 static __inline int
204 pipe_start_uio(struct pipe *cpipe, int *ipp)
205 {
206 int error;
207
208 while (*ipp) {
209 *ipp = -1;
210 error = tsleep(ipp, PCATCH, "pipexx", 0);
211 if (error)
212 return (error);
213 }
214 *ipp = 1;
215 return (0);
216 }
217
218 static __inline void
219 pipe_end_uio(struct pipe *cpipe, int *ipp)
220 {
221 if (*ipp < 0) {
222 *ipp = 0;
223 wakeup(ipp);
224 } else {
225 KKASSERT(*ipp > 0);
226 *ipp = 0;
227 }
228 }
229
230 static __inline void
231 pipe_get_mplock(int *save)
232 {
233 #ifdef SMP
234 if (pipe_mpsafe == 0) {
235 get_mplock();
236 *save = 1;
237 } else
238 #endif
239 {
240 *save = 0;
241 }
242 }
243
244 static __inline void
245 pipe_rel_mplock(int *save)
246 {
247 #ifdef SMP
248 if (*save)
249 rel_mplock();
250 #endif
251 }
252
253
254 /*
255 * The pipe system call for the DTYPE_PIPE type of pipes
256 *
257 * pipe_args(int dummy)
258 *
259 * MPSAFE
260 */
261 int
262 sys_pipe(struct pipe_args *uap)
263 {
264 struct thread *td = curthread;
265 struct filedesc *fdp = td->td_proc->p_fd;
266 struct file *rf, *wf;
267 struct pipe *rpipe, *wpipe;
268 int fd1, fd2, error;
269
270 rpipe = wpipe = NULL;
271 if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
272 pipeclose(rpipe);
273 pipeclose(wpipe);
274 return (ENFILE);
275 }
276
277 error = falloc(td->td_lwp, &rf, &fd1);
278 if (error) {
279 pipeclose(rpipe);
280 pipeclose(wpipe);
281 return (error);
282 }
283 uap->sysmsg_fds[0] = fd1;
284
285 /*
286 * Warning: once we've gotten past allocation of the fd for the
287 * read-side, we can only drop the read side via fdrop() in order
288 * to avoid races against processes which manage to dup() the read
289 * side while we are blocked trying to allocate the write side.
290 */
291 rf->f_type = DTYPE_PIPE;
292 rf->f_flag = FREAD | FWRITE;
293 rf->f_ops = &pipeops;
294 rf->f_data = rpipe;
295 error = falloc(td->td_lwp, &wf, &fd2);
296 if (error) {
297 fsetfd(fdp, NULL, fd1);
298 fdrop(rf);
299 /* rpipe has been closed by fdrop(). */
300 pipeclose(wpipe);
301 return (error);
302 }
303 wf->f_type = DTYPE_PIPE;
304 wf->f_flag = FREAD | FWRITE;
305 wf->f_ops = &pipeops;
306 wf->f_data = wpipe;
307 uap->sysmsg_fds[1] = fd2;
308
309 rpipe->pipe_slock = kmalloc(sizeof(struct lock),
310 M_PIPE, M_WAITOK|M_ZERO);
311 wpipe->pipe_slock = rpipe->pipe_slock;
312 rpipe->pipe_peer = wpipe;
313 wpipe->pipe_peer = rpipe;
314 lockinit(rpipe->pipe_slock, "pipecl", 0, 0);
315
316 /*
317 * Once activated the peer relationship remains valid until
318 * both sides are closed.
319 */
320 fsetfd(fdp, rf, fd1);
321 fsetfd(fdp, wf, fd2);
322 fdrop(rf);
323 fdrop(wf);
324
325 return (0);
326 }
327
328 /*
329 * Allocate kva for pipe circular buffer, the space is pageable
330 * This routine will 'realloc' the size of a pipe safely, if it fails
331 * it will retain the old buffer.
332 * If it fails it will return ENOMEM.
333 */
334 static int
335 pipespace(struct pipe *cpipe, int size)
336 {
337 struct vm_object *object;
338 caddr_t buffer;
339 int npages, error;
340
341 npages = round_page(size) / PAGE_SIZE;
342 object = cpipe->pipe_buffer.object;
343
344 /*
345 * [re]create the object if necessary and reserve space for it
346 * in the kernel_map. The object and memory are pageable. On
347 * success, free the old resources before assigning the new
348 * ones.
349 */
350 if (object == NULL || object->size != npages) {
351 get_mplock();
352 object = vm_object_allocate(OBJT_DEFAULT, npages);
353 buffer = (caddr_t)vm_map_min(&kernel_map);
354
355 error = vm_map_find(&kernel_map, object, 0,
356 (vm_offset_t *)&buffer, size,
357 1,
358 VM_MAPTYPE_NORMAL,
359 VM_PROT_ALL, VM_PROT_ALL,
360 0);
361
362 if (error != KERN_SUCCESS) {
363 vm_object_deallocate(object);
364 rel_mplock();
365 return (ENOMEM);
366 }
367 pipe_free_kmem(cpipe);
368 rel_mplock();
369 cpipe->pipe_buffer.object = object;
370 cpipe->pipe_buffer.buffer = buffer;
371 cpipe->pipe_buffer.size = size;
372 ++pipe_bkmem_alloc;
373 } else {
374 ++pipe_bcache_alloc;
375 }
376 cpipe->pipe_buffer.rindex = 0;
377 cpipe->pipe_buffer.windex = 0;
378 return (0);
379 }
380
381 /*
382 * Initialize and allocate VM and memory for pipe, pulling the pipe from
383 * our per-cpu cache if possible. For now make sure it is sized for the
384 * smaller PIPE_SIZE default.
