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 1.26 2005/03/01 23:35:14 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 #include <machine/cpufunc.h>
  90
  91 /*
  92  * interfaces to the outside world
  93  */
  94 static int pipe_read (struct file *fp, struct uio *uio,
  95                 struct ucred *cred, int flags, struct thread *td);
  96 static int pipe_write (struct file *fp, struct uio *uio,
  97                 struct ucred *cred, int flags, struct thread *td);
  98 static int pipe_close (struct file *fp, struct thread *td);
  99 static int pipe_poll (struct file *fp, int events, struct ucred *cred,
 100                 struct thread *td);
 101 static int pipe_kqfilter (struct file *fp, struct knote *kn);
 102 static int pipe_stat (struct file *fp, struct stat *sb, struct thread *td);
 103 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, struct thread *td);
 104
 105 static struct fileops pipeops = {
 106         NULL,   /* port */
 107         NULL,   /* clone */
 108         pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter,
 109         pipe_stat, pipe_close
 110 };
 111
 112 static void     filt_pipedetach(struct knote *kn);
 113 static int      filt_piperead(struct knote *kn, long hint);
 114 static int      filt_pipewrite(struct knote *kn, long hint);
 115
 116 static struct filterops pipe_rfiltops =
 117         { 1, NULL, filt_pipedetach, filt_piperead };
 118 static struct filterops pipe_wfiltops =
 119         { 1, NULL, filt_pipedetach, filt_pipewrite };
 120
 121 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures");
 122
 123 /*
 124  * Default pipe buffer size(s), this can be kind-of large now because pipe
 125  * space is pageable.  The pipe code will try to maintain locality of
 126  * reference for performance reasons, so small amounts of outstanding I/O
 127  * will not wipe the cache.
 128  */
 129 #define MINPIPESIZE (PIPE_SIZE/3)
 130 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 131
 132 /*
 133  * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
 134  * is there so that on large systems, we don't exhaust it.
 135  */
 136 #define MAXPIPEKVA (8*1024*1024)
 137
 138 /*
 139  * Limit for direct transfers, we cannot, of course limit
 140  * the amount of kva for pipes in general though.
 141  */
 142 #define LIMITPIPEKVA (16*1024*1024)
 143
 144 /*
 145  * Limit the number of "big" pipes
 146  */
 147 #define LIMITBIGPIPES   32
 148 #define PIPEQ_MAX_CACHE 16      /* per-cpu pipe structure cache */
 149
 150 static int pipe_maxbig = LIMITBIGPIPES;
 151 static int pipe_maxcache = PIPEQ_MAX_CACHE;
 152 static int pipe_nbig;
 153 static int pipe_bcache_alloc;
 154 static int pipe_bkmem_alloc;
 155 static int pipe_dwrite_enable = 1;      /* 0:copy, 1:kmem/sfbuf 2:force */
 156 static int pipe_dwrite_sfbuf = 1;       /* 0:kmem_map 1:sfbufs 2:sfbufs_dmap */
 157                                         /* 3:sfbuf_dmap w/ forced invlpg */
 158
 159 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation");
 160 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig,
 161         CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated");
 162 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache,
 163         CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu");
 164 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig,
 165         CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes");
 166 SYSCTL_INT(_kern_pipe, OID_AUTO, dwrite_enable,
 167         CTLFLAG_RW, &pipe_dwrite_enable, 0, "1:enable/2:force direct writes");
 168 SYSCTL_INT(_kern_pipe, OID_AUTO, dwrite_sfbuf,
 169         CTLFLAG_RW, &pipe_dwrite_sfbuf, 0,
 170         "(if dwrite_enable) 0:kmem 1:sfbuf 2:sfbuf_dmap 3:sfbuf_dmap_forceinvlpg");
 171 #if !defined(NO_PIPE_SYSCTL_STATS)
 172 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc,
 173         CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache");
 174 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc,
 175         CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem");
 176 #endif
 177
 178 static void pipeclose (struct pipe *cpipe);
 179 static void pipe_free_kmem (struct pipe *cpipe);
 180 static int pipe_create (struct pipe **cpipep);
 181 static __inline int pipelock (struct pipe *cpipe, int catch);
 182 static __inline void pipeunlock (struct pipe *cpipe);
 183 static __inline void pipeselwakeup (struct pipe *cpipe);
 184 #ifndef PIPE_NODIRECT
 185 static int pipe_build_write_buffer (struct pipe *wpipe, struct uio *uio);
 186 static int pipe_direct_write (struct pipe *wpipe, struct uio *uio);
 187 static void pipe_clone_write_buffer (struct pipe *wpipe);
 188 #endif
 189 static int pipespace (struct pipe *cpipe, int size);
 190
 191 /*
 192  * The pipe system call for the DTYPE_PIPE type of pipes
 193  *
 194  * pipe_ARgs(int dummy)
 195  */
 196
 197 /* ARGSUSED */
 198 int
 199 pipe(struct pipe_args *uap)
 200 {
 201         struct thread *td = curthread;
 202         struct proc *p = td->td_proc;
 203         struct filedesc *fdp;
 204         struct file *rf, *wf;
 205         struct pipe *rpipe, *wpipe;
 206         int fd1, fd2, error;
 207
 208         KKASSERT(p);
 209         fdp = p->p_fd;
 210
 211         rpipe = wpipe = NULL;
 212         if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
 213                 pipeclose(rpipe);
 214                 pipeclose(wpipe);
 215                 return (ENFILE);
 216         }
 217
 218         rpipe->pipe_state |= PIPE_DIRECTOK;
 219         wpipe->pipe_state |= PIPE_DIRECTOK;
 220
 221         /*
 222          * Select the direct-map features to use for this pipe.  Since the
 223          * sysctl's can change on the fly we record the settings when the
 224          * pipe is created.
 225          *
 226          * Generally speaking the system will default to what we consider
 227          * to be the best-balanced and most stable option.  Right now this
 228          * is SFBUF1.  Modes 2 and 3 are considered experiemental at the
 229          * moment.
