sys/kern/sys_pipe.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-4-Clause
   3  *
   4  * Copyright (c) 1996 John S. Dyson
   5  * Copyright (c) 2012 Giovanni Trematerra
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice immediately at the beginning of the file, without modification,
  13  *    this list of conditions, and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Absolutely no warranty of function or purpose is made by the author
  18  *    John S. Dyson.
  19  * 4. Modifications may be freely made to this file if the above conditions
  20  *    are met.
  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, the sending process pins the underlying pages in
  36  * memory, and the receiving process copies directly from these pinned pages
  37  * in the sending 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.
  50  *
  51  * In order to limit the resource use of pipes, two sysctls exist:
  52  *
  53  * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
  54  * address space available to us in pipe_map. This value is normally
  55  * autotuned, but may also be loader tuned.
  56  *
  57  * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
  58  * memory in use by pipes.
  59  *
  60  * Based on how large pipekva is relative to maxpipekva, the following
  61  * will happen:
  62  *
  63  * 0% - 50%:
  64  *     New pipes are given 16K of memory backing, pipes may dynamically
  65  *     grow to as large as 64K where needed.
  66  * 50% - 75%:
  67  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  68  *     existing pipes may NOT grow.
  69  * 75% - 100%:
  70  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  71  *     existing pipes will be shrunk down to 4K whenever possible.
  72  *
  73  * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0.  If
  74  * that is set,  the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
  75  * resize which MUST occur for reverse-direction pipes when they are
  76  * first used.
  77  *
  78  * Additional information about the current state of pipes may be obtained
  79  * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
  80  * and kern.ipc.piperesizefail.
  81  *
  82  * Locking rules:  There are two locks present here:  A mutex, used via
  83  * PIPE_LOCK, and a flag, used via pipelock().  All locking is done via
  84  * the flag, as mutexes can not persist over uiomove.  The mutex
  85  * exists only to guard access to the flag, and is not in itself a
  86  * locking mechanism.  Also note that there is only a single mutex for
  87  * both directions of a pipe.
  88  *
  89  * As pipelock() may have to sleep before it can acquire the flag, it
  90  * is important to reread all data after a call to pipelock(); everything
  91  * in the structure may have changed.
  92  */
  93
  94 #include <sys/cdefs.h>
  95 __FBSDID("$FreeBSD$");
  96
  97 #include <sys/param.h>
  98 #include <sys/systm.h>
  99 #include <sys/conf.h>
 100 #include <sys/fcntl.h>
 101 #include <sys/file.h>
 102 #include <sys/filedesc.h>
 103 #include <sys/filio.h>
 104 #include <sys/kernel.h>
 105 #include <sys/lock.h>
 106 #include <sys/mutex.h>
 107 #include <sys/ttycom.h>
 108 #include <sys/stat.h>
 109 #include <sys/malloc.h>
 110 #include <sys/poll.h>
 111 #include <sys/selinfo.h>
 112 #include <sys/signalvar.h>
 113 #include <sys/syscallsubr.h>
 114 #include <sys/sysctl.h>
 115 #include <sys/sysproto.h>
 116 #include <sys/pipe.h>
 117 #include <sys/proc.h>
 118 #include <sys/vnode.h>
 119 #include <sys/uio.h>
 120 #include <sys/user.h>
 121 #include <sys/event.h>
 122
 123 #include <security/mac/mac_framework.h>
 124
 125 #include <vm/vm.h>
 126 #include <vm/vm_param.h>
 127 #include <vm/vm_object.h>
 128 #include <vm/vm_kern.h>
 129 #include <vm/vm_extern.h>
 130 #include <vm/pmap.h>
 131 #include <vm/vm_map.h>
 132 #include <vm/vm_page.h>
 133 #include <vm/uma.h>
 134
 135 /*
 136  * Use this define if you want to disable *fancy* VM things.  Expect an
 137  * approx 30% decrease in transfer rate.  This could be useful for
 138  * NetBSD or OpenBSD.
 139  */
 140 /* #define PIPE_NODIRECT */
 141
 142 #define PIPE_PEER(pipe) \
 143         (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
 144
 145 /*
 146  * interfaces to the outside world
 147  */
 148 static fo_rdwr_t        pipe_read;
 149 static fo_rdwr_t        pipe_write;
 150 static fo_truncate_t    pipe_truncate;
 151 static fo_ioctl_t       pipe_ioctl;
 152 static fo_poll_t        pipe_poll;
 153 static fo_kqfilter_t    pipe_kqfilter;
 154 static fo_stat_t        pipe_stat;
 155 static fo_close_t       pipe_close;
 156 static fo_chmod_t       pipe_chmod;
 157 static fo_chown_t       pipe_chown;
 158 static fo_fill_kinfo_t  pipe_fill_kinfo;
 159
 160 struct fileops pipeops = {
 161         .fo_read = pipe_read,
 162         .fo_write = pipe_write,
 163         .fo_truncate = pipe_truncate,
 164         .fo_ioctl = pipe_ioctl,
 165         .fo_poll = pipe_poll,
 166         .fo_kqfilter = pipe_kqfilter,
 167         .fo_stat = pipe_stat,
 168         .fo_close = pipe_close,
 169         .fo_chmod = pipe_chmod,
 170         .fo_chown = pipe_chown,
 171         .fo_sendfile = invfo_sendfile,
 172         .fo_fill_kinfo = pipe_fill_kinfo,
 173         .fo_flags = DFLAG_PASSABLE
 174 };
 175
 176 static void     filt_pipedetach(struct knote *kn);
 177 static void     filt_pipedetach_notsup(struct knote *kn);
 178 static int      filt_pipenotsup(struct knote *kn, long hint);
 179 static int      filt_piperead(struct knote *kn, long hint);
 180 static int      filt_pipewrite(struct knote *kn, long hint);
 181
 182 static struct filterops pipe_nfiltops = {
 183         .f_isfd = 1,
 184         .f_detach = filt_pipedetach_notsup,
 185         .f_event = filt_pipenotsup
 186 };
 187 static struct filterops pipe_rfiltops = {
 188         .f_isfd = 1,
 189         .f_detach = filt_pipedetach,
 190         .f_event = filt_piperead
 191 };
 192 static struct filterops pipe_wfiltops = {
 193         .f_isfd = 1,
 194         .f_detach = filt_pipedetach,
 195         .f_event = filt_pipewrite
 196 };
 197
 198 /*
 199  * Default pipe buffer size(s), this can be kind-of large now because pipe
 200  * space is pageable.  The pipe code will try to maintain locality of
 201  * reference for performance reasons, so small amounts of outstanding I/O
 202  * will not wipe the cache.