385 */
386 static int
387 pipe_create(struct pipe **cpipep)
388 {
389 globaldata_t gd = mycpu;
390 struct pipe *cpipe;
391 int error;
392
393 if ((cpipe = gd->gd_pipeq) != NULL) {
394 gd->gd_pipeq = cpipe->pipe_peer;
395 --gd->gd_pipeqcount;
396 cpipe->pipe_peer = NULL;
397 cpipe->pipe_wantwcnt = 0;
398 } else {
399 cpipe = kmalloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
400 }
401 *cpipep = cpipe;
402 if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
403 return (error);
404 vfs_timestamp(&cpipe->pipe_ctime);
405 cpipe->pipe_atime = cpipe->pipe_ctime;
406 cpipe->pipe_mtime = cpipe->pipe_ctime;
407 lwkt_token_init(&cpipe->pipe_rlock);
408 lwkt_token_init(&cpipe->pipe_wlock);
409 return (0);
410 }
411
412 /*
413 * MPALMOSTSAFE (acquires mplock)
414 */
415 static int
416 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
417 {
418 struct pipe *rpipe;
419 int error;
420 size_t nread = 0;
421 int nbio;
422 u_int size; /* total bytes available */
423 u_int nsize; /* total bytes to read */
424 u_int rindex; /* contiguous bytes available */
425 int notify_writer;
426 lwkt_tokref rlock;
427 lwkt_tokref wlock;
428 int mpsave;
429 int bigread;
430 int bigcount;
431
432 if (uio->uio_resid == 0)
433 return(0);
434
435 /*
436 * Setup locks, calculate nbio
437 */
438 pipe_get_mplock(&mpsave);
439 rpipe = (struct pipe *)fp->f_data;
440 lwkt_gettoken(&rlock, &rpipe->pipe_rlock);
441
442 if (fflags & O_FBLOCKING)
443 nbio = 0;
444 else if (fflags & O_FNONBLOCKING)
445 nbio = 1;
446 else if (fp->f_flag & O_NONBLOCK)
447 nbio = 1;
448 else
449 nbio = 0;
450
451 /*
452 * Reads are serialized. Note howeverthat pipe_buffer.buffer and
453 * pipe_buffer.size can change out from under us when the number
454 * of bytes in the buffer are zero due to the write-side doing a
455 * pipespace().
456 */
457 error = pipe_start_uio(rpipe, &rpipe->pipe_rip);
458 if (error) {
459 pipe_rel_mplock(&mpsave);
460 lwkt_reltoken(&rlock);
461 return (error);
462 }
463 notify_writer = 0;
464
465 bigread = (uio->uio_resid > 10 * 1024 * 1024);
466 bigcount = 10;
467
468 while (uio->uio_resid) {
469 /*
470 * Don't hog the cpu.
471 */
472 if (bigread && --bigcount == 0) {
473 lwkt_user_yield();
474 bigcount = 10;
475 if (CURSIG(curthread->td_lwp)) {
476 error = EINTR;
477 break;
478 }
479 }
480
481 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
482 cpu_lfence();
483 if (size) {
484 rindex = rpipe->pipe_buffer.rindex &
485 (rpipe->pipe_buffer.size - 1);
486 nsize = size;
487 if (nsize > rpipe->pipe_buffer.size - rindex)
488 nsize = rpipe->pipe_buffer.size - rindex;
489 nsize = szmin(nsize, uio->uio_resid);
490
491 error = uiomove(&rpipe->pipe_buffer.buffer[rindex],
492 nsize, uio);
493 if (error)
494 break;
495 cpu_mfence();
496 rpipe->pipe_buffer.rindex += nsize;
497 nread += nsize;
498
499 /*
500 * If the FIFO is still over half full just continue
501 * and do not try to notify the writer yet.
502 */
503 if (size - nsize >= (rpipe->pipe_buffer.size >> 1)) {
504 notify_writer = 0;
505 continue;
506 }
507
508 /*
509 * When the FIFO is less then half full notify any
510 * waiting writer. WANTW can be checked while
511 * holding just the rlock.
512 */
513 notify_writer = 1;
514 if ((rpipe->pipe_state & PIPE_WANTW) == 0)
515 continue;
516 }
517
518 /*
519 * If the "write-side" was blocked we wake it up. This code
520 * is reached either when the buffer is completely emptied
521 * or if it becomes more then half-empty.
522 *
523 * Pipe_state can only be modified if both the rlock and
524 * wlock are held.
525 */
526 if (rpipe->pipe_state & PIPE_WANTW) {
527 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
528 if (rpipe->pipe_state & PIPE_WANTW) {
529 notify_writer = 0;
530 rpipe->pipe_state &= ~PIPE_WANTW;
531 lwkt_reltoken(&wlock);
532 wakeup(rpipe);
533 } else {
534 lwkt_reltoken(&wlock);
535 }
536 }
537
538 /*
539 * Pick up our copy loop again if the writer sent data to
540 * us while we were messing around.