 230          */
 231         wpipe->pipe_feature = PIPE_COPY;
 232         if (pipe_dwrite_enable) {
 233                 switch(pipe_dwrite_sfbuf) {
 234                 case 0:
 235                         wpipe->pipe_feature = PIPE_KMEM;
 236                         break;
 237                 case 1:
 238                         wpipe->pipe_feature = PIPE_SFBUF1;
 239                         break;
 240                 case 2:
 241                 case 3:
 242                         wpipe->pipe_feature = PIPE_SFBUF2;
 243                         break;
 244                 }
 245         }
 246         rpipe->pipe_feature = wpipe->pipe_feature;
 247
 248         error = falloc(p, &rf, &fd1);
 249         if (error) {
 250                 pipeclose(rpipe);
 251                 pipeclose(wpipe);
 252                 return (error);
 253         }
 254         uap->sysmsg_fds[0] = fd1;
 255
 256         /*
 257          * Warning: once we've gotten past allocation of the fd for the
 258          * read-side, we can only drop the read side via fdrop() in order
 259          * to avoid races against processes which manage to dup() the read
 260          * side while we are blocked trying to allocate the write side.
 261          */
 262         rf->f_flag = FREAD | FWRITE;
 263         rf->f_type = DTYPE_PIPE;
 264         rf->f_data = (caddr_t)rpipe;
 265         rf->f_ops = &pipeops;
 266         error = falloc(p, &wf, &fd2);
 267         if (error) {
 268                 if (fdp->fd_ofiles[fd1] == rf) {
 269                         fdp->fd_ofiles[fd1] = NULL;
 270                         fdrop(rf, td);
 271                 }
 272                 fdrop(rf, td);
 273                 /* rpipe has been closed by fdrop(). */
 274                 pipeclose(wpipe);
 275                 return (error);
 276         }
 277         wf->f_flag = FREAD | FWRITE;
 278         wf->f_type = DTYPE_PIPE;
 279         wf->f_data = (caddr_t)wpipe;
 280         wf->f_ops = &pipeops;
 281         uap->sysmsg_fds[1] = fd2;
 282
 283         rpipe->pipe_peer = wpipe;
 284         wpipe->pipe_peer = rpipe;
 285         fdrop(rf, td);
 286         fdrop(wf, td);
 287
 288         return (0);
 289 }
 290
 291 /*
 292  * Allocate kva for pipe circular buffer, the space is pageable
 293  * This routine will 'realloc' the size of a pipe safely, if it fails
 294  * it will retain the old buffer.
 295  * If it fails it will return ENOMEM.
 296  */
 297 static int
 298 pipespace(struct pipe *cpipe, int size)
 299 {
 300         struct vm_object *object;
 301         caddr_t buffer;
 302         int npages, error;
 303
 304         npages = round_page(size) / PAGE_SIZE;
 305         object = cpipe->pipe_buffer.object;
 306
 307         /*
 308          * [re]create the object if necessary and reserve space for it
 309          * in the kernel_map.  The object and memory are pageable.  On
 310          * success, free the old resources before assigning the new
 311          * ones.
 312          */
 313         if (object == NULL || object->size != npages) {
 314                 object = vm_object_allocate(OBJT_DEFAULT, npages);
 315                 buffer = (caddr_t) vm_map_min(kernel_map);
 316
 317                 error = vm_map_find(kernel_map, object, 0,
 318                         (vm_offset_t *) &buffer, size, 1,
 319                         VM_PROT_ALL, VM_PROT_ALL, 0);
 320
 321                 if (error != KERN_SUCCESS) {
 322                         vm_object_deallocate(object);
 323                         return (ENOMEM);
 324                 }
 325                 pipe_free_kmem(cpipe);
 326                 cpipe->pipe_buffer.object = object;
 327                 cpipe->pipe_buffer.buffer = buffer;
 328                 cpipe->pipe_buffer.size = size;
 329                 ++pipe_bkmem_alloc;
 330         } else {
 331                 ++pipe_bcache_alloc;
 332         }
 333         cpipe->pipe_buffer.in = 0;
 334         cpipe->pipe_buffer.out = 0;
 335         cpipe->pipe_buffer.cnt = 0;
 336         return (0);
 337 }
 338
 339 /*
 340  * Initialize and allocate VM and memory for pipe, pulling the pipe from
 341  * our per-cpu cache if possible.  For now make sure it is sized for the
 342  * smaller PIPE_SIZE default.