 203  */
 204 #define MINPIPESIZE (PIPE_SIZE/3)
 205 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 206
 207 static long amountpipekva;
 208 static int pipefragretry;
 209 static int pipeallocfail;
 210 static int piperesizefail;
 211 static int piperesizeallowed = 1;
 212
 213 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
 214            &maxpipekva, 0, "Pipe KVA limit");
 215 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
 216            &amountpipekva, 0, "Pipe KVA usage");
 217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
 218           &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
 219 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
 220           &pipeallocfail, 0, "Pipe allocation failures");
 221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
 222           &piperesizefail, 0, "Pipe resize failures");
 223 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
 224           &piperesizeallowed, 0, "Pipe resizing allowed");
 225
 226 static void pipeinit(void *dummy __unused);
 227 static void pipeclose(struct pipe *cpipe);
 228 static void pipe_free_kmem(struct pipe *cpipe);
 229 static int pipe_create(struct pipe *pipe, bool backing);
 230 static int pipe_paircreate(struct thread *td, struct pipepair **p_pp);
 231 static __inline int pipelock(struct pipe *cpipe, int catch);
 232 static __inline void pipeunlock(struct pipe *cpipe);
 233 #ifndef PIPE_NODIRECT
 234 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
 235 static void pipe_destroy_write_buffer(struct pipe *wpipe);
 236 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
 237 static void pipe_clone_write_buffer(struct pipe *wpipe);
 238 #endif
 239 static int pipespace(struct pipe *cpipe, int size);
 240 static int pipespace_new(struct pipe *cpipe, int size);
 241
 242 static int      pipe_zone_ctor(void *mem, int size, void *arg, int flags);
 243 static int      pipe_zone_init(void *mem, int size, int flags);
 244 static void     pipe_zone_fini(void *mem, int size);
 245
 246 static uma_zone_t pipe_zone;
 247 static struct unrhdr64 pipeino_unr;
 248 static dev_t pipedev_ino;
 249
 250 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
 251
 252 static void
 253 pipeinit(void *dummy __unused)
 254 {
 255
 256         pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
 257             pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
 258             UMA_ALIGN_PTR, 0);
 259         KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
 260         new_unrhdr64(&pipeino_unr, 1);
 261         pipedev_ino = devfs_alloc_cdp_inode();
 262         KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
 263 }
 264
 265 static int
 266 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
 267 {
 268         struct pipepair *pp;
 269         struct pipe *rpipe, *wpipe;
 270
 271         KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
 272
 273         pp = (struct pipepair *)mem;
 274
 275         /*
 276          * We zero both pipe endpoints to make sure all the kmem pointers
 277          * are NULL, flag fields are zero'd, etc.  We timestamp both
 278          * endpoints with the same time.
 279          */
 280         rpipe = &pp->pp_rpipe;
 281         bzero(rpipe, sizeof(*rpipe));
 282         vfs_timestamp(&rpipe->pipe_ctime);
 283         rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
 284
 285         wpipe = &pp->pp_wpipe;
 286         bzero(wpipe, sizeof(*wpipe));
 287         wpipe->pipe_ctime = rpipe->pipe_ctime;
 288         wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
 289
 290         rpipe->pipe_peer = wpipe;
 291         rpipe->pipe_pair = pp;
 292         wpipe->pipe_peer = rpipe;
 293         wpipe->pipe_pair = pp;
 294
 295         /*
 296          * Mark both endpoints as present; they will later get free'd
 297          * one at a time.  When both are free'd, then the whole pair
 298          * is released.
 299          */
 300         rpipe->pipe_present = PIPE_ACTIVE;
 301         wpipe->pipe_present = PIPE_ACTIVE;
 302
 303         /*
 304          * Eventually, the MAC Framework may initialize the label
 305          * in ctor or init, but for now we do it elswhere to avoid
 306          * blocking in ctor or init.
 307          */
 308         pp->pp_label = NULL;
 309
 310         return (0);
 311 }
 312
 313 static int
 314 pipe_zone_init(void *mem, int size, int flags)
 315 {
 316         struct pipepair *pp;
 317
 318         KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
 319
 320         pp = (struct pipepair *)mem;
 321
 322         mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW);
 323         return (0);
 324 }
 325
 326 static void
 327 pipe_zone_fini(void *mem, int size)
 328 {
 329         struct pipepair *pp;
 330
 331         KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
 332
 333         pp = (struct pipepair *)mem;
 334
 335         mtx_destroy(&pp->pp_mtx);
 336 }
 337
 338 static int
 339 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
 340 {
 341         struct pipepair *pp;
 342         struct pipe *rpipe, *wpipe;
 343         int error;
 344
 345         *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
 346 #ifdef MAC
 347         /*
 348          * The MAC label is shared between the connected endpoints.  As a
 349          * result mac_pipe_init() and mac_pipe_create() are called once
 350          * for the pair, and not on the endpoints.
 351          */
 352         mac_pipe_init(pp);
 353         mac_pipe_create(td->td_ucred, pp);
 354 #endif
 355         rpipe = &pp->pp_rpipe;
 356         wpipe = &pp->pp_wpipe;
 357
 358         knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
 359         knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
 360
 361         /*
 362          * Only the forward direction pipe is backed by big buffer by
 363          * default.
 364          */
 365         error = pipe_create(rpipe, true);
 366         if (error != 0)
 367                 goto fail;
 368         error = pipe_create(wpipe, false);
 369         if (error != 0) {
 370                 /*
 371                  * This cleanup leaves the pipe inode number for rpipe
 372                  * still allocated, but never used.  We do not free
 373                  * inode numbers for opened pipes, which is required
 374                  * for correctness because numbers must be unique.
 375                  * But also it avoids any memory use by the unr
 376                  * allocator, so stashing away the transient inode
 377                  * number is reasonable.
 378                  */
 379                 pipe_free_kmem(rpipe);
 380                 goto fail;
 381         }
 382
 383         rpipe->pipe_state |= PIPE_DIRECTOK;
 384         wpipe->pipe_state |= PIPE_DIRECTOK;
 385         return (0);
 386
 387 fail:
 388         knlist_destroy(&rpipe->pipe_sel.si_note);
 389         knlist_destroy(&wpipe->pipe_sel.si_note);
 390 #ifdef MAC
 391         mac_pipe_destroy(pp);
 392 #endif
 393         return (error);
 394 }
 395
 396 int
 397 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
 398 {
 399         struct pipepair *pp;
 400         int error;
 401
 402         error = pipe_paircreate(td, &pp);
 403         if (error != 0)
 404                 return (error);
 405         pp->pp_rpipe.pipe_state |= PIPE_NAMED;
 406         *ppipe = &pp->pp_rpipe;
 407         return (0);
 408 }
 409
 410 void
 411 pipe_dtor(struct pipe *dpipe)
 412 {
 413         struct pipe *peer;
 414
 415         peer = (dpipe->pipe_state & PIPE_NAMED) != 0 ? dpipe->pipe_peer : NULL;
 416         funsetown(&dpipe->pipe_sigio);
 417         pipeclose(dpipe);
 418         if (peer != NULL) {
 419                 funsetown(&peer->pipe_sigio);
 420                 pipeclose(peer);
 421         }
 422 }
 423
 424 /*
 425  * The pipe system call for the DTYPE_PIPE type of pipes.  If we fail, let
 426  * the zone pick up the pieces via pipeclose().
 427  */
 428 int
 429 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
 430     struct filecaps *fcaps2)
 431 {
 432         struct file *rf, *wf;
 433         struct pipe *rpipe, *wpipe;
 434         struct pipepair *pp;
 435         int fd, fflags, error;
 436
 437         error = pipe_paircreate(td, &pp);
 438         if (error != 0)
 439                 return (error);
 440         rpipe = &pp->pp_rpipe;
 441         wpipe = &pp->pp_wpipe;
 442         error = falloc_caps(td, &rf, &fd, flags, fcaps1);
 443         if (error) {
 444                 pipeclose(rpipe);
 445                 pipeclose(wpipe);
 446                 return (error);
 447         }
 448         /* An extra reference on `rf' has been held for us by falloc_caps(). */
 449         fildes[0] = fd;
 450
 451         fflags = FREAD | FWRITE;
 452         if ((flags & O_NONBLOCK) != 0)
 453                 fflags |= FNONBLOCK;
 454
 455         /*
 456          * Warning: once we've gotten past allocation of the fd for the
 457          * read-side, we can only drop the read side via fdrop() in order
 458          * to avoid races against processes which manage to dup() the read
 459          * side while we are blocked trying to allocate the write side.
