Enhance the pmap_kenter*() API and friends, separating out entries which
[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 1.17 2004/04/01 17:58:02 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
30 /*
31  * This code has two modes of operation, a small write mode and a large
32  * write mode.  The small write mode acts like conventional pipes with
33  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
34  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
35  * and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and
36  * the receiving process can copy it directly from the pages in the sending
37  * process.
38  *
39  * If the sending process receives a signal, it is possible that it will
40  * go away, and certainly its address space can change, because control
41  * is returned back to the user-mode side.  In that case, the pipe code
42  * arranges to copy the buffer supplied by the user process, to a pageable
43  * kernel buffer, and the receiving process will grab the data from the
44  * pageable kernel buffer.  Since signals don't happen all that often,
45  * the copy operation is normally eliminated.
46  *
47  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
48  * happen for small transfers so that the system will not spend all of
49  * its time context switching.  PIPE_SIZE is constrained by the
50  * amount of kernel virtual memory.
51  */
52
53 #include <sys/param.h>
54 #include <sys/systm.h>
55 #include <sys/kernel.h>
56 #include <sys/proc.h>
57 #include <sys/fcntl.h>
58 #include <sys/file.h>
59 #include <sys/filedesc.h>
60 #include <sys/filio.h>
61 #include <sys/ttycom.h>
62 #include <sys/stat.h>
63 #include <sys/poll.h>
64 #include <sys/select.h>
65 #include <sys/signalvar.h>
66 #include <sys/sysproto.h>
67 #include <sys/pipe.h>
68 #include <sys/vnode.h>
69 #include <sys/uio.h>
70 #include <sys/event.h>
71 #include <sys/globaldata.h>
72 #include <sys/module.h>
73 #include <sys/malloc.h>
74 #include <sys/sysctl.h>
75
76 #include <vm/vm.h>
77 #include <vm/vm_param.h>
78 #include <sys/lock.h>
79 #include <vm/vm_object.h>
80 #include <vm/vm_kern.h>
81 #include <vm/vm_extern.h>
82 #include <vm/pmap.h>
83 #include <vm/vm_map.h>
84 #include <vm/vm_page.h>
85 #include <vm/vm_zone.h>
86
87 #include <sys/file2.h>
88
89 /*
90  * Use this define if you want to disable *fancy* VM things.  Expect an
91  * approx 30% decrease in transfer rate.  This could be useful for
92  * NetBSD or OpenBSD.
93  */
94 /* #define PIPE_NODIRECT */
95
96 /*
97  * interfaces to the outside world
98  */
99 static int pipe_read (struct file *fp, struct uio *uio, 
100                 struct ucred *cred, int flags, struct thread *td);
101 static int pipe_write (struct file *fp, struct uio *uio, 
102                 struct ucred *cred, int flags, struct thread *td);
103 static int pipe_close (struct file *fp, struct thread *td);
104 static int pipe_poll (struct file *fp, int events, struct ucred *cred,
105                 struct thread *td);
106 static int pipe_kqfilter (struct file *fp, struct knote *kn);
107 static int pipe_stat (struct file *fp, struct stat *sb, struct thread *td);
108 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, struct thread *td);
109
110 static struct fileops pipeops = {
111         NULL,   /* port */
112         0,      /* autoq */
113         pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter,
114         pipe_stat, pipe_close
115 };
116
117 static void     filt_pipedetach(struct knote *kn);
118 static int      filt_piperead(struct knote *kn, long hint);
119 static int      filt_pipewrite(struct knote *kn, long hint);
120
121 static struct filterops pipe_rfiltops =
122         { 1, NULL, filt_pipedetach, filt_piperead };
123 static struct filterops pipe_wfiltops =
124         { 1, NULL, filt_pipedetach, filt_pipewrite };
125
126 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures");
127
128 /*
129  * Default pipe buffer size(s), this can be kind-of large now because pipe
130  * space is pageable.  The pipe code will try to maintain locality of
131  * reference for performance reasons, so small amounts of outstanding I/O
132  * will not wipe the cache.
133  */
134 #define MINPIPESIZE (PIPE_SIZE/3)
135 #define MAXPIPESIZE (2*PIPE_SIZE/3)
136
137 /*
138  * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
139  * is there so that on large systems, we don't exhaust it.
140  */
141 #define MAXPIPEKVA (8*1024*1024)
142
143 /*
144  * Limit for direct transfers, we cannot, of course limit
145  * the amount of kva for pipes in general though.
