1/*- 2 * Copyright (c) 1996 John S. Dyson 3 * Copyright (c) 2012 Giovanni Trematerra 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice immediately at the beginning of the file, without modification, 11 * this list of conditions, and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Absolutely no warranty of function or purpose is made by the author 16 * John S. Dyson. 17 * 4. Modifications may be freely made to this file if the above conditions 18 * are met. 19 */ 20 21/* 22 * This file contains a high-performance replacement for the socket-based 23 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 24 * all features of sockets, but does do everything that pipes normally 25 * do. 26 */ 27 28/* 29 * This code has two modes of operation, a small write mode and a large 30 * write mode. The small write mode acts like conventional pipes with 31 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 32 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 33 * and PIPE_SIZE in size, the sending process pins the underlying pages in 34 * memory, and the receiving process copies directly from these pinned pages 35 * in the sending process. 36 * 37 * If the sending process receives a signal, it is possible that it will 38 * go away, and certainly its address space can change, because control 39 * is returned back to the user-mode side. In that case, the pipe code 40 * arranges to copy the buffer supplied by the user process, to a pageable 41 * kernel buffer, and the receiving process will grab the data from the 42 * pageable kernel buffer. Since signals don't happen all that often, 43 * the copy operation is normally eliminated. 44 * 45 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 46 * happen for small transfers so that the system will not spend all of 47 * its time context switching. 48 * 49 * In order to limit the resource use of pipes, two sysctls exist: 50 * 51 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable 52 * address space available to us in pipe_map. This value is normally 53 * autotuned, but may also be loader tuned. 54 * 55 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of 56 * memory in use by pipes. 57 * 58 * Based on how large pipekva is relative to maxpipekva, the following 59 * will happen: 60 * 61 * 0% - 50%: 62 * New pipes are given 16K of memory backing, pipes may dynamically 63 * grow to as large as 64K where needed. 64 * 50% - 75%: 65 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 66 * existing pipes may NOT grow. 67 * 75% - 100%: 68 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 69 * existing pipes will be shrunk down to 4K whenever possible. 70 * 71 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If 72 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE 73 * resize which MUST occur for reverse-direction pipes when they are 74 * first used. 75 * 76 * Additional information about the current state of pipes may be obtained 77 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail, 78 * and kern.ipc.piperesizefail. 79 * 80 * Locking rules: There are two locks present here: A mutex, used via 81 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via 82 * the flag, as mutexes can not persist over uiomove. The mutex 83 * exists only to guard access to the flag, and is not in itself a 84 * locking mechanism. Also note that there is only a single mutex for 85 * both directions of a pipe. 86 * 87 * As pipelock() may have to sleep before it can acquire the flag, it 88 * is important to reread all data after a call to pipelock(); everything 89 * in the structure may have changed. 