541 *
542 * On a SMP box poll up to pipe_delay nanoseconds for new
543 * data. Typically a value of 2000 to 4000 is sufficient
544 * to eradicate most IPIs/tsleeps/wakeups when a pipe
545 * is used for synchronous communications with small packets,
546 * and 8000 or so (8uS) will pipeline large buffer xfers
547 * between cpus over a pipe.
548 *
549 * For synchronous communications a hit means doing a
550 * full Awrite-Bread-Bwrite-Aread cycle in less then 2uS,
551 * where as miss requiring a tsleep/wakeup sequence
552 * will take 7uS or more.
553 */
554 if (rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex)
555 continue;
556
557 #if defined(SMP) && defined(_RDTSC_SUPPORTED_)
558 if (pipe_delay) {
559 int64_t tsc_target;
560 int good = 0;
561
562 tsc_target = tsc_get_target(pipe_delay);
563 while (tsc_test_target(tsc_target) == 0) {
564 if (rpipe->pipe_buffer.windex !=
565 rpipe->pipe_buffer.rindex) {
566 good = 1;
567 break;
568 }
569 }
570 if (good)
571 continue;
572 }
573 #endif
574
575 /*
576 * Detect EOF condition, do not set error.
577 */
578 if (rpipe->pipe_state & PIPE_REOF)
579 break;
580
581 /*
582 * Break if some data was read, or if this was a non-blocking
583 * read.
584 */
585 if (nread > 0)
586 break;
587
588 if (nbio) {
589 error = EAGAIN;
590 break;
591 }
592
593 /*
594 * Last chance, interlock with WANTR.
595 */
596 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
597 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
598 if (size) {
599 lwkt_reltoken(&wlock);
600 continue;
601 }
602
603 /*
604 * Retest EOF - acquiring a new token can temporarily release
605 * tokens already held.
606 */
607 if (rpipe->pipe_state & PIPE_REOF) {
608 lwkt_reltoken(&wlock);
609 break;
610 }
611
612 /*
613 * If there is no more to read in the pipe, reset its
614 * pointers to the beginning. This improves cache hit
615 * stats.
616 *
617 * We need both locks to modify both pointers, and there
618 * must also not be a write in progress or the uiomove()
619 * in the write might block and temporarily release
620 * its wlock, then reacquire and update windex. We are
621 * only serialized against reads, not writes.
622 *
623 * XXX should we even bother resetting the indices? It
624 * might actually be more cache efficient not to.
625 */
626 if (rpipe->pipe_buffer.rindex == rpipe->pipe_buffer.windex &&
627 rpipe->pipe_wip == 0) {
628 rpipe->pipe_buffer.rindex = 0;
629 rpipe->pipe_buffer.windex = 0;
630 }
631
632 /*
633 * Wait for more data.
634 *
635 * Pipe_state can only be set if both the rlock and wlock
636 * are held.
637 */
638 rpipe->pipe_state |= PIPE_WANTR;
639 tsleep_interlock(rpipe, PCATCH);
640 lwkt_reltoken(&wlock);
641 error = tsleep(rpipe, PCATCH | PINTERLOCKED, "piperd", 0);
642 ++pipe_rblocked_count;
643 if (error)
644 break;
645 }
646 pipe_end_uio(rpipe, &rpipe->pipe_rip);
647
648 /*
649 * Uptime last access time
650 */
651 if (error == 0 && nread)
652 vfs_timestamp(&rpipe->pipe_atime);
653
654 /*
655 * If we drained the FIFO more then half way then handle
656 * write blocking hysteresis.
657 *
658 * Note that PIPE_WANTW cannot be set by the writer without
659 * it holding both rlock and wlock, so we can test it
660 * while holding just rlock.
661 */
662 if (notify_writer) {
663 if (rpipe->pipe_state & PIPE_WANTW) {
664 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
665 if (rpipe->pipe_state & PIPE_WANTW) {
666 rpipe->pipe_state &= ~PIPE_WANTW;
667 lwkt_reltoken(&wlock);
668 wakeup(rpipe);
669 } else {
670 lwkt_reltoken(&wlock);
671 }
672 }
673 if (pipeseltest(rpipe)) {
674 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
675 pipeselwakeup(rpipe);
676 lwkt_reltoken(&wlock);
677 }
678 }
679 /*size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;*/
680 lwkt_reltoken(&rlock);
681
682 pipe_rel_mplock(&mpsave);
683 return (error);
684 }
685
686 /*
687 * MPALMOSTSAFE - acquires mplock
688 */
689 static int
690 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
691 {
692 int error;
693 int orig_resid;
694 int nbio;
695 struct pipe *wpipe, *rpipe;
696 lwkt_tokref rlock;
697 lwkt_tokref wlock;
698 u_int windex;
699 u_int space;
700 u_int wcount;
701 int mpsave;
702 int bigwrite;
703 int bigcount;
704
705 pipe_get_mplock(&mpsave);
706
707 /*
708 * Writes go to the peer. The peer will always exist.