 343  */
 344 static int
 345 pipe_create(cpipep)
 346         struct pipe **cpipep;
 347 {
 348         globaldata_t gd = mycpu;
 349         struct pipe *cpipe;
 350         int error;
 351
 352         if ((cpipe = gd->gd_pipeq) != NULL) {
 353                 gd->gd_pipeq = cpipe->pipe_peer;
 354                 --gd->gd_pipeqcount;
 355                 cpipe->pipe_peer = NULL;
 356         } else {
 357                 cpipe = malloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
 358         }
 359         *cpipep = cpipe;
 360         if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
 361                 return (error);
 362         vfs_timestamp(&cpipe->pipe_ctime);
 363         cpipe->pipe_atime = cpipe->pipe_ctime;
 364         cpipe->pipe_mtime = cpipe->pipe_ctime;
 365         return (0);
 366 }
 367
 368
 369 /*
 370  * lock a pipe for I/O, blocking other access
 371  */
 372 static __inline int
 373 pipelock(cpipe, catch)
 374         struct pipe *cpipe;
 375         int catch;
 376 {
 377         int error;
 378
 379         while (cpipe->pipe_state & PIPE_LOCK) {
 380                 cpipe->pipe_state |= PIPE_LWANT;
 381                 error = tsleep(cpipe, (catch ? PCATCH : 0), "pipelk", 0);
 382                 if (error != 0)
 383                         return (error);
 384         }
 385         cpipe->pipe_state |= PIPE_LOCK;
 386         return (0);
 387 }
 388
 389 /*
 390  * unlock a pipe I/O lock
 391  */
 392 static __inline void
 393 pipeunlock(cpipe)
 394         struct pipe *cpipe;
 395 {
 396
 397         cpipe->pipe_state &= ~PIPE_LOCK;
 398         if (cpipe->pipe_state & PIPE_LWANT) {
 399                 cpipe->pipe_state &= ~PIPE_LWANT;
 400                 wakeup(cpipe);
 401         }
 402 }
 403
 404 static __inline void
 405 pipeselwakeup(cpipe)
 406         struct pipe *cpipe;
 407 {
 408
 409         if (cpipe->pipe_state & PIPE_SEL) {
 410                 cpipe->pipe_state &= ~PIPE_SEL;
 411                 selwakeup(&cpipe->pipe_sel);
 412         }
 413         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 414                 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
 415         KNOTE(&cpipe->pipe_sel.si_note, 0);
 416 }
 417
 418 /* ARGSUSED */
 419 static int
 420 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred,
 421         int flags, struct thread *td)
 422 {
 423         struct pipe *rpipe = (struct pipe *) fp->f_data;
 424         int error;
 425         int nread = 0;
 426         u_int size;
 427
 428         ++rpipe->pipe_busy;
 429         error = pipelock(rpipe, 1);
 430         if (error)
 431                 goto unlocked_error;
 432
 433         while (uio->uio_resid) {
 434                 caddr_t va;
 435
 436                 if (rpipe->pipe_buffer.cnt > 0) {
 437                         /*
 438                          * normal pipe buffer receive
 439                          */
 440                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 441                         if (size > rpipe->pipe_buffer.cnt)
 442                                 size = rpipe->pipe_buffer.cnt;
 443                         if (size > (u_int) uio->uio_resid)
 444                                 size = (u_int) uio->uio_resid;
 445
 446                         error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 447                                         size, uio);
 448                         if (error)
 449                                 break;
 450
 451                         rpipe->pipe_buffer.out += size;
 452                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 453                                 rpipe->pipe_buffer.out = 0;
 454
 455                         rpipe->pipe_buffer.cnt -= size;
 456
 457                         /*
 458                          * If there is no more to read in the pipe, reset
 459                          * its pointers to the beginning.  This improves
 460                          * cache hit stats.
 461                          */
 462                         if (rpipe->pipe_buffer.cnt == 0) {
 463                                 rpipe->pipe_buffer.in = 0;
 464                                 rpipe->pipe_buffer.out = 0;
 465                         }
 466                         nread += size;
 467 #ifndef PIPE_NODIRECT
 468                 } else if (rpipe->pipe_kva &&
 469                            rpipe->pipe_feature == PIPE_KMEM &&
 470                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
 471                                == PIPE_DIRECTW
 472                 ) {
 473                         /*
 474                          * Direct copy using source-side kva mapping
 475                          */
 476                         size = rpipe->pipe_map.xio_bytes -
 477                                 rpipe->pipe_buffer.out;
 478                         if (size > (u_int)uio->uio_resid)
 479                                 size = (u_int)uio->uio_resid;
 480                         va = (caddr_t)rpipe->pipe_kva +
 481                                 xio_kvaoffset(&rpipe->pipe_map, rpipe->pipe_buffer.out);
 482                         error = uiomove(va, size, uio);
 483                         if (error)
 484                                 break;
 485                         nread += size;
 486                         rpipe->pipe_buffer.out += size;
 487                         if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
 488                                 rpipe->pipe_state |= PIPE_DIRECTIP;
 489                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 490                                 wakeup(rpipe);
 491                         }
 492                 } else if (rpipe->pipe_buffer.out != rpipe->pipe_map.xio_bytes &&
 493                            rpipe->pipe_kva &&
 494                            rpipe->pipe_feature == PIPE_SFBUF2 &&
 495                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
 496                                == PIPE_DIRECTW
 497                 ) {
 498                         /*
 499                          * Direct copy, bypassing a kernel buffer.  We cannot
 500                          * mess with the direct-write buffer until
 501                          * PIPE_DIRECTIP is cleared.  In order to prevent
 502                          * the pipe_write code from racing itself in
 503                          * direct_write, we set DIRECTIP when we clear
 504                          * DIRECTW after we have exhausted the buffer.
 505                          */
 506                         if (pipe_dwrite_sfbuf == 3)
 507                                 rpipe->pipe_kvamask = 0;
 508                         pmap_qenter2(rpipe->pipe_kva, rpipe->pipe_map.xio_pages,
 509                                     rpipe->pipe_map.xio_npages,
 510                                     &rpipe->pipe_kvamask);
 511                         size = rpipe->pipe_map.xio_bytes -
 512                                 rpipe->pipe_buffer.out;
 513                         if (size > (u_int)uio->uio_resid)
 514                                 size = (u_int)uio->uio_resid;
 515                         va = (caddr_t)rpipe->pipe_kva + xio_kvaoffset(&rpipe->pipe_map, rpipe->pipe_buffer.out);
 516                         error = uiomove(va, size, uio);
 517                         if (error)
 518                                 break;
 519                         nread += size;
 520                         rpipe->pipe_buffer.out += size;
 521                         if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
 522                                 rpipe->pipe_state |= PIPE_DIRECTIP;
 523                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 524                                 wakeup(rpipe);
 525                         }
 526                 } else if (rpipe->pipe_buffer.out != rpipe->pipe_map.xio_bytes &&
 527                            rpipe->pipe_feature == PIPE_SFBUF1 &&
 528                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
 529                                 == PIPE_DIRECTW
 530                 ) {
 531                         /*
 532                          * Direct copy, bypassing a kernel buffer.  We cannot
 533                          * mess with the direct-write buffer until
 534                          * PIPE_DIRECTIP is cleared.  In order to prevent
 535                          * the pipe_write code from racing itself in
 536                          * direct_write, we set DIRECTIP when we clear
 537                          * DIRECTW after we have exhausted the buffer.