90 */ 91 92#include <sys/param.h> 93#include <sys/systm.h> 94#include <sys/conf.h> 95#include <sys/fcntl.h> 96#include <sys/file.h> 97#include <sys/filedesc.h> 98#include <sys/filio.h> 99#include <sys/kernel.h> 100#include <sys/lock.h> 101#include <sys/mutex.h> 102#include <sys/ttycom.h> 103#include <sys/stat.h> 104#include <sys/malloc.h> 105#include <sys/poll.h> 106#include <sys/selinfo.h> 107#include <sys/signalvar.h> 108#include <sys/syscallsubr.h> 109#include <sys/sysctl.h> 110#include <sys/sysproto.h> 111#include <sys/pipe.h> 112#include <sys/proc.h> 113#include <sys/vnode.h> 114#include <sys/uio.h> 115#include <sys/user.h> 116#include <sys/event.h> 117 118#include <security/mac/mac_framework.h> 119 120#include <vm/vm.h> 121#include <vm/vm_param.h> 122#include <vm/vm_object.h> 123#include <vm/vm_kern.h> 124#include <vm/vm_extern.h> 125#include <vm/pmap.h> 126#include <vm/vm_map.h> 127#include <vm/vm_page.h> 128#include <vm/uma.h> 129 130/* 131 * Use this define if you want to disable *fancy* VM things. Expect an 132 * approx 30% decrease in transfer rate. This could be useful for 133 * NetBSD or OpenBSD. 134 */ 135/* #define PIPE_NODIRECT */ 136 137#define PIPE_PEER(pipe) \ 138 (((pipe)->pipe_type & PIPE_TYPE_NAMED) ? (pipe) : ((pipe)->pipe_peer)) 139 140/* 141 * interfaces to the outside world 142 */ 143static fo_rdwr_t pipe_read; 144static fo_rdwr_t pipe_write; 145static fo_truncate_t pipe_truncate; 146static fo_ioctl_t pipe_ioctl; 147static fo_poll_t pipe_poll; 148static fo_kqfilter_t pipe_kqfilter; 149static fo_stat_t pipe_stat; 150static fo_close_t pipe_close; 151static fo_chmod_t pipe_chmod; 152static fo_chown_t pipe_chown; 153static fo_fill_kinfo_t pipe_fill_kinfo; 154 155struct fileops pipeops = { 156 .fo_read = pipe_read, 157 .fo_write = pipe_write, 158 .fo_truncate = pipe_truncate, 159 .fo_ioctl = pipe_ioctl, 160 .fo_poll = pipe_poll, 161 .fo_kqfilter = pipe_kqfilter, 162 .fo_stat = pipe_stat, 163 .fo_close = pipe_close, 164 .fo_chmod = pipe_chmod, 165 .fo_chown = pipe_chown, 166 .fo_sendfile = invfo_sendfile, 167 .fo_fill_kinfo = pipe_fill_kinfo, 168 .fo_cmp = file_kcmp_generic, 169 .fo_flags = DFLAG_PASSABLE 170}; 171 172static void filt_pipedetach(struct knote *kn); 173static void filt_pipedetach_notsup(struct knote *kn); 174static int filt_pipenotsup(struct knote *kn, long hint); 175static int filt_piperead(struct knote *kn, long hint); 176static int filt_pipewrite(struct knote *kn, long hint); 177 178static struct filterops pipe_nfiltops = { 179 .f_isfd = 1, 180 .f_detach = filt_pipedetach_notsup, 181 .f_event = filt_pipenotsup 182}; 183static struct filterops pipe_rfiltops = { 184 .f_isfd = 1, 185 .f_detach = filt_pipedetach, 186 .f_event = filt_piperead 187}; 188static struct filterops pipe_wfiltops = { 189 .f_isfd = 1, 190 .f_detach = filt_pipedetach, 191 .f_event = filt_pipewrite 192}; 193 194/* 195 * Default pipe buffer size(s), this can be kind-of large now because pipe 196 * space is pageable. The pipe code will try to maintain locality of 197 * reference for performance reasons, so small amounts of outstanding I/O 198 * will not wipe the cache. 199 */ 200#define MINPIPESIZE (PIPE_SIZE/3) 201#define MAXPIPESIZE (2*PIPE_SIZE/3) 202 203static long amountpipekva; 204static int pipefragretry; 205static int pipeallocfail; 206static int piperesizefail; 207static int piperesizeallowed = 1; 208static long pipe_mindirect = PIPE_MINDIRECT; 209 210SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, 211 &maxpipekva, 0, "Pipe KVA limit"); 212SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD, 213 &amountpipekva, 0, "Pipe KVA usage"); 214SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD, 215 &pipefragretry, 0, "Pipe allocation retries due to fragmentation"); 216SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD, 217 &pipeallocfail, 0, "Pipe allocation failures"); 218SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD, 219 &piperesizefail, 0, "Pipe resize failures"); 220SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW, 221 &piperesizeallowed, 0, "Pipe resizing allowed"); 222 223static void pipeinit(void *dummy __unused); 224static void pipeclose(struct pipe *cpipe); 225static void pipe_free_kmem(struct pipe *cpipe); 226static int pipe_create(struct pipe *pipe, bool backing); 227static int