146  */
147 #define LIMITPIPEKVA (16*1024*1024)
148
149 /*
150  * Limit the number of "big" pipes
151  */
152 #define LIMITBIGPIPES   32
153 #define PIPEQ_MAX_CACHE 16      /* per-cpu pipe structure cache */
154
155 static int pipe_maxbig = LIMITBIGPIPES;
156 static int pipe_maxcache = PIPEQ_MAX_CACHE;
157 static int pipe_nbig;
158 static int pipe_bcache_alloc;
159 static int pipe_bkmem_alloc;
160
161 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation");
162 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig,
163         CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated");
164 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache,
165         CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu");
166 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig,
167         CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes");
168 #if !defined(NO_PIPE_SYSCTL_STATS)
169 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc,
170         CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache");
171 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc,
172         CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem");
173 #endif
174
175 static void pipeclose (struct pipe *cpipe);
176 static void pipe_free_kmem (struct pipe *cpipe);
177 static int pipe_create (struct pipe **cpipep);
178 static __inline int pipelock (struct pipe *cpipe, int catch);
179 static __inline void pipeunlock (struct pipe *cpipe);
180 static __inline void pipeselwakeup (struct pipe *cpipe);
181 #ifndef PIPE_NODIRECT
182 static int pipe_build_write_buffer (struct pipe *wpipe, struct uio *uio);
183 static int pipe_direct_write (struct pipe *wpipe, struct uio *uio);
184 static void pipe_clone_write_buffer (struct pipe *wpipe);
185 #endif
186 static int pipespace (struct pipe *cpipe, int size);
187
188 /*
189  * The pipe system call for the DTYPE_PIPE type of pipes
190  *
191  * pipe_ARgs(int dummy)
192  */
193
194 /* ARGSUSED */
195 int
196 pipe(struct pipe_args *uap)
197 {
198         struct thread *td = curthread;
199         struct proc *p = td->td_proc;
200         struct filedesc *fdp;
201         struct file *rf, *wf;
202         struct pipe *rpipe, *wpipe;
203         int fd1, fd2, error;
204
205         KKASSERT(p);
206         fdp = p->p_fd;
207
208         rpipe = wpipe = NULL;
209         if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
210                 pipeclose(rpipe); 
211                 pipeclose(wpipe); 
212                 return (ENFILE);
213         }
214         
215         rpipe->pipe_state |= PIPE_DIRECTOK;
216         wpipe->pipe_state |= PIPE_DIRECTOK;
217
218         error = falloc(p, &rf, &fd1);
219         if (error) {
220                 pipeclose(rpipe);
221                 pipeclose(wpipe);
222                 return (error);
223         }
224         fhold(rf);
225         uap->sysmsg_fds[0] = fd1;
226
227         /*
228          * Warning: once we've gotten past allocation of the fd for the
229          * read-side, we can only drop the read side via fdrop() in order
230          * to avoid races against processes which manage to dup() the read
231          * side while we are blocked trying to allocate the write side.
232          */
233         rf->f_flag = FREAD | FWRITE;
234         rf->f_type = DTYPE_PIPE;
235         rf->f_data = (caddr_t)rpipe;
236         rf->f_ops = &pipeops;
237         error = falloc(p, &wf, &fd2);
238         if (error) {
239                 if (fdp->fd_ofiles[fd1] == rf) {
240                         fdp->fd_ofiles[fd1] = NULL;
241                         fdrop(rf, td);
242                 }
243                 fdrop(rf, td);
244                 /* rpipe has been closed by fdrop(). */
245                 pipeclose(wpipe);
246                 return (error);
247         }
248         wf->f_flag = FREAD | FWRITE;
249         wf->f_type = DTYPE_PIPE;
250         wf->f_data = (caddr_t)wpipe;
251         wf->f_ops = &pipeops;
252         uap->sysmsg_fds[1] = fd2;
253
254         rpipe->pipe_peer = wpipe;
255         wpipe->pipe_peer = rpipe;
256         fdrop(rf, td);
257
258         return (0);
259 }
260
261 /*
262  * Allocate kva for pipe circular buffer, the space is pageable
263  * This routine will 'realloc' the size of a pipe safely, if it fails
264  * it will retain the old buffer.
265  * If it fails it will return ENOMEM.
266  */
267 static int
268 pipespace(struct pipe *cpipe, int size)
269 {
270         struct vm_object *object;
271         caddr_t buffer;
272         int npages, error;
273
274         npages = round_page(size) / PAGE_SIZE;
275         object = cpipe->pipe_buffer.object;
276
277         /*
278          * [re]create the object if necessary and reserve space for it
279          * in the kernel_map.  The object and memory are pageable.  On
280          * success, free the old resources before assigning the new
281          * ones.
282          */
283         if (object == NULL || object->size != npages) {
284                 object = vm_object_allocate(OBJT_DEFAULT, npages);
285                 buffer = (caddr_t) vm_map_min(kernel_map);
286
287                 error = vm_map_find(kernel_map, object, 0,
288                         (vm_offset_t *) &buffer, size, 1,
289                         VM_PROT_ALL, VM_PROT_ALL, 0);
290
291                 if (error != KERN_SUCCESS) {
292                         vm_object_deallocate(object);
293                         return (ENOMEM);
294                 }
295                 pipe_free_kmem(cpipe);
296                 cpipe->pipe_buffer.object = object;
297                 cpipe->pipe_buffer.buffer = buffer;
298                 cpipe->pipe_buffer.size = size;
299                 ++pipe_bkmem_alloc;
300         } else {
301                 ++pipe_bcache_alloc;
302         }
303         cpipe->pipe_buffer.in = 0;
304         cpipe->pipe_buffer.out = 0;
305         cpipe->pipe_buffer.cnt = 0;
306         return (0);
307 }
308
309 /*
310  * Initialize and allocate VM and memory for pipe, pulling the pipe from
311  * our per-cpu cache if possible.  For now make sure it is sized for the
312  * smaller PIPE_SIZE default.
