13c0c69b71515ba7cd8ece3d1a0d3d2d67bde397
[dragonfly.git] / sys / kern / sys_pipe.c
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,
357                                     size, PAGE_SIZE,
358                                     1, 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 }