pipe_paircreate(struct thread *td, struct pipepair **p_pp); 228static __inline int pipelock(struct pipe *cpipe, int catch); 229static __inline void pipeunlock(struct pipe *cpipe); 230static void pipe_timestamp(struct timespec *tsp); 231#ifndef PIPE_NODIRECT 232static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 233static void pipe_destroy_write_buffer(struct pipe *wpipe); 234static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 235static void pipe_clone_write_buffer(struct pipe *wpipe); 236#endif 237static int pipespace(struct pipe *cpipe, int size); 238static int pipespace_new(struct pipe *cpipe, int size); 239 240static int pipe_zone_ctor(void *mem, int size, void *arg, int flags); 241static int pipe_zone_init(void *mem, int size, int flags); 242static void pipe_zone_fini(void *mem, int size); 243 244static uma_zone_t pipe_zone; 245static struct unrhdr64 pipeino_unr; 246static dev_t pipedev_ino; 247 248SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 249 250static void 251pipeinit(void *dummy __unused) 252{ 253 254 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair), 255 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini, 256 UMA_ALIGN_PTR, 0); 257 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 258 new_unrhdr64(&pipeino_unr, 1); 259 pipedev_ino = devfs_alloc_cdp_inode(); 260 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized")); 261} 262 263static int 264sysctl_handle_pipe_mindirect(SYSCTL_HANDLER_ARGS) 265{ 266 int error = 0; 267 long tmp_pipe_mindirect = pipe_mindirect; 268 269 error = sysctl_handle_long(oidp, &tmp_pipe_mindirect, arg2, req); 270 if (error != 0 || req->newptr == NULL) 271 return (error); 272 273 /* 274 * Don't allow pipe_mindirect to be set so low that we violate 275 * atomicity requirements. 276 */ 277 if (tmp_pipe_mindirect <= PIPE_BUF) 278 return (EINVAL); 279 pipe_mindirect = tmp_pipe_mindirect; 280 return (0); 281} 282SYSCTL_OID(_kern_ipc, OID_AUTO, pipe_mindirect, CTLTYPE_LONG | CTLFLAG_RW, 283 &pipe_mindirect, 0, sysctl_handle_pipe_mindirect, "L", 284 "Minimum write size triggering VM optimization"); 285 286static int 287pipe_zone_ctor(void *mem, int size, void *arg, int flags) 288{ 289 struct pipepair *pp; 290 struct pipe *rpipe, *wpipe; 291 292 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size")); 293 294 pp = (struct pipepair *)mem; 295 296 /* 297 * We zero both pipe endpoints to make sure all the kmem pointers 298 * are NULL, flag fields are zero'd, etc. We timestamp both 299 * endpoints with the same time. 300 */ 301 rpipe = &pp->pp_rpipe; 302 bzero(rpipe, sizeof(*rpipe)); 303 pipe_timestamp(&rpipe->pipe_ctime); 304 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime; 305 306 wpipe = &pp->pp_wpipe; 307 bzero(wpipe, sizeof(*wpipe)); 308 wpipe->pipe_ctime = rpipe->pipe_ctime; 309 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime; 310 311 rpipe->pipe_peer = wpipe; 312 rpipe->pipe_pair = pp; 313 wpipe->pipe_peer = rpipe; 314 wpipe->pipe_pair = pp; 315 316 /* 317 * Mark both endpoints as present; they will later get free'd 318 * one at a time. When both are free'd, then the whole pair 319 * is released. 320 */ 321 rpipe->pipe_present = PIPE_ACTIVE; 322 wpipe->pipe_present = PIPE_ACTIVE; 323 324 /* 325 * Eventually, the MAC Framework may initialize the label 326 * in ctor or init, but for now we do it elswhere to avoid 327 * blocking in ctor or init. 328 */ 329 pp->pp_label = NULL; 330 331 return (0); 332} 333 334static int 335pipe_zone_init(void *mem, int size, int flags) 336{ 337 struct pipepair *pp; 338 339 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size")); 340 341 pp = (struct pipepair *)mem; 342 343 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW); 344 return (0); 345} 346 347static void 348pipe_zone_fini(void *mem, int size) 349{ 350 struct pipepair *pp; 351 352 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size")); 353 354 pp = (struct pipepair *)mem; 355 356 mtx_destroy(&pp->pp_mtx); 357} 358 359static int 360pipe_paircreate(struct thread *td, struct pipepair **p_pp) 361{ 362 struct pipepair *pp; 363 struct pipe *rpipe, *wpipe; 364 int error; 365 366 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK); 367#ifdef MAC 368 /* 369 * The MAC label is shared between the connected endpoints. As a 370 * result mac_pipe_init() and mac_pipe_create() are called once 371 * for the pair, and not on the endpoints. 