313  */
314 static int
315 pipe_create(cpipep)
316         struct pipe **cpipep;
317 {
318         globaldata_t gd = mycpu;
319         struct pipe *cpipe;
320         int error;
321
322         if ((cpipe = gd->gd_pipeq) != NULL) {
323                 gd->gd_pipeq = cpipe->pipe_peer;
324                 --gd->gd_pipeqcount;
325                 cpipe->pipe_peer = NULL;
326         } else {
327                 cpipe = malloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
328         }
329         *cpipep = cpipe;
330         if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
331                 return (error);
332         vfs_timestamp(&cpipe->pipe_ctime);
333         cpipe->pipe_atime = cpipe->pipe_ctime;
334         cpipe->pipe_mtime = cpipe->pipe_ctime;
335         return (0);
336 }
337
338
339 /*
340  * lock a pipe for I/O, blocking other access
341  */
342 static __inline int
343 pipelock(cpipe, catch)
344         struct pipe *cpipe;
345         int catch;
346 {
347         int error;
348
349         while (cpipe->pipe_state & PIPE_LOCK) {
350                 cpipe->pipe_state |= PIPE_LWANT;
351                 error = tsleep(cpipe, (catch ? PCATCH : 0), "pipelk", 0);
352                 if (error != 0) 
353                         return (error);
354         }
355         cpipe->pipe_state |= PIPE_LOCK;
356         return (0);
357 }
358
359 /*
360  * unlock a pipe I/O lock
361  */
362 static __inline void
363 pipeunlock(cpipe)
364         struct pipe *cpipe;
365 {
366
367         cpipe->pipe_state &= ~PIPE_LOCK;
368         if (cpipe->pipe_state & PIPE_LWANT) {
369                 cpipe->pipe_state &= ~PIPE_LWANT;
370                 wakeup(cpipe);
371         }
372 }
373
374 static __inline void
375 pipeselwakeup(cpipe)
376         struct pipe *cpipe;
377 {
378
379         if (cpipe->pipe_state & PIPE_SEL) {
380                 cpipe->pipe_state &= ~PIPE_SEL;
381                 selwakeup(&cpipe->pipe_sel);
382         }
383         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
384                 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
385         KNOTE(&cpipe->pipe_sel.si_note, 0);
386 }
387
388 /* ARGSUSED */
389 static int
390 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred,
391         int flags, struct thread *td)
392 {
393         struct pipe *rpipe = (struct pipe *) fp->f_data;
394         int error;
395         int nread = 0;
396         u_int size;
397
398         ++rpipe->pipe_busy;
399         error = pipelock(rpipe, 1);
400         if (error)
401                 goto unlocked_error;
402
403         while (uio->uio_resid) {
404                 /*
405                  * normal pipe buffer receive
406                  */
407                 if (rpipe->pipe_buffer.cnt > 0) {
408                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
409                         if (size > rpipe->pipe_buffer.cnt)
410                                 size = rpipe->pipe_buffer.cnt;
411                         if (size > (u_int) uio->uio_resid)
412                                 size = (u_int) uio->uio_resid;
413
414                         error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
415                                         size, uio);
416                         if (error)
417                                 break;
418
419                         rpipe->pipe_buffer.out += size;
420                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
421                                 rpipe->pipe_buffer.out = 0;
422
423                         rpipe->pipe_buffer.cnt -= size;
424
425                         /*
426                          * If there is no more to read in the pipe, reset
427                          * its pointers to the beginning.  This improves
428                          * cache hit stats.
429                          */
430                         if (rpipe->pipe_buffer.cnt == 0) {
431                                 rpipe->pipe_buffer.in = 0;
432                                 rpipe->pipe_buffer.out = 0;
433                         }
434                         nread += size;
435 #ifndef PIPE_NODIRECT
436                 /*
437                  * Direct copy, bypassing a kernel buffer.  We cannot mess
438                  * with the direct-write buffer until PIPE_DIRECTIP is
439                  * cleared.  In order to prevent the pipe_write code from
440                  * racing itself in direct_write, we set DIRECTIP when we
441                  * clear DIRECTW after we have exhausted the buffer.
442                  */
443                 } else if (rpipe->pipe_map.xio_bytes &&
444                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) == PIPE_DIRECTW) {
445                         error = xio_uio_copy(&rpipe->pipe_map, uio, &size);
446                         if (error)
447                                 break;
448                         nread += size;
449                         if (rpipe->pipe_map.xio_bytes == 0) {
450                                 rpipe->pipe_state |= PIPE_DIRECTIP;
451                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
452                                 wakeup(rpipe);
453                         }
454 #endif
455                 } else {
456                         /*
457                          * detect EOF condition
458                          * read returns 0 on EOF, no need to set error
459                          */
460                         if (rpipe->pipe_state & PIPE_EOF)
461                                 break;
462
463                         /*
464                          * If the "write-side" has been blocked, wake it up now.