 538                          */
 539                         error = xio_uio_copy(&rpipe->pipe_map, rpipe->pipe_buffer.out, uio, &size);
 540                         if (error)
 541                                 break;
 542                         nread += size;
 543                         rpipe->pipe_buffer.out += size;
 544                         if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
 545                                 rpipe->pipe_state |= PIPE_DIRECTIP;
 546                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 547                                 wakeup(rpipe);
 548                         }
 549 #endif
 550                 } else {
 551                         /*
 552                          * detect EOF condition
 553                          * read returns 0 on EOF, no need to set error
 554                          */
 555                         if (rpipe->pipe_state & PIPE_EOF)
 556                                 break;
 557
 558                         /*
 559                          * If the "write-side" has been blocked, wake it up now.
 560                          */
 561                         if (rpipe->pipe_state & PIPE_WANTW) {
 562                                 rpipe->pipe_state &= ~PIPE_WANTW;
 563                                 wakeup(rpipe);
 564                         }
 565
 566                         /*
 567                          * Break if some data was read.
 568                          */
 569                         if (nread > 0)
 570                                 break;
 571
 572                         /*
 573                          * Unlock the pipe buffer for our remaining
 574                          * processing.  We will either break out with an
 575                          * error or we will sleep and relock to loop.
 576                          */
 577                         pipeunlock(rpipe);
 578
 579                         /*
 580                          * Handle non-blocking mode operation or
 581                          * wait for more data.
 582                          */
 583                         if (fp->f_flag & FNONBLOCK) {
 584                                 error = EAGAIN;
 585                         } else {
 586                                 rpipe->pipe_state |= PIPE_WANTR;
 587                                 if ((error = tsleep(rpipe, PCATCH|PNORESCHED,
 588                                     "piperd", 0)) == 0) {
 589                                         error = pipelock(rpipe, 1);
 590                                 }
 591                         }
 592                         if (error)
 593                                 goto unlocked_error;
 594                 }
 595         }
 596         pipeunlock(rpipe);
 597
 598         if (error == 0)
 599                 vfs_timestamp(&rpipe->pipe_atime);
 600 unlocked_error:
 601         --rpipe->pipe_busy;
 602
 603         /*
 604          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 605          */
 606         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 607                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 608                 wakeup(rpipe);
 609         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 610                 /*
 611                  * Handle write blocking hysteresis.
 612                  */
 613                 if (rpipe->pipe_state & PIPE_WANTW) {
 614                         rpipe->pipe_state &= ~PIPE_WANTW;
 615                         wakeup(rpipe);
 616                 }
 617         }
 618
 619         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 620                 pipeselwakeup(rpipe);
 621         return (error);
 622 }
 623
 624 #ifndef PIPE_NODIRECT
 625 /*
 626  * Map the sending processes' buffer into kernel space and wire it.
 627  * This is similar to a physical write operation.
 628  */
 629 static int
 630 pipe_build_write_buffer(wpipe, uio)
 631         struct pipe *wpipe;
 632         struct uio *uio;
 633 {
 634         int error;
 635         u_int size;
 636
 637         size = (u_int) uio->uio_iov->iov_len;
 638         if (size > wpipe->pipe_buffer.size)
 639                 size = wpipe->pipe_buffer.size;
 640
 641         error = xio_init_ubuf(&wpipe->pipe_map, uio->uio_iov->iov_base,
 642                                 size, XIOF_READ);
 643         wpipe->pipe_buffer.out = 0;
 644         if (error)
 645                 return(error);
 646
 647         /*
 648          * Create a kernel map for KMEM and SFBUF2 copy modes.  SFBUF2 will
 649          * map the pages on the target while KMEM maps the pages now.
 650          */
 651         switch(wpipe->pipe_feature) {
 652         case PIPE_KMEM:
 653         case PIPE_SFBUF2:
 654                 if (wpipe->pipe_kva == NULL) {
 655                         wpipe->pipe_kva =
 656                             kmem_alloc_nofault(kernel_map, XIO_INTERNAL_SIZE);
 657                         wpipe->pipe_kvamask = 0;
 658                 }
 659                 if (wpipe->pipe_feature == PIPE_KMEM) {
 660                         pmap_qenter(wpipe->pipe_kva, wpipe->pipe_map.xio_pages,
 661                                     wpipe->pipe_map.xio_npages);
 662                 }
 663                 break;
 664         default:
 665                 break;
 666         }
 667
 668         /*
 669          * And update the uio data.  The XIO might have loaded fewer bytes
 670          * then requested so reload 'size'.
 671          */
 672         size = wpipe->pipe_map.xio_bytes;
 673         uio->uio_iov->iov_len -= size;
 674         uio->uio_iov->iov_base += size;
 675         if (uio->uio_iov->iov_len == 0)
 676                 uio->uio_iov++;
 677         uio->uio_resid -= size;
 678         uio->uio_offset += size;
 679         return (0);
 680 }
 681
 682 /*
 683  * In the case of a signal, the writing process might go away.  This
 684  * code copies the data into the circular buffer so that the source
 685  * pages can be freed without loss of data.
 686  *
 687  * Note that in direct mode pipe_buffer.out is used to track the
 688  * XIO offset.  We are converting the direct mode into buffered mode
 689  * which changes the meaning of pipe_buffer.out.
 690  */
 691 static void
 692 pipe_clone_write_buffer(wpipe)
 693         struct pipe *wpipe;
 694 {
 695         int size;
 696         int offset;
 697
 698         offset = wpipe->pipe_buffer.out;
 699         size = wpipe->pipe_map.xio_bytes - offset;
 700
 701         KKASSERT(size <= wpipe->pipe_buffer.size);
 702
 703         wpipe->pipe_buffer.in = size;
 704         wpipe->pipe_buffer.out = 0;
 705         wpipe->pipe_buffer.cnt = size;
 706         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
 707
 708         xio_copy_xtok(&wpipe->pipe_map, offset, wpipe->pipe_buffer.buffer, size);
 709         xio_release(&wpipe->pipe_map);
 710         if (wpipe->pipe_kva) {
 711                 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
 712                 kmem_free(kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
 713                 wpipe->pipe_kva = NULL;
 714         }
 715 }
 716
 717 /*
 718  * This implements the pipe buffer write mechanism.  Note that only
 719  * a direct write OR a normal pipe write can be pending at any given time.