372 */ 373 mac_pipe_init(pp); 374 mac_pipe_create(td->td_ucred, pp); 375#endif 376 rpipe = &pp->pp_rpipe; 377 wpipe = &pp->pp_wpipe; 378 379 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe)); 380 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe)); 381 382 /* 383 * Only the forward direction pipe is backed by big buffer by 384 * default. 385 */ 386 error = pipe_create(rpipe, true); 387 if (error != 0) 388 goto fail; 389 error = pipe_create(wpipe, false); 390 if (error != 0) { 391 /* 392 * This cleanup leaves the pipe inode number for rpipe 393 * still allocated, but never used. We do not free 394 * inode numbers for opened pipes, which is required 395 * for correctness because numbers must be unique. 396 * But also it avoids any memory use by the unr 397 * allocator, so stashing away the transient inode 398 * number is reasonable. 399 */ 400 pipe_free_kmem(rpipe); 401 goto fail; 402 } 403 404 rpipe->pipe_state |= PIPE_DIRECTOK; 405 wpipe->pipe_state |= PIPE_DIRECTOK; 406 return (0); 407 408fail: 409 knlist_destroy(&rpipe->pipe_sel.si_note); 410 knlist_destroy(&wpipe->pipe_sel.si_note); 411#ifdef MAC 412 mac_pipe_destroy(pp); 413#endif 414 uma_zfree(pipe_zone, pp); 415 return (error); 416} 417 418int 419pipe_named_ctor(struct pipe **ppipe, struct thread *td) 420{ 421 struct pipepair *pp; 422 int error; 423 424 error = pipe_paircreate(td, &pp); 425 if (error != 0) 426 return (error); 427 pp->pp_rpipe.pipe_type |= PIPE_TYPE_NAMED; 428 *ppipe = &pp->pp_rpipe; 429 return (0); 430} 431 432void 433pipe_dtor(struct pipe *dpipe) 434{ 435 struct pipe *peer; 436 437 peer = (dpipe->pipe_type & PIPE_TYPE_NAMED) != 0 ? dpipe->pipe_peer : NULL; 438 funsetown(&dpipe->pipe_sigio); 439 pipeclose(dpipe); 440 if (peer != NULL) { 441 funsetown(&peer->pipe_sigio); 442 pipeclose(peer); 443 } 444} 445 446/* 447 * Get a timestamp. 448 * 449 * This used to be vfs_timestamp but the higher precision is unnecessary and 450 * can very negatively affect performance in virtualized environments (e.g., on 451 * vms running on amd64 when using the rdtscp instruction). 452 */ 453static void 454pipe_timestamp(struct timespec *tsp) 455{ 456 457 getnanotime(tsp); 458} 459 460/* 461 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 462 * the zone pick up the pieces via pipeclose(). 463 */ 464int 465kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1, 466 struct filecaps *fcaps2) 467{ 468 struct file *rf, *wf; 469 struct pipe *rpipe, *wpipe; 470 struct pipepair *pp; 471 int fd, fflags, error; 472 473 error = pipe_paircreate(td, &pp); 474 if (error != 0) 475 return (error); 476 rpipe = &pp->pp_rpipe; 477 wpipe = &pp->pp_wpipe; 478 error = falloc_caps(td, &rf, &fd, flags, fcaps1); 479 if (error) { 480 pipeclose(rpipe); 481 pipeclose(wpipe); 482 return (error); 483 } 484 /* An extra reference on `rf' has been held for us by falloc_caps(). */ 485 fildes[0] = fd; 486 487 fflags = FREAD | FWRITE; 488 if ((flags & O_NONBLOCK) != 0) 489 fflags |= FNONBLOCK; 490 491 /* 492 * Warning: once we've gotten past allocation of the fd for the 493 * read-side, we can only drop the read side via fdrop() in order 494 * to avoid races against processes which manage to dup() the read 495 * side while we are blocked trying to allocate the write side. 496 */ 497 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 498 error = falloc_caps(td, &wf, &fd, flags, fcaps2); 499 if (error) { 500 fdclose(td, rf, fildes[0]); 501 fdrop(rf, td); 502 /* rpipe has been closed by fdrop(). */ 503 pipeclose(wpipe); 