 460          */
 461         finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
 462         error = falloc_caps(td, &wf, &fd, flags, fcaps2);
 463         if (error) {
 464                 fdclose(td, rf, fildes[0]);
 465                 fdrop(rf, td);
 466                 /* rpipe has been closed by fdrop(). */
 467                 pipeclose(wpipe);
 468                 return (error);
 469         }
 470         /* An extra reference on `wf' has been held for us by falloc_caps(). */
 471         finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
 472         fdrop(wf, td);
 473         fildes[1] = fd;
 474         fdrop(rf, td);
 475
 476         return (0);
 477 }
 478
 479 #ifdef COMPAT_FREEBSD10
 480 /* ARGSUSED */
 481 int
 482 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused)
 483 {
 484         int error;
 485         int fildes[2];
 486
 487         error = kern_pipe(td, fildes, 0, NULL, NULL);
 488         if (error)
 489                 return (error);
 490
 491         td->td_retval[0] = fildes[0];
 492         td->td_retval[1] = fildes[1];
 493
 494         return (0);
 495 }
 496 #endif
 497
 498 int
 499 sys_pipe2(struct thread *td, struct pipe2_args *uap)
 500 {
 501         int error, fildes[2];
 502
 503         if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
 504                 return (EINVAL);
 505         error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
 506         if (error)
 507                 return (error);
 508         error = copyout(fildes, uap->fildes, 2 * sizeof(int));
 509         if (error) {
 510                 (void)kern_close(td, fildes[0]);
 511                 (void)kern_close(td, fildes[1]);
 512         }
 513         return (error);
 514 }
 515
 516 /*
 517  * Allocate kva for pipe circular buffer, the space is pageable
 518  * This routine will 'realloc' the size of a pipe safely, if it fails
 519  * it will retain the old buffer.
 520  * If it fails it will return ENOMEM.
 521  */
 522 static int
 523 pipespace_new(struct pipe *cpipe, int size)
 524 {
 525         caddr_t buffer;
 526         int error, cnt, firstseg;
 527         static int curfail = 0;
 528         static struct timeval lastfail;
 529
 530         KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
 531         KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
 532                 ("pipespace: resize of direct writes not allowed"));
 533 retry:
 534         cnt = cpipe->pipe_buffer.cnt;
 535         if (cnt > size)
 536                 size = cnt;
 537
 538         size = round_page(size);
 539         buffer = (caddr_t) vm_map_min(pipe_map);
 540
 541         error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0,
 542             VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
 543         if (error != KERN_SUCCESS) {
 544                 if (cpipe->pipe_buffer.buffer == NULL &&
 545                     size > SMALL_PIPE_SIZE) {
 546                         size = SMALL_PIPE_SIZE;
 547                         pipefragretry++;
 548                         goto retry;
 549                 }
 550                 if (cpipe->pipe_buffer.buffer == NULL) {
 551                         pipeallocfail++;
 552                         if (ppsratecheck(&lastfail, &curfail, 1))
 553                                 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
 554                 } else {
 555                         piperesizefail++;
 556                 }
 557                 return (ENOMEM);
 558         }
 559
 560         /* copy data, then free old resources if we're resizing */
 561         if (cnt > 0) {
 562                 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
 563                         firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
 564                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 565                                 buffer, firstseg);
 566                         if ((cnt - firstseg) > 0)
 567                                 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
 568                                         cpipe->pipe_buffer.in);
 569                 } else {
 570                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 571                                 buffer, cnt);
 572                 }
 573         }
 574         pipe_free_kmem(cpipe);
 575         cpipe->pipe_buffer.buffer = buffer;
 576         cpipe->pipe_buffer.size = size;
 577         cpipe->pipe_buffer.in = cnt;
 578         cpipe->pipe_buffer.out = 0;
 579         cpipe->pipe_buffer.cnt = cnt;
 580         atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
 581         return (0);
 582 }
 583
 584 /*
 585  * Wrapper for pipespace_new() that performs locking assertions.
 586  */
 587 static int
 588 pipespace(struct pipe *cpipe, int size)
 589 {
 590
 591         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 592             ("Unlocked pipe passed to pipespace"));
 593         return (pipespace_new(cpipe, size));
 594 }
 595
 596 /*
 597  * lock a pipe for I/O, blocking other access
 598  */
 599 static __inline int
 600 pipelock(struct pipe *cpipe, int catch)
 601 {
 602         int error;
 603
 604         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 605         while (cpipe->pipe_state & PIPE_LOCKFL) {
 606                 cpipe->pipe_state |= PIPE_LWANT;
 607                 error = msleep(cpipe, PIPE_MTX(cpipe),
 608                     catch ? (PRIBIO | PCATCH) : PRIBIO,
 609                     "pipelk", 0);
 610                 if (error != 0)
 611                         return (error);
 612         }
 613         cpipe->pipe_state |= PIPE_LOCKFL;
 614         return (0);
 615 }
 616
 617 /*
 618  * unlock a pipe I/O lock
 619  */
 620 static __inline void
 621 pipeunlock(struct pipe *cpipe)
 622 {
 623
 624         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 625         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 626                 ("Unlocked pipe passed to pipeunlock"));
 627         cpipe->pipe_state &= ~PIPE_LOCKFL;
 628         if (cpipe->pipe_state & PIPE_LWANT) {
 629                 cpipe->pipe_state &= ~PIPE_LWANT;
 630                 wakeup(cpipe);
 631         }
 632 }
 633
 634 void
 635 pipeselwakeup(struct pipe *cpipe)
 636 {
 637
 638         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 639         if (cpipe->pipe_state & PIPE_SEL) {
 640                 selwakeuppri(&cpipe->pipe_sel, PSOCK);
 641                 if (!SEL_WAITING(&cpipe->pipe_sel))
 642                         cpipe->pipe_state &= ~PIPE_SEL;
 643         }
 644         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 645                 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
 646         KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
 647 }
 648
 649 /*
 650  * Initialize and allocate VM and memory for pipe.  The structure
 651  * will start out zero'd from the ctor, so we just manage the kmem.
 652  */
 653 static int
 654 pipe_create(struct pipe *pipe, bool large_backing)
 655 {
 656         int error;
 657
 658         error = pipespace_new(pipe, !large_backing || amountpipekva >
 659             maxpipekva / 2 ? SMALL_PIPE_SIZE : PIPE_SIZE);
 660         if (error == 0)
 661                 pipe->pipe_ino = alloc_unr64(&pipeino_unr);
 662         return (error);
 663 }
 664
 665 /* ARGSUSED */
 666 static int
 667 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
 668     int flags, struct thread *td)
 669 {
 670         struct pipe *rpipe;
 671         int error;
 672         int nread = 0;
 673         int size;
 674
 675         rpipe = fp->f_data;
 676         PIPE_LOCK(rpipe);
 677         ++rpipe->pipe_busy;
 678         error = pipelock(rpipe, 1);
 679         if (error)
 680                 goto unlocked_error;
 681
 682 #ifdef MAC
 683         error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
 684         if (error)
 685                 goto locked_error;
 686 #endif
 687         if (amountpipekva > (3 * maxpipekva) / 4) {
 688                 if ((rpipe->pipe_state & PIPE_DIRECTW) == 0 &&
 689                     rpipe->pipe_buffer.size > SMALL_PIPE_SIZE &&
 690                     rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE &&
 691                     piperesizeallowed == 1) {
 692                         PIPE_UNLOCK(rpipe);
 693                         pipespace(rpipe, SMALL_PIPE_SIZE);
 694                         PIPE_LOCK(rpipe);
 695                 }
 696         }
 697
 698         while (uio->uio_resid) {
 699                 /*
 700                  * normal pipe buffer receive
 701                  */
 702                 if (rpipe->pipe_buffer.cnt > 0) {
 703                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 704                         if (size > rpipe->pipe_buffer.cnt)
 705                                 size = rpipe->pipe_buffer.cnt;
 706                         if (size > uio->uio_resid)
 707                                 size = uio->uio_resid;
 708
 709                         PIPE_UNLOCK(rpipe);
 710                         error = uiomove(
 711                             &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 712                             size, uio);
 713                         PIPE_LOCK(rpipe);
 714                         if (error)
 715                                 break;
 716
 717                         rpipe->pipe_buffer.out += size;
 718                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 719                                 rpipe->pipe_buffer.out = 0;
 720
 721                         rpipe->pipe_buffer.cnt -= size;
 722
 723                         /*
 724                          * If there is no more to read in the pipe, reset
 725                          * its pointers to the beginning.  This improves
 726                          * cache hit stats.