709 */
710 rpipe = (struct pipe *) fp->f_data;
711 wpipe = rpipe->pipe_peer;
712 lwkt_gettoken(&wlock, &wpipe->pipe_wlock);
713 if (wpipe->pipe_state & PIPE_WEOF) {
714 pipe_rel_mplock(&mpsave);
715 lwkt_reltoken(&wlock);
716 return (EPIPE);
717 }
718
719 /*
720 * Degenerate case (EPIPE takes prec)
721 */
722 if (uio->uio_resid == 0) {
723 pipe_rel_mplock(&mpsave);
724 lwkt_reltoken(&wlock);
725 return(0);
726 }
727
728 /*
729 * Writes are serialized (start_uio must be called with wlock)
730 */
731 error = pipe_start_uio(wpipe, &wpipe->pipe_wip);
732 if (error) {
733 pipe_rel_mplock(&mpsave);
734 lwkt_reltoken(&wlock);
735 return (error);
736 }
737
738 if (fflags & O_FBLOCKING)
739 nbio = 0;
740 else if (fflags & O_FNONBLOCKING)
741 nbio = 1;
742 else if (fp->f_flag & O_NONBLOCK)
743 nbio = 1;
744 else
745 nbio = 0;
746
747 /*
748 * If it is advantageous to resize the pipe buffer, do
749 * so. We are write-serialized so we can block safely.
750 */
751 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) &&
752 (pipe_nbig < pipe_maxbig) &&
753 wpipe->pipe_wantwcnt > 4 &&
754 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) {
755 /*
756 * Recheck after lock.
757 */
758 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
759 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) &&
760 (pipe_nbig < pipe_maxbig) &&
761 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) {
762 atomic_add_int(&pipe_nbig, 1);
763 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
764 ++pipe_bigcount;
765 else
766 atomic_subtract_int(&pipe_nbig, 1);
767 }
768 lwkt_reltoken(&rlock);
769 }
770
771 orig_resid = uio->uio_resid;
772 wcount = 0;
773
774 bigwrite = (uio->uio_resid > 10 * 1024 * 1024);
775 bigcount = 10;
776
777 while (uio->uio_resid) {
778 if (wpipe->pipe_state & PIPE_WEOF) {
779 error = EPIPE;
780 break;
781 }
782
783 /*
784 * Don't hog the cpu.
785 */
786 if (bigwrite && --bigcount == 0) {
787 lwkt_user_yield();
788 bigcount = 10;
789 if (CURSIG(curthread->td_lwp)) {
790 error = EINTR;
791 break;
792 }
793 }
794
795 windex = wpipe->pipe_buffer.windex &
796 (wpipe->pipe_buffer.size - 1);
797 space = wpipe->pipe_buffer.size -
798 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex);
799 cpu_lfence();
800
801 /* Writes of size <= PIPE_BUF must be atomic. */
802 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
803 space = 0;
804
805 /*
806 * Write to fill, read size handles write hysteresis. Also
807 * additional restrictions can cause select-based non-blocking
808 * writes to spin.
809 */
810 if (space > 0) {
811 u_int segsize;
812
813 /*
814 * Transfer size is minimum of uio transfer
815 * and free space in pipe buffer.
816 *
817 * Limit each uiocopy to no more then PIPE_SIZE
818 * so we can keep the gravy train going on a
819 * SMP box. This doubles the performance for
820 * write sizes > 16K. Otherwise large writes
821 * wind up doing an inefficient synchronous
822 * ping-pong.
823 */
824 space = szmin(space, uio->uio_resid);
825 if (space > PIPE_SIZE)
826 space = PIPE_SIZE;
827
828 /*
829 * First segment to transfer is minimum of
830 * transfer size and contiguous space in
831 * pipe buffer. If first segment to transfer
832 * is less than the transfer size, we've got
833 * a wraparound in the buffer.
834 */
835 segsize = wpipe->pipe_buffer.size - windex;
836 if (segsize > space)
837 segsize = space;
838
839 #ifdef SMP
840 /*
841 * If this is the first loop and the reader is
842 * blocked, do a preemptive wakeup of the reader.
843 *
844 * On SMP the IPI latency plus the wlock interlock
845 * on the reader side is the fastest way to get the
846 * reader going. (The scheduler will hard loop on
847 * lock tokens).
848 *
849 * NOTE: We can't clear WANTR here without acquiring
850 * the rlock, which we don't want to do here!
851 */
852 if ((wpipe->pipe_state & PIPE_WANTR) && pipe_mpsafe > 1)
853 wakeup(wpipe);
854 #endif
855
856 /*
857 * Transfer segment, which may include a wrap-around.
858 * Update windex to account for both all in one go
859 * so the reader can read() the data atomically.
860 */
861 error = uiomove(&wpipe->pipe_buffer.buffer[windex],
862 segsize, uio);
863 if (error == 0 && segsize < space) {
864 segsize = space - segsize;
865 error = uiomove(&wpipe->pipe_buffer.buffer[0],
866 segsize, uio);
867 }
868 if (error)
869 break;
870 cpu_mfence();
871 wpipe->pipe_buffer.windex += space;
872 wcount += space;
873 continue;
874 }
875
876 /*
877 * We need both the rlock and the wlock to interlock against
878 * the EOF, WANTW, and size checks, and to modify pipe_state.