465                          */
466                         if (rpipe->pipe_state & PIPE_WANTW) {
467                                 rpipe->pipe_state &= ~PIPE_WANTW;
468                                 wakeup(rpipe);
469                         }
470
471                         /*
472                          * Break if some data was read.
473                          */
474                         if (nread > 0)
475                                 break;
476
477                         /*
478                          * Unlock the pipe buffer for our remaining processing.  We
479                          * will either break out with an error or we will sleep and
480                          * relock to loop.
481                          */
482                         pipeunlock(rpipe);
483
484                         /*
485                          * Handle non-blocking mode operation or
486                          * wait for more data.
487                          */
488                         if (fp->f_flag & FNONBLOCK) {
489                                 error = EAGAIN;
490                         } else {
491                                 rpipe->pipe_state |= PIPE_WANTR;
492                                 if ((error = tsleep(rpipe, PCATCH|PNORESCHED,
493                                     "piperd", 0)) == 0) {
494                                         error = pipelock(rpipe, 1);
495                                 }
496                         }
497                         if (error)
498                                 goto unlocked_error;
499                 }
500         }
501         pipeunlock(rpipe);
502
503         if (error == 0)
504                 vfs_timestamp(&rpipe->pipe_atime);
505 unlocked_error:
506         --rpipe->pipe_busy;
507
508         /*
509          * PIPE_WANT processing only makes sense if pipe_busy is 0.
510          */
511         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
512                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
513                 wakeup(rpipe);
514         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
515                 /*
516                  * Handle write blocking hysteresis.
517                  */
518                 if (rpipe->pipe_state & PIPE_WANTW) {
519                         rpipe->pipe_state &= ~PIPE_WANTW;
520                         wakeup(rpipe);
521                 }
522         }
523
524         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
525                 pipeselwakeup(rpipe);
526
527         return (error);
528 }
529
530 #ifndef PIPE_NODIRECT
531 /*
532  * Map the sending processes' buffer into kernel space and wire it.
533  * This is similar to a physical write operation.
534  */
535 static int
536 pipe_build_write_buffer(wpipe, uio)
537         struct pipe *wpipe;
538         struct uio *uio;
539 {
540         int error;
541         u_int size;
542
543         size = (u_int) uio->uio_iov->iov_len;
544         if (size > wpipe->pipe_buffer.size)
545                 size = wpipe->pipe_buffer.size;
546         if (size > XIO_INTERNAL_SIZE)
547                 size = XIO_INTERNAL_SIZE;
548
549         error = xio_init_ubuf(&wpipe->pipe_map, uio->uio_iov->iov_base, 
550                                 size, XIOF_READ);
551         if (error)
552                 return(error);
553
554         /*
555          * and update the uio data
556          */
557         uio->uio_iov->iov_len -= size;
558         uio->uio_iov->iov_base += size;
559         if (uio->uio_iov->iov_len == 0)
560                 uio->uio_iov++;
561         uio->uio_resid -= size;
562         uio->uio_offset += size;
563         return (0);
564 }
565
566 /*
567  * In the case of a signal, the writing process might go away.  This
568  * code copies the data into the circular buffer so that the source
569  * pages can be freed without loss of data.
570  */
571 static void
572 pipe_clone_write_buffer(wpipe)
573         struct pipe *wpipe;
574 {
575         int size;
576
577         size = wpipe->pipe_map.xio_bytes;
578
579         wpipe->pipe_buffer.in = size;
580         wpipe->pipe_buffer.out = 0;
581         wpipe->pipe_buffer.cnt = size;
582         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
583
584         xio_copy_xtok(&wpipe->pipe_map, wpipe->pipe_buffer.buffer, size);
585         xio_release(&wpipe->pipe_map);
586 }
587
588 /*
589  * This implements the pipe buffer write mechanism.  Note that only
590  * a direct write OR a normal pipe write can be pending at any given time.
591  * If there are any characters in the pipe buffer, the direct write will
592  * be deferred until the receiving process grabs all of the bytes from
593  * the pipe buffer.  Then the direct mapping write is set-up.