 727                          */
 728                         if (rpipe->pipe_buffer.cnt == 0) {
 729                                 rpipe->pipe_buffer.in = 0;
 730                                 rpipe->pipe_buffer.out = 0;
 731                         }
 732                         nread += size;
 733 #ifndef PIPE_NODIRECT
 734                 /*
 735                  * Direct copy, bypassing a kernel buffer.
 736                  */
 737                 } else if ((size = rpipe->pipe_map.cnt) != 0) {
 738                         if (size > uio->uio_resid)
 739                                 size = (u_int) uio->uio_resid;
 740                         PIPE_UNLOCK(rpipe);
 741                         error = uiomove_fromphys(rpipe->pipe_map.ms,
 742                             rpipe->pipe_map.pos, size, uio);
 743                         PIPE_LOCK(rpipe);
 744                         if (error)
 745                                 break;
 746                         nread += size;
 747                         rpipe->pipe_map.pos += size;
 748                         rpipe->pipe_map.cnt -= size;
 749                         if (rpipe->pipe_map.cnt == 0) {
 750                                 rpipe->pipe_state &= ~PIPE_WANTW;
 751                                 wakeup(rpipe);
 752                         }
 753 #endif
 754                 } else {
 755                         /*
 756                          * detect EOF condition
 757                          * read returns 0 on EOF, no need to set error
 758                          */
 759                         if (rpipe->pipe_state & PIPE_EOF)
 760                                 break;
 761
 762                         /*
 763                          * If the "write-side" has been blocked, wake it up now.
 764                          */
 765                         if (rpipe->pipe_state & PIPE_WANTW) {
 766                                 rpipe->pipe_state &= ~PIPE_WANTW;
 767                                 wakeup(rpipe);
 768                         }
 769
 770                         /*
 771                          * Break if some data was read.
 772                          */
 773                         if (nread > 0)
 774                                 break;
 775
 776                         /*
 777                          * Unlock the pipe buffer for our remaining processing.
 778                          * We will either break out with an error or we will
 779                          * sleep and relock to loop.
 780                          */
 781                         pipeunlock(rpipe);
 782
 783                         /*
 784                          * Handle non-blocking mode operation or
 785                          * wait for more data.
 786                          */
 787                         if (fp->f_flag & FNONBLOCK) {
 788                                 error = EAGAIN;
 789                         } else {
 790                                 rpipe->pipe_state |= PIPE_WANTR;
 791                                 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
 792                                     PRIBIO | PCATCH,
 793                                     "piperd", 0)) == 0)
 794                                         error = pipelock(rpipe, 1);
 795                         }
 796                         if (error)
 797                                 goto unlocked_error;
 798                 }
 799         }
 800 #ifdef MAC
 801 locked_error:
 802 #endif
 803         pipeunlock(rpipe);
 804
 805         /* XXX: should probably do this before getting any locks. */
 806         if (error == 0)
 807                 vfs_timestamp(&rpipe->pipe_atime);
 808 unlocked_error:
 809         --rpipe->pipe_busy;
 810
 811         /*
 812          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 813          */
 814         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 815                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 816                 wakeup(rpipe);
 817         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 818                 /*
 819                  * Handle write blocking hysteresis.
 820                  */
 821                 if (rpipe->pipe_state & PIPE_WANTW) {
 822                         rpipe->pipe_state &= ~PIPE_WANTW;
 823                         wakeup(rpipe);
 824                 }
 825         }
 826
 827         /*
 828          * Only wake up writers if there was actually something read.
 829          * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs.
 830          */
 831         if (nread > 0 &&
 832             rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF)
 833                 pipeselwakeup(rpipe);
 834
 835         PIPE_UNLOCK(rpipe);
 836         return (error);
 837 }
 838
 839 #ifndef PIPE_NODIRECT
 840 /*
 841  * Map the sending processes' buffer into kernel space and wire it.
 842  * This is similar to a physical write operation.
 843  */
 844 static int
 845 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio)
 846 {
 847         u_int size;
 848         int i;
 849
 850         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 851         KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
 852             ("%s: PIPE_DIRECTW set on %p", __func__, wpipe));
 853         KASSERT(wpipe->pipe_map.cnt == 0,
 854             ("%s: pipe map for %p contains residual data", __func__, wpipe));
 855
 856         if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
 857                 size = wpipe->pipe_buffer.size;
 858         else
 859                 size = uio->uio_iov->iov_len;
 860
 861         wpipe->pipe_state |= PIPE_DIRECTW;
 862         PIPE_UNLOCK(wpipe);
 863         i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
 864             (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
 865             wpipe->pipe_map.ms, PIPENPAGES);
 866         PIPE_LOCK(wpipe);
 867         if (i < 0) {
 868                 wpipe->pipe_state &= ~PIPE_DIRECTW;
 869                 return (EFAULT);
 870         }
 871
 872         wpipe->pipe_map.npages = i;
 873         wpipe->pipe_map.pos =
 874             ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
 875         wpipe->pipe_map.cnt = size;
 876
 877         uio->uio_iov->iov_len -= size;
 878         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
 879         if (uio->uio_iov->iov_len == 0)
 880                 uio->uio_iov++;
 881         uio->uio_resid -= size;
 882         uio->uio_offset += size;
 883         return (0);
 884 }
 885
 886 /*
 887  * Unwire the process buffer.
 888  */
 889 static void
 890 pipe_destroy_write_buffer(struct pipe *wpipe)
 891 {
 892
 893         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 894         KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
 895             ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
 896         KASSERT(wpipe->pipe_map.cnt == 0,
 897             ("%s: pipe map for %p contains residual data", __func__, wpipe));
 898
 899         wpipe->pipe_state &= ~PIPE_DIRECTW;
 900         vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
 901         wpipe->pipe_map.npages = 0;
 902 }
 903
 904 /*
 905  * In the case of a signal, the writing process might go away.  This
 906  * code copies the data into the circular buffer so that the source
 907  * pages can be freed without loss of data.