879 *
880 * These are token locks so we do not have to worry about
881 * deadlocks.
882 */
883 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
884
885 /*
886 * If the "read-side" has been blocked, wake it up now
887 * and yield to let it drain synchronously rather
888 * then block.
889 */
890 if (wpipe->pipe_state & PIPE_WANTR) {
891 wpipe->pipe_state &= ~PIPE_WANTR;
892 wakeup(wpipe);
893 }
894
895 /*
896 * don't block on non-blocking I/O
897 */
898 if (nbio) {
899 lwkt_reltoken(&rlock);
900 error = EAGAIN;
901 break;
902 }
903
904 /*
905 * re-test whether we have to block in the writer after
906 * acquiring both locks, in case the reader opened up
907 * some space.
908 */
909 space = wpipe->pipe_buffer.size -
910 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex);
911 cpu_lfence();
912 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
913 space = 0;
914
915 /*
916 * Retest EOF - acquiring a new token can temporarily release
917 * tokens already held.
918 */
919 if (wpipe->pipe_state & PIPE_WEOF) {
920 lwkt_reltoken(&rlock);
921 error = EPIPE;
922 break;
923 }
924
925 /*
926 * We have no more space and have something to offer,
927 * wake up select/poll.
928 */
929 if (space == 0) {
930 wpipe->pipe_state |= PIPE_WANTW;
931 ++wpipe->pipe_wantwcnt;
932 pipeselwakeup(wpipe);
933 if (wpipe->pipe_state & PIPE_WANTW)
934 error = tsleep(wpipe, PCATCH, "pipewr", 0);
935 ++pipe_wblocked_count;
936 }
937 lwkt_reltoken(&rlock);
938
939 /*
940 * Break out if we errored or the read side wants us to go
941 * away.
942 */
943 if (error)
944 break;
945 if (wpipe->pipe_state & PIPE_WEOF) {
946 error = EPIPE;
947 break;
948 }
949 }
950 pipe_end_uio(wpipe, &wpipe->pipe_wip);
951
952 /*
953 * If we have put any characters in the buffer, we wake up
954 * the reader.
955 *
956 * Both rlock and wlock are required to be able to modify pipe_state.
957 */
958 if (wpipe->pipe_buffer.windex != wpipe->pipe_buffer.rindex) {
959 if (wpipe->pipe_state & PIPE_WANTR) {
960 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
961 if (wpipe->pipe_state & PIPE_WANTR) {
962 wpipe->pipe_state &= ~PIPE_WANTR;
963 lwkt_reltoken(&rlock);
964 wakeup(wpipe);
965 } else {
966 lwkt_reltoken(&rlock);
967 }
968 }
969 if (pipeseltest(wpipe)) {
970 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
971 pipeselwakeup(wpipe);
972 lwkt_reltoken(&rlock);
973 }
974 }
975
976 /*
977 * Don't return EPIPE if I/O was successful
978 */
979 if ((wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex) &&
980 (uio->uio_resid == 0) &&
981 (error == EPIPE)) {
982 error = 0;
983 }
984
985 if (error == 0)
986 vfs_timestamp(&wpipe->pipe_mtime);
987
988 /*
989 * We have something to offer,
990 * wake up select/poll.
991 */
992 /*space = wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex;*/
993 lwkt_reltoken(&wlock);
994 pipe_rel_mplock(&mpsave);
995 return (error);
996 }
997
998 /*
999 * MPALMOSTSAFE - acquires mplock
1000 *
1001 * we implement a very minimal set of ioctls for compatibility with sockets.
1002 */
1003 int
1004 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data,
1005 struct ucred *cred, struct sysmsg *msg)
1006 {
1007 struct pipe *mpipe;
1008 lwkt_tokref rlock;
1009 lwkt_tokref wlock;
1010 int error;
1011 int mpsave;
1012
1013 pipe_get_mplock(&mpsave);
1014 mpipe = (struct pipe *)fp->f_data;
1015
1016 lwkt_gettoken(&rlock, &mpipe->pipe_rlock);
1017 lwkt_gettoken(&wlock, &mpipe->pipe_wlock);
1018
1019 switch (cmd) {
1020 case FIOASYNC:
1021 if (*(int *)data) {
1022 mpipe->pipe_state |= PIPE_ASYNC;
1023 } else {
1024 mpipe->pipe_state &= ~PIPE_ASYNC;
1025 }
1026 error = 0;
1027 break;
1028 case FIONREAD:
1029 *(int *)data = mpipe->pipe_buffer.windex -
1030 mpipe->pipe_buffer.rindex;
1031 error = 0;
1032 break;
1033 case FIOSETOWN:
1034 get_mplock();
1035 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1036 rel_mplock();
1037 break;
1038 case FIOGETOWN:
1039 *(int *)data = fgetown(mpipe->pipe_sigio);
1040 error = 0;
1041 break;
1042 case TIOCSPGRP:
1043 /* This is deprecated, FIOSETOWN should be used instead. */
1044 get_mplock();
1045 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1046 rel_mplock();
1047 break;
1048
1049 case TIOCGPGRP:
1050 /* This is deprecated, FIOGETOWN should be used instead. */
1051 *(int *)data = -fgetown(mpipe->pipe_sigio);
1052 error = 0;
1053 break;
1054 default:
1055 error = ENOTTY;
1056 break;
1057 }
1058 lwkt_reltoken(&rlock);
1059 lwkt_reltoken(&wlock);
1060 pipe_rel_mplock(&mpsave);
1061
1062 return (error);
1063 }
1064
1065 /*
1066 * MPALMOSTSAFE - acquires mplock
1067 *
1068 * poll for events (helper)
1069 */
1070 static int
1071 pipe_poll_events(struct pipe *rpipe, struct pipe *wpipe, int events)
1072 {
1073 int revents = 0;
1074 u_int space;
1075
1076 if (events & (POLLIN | POLLRDNORM)) {
1077 if ((rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex) ||
1078 (rpipe->pipe_state & PIPE_REOF)) {
1079 revents |= events & (POLLIN | POLLRDNORM);
1080 }
1081 }
1082
1083 if (events & (POLLOUT | POLLWRNORM)) {
1084 if (wpipe == NULL || (wpipe->pipe_state & PIPE_WEOF)) {
1085 revents |= events & (POLLOUT | POLLWRNORM);
1086 } else {
1087 space = wpipe->pipe_buffer.windex -
1088 wpipe->pipe_buffer.rindex;
1089 space = wpipe->pipe_buffer.size - space;
1090 if (space >= PIPE_BUF)
1091 revents |= events & (POLLOUT | POLLWRNORM);
1092 }
1093 }
1094
1095 if ((rpipe->pipe_state & PIPE_REOF) ||
1096 (wpipe == NULL) ||
1097 (wpipe->pipe_state & PIPE_WEOF)) {
1098 revents |= POLLHUP;
1099 }
1100 return (revents);
1101 }
1102
1103 /*
1104 * Poll for events from file pointer.
1105 */
1106 int
1107 pipe_poll(struct file *fp, int events, struct ucred *cred)
1108 {
1109 lwkt_tokref rpipe_rlock;
1110 lwkt_tokref rpipe_wlock;
1111 lwkt_tokref wpipe_rlock;
1112 lwkt_tokref wpipe_wlock;
1113 struct pipe *rpipe;
1114 struct pipe *wpipe;
1115 int revents = 0;
1116 int mpsave;
1117
1118 pipe_get_mplock(&mpsave);
1119 rpipe = (struct pipe *)fp->f_data;
1120 wpipe = rpipe->pipe_peer;
1121
1122 revents = pipe_poll_events(rpipe, wpipe, events);
1123 if (revents == 0) {
1124 if (events & (POLLIN | POLLRDNORM)) {
1125 lwkt_gettoken(&rpipe_rlock, &rpipe->pipe_rlock);
1126 lwkt_gettoken(&rpipe_wlock, &rpipe->pipe_wlock);
1127 }
1128 if (events & (POLLOUT | POLLWRNORM)) {
1129 lwkt_gettoken(&wpipe_rlock, &wpipe->pipe_rlock);
1130 lwkt_gettoken(&wpipe_wlock, &wpipe->pipe_wlock);
1131 }
1132 revents = pipe_poll_events(rpipe, wpipe, events);
1133 if (revents == 0) {
1134 if (events & (POLLIN | POLLRDNORM)) {
1135 selrecord(curthread, &rpipe->pipe_sel);
1136 rpipe->pipe_state |= PIPE_SEL;
1137 }
1138
1139 if (events & (POLLOUT | POLLWRNORM)) {
1140 selrecord(curthread, &wpipe->pipe_sel);
1141 wpipe->pipe_state |= PIPE_SEL;
1142 }
1143 }
1144 if (events & (POLLIN | POLLRDNORM)) {
1145 lwkt_reltoken(&rpipe_rlock);
1146 lwkt_reltoken(&rpipe_wlock);
1147 }
1148 if (events & (POLLOUT | POLLWRNORM)) {
1149 lwkt_reltoken(&wpipe_rlock);
1150 lwkt_reltoken(&wpipe_wlock);
1151 }
1152 }
1153 pipe_rel_mplock(&mpsave);
1154 return (revents);
1155 }
1156
1157 /*
1158 * MPSAFE
1159 */
1160 static int
1161 pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred)
1162 {
1163 struct pipe *pipe;
1164 int mpsave;
1165
1166 pipe_get_mplock(&mpsave);
1167 pipe = (struct pipe *)fp->f_data;
1168
1169 bzero((caddr_t)ub, sizeof(*ub));
1170 ub->st_mode = S_IFIFO;
1171 ub->st_blksize = pipe->pipe_buffer.size;
1172 ub->st_size = pipe->pipe_buffer.windex - pipe->pipe_buffer.rindex;
1173 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1174 ub->st_atimespec = pipe->pipe_atime;
1175 ub->st_mtimespec = pipe->pipe_mtime;
1176 ub->st_ctimespec = pipe->pipe_ctime;
1177 /*
1178 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1179 * st_flags, st_gen.
1180 * XXX (st_dev, st_ino) should be unique.