594  */
595 static int
596 pipe_direct_write(wpipe, uio)
597         struct pipe *wpipe;
598         struct uio *uio;
599 {
600         int error;
601
602 retry:
603         while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
604                 if (wpipe->pipe_state & PIPE_WANTR) {
605                         wpipe->pipe_state &= ~PIPE_WANTR;
606                         wakeup(wpipe);
607                 }
608                 wpipe->pipe_state |= PIPE_WANTW;
609                 error = tsleep(wpipe, PCATCH, "pipdww", 0);
610                 if (error)
611                         goto error2;
612                 if (wpipe->pipe_state & PIPE_EOF) {
613                         error = EPIPE;
614                         goto error2;
615                 }
616         }
617         KKASSERT(wpipe->pipe_map.xio_bytes == 0);
618         if (wpipe->pipe_buffer.cnt > 0) {
619                 if (wpipe->pipe_state & PIPE_WANTR) {
620                         wpipe->pipe_state &= ~PIPE_WANTR;
621                         wakeup(wpipe);
622                 }
623                         
624                 wpipe->pipe_state |= PIPE_WANTW;
625                 error = tsleep(wpipe, PCATCH, "pipdwc", 0);
626                 if (error)
627                         goto error2;
628                 if (wpipe->pipe_state & PIPE_EOF) {
629                         error = EPIPE;
630                         goto error2;
631                 }
632                 goto retry;
633         }
634
635         /*
636          * Build our direct-write buffer
637          */
638         wpipe->pipe_state |= PIPE_DIRECTW | PIPE_DIRECTIP;
639         error = pipe_build_write_buffer(wpipe, uio);
640         if (error)
641                 goto error1;
642         wpipe->pipe_state &= ~PIPE_DIRECTIP;
643
644         /*
645          * Wait until the receiver has snarfed the data.  Since we are likely
646          * going to sleep we optimize the case and yield synchronously,
647          * possibly avoiding the tsleep().
648          */
649         error = 0;
650         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
651                 if (wpipe->pipe_state & PIPE_EOF) {
652                         pipelock(wpipe, 0);
653                         xio_release(&wpipe->pipe_map);
654                         pipeunlock(wpipe);
655                         pipeselwakeup(wpipe);
656                         error = EPIPE;
657                         goto error1;
658                 }
659                 if (wpipe->pipe_state & PIPE_WANTR) {
660                         wpipe->pipe_state &= ~PIPE_WANTR;
661                         wakeup(wpipe);
662                 }
663                 pipeselwakeup(wpipe);
664                 error = tsleep(wpipe, PCATCH|PNORESCHED, "pipdwt", 0);
665         }
666         pipelock(wpipe,0);
667         if (wpipe->pipe_state & PIPE_DIRECTW) {
668                 /*
669                  * this bit of trickery substitutes a kernel buffer for
670                  * the process that might be going away.
671                  */
672                 pipe_clone_write_buffer(wpipe);
673                 KKASSERT((wpipe->pipe_state & PIPE_DIRECTIP) == 0);
674         } else {
675                 KKASSERT(wpipe->pipe_state & PIPE_DIRECTIP);
676                 xio_release(&wpipe->pipe_map);
677                 wpipe->pipe_state &= ~PIPE_DIRECTIP;
678         }
679         pipeunlock(wpipe);
680         return (error);
681
682         /*
683          * Direct-write error, clear the direct write flags.
684          */
685 error1:
686         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
687         /* fallthrough */
688
689         /*
690          * General error, wakeup the other side if it happens to be sleeping.
691          */
692 error2:
693         wakeup(wpipe);
694         return (error);
695 }
696 #endif
697         
698 static int
699 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred,
700         int flags, struct thread *td)
701 {
702         int error = 0;
703         int orig_resid;
704         struct pipe *wpipe, *rpipe;
705
706         rpipe = (struct pipe *) fp->f_data;
707         wpipe = rpipe->pipe_peer;
708
709         /*
710          * detect loss of pipe read side, issue SIGPIPE if lost.
711          */
712         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
713                 return (EPIPE);
714         }
715         ++wpipe->pipe_busy;
716
717         /*
718          * If it is advantageous to resize the pipe buffer, do
719          * so.
720          */
721         if ((uio->uio_resid > PIPE_SIZE) &&
722                 (pipe_nbig < pipe_maxbig) &&
723                 (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) == 0 &&
724                 (wpipe->pipe_buffer.size <= PIPE_SIZE) &&
725                 (wpipe->pipe_buffer.cnt == 0)) {
726
727                 if ((error = pipelock(wpipe,1)) == 0) {
728                         if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
729                                 pipe_nbig++;
730                         pipeunlock(wpipe);
731                 }
732         }
733
734         /*
735          * If an early error occured unbusy and return, waking up any pending
736          * readers.
737          */
738         if (error) {
739                 --wpipe->pipe_busy;
740                 if ((wpipe->pipe_busy == 0) && 
741                     (wpipe->pipe_state & PIPE_WANT)) {
742                         wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
743                         wakeup(wpipe);
744                 }
745                 return(error);
746         }
747                 
748         KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone"));
749
750         orig_resid = uio->uio_resid;
751
752         while (uio->uio_resid) {
753                 int space;
754
755 #ifndef PIPE_NODIRECT
756                 /*
757                  * If the transfer is large, we can gain performance if
758                  * we do process-to-process copies directly.
759                  * If the write is non-blocking, we don't use the
760                  * direct write mechanism.
761                  *
762                  * The direct write mechanism will detect the reader going
763                  * away on us.
764                  */
765                 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
766                     (fp->f_flag & FNONBLOCK) == 0) {
767                         error = pipe_direct_write( wpipe, uio);
768                         if (error)
769                                 break;
770                         continue;
771                 }
772 #endif
773
774                 /*
775                  * Pipe buffered writes cannot be coincidental with
776                  * direct writes.  We wait until the currently executing
777                  * direct write is completed before we start filling the
778                  * pipe buffer.  We break out if a signal occurs or the
779                  * reader goes away.