 720  * If there are any characters in the pipe buffer, the direct write will
 721  * be deferred until the receiving process grabs all of the bytes from
 722  * the pipe buffer.  Then the direct mapping write is set-up.
 723  */
 724 static int
 725 pipe_direct_write(wpipe, uio)
 726         struct pipe *wpipe;
 727         struct uio *uio;
 728 {
 729         int error;
 730
 731 retry:
 732         while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
 733                 if (wpipe->pipe_state & PIPE_WANTR) {
 734                         wpipe->pipe_state &= ~PIPE_WANTR;
 735                         wakeup(wpipe);
 736                 }
 737                 wpipe->pipe_state |= PIPE_WANTW;
 738                 error = tsleep(wpipe, PCATCH, "pipdww", 0);
 739                 if (error)
 740                         goto error2;
 741                 if (wpipe->pipe_state & PIPE_EOF) {
 742                         error = EPIPE;
 743                         goto error2;
 744                 }
 745         }
 746         KKASSERT(wpipe->pipe_map.xio_bytes == 0);
 747         if (wpipe->pipe_buffer.cnt > 0) {
 748                 if (wpipe->pipe_state & PIPE_WANTR) {
 749                         wpipe->pipe_state &= ~PIPE_WANTR;
 750                         wakeup(wpipe);
 751                 }
 752
 753                 wpipe->pipe_state |= PIPE_WANTW;
 754                 error = tsleep(wpipe, PCATCH, "pipdwc", 0);
 755                 if (error)
 756                         goto error2;
 757                 if (wpipe->pipe_state & PIPE_EOF) {
 758                         error = EPIPE;
 759                         goto error2;
 760                 }
 761                 goto retry;
 762         }
 763
 764         /*
 765          * Build our direct-write buffer
 766          */
 767         wpipe->pipe_state |= PIPE_DIRECTW | PIPE_DIRECTIP;
 768         error = pipe_build_write_buffer(wpipe, uio);
 769         if (error)
 770                 goto error1;
 771         wpipe->pipe_state &= ~PIPE_DIRECTIP;
 772
 773         /*
 774          * Wait until the receiver has snarfed the data.  Since we are likely
 775          * going to sleep we optimize the case and yield synchronously,
 776          * possibly avoiding the tsleep().
 777          */
 778         error = 0;
 779         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
 780                 if (wpipe->pipe_state & PIPE_EOF) {
 781                         pipelock(wpipe, 0);
 782                         xio_release(&wpipe->pipe_map);
 783                         if (wpipe->pipe_kva) {
 784                                 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
 785                                 kmem_free(kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
 786                                 wpipe->pipe_kva = NULL;
 787                         }
 788                         pipeunlock(wpipe);
 789                         pipeselwakeup(wpipe);
 790                         error = EPIPE;
 791                         goto error1;
 792                 }
 793                 if (wpipe->pipe_state & PIPE_WANTR) {
 794                         wpipe->pipe_state &= ~PIPE_WANTR;
 795                         wakeup(wpipe);
 796                 }
 797                 pipeselwakeup(wpipe);
 798                 error = tsleep(wpipe, PCATCH|PNORESCHED, "pipdwt", 0);
 799         }
 800         pipelock(wpipe,0);
 801         if (wpipe->pipe_state & PIPE_DIRECTW) {
 802                 /*
 803                  * this bit of trickery substitutes a kernel buffer for
 804                  * the process that might be going away.
 805                  */
 806                 pipe_clone_write_buffer(wpipe);
 807                 KKASSERT((wpipe->pipe_state & PIPE_DIRECTIP) == 0);
 808         } else {
 809                 /*
 810                  * note: The pipe_kva mapping is not qremove'd here.  For
 811                  * legacy PIPE_KMEM mode this constitutes an improvement
 812                  * over the original FreeBSD-4 algorithm.  For PIPE_SFBUF2
 813                  * mode the kva mapping must not be removed to get the
 814                  * caching benefit.
 815                  *
 816                  * For testing purposes we will give the original algorithm
 817                  * the benefit of the doubt 'what it could have been', and
 818                  * keep the optimization.
 819                  */
 820                 KKASSERT(wpipe->pipe_state & PIPE_DIRECTIP);
 821                 xio_release(&wpipe->pipe_map);
 822                 wpipe->pipe_state &= ~PIPE_DIRECTIP;
 823         }
 824         pipeunlock(wpipe);
 825         return (error);
 826
 827         /*
 828          * Direct-write error, clear the direct write flags.
 829          */
 830 error1:
 831         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
 832         /* fallthrough */
 833
 834         /*
 835          * General error, wakeup the other side if it happens to be sleeping.
 836          */
 837 error2:
 838         wakeup(wpipe);
 839         return (error);
 840 }
 841 #endif
 842
 843 static int
 844 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred,
 845         int flags, struct thread *td)
 846 {
 847         int error = 0;
 848         int orig_resid;
 849         struct pipe *wpipe, *rpipe;
 850
 851         rpipe = (struct pipe *) fp->f_data;
 852         wpipe = rpipe->pipe_peer;
 853
 854         /*
 855          * detect loss of pipe read side, issue SIGPIPE if lost.
 856          */
 857         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 858                 return (EPIPE);
 859         }
 860         ++wpipe->pipe_busy;
 861
 862         /*
 863          * If it is advantageous to resize the pipe buffer, do
 864          * so.
 865          */
 866         if ((uio->uio_resid > PIPE_SIZE) &&
 867                 (pipe_nbig < pipe_maxbig) &&
 868                 (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) == 0 &&
 869                 (wpipe->pipe_buffer.size <= PIPE_SIZE) &&
 870                 (wpipe->pipe_buffer.cnt == 0)) {
 871
 872                 if ((error = pipelock(wpipe,1)) == 0) {
 873                         if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
 874                                 pipe_nbig++;
 875                         pipeunlock(wpipe);
 876                 }
 877         }
 878
 879         /*
 880          * If an early error occured unbusy and return, waking up any pending
 881          * readers.