1181 */
1182 pipe_rel_mplock(&mpsave);
1183 return (0);
1184 }
1185
1186 /*
1187 * MPALMOSTSAFE - acquires mplock
1188 */
1189 static int
1190 pipe_close(struct file *fp)
1191 {
1192 struct pipe *cpipe;
1193
1194 get_mplock();
1195 cpipe = (struct pipe *)fp->f_data;
1196 fp->f_ops = &badfileops;
1197 fp->f_data = NULL;
1198 funsetown(cpipe->pipe_sigio);
1199 pipeclose(cpipe);
1200 rel_mplock();
1201 return (0);
1202 }
1203
1204 /*
1205 * Shutdown one or both directions of a full-duplex pipe.
1206 *
1207 * MPALMOSTSAFE - acquires mplock
1208 */
1209 static int
1210 pipe_shutdown(struct file *fp, int how)
1211 {
1212 struct pipe *rpipe;
1213 struct pipe *wpipe;
1214 int error = EPIPE;
1215 lwkt_tokref rpipe_rlock;
1216 lwkt_tokref rpipe_wlock;
1217 lwkt_tokref wpipe_rlock;
1218 lwkt_tokref wpipe_wlock;
1219 int mpsave;
1220
1221 pipe_get_mplock(&mpsave);
1222 rpipe = (struct pipe *)fp->f_data;
1223 wpipe = rpipe->pipe_peer;
1224
1225 /*
1226 * We modify pipe_state on both pipes, which means we need
1227 * all four tokens!
1228 */
1229 lwkt_gettoken(&rpipe_rlock, &rpipe->pipe_rlock);
1230 lwkt_gettoken(&rpipe_wlock, &rpipe->pipe_wlock);
1231 lwkt_gettoken(&wpipe_rlock, &wpipe->pipe_rlock);
1232 lwkt_gettoken(&wpipe_wlock, &wpipe->pipe_wlock);
1233
1234 switch(how) {
1235 case SHUT_RDWR:
1236 case SHUT_RD:
1237 rpipe->pipe_state |= PIPE_REOF; /* my reads */
1238 rpipe->pipe_state |= PIPE_WEOF; /* peer writes */
1239 if (rpipe->pipe_state & PIPE_WANTR) {
1240 rpipe->pipe_state &= ~PIPE_WANTR;
1241 wakeup(rpipe);
1242 }
1243 if (rpipe->pipe_state & PIPE_WANTW) {
1244 rpipe->pipe_state &= ~PIPE_WANTW;
1245 wakeup(rpipe);
1246 }
1247 error = 0;
1248 if (how == SHUT_RD)
1249 break;
1250 /* fall through */
1251 case SHUT_WR:
1252 wpipe->pipe_state |= PIPE_REOF; /* peer reads */
1253 wpipe->pipe_state |= PIPE_WEOF; /* my writes */
1254 if (wpipe->pipe_state & PIPE_WANTR) {
1255 wpipe->pipe_state &= ~PIPE_WANTR;
1256 wakeup(wpipe);
1257 }
1258 if (wpipe->pipe_state & PIPE_WANTW) {
1259 wpipe->pipe_state &= ~PIPE_WANTW;
1260 wakeup(wpipe);
1261 }
1262 error = 0;
1263 break;
1264 }
1265 pipeselwakeup(rpipe);
1266 pipeselwakeup(wpipe);
1267
1268 lwkt_reltoken(&rpipe_rlock);
1269 lwkt_reltoken(&rpipe_wlock);
1270 lwkt_reltoken(&wpipe_rlock);
1271 lwkt_reltoken(&wpipe_wlock);
1272
1273 pipe_rel_mplock(&mpsave);
1274 return (error);
1275 }
1276
1277 static void
1278 pipe_free_kmem(struct pipe *cpipe)
1279 {
1280 if (cpipe->pipe_buffer.buffer != NULL) {
1281 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1282 atomic_subtract_int(&pipe_nbig, 1);
1283 kmem_free(&kernel_map,
1284 (vm_offset_t)cpipe->pipe_buffer.buffer,
1285 cpipe->pipe_buffer.size);
1286 cpipe->pipe_buffer.buffer = NULL;
1287 cpipe->pipe_buffer.object = NULL;
1288 }
1289 }
1290
1291 /*
1292 * Close the pipe. The slock must be held to interlock against simultanious
1293 * closes. The rlock and wlock must be held to adjust the pipe_state.
1294 */
1295 static void
1296 pipeclose(struct pipe *cpipe)
1297 {
1298 globaldata_t gd;
1299 struct pipe *ppipe;
1300 lwkt_tokref cpipe_rlock;
1301 lwkt_tokref cpipe_wlock;
1302 lwkt_tokref ppipe_rlock;
1303 lwkt_tokref ppipe_wlock;
1304
1305 if (cpipe == NULL)
1306 return;
1307
1308 /*
1309 * The slock may not have been allocated yet (close during
1310 * initialization)
1311 *
1312 * We need both the read and write tokens to modify pipe_state.
1313 */
1314 if (cpipe->pipe_slock)
1315 lockmgr(cpipe->pipe_slock, LK_EXCLUSIVE);
1316 lwkt_gettoken(&cpipe_rlock, &cpipe->pipe_rlock);
1317 lwkt_gettoken(&cpipe_wlock, &cpipe->pipe_wlock);
1318
1319 /*
1320 * Set our state, wakeup anyone waiting in select, and
1321 * wakeup anyone blocked on our pipe.