780                  */
781         retrywrite:
782                 while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
783                         if (wpipe->pipe_state & PIPE_WANTR) {
784                                 wpipe->pipe_state &= ~PIPE_WANTR;
785                                 wakeup(wpipe);
786                         }
787                         error = tsleep(wpipe, PCATCH, "pipbww", 0);
788                         if (wpipe->pipe_state & PIPE_EOF)
789                                 break;
790                         if (error)
791                                 break;
792                 }
793                 if (wpipe->pipe_state & PIPE_EOF) {
794                         error = EPIPE;
795                         break;
796                 }
797
798                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
799
800                 /* Writes of size <= PIPE_BUF must be atomic. */
801                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
802                         space = 0;
803
804                 /* 
805                  * Write to fill, read size handles write hysteresis.  Also
806                  * additional restrictions can cause select-based non-blocking
807                  * writes to spin.
808                  */
809                 if (space > 0) {
810                         if ((error = pipelock(wpipe,1)) == 0) {
811                                 int size;       /* Transfer size */
812                                 int segsize;    /* first segment to transfer */
813
814                                 /*
815                                  * It is possible for a direct write to
816                                  * slip in on us... handle it here...
817                                  */
818                                 if (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
819                                         pipeunlock(wpipe);
820                                         goto retrywrite;
821                                 }
822                                 /* 
823                                  * If a process blocked in uiomove, our
824                                  * value for space might be bad.
825                                  *
826                                  * XXX will we be ok if the reader has gone
827                                  * away here?
828                                  */
829                                 if (space > wpipe->pipe_buffer.size - 
830                                     wpipe->pipe_buffer.cnt) {
831                                         pipeunlock(wpipe);
832                                         goto retrywrite;
833                                 }
834
835                                 /*
836                                  * Transfer size is minimum of uio transfer
837                                  * and free space in pipe buffer.
838                                  */
839                                 if (space > uio->uio_resid)
840                                         size = uio->uio_resid;
841                                 else
842                                         size = space;
843                                 /*
844                                  * First segment to transfer is minimum of 
845                                  * transfer size and contiguous space in
846                                  * pipe buffer.  If first segment to transfer
847                                  * is less than the transfer size, we've got
848                                  * a wraparound in the buffer.
849                                  */
850                                 segsize = wpipe->pipe_buffer.size - 
851                                         wpipe->pipe_buffer.in;
852                                 if (segsize > size)
853                                         segsize = size;
854                                 
855                                 /* Transfer first segment */
856
857                                 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 
858                                                 segsize, uio);
859                                 
860                                 if (error == 0 && segsize < size) {
861                                         /* 
862                                          * Transfer remaining part now, to
863                                          * support atomic writes.  Wraparound
864                                          * happened.
865                                          */
866                                         if (wpipe->pipe_buffer.in + segsize != 
867                                             wpipe->pipe_buffer.size)
868                                                 panic("Expected pipe buffer wraparound disappeared");
869                                                 
870                                         error = uiomove(&wpipe->pipe_buffer.buffer[0],
871                                                         size - segsize, uio);
872                                 }
873                                 if (error == 0) {
874                                         wpipe->pipe_buffer.in += size;
875                                         if (wpipe->pipe_buffer.in >=
876                                             wpipe->pipe_buffer.size) {
877                                                 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
878                                                         panic("Expected wraparound bad");
879                                                 wpipe->pipe_buffer.in = size - segsize;
880                                         }
881                                 
882                                         wpipe->pipe_buffer.cnt += size;
883                                         if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
884                                                 panic("Pipe buffer overflow");
885                                 
886                                 }
887                                 pipeunlock(wpipe);
888                         }
889                         if (error)
890                                 break;
891
892                 } else {
893                         /*
894                          * If the "read-side" has been blocked, wake it up now
895                          * and yield to let it drain synchronously rather
896                          * then block.
897                          */
898                         if (wpipe->pipe_state & PIPE_WANTR) {
899                                 wpipe->pipe_state &= ~PIPE_WANTR;
900                                 wakeup(wpipe);
901                         }
902
903                         /*
904                          * don't block on non-blocking I/O
905                          */
906                         if (fp->f_flag & FNONBLOCK) {
907                                 error = EAGAIN;
908                                 break;
909                         }
910
911                         /*
912                          * We have no more space and have something to offer,
913                          * wake up select/poll.
914                          */
915                         pipeselwakeup(wpipe);
916
917                         wpipe->pipe_state |= PIPE_WANTW;
918                         error = tsleep(wpipe, PCATCH|PNORESCHED, "pipewr", 0);
919                         if (error != 0)
920                                 break;
921                         /*
922                          * If read side wants to go away, we just issue a signal
923                          * to ourselves.
924                          */
925                         if (wpipe->pipe_state & PIPE_EOF) {
926                                 error = EPIPE;
927                                 break;
928                         }       
929                 }
930         }
931
932         --wpipe->pipe_busy;
933
934         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
935                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
936                 wakeup(wpipe);
937         } else if (wpipe->pipe_buffer.cnt > 0) {
938                 /*
939                  * If we have put any characters in the buffer, we wake up
940                  * the reader.