 908  */
 909 static void
 910 pipe_clone_write_buffer(struct pipe *wpipe)
 911 {
 912         struct uio uio;
 913         struct iovec iov;
 914         int size;
 915         int pos;
 916
 917         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 918         KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
 919             ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
 920
 921         size = wpipe->pipe_map.cnt;
 922         pos = wpipe->pipe_map.pos;
 923         wpipe->pipe_map.cnt = 0;
 924
 925         wpipe->pipe_buffer.in = size;
 926         wpipe->pipe_buffer.out = 0;
 927         wpipe->pipe_buffer.cnt = size;
 928
 929         PIPE_UNLOCK(wpipe);
 930         iov.iov_base = wpipe->pipe_buffer.buffer;
 931         iov.iov_len = size;
 932         uio.uio_iov = &iov;
 933         uio.uio_iovcnt = 1;
 934         uio.uio_offset = 0;
 935         uio.uio_resid = size;
 936         uio.uio_segflg = UIO_SYSSPACE;
 937         uio.uio_rw = UIO_READ;
 938         uio.uio_td = curthread;
 939         uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
 940         PIPE_LOCK(wpipe);
 941         pipe_destroy_write_buffer(wpipe);
 942 }
 943
 944 /*
 945  * This implements the pipe buffer write mechanism.  Note that only
 946  * a direct write OR a normal pipe write can be pending at any given time.
 947  * If there are any characters in the pipe buffer, the direct write will
 948  * be deferred until the receiving process grabs all of the bytes from
 949  * the pipe buffer.  Then the direct mapping write is set-up.
 950  */
 951 static int
 952 pipe_direct_write(struct pipe *wpipe, struct uio *uio)
 953 {
 954         int error;
 955
 956 retry:
 957         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 958         error = pipelock(wpipe, 1);
 959         if (error != 0)
 960                 goto error1;
 961         if ((wpipe->pipe_state & PIPE_EOF) != 0) {
 962                 error = EPIPE;
 963                 pipeunlock(wpipe);
 964                 goto error1;
 965         }
 966         if (wpipe->pipe_state & PIPE_DIRECTW) {
 967                 if (wpipe->pipe_state & PIPE_WANTR) {
 968                         wpipe->pipe_state &= ~PIPE_WANTR;
 969                         wakeup(wpipe);
 970                 }
 971                 pipeselwakeup(wpipe);
 972                 wpipe->pipe_state |= PIPE_WANTW;
 973                 pipeunlock(wpipe);
 974                 error = msleep(wpipe, PIPE_MTX(wpipe),
 975                     PRIBIO | PCATCH, "pipdww", 0);
 976                 if (error)
 977                         goto error1;
 978                 else
 979                         goto retry;
 980         }
 981         if (wpipe->pipe_buffer.cnt > 0) {
 982                 if (wpipe->pipe_state & PIPE_WANTR) {
 983                         wpipe->pipe_state &= ~PIPE_WANTR;
 984                         wakeup(wpipe);
 985                 }
 986                 pipeselwakeup(wpipe);
 987                 wpipe->pipe_state |= PIPE_WANTW;
 988                 pipeunlock(wpipe);
 989                 error = msleep(wpipe, PIPE_MTX(wpipe),
 990                     PRIBIO | PCATCH, "pipdwc", 0);
 991                 if (error)
 992                         goto error1;
 993                 else
 994                         goto retry;
 995         }
 996
 997         error = pipe_build_write_buffer(wpipe, uio);
 998         if (error) {
 999                 pipeunlock(wpipe);
1000                 goto error1;
1001         }
1002
1003         while (wpipe->pipe_map.cnt != 0 &&
1004             (wpipe->pipe_state & PIPE_EOF) == 0) {
1005                 if (wpipe->pipe_state & PIPE_WANTR) {
1006                         wpipe->pipe_state &= ~PIPE_WANTR;
1007                         wakeup(wpipe);
1008                 }
1009                 pipeselwakeup(wpipe);
1010                 wpipe->pipe_state |= PIPE_WANTW;
1011                 pipeunlock(wpipe);
1012                 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
1013                     "pipdwt", 0);
1014                 pipelock(wpipe, 0);
1015                 if (error != 0)
1016                         break;
1017         }
1018
1019         if ((wpipe->pipe_state & PIPE_EOF) != 0) {
1020                 wpipe->pipe_map.cnt = 0;
1021                 pipe_destroy_write_buffer(wpipe);
1022                 pipeselwakeup(wpipe);
1023                 error = EPIPE;
1024         } else if (error == EINTR || error == ERESTART) {
1025                 pipe_clone_write_buffer(wpipe);
1026         } else {
1027                 pipe_destroy_write_buffer(wpipe);
1028         }
1029         pipeunlock(wpipe);
1030         KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
1031             ("pipe %p leaked PIPE_DIRECTW", wpipe));
1032         return (error);
1033
1034 error1:
1035         wakeup(wpipe);
1036         return (error);
1037 }
1038 #endif
1039
1040 static int
1041 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
1042     int flags, struct thread *td)
1043 {
1044         struct pipe *wpipe, *rpipe;
1045         ssize_t orig_resid;
1046         int desiredsize, error;
1047
1048         rpipe = fp->f_data;
1049         wpipe = PIPE_PEER(rpipe);
1050         PIPE_LOCK(rpipe);
1051         error = pipelock(wpipe, 1);
1052         if (error) {
1053                 PIPE_UNLOCK(rpipe);
1054                 return (error);
1055         }
1056         /*
1057          * detect loss of pipe read side, issue SIGPIPE if lost.
1058          */
1059         if (wpipe->pipe_present != PIPE_ACTIVE ||
1060             (wpipe->pipe_state & PIPE_EOF)) {
1061                 pipeunlock(wpipe);
1062                 PIPE_UNLOCK(rpipe);
1063                 return (EPIPE);
1064         }
1065 #ifdef MAC
1066         error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1067         if (error) {
1068                 pipeunlock(wpipe);
1069                 PIPE_UNLOCK(rpipe);
1070                 return (error);
1071         }
1072 #endif
1073         ++wpipe->pipe_busy;
1074
1075         /* Choose a larger size if it's advantageous */
1076         desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1077         while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1078                 if (piperesizeallowed != 1)
1079                         break;
1080                 if (amountpipekva > maxpipekva / 2)
1081                         break;
1082                 if (desiredsize == BIG_PIPE_SIZE)
1083                         break;
1084                 desiredsize = desiredsize * 2;
1085         }
1086
1087         /* Choose a smaller size if we're in a OOM situation */
1088         if (amountpipekva > (3 * maxpipekva) / 4 &&
1089             wpipe->pipe_buffer.size > SMALL_PIPE_SIZE &&
1090             wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE &&
1091             piperesizeallowed == 1)
1092                 desiredsize = SMALL_PIPE_SIZE;
1093
1094         /* Resize if the above determined that a new size was necessary */
1095         if (desiredsize != wpipe->pipe_buffer.size &&
1096             (wpipe->pipe_state & PIPE_DIRECTW) == 0) {
1097                 PIPE_UNLOCK(wpipe);
1098                 pipespace(wpipe, desiredsize);
1099                 PIPE_LOCK(wpipe);
1100         }
1101         MPASS(wpipe->pipe_buffer.size != 0);
1102
1103         pipeunlock(wpipe);
1104
1105         orig_resid = uio->uio_resid;
1106
1107         while (uio->uio_resid) {
1108                 int space;
1109
1110                 pipelock(wpipe, 0);
1111                 if (wpipe->pipe_state & PIPE_EOF) {
1112                         pipeunlock(wpipe);
1113                         error = EPIPE;
1114                         break;
1115                 }
1116 #ifndef PIPE_NODIRECT
1117                 /*
1118                  * If the transfer is large, we can gain performance if
1119                  * we do process-to-process copies directly.
1120                  * If the write is non-blocking, we don't use the
1121                  * direct write mechanism.