1322 */
1323 cpipe->pipe_state |= PIPE_CLOSED | PIPE_REOF | PIPE_WEOF;
1324 pipeselwakeup(cpipe);
1325 if (cpipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) {
1326 cpipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW);
1327 wakeup(cpipe);
1328 }
1329
1330 /*
1331 * Disconnect from peer.
1332 */
1333 if ((ppipe = cpipe->pipe_peer) != NULL) {
1334 lwkt_gettoken(&ppipe_rlock, &ppipe->pipe_rlock);
1335 lwkt_gettoken(&ppipe_wlock, &ppipe->pipe_wlock);
1336 ppipe->pipe_state |= PIPE_REOF | PIPE_WEOF;
1337 pipeselwakeup(ppipe);
1338 if (ppipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) {
1339 ppipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW);
1340 wakeup(ppipe);
1341 }
1342 if (SLIST_FIRST(&ppipe->pipe_sel.si_note)) {
1343 get_mplock();
1344 KNOTE(&ppipe->pipe_sel.si_note, 0);
1345 rel_mplock();
1346 }
1347 lwkt_reltoken(&ppipe_rlock);
1348 lwkt_reltoken(&ppipe_wlock);
1349 }
1350
1351 /*
1352 * If the peer is also closed we can free resources for both
1353 * sides, otherwise we leave our side intact to deal with any
1354 * races (since we only have the slock).
1355 */
1356 if (ppipe && (ppipe->pipe_state & PIPE_CLOSED)) {
1357 cpipe->pipe_peer = NULL;
1358 ppipe->pipe_peer = NULL;
1359 ppipe->pipe_slock = NULL; /* we will free the slock */
1360 pipeclose(ppipe);
1361 ppipe = NULL;
1362 }
1363
1364 lwkt_reltoken(&cpipe_rlock);
1365 lwkt_reltoken(&cpipe_wlock);
1366 if (cpipe->pipe_slock)
1367 lockmgr(cpipe->pipe_slock, LK_RELEASE);
1368
1369 /*
1370 * If we disassociated from our peer we can free resources
1371 */
1372 if (ppipe == NULL) {
1373 gd = mycpu;
1374 if (cpipe->pipe_slock) {
1375 kfree(cpipe->pipe_slock, M_PIPE);
1376 cpipe->pipe_slock = NULL;
1377 }
1378 if (gd->gd_pipeqcount >= pipe_maxcache ||
1379 cpipe->pipe_buffer.size != PIPE_SIZE
1380 ) {
1381 pipe_free_kmem(cpipe);
1382 kfree(cpipe, M_PIPE);
1383 } else {
1384 cpipe->pipe_state = 0;
1385 cpipe->pipe_peer = gd->gd_pipeq;
1386 gd->gd_pipeq = cpipe;
1387 ++gd->gd_pipeqcount;
1388 }
1389 }
1390 }
1391
1392 /*
1393 * MPALMOSTSAFE - acquires mplock
1394 */
1395 static int
1396 pipe_kqfilter(struct file *fp, struct knote *kn)
1397 {
1398 struct pipe *cpipe;
1399
1400 get_mplock();
1401 cpipe = (struct pipe *)kn->kn_fp->f_data;
1402
1403 switch (kn->kn_filter) {
1404 case EVFILT_READ:
1405 kn->kn_fop = &pipe_rfiltops;
1406 break;
1407 case EVFILT_WRITE:
1408 kn->kn_fop = &pipe_wfiltops;
1409 cpipe = cpipe->pipe_peer;
1410 if (cpipe == NULL) {
1411 /* other end of pipe has been closed */
1412 rel_mplock();
1413 return (EPIPE);
1414 }
1415 break;
1416 default:
1417 return (1);
1418 }
1419 kn->kn_hook = (caddr_t)cpipe;
1420
1421 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1422 rel_mplock();
1423 return (0);
1424 }
1425
1426 static void
1427 filt_pipedetach(struct knote *kn)
1428 {
1429 struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1430
1431 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1432 }
1433
1434 /*ARGSUSED*/
1435 static int
1436 filt_piperead(struct knote *kn, long hint)
1437 {
1438 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1439
1440 kn->kn_data = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
1441
1442 /* XXX RACE */
1443 if (rpipe->pipe_state & PIPE_REOF) {
1444 kn->kn_flags |= EV_EOF;
1445 return (1);
1446 }
1447 return (kn->kn_data > 0);
1448 }
1449
1450 /*ARGSUSED*/
1451 static int
1452 filt_pipewrite(struct knote *kn, long hint)
1453 {
1454 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1455 struct pipe *wpipe = rpipe->pipe_peer;
1456 u_int32_t space;
1457
1458 /* XXX RACE */
1459 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_WEOF)) {
1460 kn->kn_data = 0;
1461 kn->kn_flags |= EV_EOF;
1462 return (1);
1463 }
1464 space = wpipe->pipe_buffer.windex -
1465 wpipe->pipe_buffer.rindex;
1466 space = wpipe->pipe_buffer.size - space;
1467 kn->kn_data = space;
1468 return (kn->kn_data >= PIPE_BUF);
1469 }
DragonFly BSD