941                  */
942                 if (wpipe->pipe_state & PIPE_WANTR) {
943                         wpipe->pipe_state &= ~PIPE_WANTR;
944                         wakeup(wpipe);
945                 }
946         }
947
948         /*
949          * Don't return EPIPE if I/O was successful
950          */
951         if ((wpipe->pipe_buffer.cnt == 0) &&
952             (uio->uio_resid == 0) &&
953             (error == EPIPE)) {
954                 error = 0;
955         }
956
957         if (error == 0)
958                 vfs_timestamp(&wpipe->pipe_mtime);
959
960         /*
961          * We have something to offer,
962          * wake up select/poll.
963          */
964         if (wpipe->pipe_buffer.cnt)
965                 pipeselwakeup(wpipe);
966
967         return (error);
968 }
969
970 /*
971  * we implement a very minimal set of ioctls for compatibility with sockets.
972  */
973 int
974 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct thread *td)
975 {
976         struct pipe *mpipe = (struct pipe *)fp->f_data;
977
978         switch (cmd) {
979
980         case FIONBIO:
981                 return (0);
982
983         case FIOASYNC:
984                 if (*(int *)data) {
985                         mpipe->pipe_state |= PIPE_ASYNC;
986                 } else {
987                         mpipe->pipe_state &= ~PIPE_ASYNC;
988                 }
989                 return (0);
990
991         case FIONREAD:
992                 if (mpipe->pipe_state & PIPE_DIRECTW) {
993                         *(int *)data = mpipe->pipe_map.xio_bytes;
994                 } else {
995                         *(int *)data = mpipe->pipe_buffer.cnt;
996                 }
997                 return (0);
998
999         case FIOSETOWN:
1000                 return (fsetown(*(int *)data, &mpipe->pipe_sigio));
1001
1002         case FIOGETOWN:
1003                 *(int *)data = fgetown(mpipe->pipe_sigio);
1004                 return (0);
1005
1006         /* This is deprecated, FIOSETOWN should be used instead. */
1007         case TIOCSPGRP:
1008                 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
1009
1010         /* This is deprecated, FIOGETOWN should be used instead. */
1011         case TIOCGPGRP:
1012                 *(int *)data = -fgetown(mpipe->pipe_sigio);
1013                 return (0);
1014
1015         }
1016         return (ENOTTY);
1017 }
1018
1019 int
1020 pipe_poll(struct file *fp, int events, struct ucred *cred, struct thread *td)
1021 {
1022         struct pipe *rpipe = (struct pipe *)fp->f_data;
1023         struct pipe *wpipe;
1024         int revents = 0;
1025
1026         wpipe = rpipe->pipe_peer;
1027         if (events & (POLLIN | POLLRDNORM))
1028                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1029                     (rpipe->pipe_buffer.cnt > 0) ||
1030                     (rpipe->pipe_state & PIPE_EOF))
1031                         revents |= events & (POLLIN | POLLRDNORM);
1032
1033         if (events & (POLLOUT | POLLWRNORM))
1034                 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) ||
1035                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1036                      (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1037                         revents |= events & (POLLOUT | POLLWRNORM);
1038
1039         if ((rpipe->pipe_state & PIPE_EOF) ||
1040             (wpipe == NULL) ||
1041             (wpipe->pipe_state & PIPE_EOF))
1042                 revents |= POLLHUP;
1043
1044         if (revents == 0) {
1045                 if (events & (POLLIN | POLLRDNORM)) {
1046                         selrecord(td, &rpipe->pipe_sel);
1047                         rpipe->pipe_state |= PIPE_SEL;
1048                 }
1049
1050                 if (events & (POLLOUT | POLLWRNORM)) {
1051                         selrecord(td, &wpipe->pipe_sel);
1052                         wpipe->pipe_state |= PIPE_SEL;
1053                 }
1054         }
1055
1056         return (revents);
1057 }
1058
1059 static int
1060 pipe_stat(struct file *fp, struct stat *ub, struct thread *td)
1061 {
1062         struct pipe *pipe = (struct pipe *)fp->f_data;
1063
1064         bzero((caddr_t)ub, sizeof(*ub));
1065         ub->st_mode = S_IFIFO;
1066         ub->st_blksize = pipe->pipe_buffer.size;
1067         ub->st_size = pipe->pipe_buffer.cnt;
1068         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1069         ub->st_atimespec = pipe->pipe_atime;
1070         ub->st_mtimespec = pipe->pipe_mtime;
1071         ub->st_ctimespec = pipe->pipe_ctime;
1072         /*
1073          * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1074          * st_flags, st_gen.
1075          * XXX (st_dev, st_ino) should be unique.