1122                  *
1123                  * The direct write mechanism will detect the reader going
1124                  * away on us.
1125                  */
1126                 if (uio->uio_segflg == UIO_USERSPACE &&
1127                     uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1128                     wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1129                     (fp->f_flag & FNONBLOCK) == 0) {
1130                         pipeunlock(wpipe);
1131                         error = pipe_direct_write(wpipe, uio);
1132                         if (error)
1133                                 break;
1134                         continue;
1135                 }
1136 #endif
1137
1138                 /*
1139                  * Pipe buffered writes cannot be coincidental with
1140                  * direct writes.  We wait until the currently executing
1141                  * direct write is completed before we start filling the
1142                  * pipe buffer.  We break out if a signal occurs or the
1143                  * reader goes away.
1144                  */
1145                 if (wpipe->pipe_map.cnt != 0) {
1146                         if (wpipe->pipe_state & PIPE_WANTR) {
1147                                 wpipe->pipe_state &= ~PIPE_WANTR;
1148                                 wakeup(wpipe);
1149                         }
1150                         pipeselwakeup(wpipe);
1151                         wpipe->pipe_state |= PIPE_WANTW;
1152                         pipeunlock(wpipe);
1153                         error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1154                             "pipbww", 0);
1155                         if (error)
1156                                 break;
1157                         else
1158                                 continue;
1159                 }
1160
1161                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1162
1163                 /* Writes of size <= PIPE_BUF must be atomic. */
1164                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1165                         space = 0;
1166
1167                 if (space > 0) {
1168                         int size;       /* Transfer size */
1169                         int segsize;    /* first segment to transfer */
1170
1171                         /*
1172                          * Transfer size is minimum of uio transfer
1173                          * and free space in pipe buffer.
1174                          */
1175                         if (space > uio->uio_resid)
1176                                 size = uio->uio_resid;
1177                         else
1178                                 size = space;
1179                         /*
1180                          * First segment to transfer is minimum of
1181                          * transfer size and contiguous space in
1182                          * pipe buffer.  If first segment to transfer
1183                          * is less than the transfer size, we've got
1184                          * a wraparound in the buffer.
1185                          */
1186                         segsize = wpipe->pipe_buffer.size -
1187                                 wpipe->pipe_buffer.in;
1188                         if (segsize > size)
1189                                 segsize = size;
1190
1191                         /* Transfer first segment */
1192
1193                         PIPE_UNLOCK(rpipe);
1194                         error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1195                                         segsize, uio);
1196                         PIPE_LOCK(rpipe);
1197
1198                         if (error == 0 && segsize < size) {
1199                                 KASSERT(wpipe->pipe_buffer.in + segsize ==
1200                                         wpipe->pipe_buffer.size,
1201                                         ("Pipe buffer wraparound disappeared"));
1202                                 /*
1203                                  * Transfer remaining part now, to
1204                                  * support atomic writes.  Wraparound
1205                                  * happened.
1206                                  */
1207
1208                                 PIPE_UNLOCK(rpipe);
1209                                 error = uiomove(
1210                                     &wpipe->pipe_buffer.buffer[0],
1211                                     size - segsize, uio);
1212                                 PIPE_LOCK(rpipe);
1213                         }
1214                         if (error == 0) {
1215                                 wpipe->pipe_buffer.in += size;
1216                                 if (wpipe->pipe_buffer.in >=
1217                                     wpipe->pipe_buffer.size) {
1218                                         KASSERT(wpipe->pipe_buffer.in ==
1219                                                 size - segsize +
1220                                                 wpipe->pipe_buffer.size,
1221                                                 ("Expected wraparound bad"));
1222                                         wpipe->pipe_buffer.in = size - segsize;
1223                                 }
1224
1225                                 wpipe->pipe_buffer.cnt += size;
1226                                 KASSERT(wpipe->pipe_buffer.cnt <=
1227                                         wpipe->pipe_buffer.size,
1228                                         ("Pipe buffer overflow"));
1229                         }
1230                         pipeunlock(wpipe);
1231                         if (error != 0)
1232                                 break;
1233                 } else {
1234                         /*
1235                          * If the "read-side" has been blocked, wake it up now.
1236                          */
1237                         if (wpipe->pipe_state & PIPE_WANTR) {
1238                                 wpipe->pipe_state &= ~PIPE_WANTR;
1239                                 wakeup(wpipe);
1240                         }
1241
1242                         /*
1243                          * don't block on non-blocking I/O
1244                          */
1245                         if (fp->f_flag & FNONBLOCK) {
1246                                 error = EAGAIN;
1247                                 pipeunlock(wpipe);
1248                                 break;
1249                         }
1250
1251                         /*
1252                          * We have no more space and have something to offer,
1253                          * wake up select/poll.
1254                          */
1255                         pipeselwakeup(wpipe);
1256
1257                         wpipe->pipe_state |= PIPE_WANTW;
1258                         pipeunlock(wpipe);
1259                         error = msleep(wpipe, PIPE_MTX(rpipe),
1260                             PRIBIO | PCATCH, "pipewr", 0);
1261                         if (error != 0)
1262                                 break;
1263                 }
1264         }
1265
1266         pipelock(wpipe, 0);
1267         --wpipe->pipe_busy;
1268
1269         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1270                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1271                 wakeup(wpipe);
1272         } else if (wpipe->pipe_buffer.cnt > 0) {
1273                 /*
1274                  * If we have put any characters in the buffer, we wake up
1275                  * the reader.
1276                  */
1277                 if (wpipe->pipe_state & PIPE_WANTR) {
1278                         wpipe->pipe_state &= ~PIPE_WANTR;
1279                         wakeup(wpipe);
1280                 }
1281         }
1282
1283         /*
1284          * Don't return EPIPE if any byte was written.
1285          * EINTR and other interrupts are handled by generic I/O layer.
1286          * Do not pretend that I/O succeeded for obvious user error
1287          * like EFAULT.
1288          */
1289         if (uio->uio_resid != orig_resid && error == EPIPE)
1290                 error = 0;
1291
1292         if (error == 0)
1293                 vfs_timestamp(&wpipe->pipe_mtime);
1294
1295         /*
1296          * We have something to offer,
1297          * wake up select/poll.
1298          */
1299         if (wpipe->pipe_buffer.cnt)
1300                 pipeselwakeup(wpipe);
1301
1302         pipeunlock(wpipe);
1303         PIPE_UNLOCK(rpipe);
1304         return (error);
1305 }
1306
1307 /* ARGSUSED */
1308 static int
1309 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred,
1310     struct thread *td)
1311 {
1312         struct pipe *cpipe;
1313         int error;
1314
1315         cpipe = fp->f_data;
1316         if (cpipe->pipe_state & PIPE_NAMED)
1317                 error = vnops.fo_truncate(fp, length, active_cred, td);
1318         else
1319                 error = invfo_truncate(fp, length, active_cred, td);
1320         return (error);
1321 }
1322
1323 /*
1324  * we implement a very minimal set of ioctls for compatibility with sockets.