 882          */
 883         if (error) {
 884                 --wpipe->pipe_busy;
 885                 if ((wpipe->pipe_busy == 0) &&
 886                     (wpipe->pipe_state & PIPE_WANT)) {
 887                         wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
 888                         wakeup(wpipe);
 889                 }
 890                 return(error);
 891         }
 892
 893         KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone"));
 894
 895         orig_resid = uio->uio_resid;
 896
 897         while (uio->uio_resid) {
 898                 int space;
 899
 900 #ifndef PIPE_NODIRECT
 901                 /*
 902                  * If the transfer is large, we can gain performance if
 903                  * we do process-to-process copies directly.
 904                  * If the write is non-blocking, we don't use the
 905                  * direct write mechanism.
 906                  *
 907                  * The direct write mechanism will detect the reader going
 908                  * away on us.
 909                  */
 910                 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT ||
 911                     pipe_dwrite_enable > 1) &&
 912                     (fp->f_flag & FNONBLOCK) == 0 &&
 913                     pipe_dwrite_enable) {
 914                         error = pipe_direct_write( wpipe, uio);
 915                         if (error)
 916                                 break;
 917                         continue;
 918                 }
 919 #endif
 920
 921                 /*
 922                  * Pipe buffered writes cannot be coincidental with
 923                  * direct writes.  We wait until the currently executing
 924                  * direct write is completed before we start filling the
 925                  * pipe buffer.  We break out if a signal occurs or the
 926                  * reader goes away.
 927                  */
 928         retrywrite:
 929                 while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
 930                         if (wpipe->pipe_state & PIPE_WANTR) {
 931                                 wpipe->pipe_state &= ~PIPE_WANTR;
 932                                 wakeup(wpipe);
 933                         }
 934                         error = tsleep(wpipe, PCATCH, "pipbww", 0);
 935                         if (wpipe->pipe_state & PIPE_EOF)
 936                                 break;
 937                         if (error)
 938                                 break;
 939                 }
 940                 if (wpipe->pipe_state & PIPE_EOF) {
 941                         error = EPIPE;
 942                         break;
 943                 }
 944
 945                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
 946
 947                 /* Writes of size <= PIPE_BUF must be atomic. */
 948                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
 949                         space = 0;
 950
 951                 /*
 952                  * Write to fill, read size handles write hysteresis.  Also
 953                  * additional restrictions can cause select-based non-blocking
 954                  * writes to spin.
 955                  */
 956                 if (space > 0) {
 957                         if ((error = pipelock(wpipe,1)) == 0) {
 958                                 int size;       /* Transfer size */
 959                                 int segsize;    /* first segment to transfer */
 960
 961                                 /*
 962                                  * It is possible for a direct write to
 963                                  * slip in on us... handle it here...
 964                                  */
 965                                 if (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
 966                                         pipeunlock(wpipe);
 967                                         goto retrywrite;
 968                                 }
 969                                 /*
 970                                  * If a process blocked in uiomove, our
 971                                  * value for space might be bad.
 972                                  *
 973                                  * XXX will we be ok if the reader has gone
 974                                  * away here?
 975                                  */
 976                                 if (space > wpipe->pipe_buffer.size -
 977                                     wpipe->pipe_buffer.cnt) {
 978                                         pipeunlock(wpipe);
 979                                         goto retrywrite;
 980                                 }
 981
 982                                 /*
 983                                  * Transfer size is minimum of uio transfer
 984                                  * and free space in pipe buffer.
 985                                  */
 986                                 if (space > uio->uio_resid)
 987                                         size = uio->uio_resid;
 988                                 else
 989                                         size = space;
 990                                 /*
 991                                  * First segment to transfer is minimum of
 992                                  * transfer size and contiguous space in
 993                                  * pipe buffer.  If first segment to transfer
 994                                  * is less than the transfer size, we've got
 995                                  * a wraparound in the buffer.
 996                                  */
 997                                 segsize = wpipe->pipe_buffer.size -
 998                                         wpipe->pipe_buffer.in;
 999                                 if (segsize > size)
1000                                         segsize = size;
1001
1002                                 /* Transfer first segment */
1003
1004                                 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1005                                                 segsize, uio);
1006
1007                                 if (error == 0 && segsize < size) {
1008                                         /*
1009                                          * Transfer remaining part now, to
1010                                          * support atomic writes.  Wraparound
1011                                          * happened.
1012                                          */
1013                                         if (wpipe->pipe_buffer.in + segsize !=
1014                                             wpipe->pipe_buffer.size)
1015                                                 panic("Expected pipe buffer wraparound disappeared");
1016
1017                                         error = uiomove(&wpipe->pipe_buffer.buffer[0],
1018                                                         size - segsize, uio);
1019                                 }
1020                                 if (error == 0) {
1021                                         wpipe->pipe_buffer.in += size;
1022                                         if (wpipe->pipe_buffer.in >=
1023                                             wpipe->pipe_buffer.size) {
1024                                                 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
1025                                                         panic("Expected wraparound bad");
1026                                                 wpipe->pipe_buffer.in = size - segsize;
1027                                         }
1028
1029                                         wpipe->pipe_buffer.cnt += size;
1030                                         if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
1031                                                 panic("Pipe buffer overflow");
1032
1033                                 }
1034                                 pipeunlock(wpipe);
1035                         }
1036                         if (error)
1037                                 break;
1038
1039                 } else {
1040                         /*
1041                          * If the "read-side" has been blocked, wake it up now
1042                          * and yield to let it drain synchronously rather
1043                          * then block.