1076          */
1077         return (0);
1078 }
1079
1080 /* ARGSUSED */
1081 static int
1082 pipe_close(struct file *fp, struct thread *td)
1083 {
1084         struct pipe *cpipe = (struct pipe *)fp->f_data;
1085
1086         fp->f_ops = &badfileops;
1087         fp->f_data = NULL;
1088         funsetown(cpipe->pipe_sigio);
1089         pipeclose(cpipe);
1090         return (0);
1091 }
1092
1093 static void
1094 pipe_free_kmem(struct pipe *cpipe)
1095 {
1096         if (cpipe->pipe_buffer.buffer != NULL) {
1097                 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1098                         --pipe_nbig;
1099                 kmem_free(kernel_map,
1100                         (vm_offset_t)cpipe->pipe_buffer.buffer,
1101                         cpipe->pipe_buffer.size);
1102                 cpipe->pipe_buffer.buffer = NULL;
1103                 cpipe->pipe_buffer.object = NULL;
1104         }
1105 #ifndef PIPE_NODIRECT
1106         KKASSERT(cpipe->pipe_map.xio_bytes == 0 &&
1107                 cpipe->pipe_map.xio_offset == 0 &&
1108                 cpipe->pipe_map.xio_npages == 0);
1109 #endif
1110 }
1111
1112 /*
1113  * shutdown the pipe
1114  */
1115 static void
1116 pipeclose(struct pipe *cpipe)
1117 {
1118         globaldata_t gd;
1119         struct pipe *ppipe;
1120
1121         if (cpipe == NULL)
1122                 return;
1123
1124         pipeselwakeup(cpipe);
1125
1126         /*
1127          * If the other side is blocked, wake it up saying that
1128          * we want to close it down.
1129          */
1130         while (cpipe->pipe_busy) {
1131                 wakeup(cpipe);
1132                 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
1133                 tsleep(cpipe, 0, "pipecl", 0);
1134         }
1135
1136         /*
1137          * Disconnect from peer
1138          */
1139         if ((ppipe = cpipe->pipe_peer) != NULL) {
1140                 pipeselwakeup(ppipe);
1141
1142                 ppipe->pipe_state |= PIPE_EOF;
1143                 wakeup(ppipe);
1144                 KNOTE(&ppipe->pipe_sel.si_note, 0);
1145                 ppipe->pipe_peer = NULL;
1146         }
1147
1148         /*
1149          * free or cache resources
1150          */
1151         gd = mycpu;
1152         if (gd->gd_pipeqcount >= pipe_maxcache ||
1153             cpipe->pipe_buffer.size != PIPE_SIZE
1154         ) {
1155                 pipe_free_kmem(cpipe);
1156                 free(cpipe, M_PIPE);
1157         } else {
1158                 KKASSERT(cpipe->pipe_map.xio_npages == 0 &&
1159                         cpipe->pipe_map.xio_bytes == 0 &&
1160                         cpipe->pipe_map.xio_offset == 0);
1161                 cpipe->pipe_state = 0;
1162                 cpipe->pipe_busy = 0;
1163                 cpipe->pipe_peer = gd->gd_pipeq;
1164                 gd->gd_pipeq = cpipe;
1165                 ++gd->gd_pipeqcount;
1166         }
1167 }
1168
1169 /*ARGSUSED*/
1170 static int
1171 pipe_kqfilter(struct file *fp, struct knote *kn)
1172 {
1173         struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
1174
1175         switch (kn->kn_filter) {
1176         case EVFILT_READ:
1177                 kn->kn_fop = &pipe_rfiltops;
1178                 break;
1179         case EVFILT_WRITE:
1180                 kn->kn_fop = &pipe_wfiltops;
1181                 cpipe = cpipe->pipe_peer;
1182                 if (cpipe == NULL)
1183                         /* other end of pipe has been closed */
1184                         return (EPIPE);
1185                 break;
1186         default:
1187                 return (1);
1188         }
1189         kn->kn_hook = (caddr_t)cpipe;
1190
1191         SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1192         return (0);
1193 }
1194
1195 static void
1196 filt_pipedetach(struct knote *kn)
1197 {
1198         struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1199
1200         SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1201 }
1202
1203 /*ARGSUSED*/
1204 static int
1205 filt_piperead(struct knote *kn, long hint)
1206 {
1207         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1208         struct pipe *wpipe = rpipe->pipe_peer;
1209
1210         kn->kn_data = rpipe->pipe_buffer.cnt;
1211         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1212                 kn->kn_data = rpipe->pipe_map.xio_bytes;
1213
1214         if ((rpipe->pipe_state & PIPE_EOF) ||
1215             (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1216                 kn->kn_flags |= EV_EOF; 
1217                 return (1);
1218         }
1219         return (kn->kn_data > 0);
1220 }
1221
1222 /*ARGSUSED*/
1223 static int
1224 filt_pipewrite(struct knote *kn, long hint)
1225 {
1226         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1227         struct pipe *wpipe = rpipe->pipe_peer;
1228
1229         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1230                 kn->kn_data = 0;
1231                 kn->kn_flags |= EV_EOF; 
1232                 return (1);
1233         }
1234         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1235         if (wpipe->pipe_state & PIPE_DIRECTW)
1236                 kn->kn_data = 0;
1237
1238         return (kn->kn_data >= PIPE_BUF);
1239 }