1325  */
1326 static int
1327 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred,
1328     struct thread *td)
1329 {
1330         struct pipe *mpipe = fp->f_data;
1331         int error;
1332
1333         PIPE_LOCK(mpipe);
1334
1335 #ifdef MAC
1336         error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1337         if (error) {
1338                 PIPE_UNLOCK(mpipe);
1339                 return (error);
1340         }
1341 #endif
1342
1343         error = 0;
1344         switch (cmd) {
1345
1346         case FIONBIO:
1347                 break;
1348
1349         case FIOASYNC:
1350                 if (*(int *)data) {
1351                         mpipe->pipe_state |= PIPE_ASYNC;
1352                 } else {
1353                         mpipe->pipe_state &= ~PIPE_ASYNC;
1354                 }
1355                 break;
1356
1357         case FIONREAD:
1358                 if (!(fp->f_flag & FREAD)) {
1359                         *(int *)data = 0;
1360                         PIPE_UNLOCK(mpipe);
1361                         return (0);
1362                 }
1363                 if (mpipe->pipe_map.cnt != 0)
1364                         *(int *)data = mpipe->pipe_map.cnt;
1365                 else
1366                         *(int *)data = mpipe->pipe_buffer.cnt;
1367                 break;
1368
1369         case FIOSETOWN:
1370                 PIPE_UNLOCK(mpipe);
1371                 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1372                 goto out_unlocked;
1373
1374         case FIOGETOWN:
1375                 *(int *)data = fgetown(&mpipe->pipe_sigio);
1376                 break;
1377
1378         /* This is deprecated, FIOSETOWN should be used instead. */
1379         case TIOCSPGRP:
1380                 PIPE_UNLOCK(mpipe);
1381                 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1382                 goto out_unlocked;
1383
1384         /* This is deprecated, FIOGETOWN should be used instead. */
1385         case TIOCGPGRP:
1386                 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1387                 break;
1388
1389         default:
1390                 error = ENOTTY;
1391                 break;
1392         }
1393         PIPE_UNLOCK(mpipe);
1394 out_unlocked:
1395         return (error);
1396 }
1397
1398 static int
1399 pipe_poll(struct file *fp, int events, struct ucred *active_cred,
1400     struct thread *td)
1401 {
1402         struct pipe *rpipe;
1403         struct pipe *wpipe;
1404         int levents, revents;
1405 #ifdef MAC
1406         int error;
1407 #endif
1408
1409         revents = 0;
1410         rpipe = fp->f_data;
1411         wpipe = PIPE_PEER(rpipe);
1412         PIPE_LOCK(rpipe);
1413 #ifdef MAC
1414         error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1415         if (error)
1416                 goto locked_error;
1417 #endif
1418         if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1419                 if (rpipe->pipe_map.cnt > 0 || rpipe->pipe_buffer.cnt > 0)
1420                         revents |= events & (POLLIN | POLLRDNORM);
1421
1422         if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1423                 if (wpipe->pipe_present != PIPE_ACTIVE ||
1424                     (wpipe->pipe_state & PIPE_EOF) ||
1425                     ((wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
1426                      ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1427                          wpipe->pipe_buffer.size == 0)))
1428                         revents |= events & (POLLOUT | POLLWRNORM);
1429
1430         levents = events &
1431             (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1432         if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
1433             fp->f_pipegen == rpipe->pipe_wgen)
1434                 events |= POLLINIGNEOF;
1435
1436         if ((events & POLLINIGNEOF) == 0) {
1437                 if (rpipe->pipe_state & PIPE_EOF) {
1438                         if (fp->f_flag & FREAD)
1439                                 revents |= (events & (POLLIN | POLLRDNORM));
1440                         if (wpipe->pipe_present != PIPE_ACTIVE ||
1441                             (wpipe->pipe_state & PIPE_EOF))
1442                                 revents |= POLLHUP;
1443                 }
1444         }
1445
1446         if (revents == 0) {
1447                 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) {
1448                         selrecord(td, &rpipe->pipe_sel);
1449                         if (SEL_WAITING(&rpipe->pipe_sel))
1450                                 rpipe->pipe_state |= PIPE_SEL;
1451                 }
1452
1453                 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) {
1454                         selrecord(td, &wpipe->pipe_sel);
1455                         if (SEL_WAITING(&wpipe->pipe_sel))
1456                                 wpipe->pipe_state |= PIPE_SEL;
1457                 }
1458         }
1459 #ifdef MAC
1460 locked_error:
1461 #endif
1462         PIPE_UNLOCK(rpipe);
1463
1464         return (revents);
1465 }
1466
1467 /*
1468  * We shouldn't need locks here as we're doing a read and this should
1469  * be a natural race.
1470  */
1471 static int
1472 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred,
1473     struct thread *td)
1474 {
1475         struct pipe *pipe;
1476 #ifdef MAC
1477         int error;
1478 #endif
1479
1480         pipe = fp->f_data;
1481         PIPE_LOCK(pipe);
1482 #ifdef MAC
1483         error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1484         if (error) {
1485                 PIPE_UNLOCK(pipe);
1486                 return (error);
1487         }
1488 #endif
1489
1490         /* For named pipes ask the underlying filesystem. */
1491         if (pipe->pipe_state & PIPE_NAMED) {
1492                 PIPE_UNLOCK(pipe);
1493                 return (vnops.fo_stat(fp, ub, active_cred, td));
1494         }
1495
1496         PIPE_UNLOCK(pipe);
1497
1498         bzero(ub, sizeof(*ub));
1499         ub->st_mode = S_IFIFO;
1500         ub->st_blksize = PAGE_SIZE;
1501         if (pipe->pipe_map.cnt != 0)
1502                 ub->st_size = pipe->pipe_map.cnt;
1503         else
1504                 ub->st_size = pipe->pipe_buffer.cnt;
1505         ub->st_blocks = howmany(ub->st_size, ub->st_blksize);
1506         ub->st_atim = pipe->pipe_atime;
1507         ub->st_mtim = pipe->pipe_mtime;
1508         ub->st_ctim = pipe->pipe_ctime;
1509         ub->st_uid = fp->f_cred->cr_uid;
1510         ub->st_gid = fp->f_cred->cr_gid;
1511         ub->st_dev = pipedev_ino;
1512         ub->st_ino = pipe->pipe_ino;
1513         /*
1514          * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1515          */
1516         return (0);
1517 }
1518
1519 /* ARGSUSED */
1520 static int
1521 pipe_close(struct file *fp, struct thread *td)
1522 {
1523
1524         if (fp->f_vnode != NULL)
1525                 return vnops.fo_close(fp, td);
1526         fp->f_ops = &badfileops;
1527         pipe_dtor(fp->f_data);
1528         fp->f_data = NULL;
1529         return (0);
1530 }
1531
1532 static int
1533 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1534 {
1535         struct pipe *cpipe;
1536         int error;
1537
1538         cpipe = fp->f_data;
1539         if (cpipe->pipe_state & PIPE_NAMED)
1540                 error = vn_chmod(fp, mode, active_cred, td);
1541         else
1542                 error = invfo_chmod(fp, mode, active_cred, td);
1543         return (error);
1544 }
1545
1546 static int
1547 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1548     struct thread *td)
1549 {
1550         struct pipe *cpipe;
1551         int error;
1552
1553         cpipe = fp->f_data;
1554         if (cpipe->pipe_state & PIPE_NAMED)
1555                 error = vn_chown(fp, uid, gid, active_cred, td);
1556         else
1557                 error = invfo_chown(fp, uid, gid, active_cred, td);
1558         return (error);
1559 }
1560
1561 static int
1562 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1563 {
1564         struct pipe *pi;
1565
1566         if (fp->f_type == DTYPE_FIFO)
1567                 return (vn_fill_kinfo(fp, kif, fdp));
1568         kif->kf_type = KF_TYPE_PIPE;
1569         pi = fp->f_data;
1570         kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
1571         kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
1572         kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
1573         return (0);
1574 }
1575
1576 static void
1577 pipe_free_kmem(struct pipe *cpipe)
1578 {
1579
1580         KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1581             ("pipe_free_kmem: pipe mutex locked"));
1582
1583         if (cpipe->pipe_buffer.buffer != NULL) {
1584                 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1585                 vm_map_remove(pipe_map,
1586                     (vm_offset_t)cpipe->pipe_buffer.buffer,
1587                     (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1588                 cpipe->pipe_buffer.buffer = NULL;
1589         }
1590 #ifndef PIPE_NODIRECT
1591         {
1592                 cpipe->pipe_map.cnt = 0;
1593                 cpipe->pipe_map.pos = 0;
1594                 cpipe->pipe_map.npages = 0;
1595         }
1596 #endif
1597 }
1598
1599 /*
1600  * shutdown the pipe
1601  */
1602 static void
1603 pipeclose(struct pipe *cpipe)
1604 {
1605         struct pipepair *pp;
1606         struct pipe *ppipe;
1607
1608         KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1609
1610         PIPE_LOCK(cpipe);
1611         pipelock(cpipe, 0);
1612         pp = cpipe->pipe_pair;
1613
1614         /*
1615          * If the other side is blocked, wake it up saying that
1616          * we want to close it down.