1044                          */
1045                         if (wpipe->pipe_state & PIPE_WANTR) {
1046                                 wpipe->pipe_state &= ~PIPE_WANTR;
1047                                 wakeup(wpipe);
1048                         }
1049
1050                         /*
1051                          * don't block on non-blocking I/O
1052                          */
1053                         if (fp->f_flag & FNONBLOCK) {
1054                                 error = EAGAIN;
1055                                 break;
1056                         }
1057
1058                         /*
1059                          * We have no more space and have something to offer,
1060                          * wake up select/poll.
1061                          */
1062                         pipeselwakeup(wpipe);
1063
1064                         wpipe->pipe_state |= PIPE_WANTW;
1065                         error = tsleep(wpipe, PCATCH|PNORESCHED, "pipewr", 0);
1066                         if (error != 0)
1067                                 break;
1068                         /*
1069                          * If read side wants to go away, we just issue a signal
1070                          * to ourselves.
1071                          */
1072                         if (wpipe->pipe_state & PIPE_EOF) {
1073                                 error = EPIPE;
1074                                 break;
1075                         }
1076                 }
1077         }
1078
1079         --wpipe->pipe_busy;
1080
1081         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1082                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1083                 wakeup(wpipe);
1084         } else if (wpipe->pipe_buffer.cnt > 0) {
1085                 /*
1086                  * If we have put any characters in the buffer, we wake up
1087                  * the reader.
1088                  */
1089                 if (wpipe->pipe_state & PIPE_WANTR) {
1090                         wpipe->pipe_state &= ~PIPE_WANTR;
1091                         wakeup(wpipe);
1092                 }
1093         }
1094
1095         /*
1096          * Don't return EPIPE if I/O was successful
1097          */
1098         if ((wpipe->pipe_buffer.cnt == 0) &&
1099             (uio->uio_resid == 0) &&
1100             (error == EPIPE)) {
1101                 error = 0;
1102         }
1103
1104         if (error == 0)
1105                 vfs_timestamp(&wpipe->pipe_mtime);
1106
1107         /*
1108          * We have something to offer,
1109          * wake up select/poll.
1110          */
1111         if (wpipe->pipe_buffer.cnt)
1112                 pipeselwakeup(wpipe);
1113
1114         return (error);
1115 }
1116
1117 /*
1118  * we implement a very minimal set of ioctls for compatibility with sockets.
1119  */
1120 int
1121 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct thread *td)
1122 {
1123         struct pipe *mpipe = (struct pipe *)fp->f_data;
1124
1125         switch (cmd) {
1126
1127         case FIONBIO:
1128                 return (0);
1129
1130         case FIOASYNC:
1131                 if (*(int *)data) {
1132                         mpipe->pipe_state |= PIPE_ASYNC;
1133                 } else {
1134                         mpipe->pipe_state &= ~PIPE_ASYNC;
1135                 }
1136                 return (0);
1137
1138         case FIONREAD:
1139                 if (mpipe->pipe_state & PIPE_DIRECTW) {
1140                         *(int *)data = mpipe->pipe_map.xio_bytes -
1141                                         mpipe->pipe_buffer.out;
1142                 } else {
1143                         *(int *)data = mpipe->pipe_buffer.cnt;
1144                 }
1145                 return (0);
1146
1147         case FIOSETOWN:
1148                 return (fsetown(*(int *)data, &mpipe->pipe_sigio));
1149
1150         case FIOGETOWN:
1151                 *(int *)data = fgetown(mpipe->pipe_sigio);
1152                 return (0);
1153
1154         /* This is deprecated, FIOSETOWN should be used instead. */
1155         case TIOCSPGRP:
1156                 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
1157
1158         /* This is deprecated, FIOGETOWN should be used instead. */
1159         case TIOCGPGRP:
1160                 *(int *)data = -fgetown(mpipe->pipe_sigio);
1161                 return (0);
1162
1163         }
1164         return (ENOTTY);
1165 }
1166
1167 int
1168 pipe_poll(struct file *fp, int events, struct ucred *cred, struct thread *td)
1169 {
1170         struct pipe *rpipe = (struct pipe *)fp->f_data;
1171         struct pipe *wpipe;
1172         int revents = 0;
1173
1174         wpipe = rpipe->pipe_peer;
1175         if (events & (POLLIN | POLLRDNORM))
1176                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1177                     (rpipe->pipe_buffer.cnt > 0) ||
1178                     (rpipe->pipe_state & PIPE_EOF))
1179                         revents |= events & (POLLIN | POLLRDNORM);
1180
1181         if (events & (POLLOUT | POLLWRNORM))
1182                 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) ||
1183                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1184                      (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1185                         revents |= events & (POLLOUT | POLLWRNORM);
1186
1187         if ((rpipe->pipe_state & PIPE_EOF) ||
1188             (wpipe == NULL) ||
1189             (wpipe->pipe_state & PIPE_EOF))
1190                 revents |= POLLHUP;
1191
1192         if (revents == 0) {
1193                 if (events & (POLLIN | POLLRDNORM)) {
1194                         selrecord(td, &rpipe->pipe_sel);
1195                         rpipe->pipe_state |= PIPE_SEL;
1196                 }
1197
1198                 if (events & (POLLOUT | POLLWRNORM)) {
1199                         selrecord(td, &wpipe->pipe_sel);
1200                         wpipe->pipe_state |= PIPE_SEL;
1201                 }
1202         }
1203
1204         return (revents);
1205 }
1206
1207 static int
1208 pipe_stat(struct file *fp, struct stat *ub, struct thread *td)
1209 {
1210         struct pipe *pipe = (struct pipe *)fp->f_data;
1211
1212         bzero((caddr_t)ub, sizeof(*ub));
1213         ub->st_mode = S_IFIFO;
1214         ub->st_blksize = pipe->pipe_buffer.size;
1215         ub->st_size = pipe->pipe_buffer.cnt;
1216         if (ub->st_size == 0 && (pipe->pipe_state & PIPE_DIRECTW)) {
1217                 ub->st_size = pipe->pipe_map.xio_bytes -
1218                                 pipe->pipe_buffer.out;
1219         }
1220         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1221         ub->st_atimespec = pipe->pipe_atime;
1222         ub->st_mtimespec = pipe->pipe_mtime;
1223         ub->st_ctimespec = pipe->pipe_ctime;
1224         /*
1225          * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1226          * st_flags, st_gen.
1227          * XXX (st_dev, st_ino) should be unique.
1228          */
1229         return (0);
1230 }
1231
1232 /* ARGSUSED */
1233 static int
1234 pipe_close(struct file *fp, struct thread *td)
1235 {
1236         struct pipe *cpipe = (struct pipe *)fp->f_data;
1237
1238         fp->f_ops = &badfileops;
1239         fp->f_data = NULL;
1240         funsetown(cpipe->pipe_sigio);
1241         pipeclose(cpipe);
1242         return (0);
1243 }
1244
1245 static void
1246 pipe_free_kmem(struct pipe *cpipe)
1247 {
1248         if (cpipe->pipe_buffer.buffer != NULL) {
1249                 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1250                         --pipe_nbig;
1251                 kmem_free(kernel_map,
1252                         (vm_offset_t)cpipe->pipe_buffer.buffer,
1253                         cpipe->pipe_buffer.size);
1254                 cpipe->pipe_buffer.buffer = NULL;
1255                 cpipe->pipe_buffer.object = NULL;
1256         }
1257 #ifndef PIPE_NODIRECT
1258         KKASSERT(cpipe->pipe_map.xio_bytes == 0 &&
1259                 cpipe->pipe_map.xio_offset == 0 &&
1260                 cpipe->pipe_map.xio_npages == 0);
1261 #endif
1262 }
1263
1264 /*
1265  * shutdown the pipe
1266  */
1267 static void
1268 pipeclose(struct pipe *cpipe)
1269 {
1270         globaldata_t gd;
1271         struct pipe *ppipe;
1272
1273         if (cpipe == NULL)
1274                 return;
1275
1276         pipeselwakeup(cpipe);
1277
1278         /*
1279          * If the other side is blocked, wake it up saying that
1280          * we want to close it down.
1281          */
1282         while (cpipe->pipe_busy) {
1283                 wakeup(cpipe);
1284                 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
1285                 tsleep(cpipe, 0, "pipecl", 0);
1286         }
1287
1288         /*
1289          * Disconnect from peer
1290          */
1291         if ((ppipe = cpipe->pipe_peer) != NULL) {
1292                 pipeselwakeup(ppipe);
1293
1294                 ppipe->pipe_state |= PIPE_EOF;
1295                 wakeup(ppipe);
1296                 KNOTE(&ppipe->pipe_sel.si_note, 0);
1297                 ppipe->pipe_peer = NULL;
1298         }
1299
1300         if (cpipe->pipe_kva) {
1301                 pmap_qremove(cpipe->pipe_kva, XIO_INTERNAL_PAGES);
1302                 kmem_free(kernel_map, cpipe->pipe_kva, XIO_INTERNAL_SIZE);
1303                 cpipe->pipe_kva = NULL;
1304         }
1305
1306         /*
1307          * free or cache resources
1308          */
1309         gd = mycpu;
1310         if (gd->gd_pipeqcount >= pipe_maxcache ||
1311             cpipe->pipe_buffer.size != PIPE_SIZE
1312         ) {
1313                 pipe_free_kmem(cpipe);
1314                 free(cpipe, M_PIPE);
1315         } else {
1316                 KKASSERT(cpipe->pipe_map.xio_npages == 0 &&
1317                         cpipe->pipe_map.xio_bytes == 0 &&
1318                         cpipe->pipe_map.xio_offset == 0);
1319                 cpipe->pipe_state = 0;
1320                 cpipe->pipe_busy = 0;
1321                 cpipe->pipe_peer = gd->gd_pipeq;
1322                 gd->gd_pipeq = cpipe;
1323                 ++gd->gd_pipeqcount;
1324         }
1325 }
1326
1327 /*ARGSUSED*/
1328 static int
1329 pipe_kqfilter(struct file *fp, struct knote *kn)
1330 {
1331         struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
1332
1333         switch (kn->kn_filter) {
1334         case EVFILT_READ:
1335                 kn->kn_fop = &pipe_rfiltops;
1336                 break;
1337         case EVFILT_WRITE:
1338                 kn->kn_fop = &pipe_wfiltops;
1339                 cpipe = cpipe->pipe_peer;
1340                 if (cpipe == NULL)
1341                         /* other end of pipe has been closed */
1342                         return (EPIPE);
1343                 break;
1344         default:
1345                 return (1);
1346         }
1347         kn->kn_hook = (caddr_t)cpipe;
1348
1349         SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1350         return (0);
1351 }
1352
1353 static void
1354 filt_pipedetach(struct knote *kn)
1355 {
1356         struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1357
1358         SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1359 }
1360
1361 /*ARGSUSED*/
1362 static int
1363 filt_piperead(struct knote *kn, long hint)
1364 {
1365         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1366         struct pipe *wpipe = rpipe->pipe_peer;
1367
1368         kn->kn_data = rpipe->pipe_buffer.cnt;
1369         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) {
1370                 kn->kn_data = rpipe->pipe_map.xio_bytes -
1371                                 rpipe->pipe_buffer.out;
1372         }
1373
1374         if ((rpipe->pipe_state & PIPE_EOF) ||
1375             (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1376                 kn->kn_flags |= EV_EOF;
1377                 return (1);
1378         }
1379         return (kn->kn_data > 0);
1380 }
1381
1382 /*ARGSUSED*/
1383 static int
1384 filt_pipewrite(struct knote *kn, long hint)
1385 {
1386         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1387         struct pipe *wpipe = rpipe->pipe_peer;
1388
1389         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1390                 kn->kn_data = 0;
1391                 kn->kn_flags |= EV_EOF;
1392                 return (1);
1393         }
1394         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1395         if (wpipe->pipe_state & PIPE_DIRECTW)
1396                 kn->kn_data = 0;
1397
1398         return (kn->kn_data >= PIPE_BUF);
1399 }