1617          */
1618         cpipe->pipe_state |= PIPE_EOF;
1619         while (cpipe->pipe_busy) {
1620                 wakeup(cpipe);
1621                 cpipe->pipe_state |= PIPE_WANT;
1622                 pipeunlock(cpipe);
1623                 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1624                 pipelock(cpipe, 0);
1625         }
1626
1627         pipeselwakeup(cpipe);
1628
1629         /*
1630          * Disconnect from peer, if any.
1631          */
1632         ppipe = cpipe->pipe_peer;
1633         if (ppipe->pipe_present == PIPE_ACTIVE) {
1634                 ppipe->pipe_state |= PIPE_EOF;
1635                 wakeup(ppipe);
1636                 pipeselwakeup(ppipe);
1637         }
1638
1639         /*
1640          * Mark this endpoint as free.  Release kmem resources.  We
1641          * don't mark this endpoint as unused until we've finished
1642          * doing that, or the pipe might disappear out from under
1643          * us.
1644          */
1645         PIPE_UNLOCK(cpipe);
1646         pipe_free_kmem(cpipe);
1647         PIPE_LOCK(cpipe);
1648         cpipe->pipe_present = PIPE_CLOSING;
1649         pipeunlock(cpipe);
1650
1651         /*
1652          * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1653          * PIPE_FINALIZED, that allows other end to free the
1654          * pipe_pair, only after the knotes are completely dismantled.
1655          */
1656         knlist_clear(&cpipe->pipe_sel.si_note, 1);
1657         cpipe->pipe_present = PIPE_FINALIZED;
1658         seldrain(&cpipe->pipe_sel);
1659         knlist_destroy(&cpipe->pipe_sel.si_note);
1660
1661         /*
1662          * If both endpoints are now closed, release the memory for the
1663          * pipe pair.  If not, unlock.
1664          */
1665         if (ppipe->pipe_present == PIPE_FINALIZED) {
1666                 PIPE_UNLOCK(cpipe);
1667 #ifdef MAC
1668                 mac_pipe_destroy(pp);
1669 #endif
1670                 uma_zfree(pipe_zone, cpipe->pipe_pair);
1671         } else
1672                 PIPE_UNLOCK(cpipe);
1673 }
1674
1675 /*ARGSUSED*/
1676 static int
1677 pipe_kqfilter(struct file *fp, struct knote *kn)
1678 {
1679         struct pipe *cpipe;
1680
1681         /*
1682          * If a filter is requested that is not supported by this file
1683          * descriptor, don't return an error, but also don't ever generate an
1684          * event.
1685          */
1686         if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1687                 kn->kn_fop = &pipe_nfiltops;
1688                 return (0);
1689         }
1690         if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1691                 kn->kn_fop = &pipe_nfiltops;
1692                 return (0);
1693         }
1694         cpipe = fp->f_data;
1695         PIPE_LOCK(cpipe);
1696         switch (kn->kn_filter) {
1697         case EVFILT_READ:
1698                 kn->kn_fop = &pipe_rfiltops;
1699                 break;
1700         case EVFILT_WRITE:
1701                 kn->kn_fop = &pipe_wfiltops;
1702                 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1703                         /* other end of pipe has been closed */
1704                         PIPE_UNLOCK(cpipe);
1705                         return (EPIPE);
1706                 }
1707                 cpipe = PIPE_PEER(cpipe);
1708                 break;
1709         default:
1710                 PIPE_UNLOCK(cpipe);
1711                 return (EINVAL);
1712         }
1713
1714         kn->kn_hook = cpipe;
1715         knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1716         PIPE_UNLOCK(cpipe);
1717         return (0);
1718 }
1719
1720 static void
1721 filt_pipedetach(struct knote *kn)
1722 {
1723         struct pipe *cpipe = kn->kn_hook;
1724
1725         PIPE_LOCK(cpipe);
1726         knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1727         PIPE_UNLOCK(cpipe);
1728 }
1729
1730 /*ARGSUSED*/
1731 static int
1732 filt_piperead(struct knote *kn, long hint)
1733 {
1734         struct file *fp = kn->kn_fp;
1735         struct pipe *rpipe = kn->kn_hook;
1736
1737         PIPE_LOCK_ASSERT(rpipe, MA_OWNED);
1738         kn->kn_data = rpipe->pipe_buffer.cnt;
1739         if (kn->kn_data == 0)
1740                 kn->kn_data = rpipe->pipe_map.cnt;
1741
1742         if ((rpipe->pipe_state & PIPE_EOF) != 0 &&
1743             ((rpipe->pipe_state & PIPE_NAMED) == 0 ||
1744             fp->f_pipegen != rpipe->pipe_wgen)) {
1745                 kn->kn_flags |= EV_EOF;
1746                 return (1);
1747         }
1748         kn->kn_flags &= ~EV_EOF;
1749         return (kn->kn_data > 0);
1750 }
1751
1752 /*ARGSUSED*/
1753 static int
1754 filt_pipewrite(struct knote *kn, long hint)
1755 {
1756         struct pipe *wpipe = kn->kn_hook;
1757
1758         /*
1759          * If this end of the pipe is closed, the knote was removed from the
1760          * knlist and the list lock (i.e., the pipe lock) is therefore not held.
1761          */
1762         if (wpipe->pipe_present == PIPE_ACTIVE ||
1763             (wpipe->pipe_state & PIPE_NAMED) != 0) {
1764                 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1765
1766                 if (wpipe->pipe_state & PIPE_DIRECTW) {
1767                         kn->kn_data = 0;
1768                 } else if (wpipe->pipe_buffer.size > 0) {
1769                         kn->kn_data = wpipe->pipe_buffer.size -
1770                             wpipe->pipe_buffer.cnt;
1771                 } else {
1772                         kn->kn_data = PIPE_BUF;
1773                 }
1774         }
1775
1776         if (wpipe->pipe_present != PIPE_ACTIVE ||
1777             (wpipe->pipe_state & PIPE_EOF)) {
1778                 kn->kn_flags |= EV_EOF;
1779                 return (1);
1780         }
1781         kn->kn_flags &= ~EV_EOF;
1782         return (kn->kn_data >= PIPE_BUF);
1783 }
1784
1785 static void
1786 filt_pipedetach_notsup(struct knote *kn)
1787 {
1788
1789 }
1790
1791 static int
1792 filt_pipenotsup(struct knote *kn, long hint)
1793 {
1794
1795         return (0);
1796 }