504 return (error); 505 } 506 /* An extra reference on `wf' has been held for us by falloc_caps(). */ 507 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 508 fdrop(wf, td); 509 fildes[1] = fd; 510 fdrop(rf, td); 511 512 return (0); 513} 514 515#ifdef COMPAT_FREEBSD10 516/* ARGSUSED */ 517int 518freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused) 519{ 520 int error; 521 int fildes[2]; 522 523 error = kern_pipe(td, fildes, 0, NULL, NULL); 524 if (error) 525 return (error); 526 527 td->td_retval[0] = fildes[0]; 528 td->td_retval[1] = fildes[1]; 529 530 return (0); 531} 532#endif 533 534int 535sys_pipe2(struct thread *td, struct pipe2_args *uap) 536{ 537 int error, fildes[2]; 538 539 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 540 return (EINVAL); 541 error = kern_pipe(td, fildes, uap->flags, NULL, NULL); 542 if (error) 543 return (error); 544 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 545 if (error) { 546 (void)kern_close(td, fildes[0]); 547 (void)kern_close(td, fildes[1]); 548 } 549 return (error); 550} 551 552/* 553 * Allocate kva for pipe circular buffer, the space is pageable 554 * This routine will 'realloc' the size of a pipe safely, if it fails 555 * it will retain the old buffer. 556 * If it fails it will return ENOMEM. 557 */ 558static int 559pipespace_new(struct pipe *cpipe, int size) 560{ 561 caddr_t buffer; 562 int error, cnt, firstseg; 563 static int curfail = 0; 564 static struct timeval lastfail; 565 566 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 567 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 568 ("pipespace: resize of direct writes not allowed")); 569retry: 570 cnt = cpipe->pipe_buffer.cnt; 571 if (cnt > size) 572 size = cnt; 573 574 size = round_page(size); 575 buffer = (caddr_t) vm_map_min(pipe_map); 576 577 error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0, 578 VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0); 579 if (error != KERN_SUCCESS) { 580 if (cpipe->pipe_buffer.buffer == NULL && 581 size > SMALL_PIPE_SIZE) { 582 size = SMALL_PIPE_SIZE; 583 pipefragretry++; 584 goto retry; 585 } 586 if (cpipe->pipe_buffer.buffer == NULL) { 587 pipeallocfail++; 588 if (ppsratecheck(&lastfail, &curfail, 1)) 589 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 590 } else { 591 piperesizefail++; 592 } 593 return (ENOMEM); 594 } 595 596 /* copy data, then free old resources if we're resizing */ 597 if (cnt > 0) { 598 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 599 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 600 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 601 buffer, firstseg); 602 if ((cnt - firstseg) > 0) 603 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 604 cpipe->pipe_buffer.in); 605 } else { 606 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 607 buffer, cnt); 608 } 609 } 610 pipe_free_kmem(cpipe); 611 cpipe->pipe_buffer.buffer = buffer; 612 cpipe->pipe_buffer.size = size; 613 cpipe->pipe_buffer.in = cnt; 614 cpipe->pipe_buffer.out = 0; 615 cpipe->pipe_buffer.cnt = cnt; 616 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 617 return (0); 618} 619 620/* 621 * Wrapper for pipespace_new() that performs locking assertions. 622 */ 623static int 624pipespace(struct pipe *cpipe, int size) 625{ 626 627 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 628 ("Unlocked pipe passed to pipespace")); 629 return (pipespace_new(cpipe, size)); 630} 631 632/* 633 * lock a pipe for I/O, blocking other access 634 */ 635static __inline int 636pipelock(struct pipe *cpipe, int catch) 637{ 638 int error, prio; 639 640 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 641 642 prio = PRIBIO; 643 if (catch) 644 prio |= PCATCH; 645 while (cpipe->pipe_state & PIPE_LOCKFL) { 646 KASSERT(cpipe->pipe_waiters >= 0, 647 ("%s: bad waiter count %d", __func__, 648 cpipe->pipe_waiters)); 649 cpipe->pipe_waiters++; 650 error = msleep(&cpipe->pipe_waiters, PIPE_MTX(cpipe), prio, 651 "pipelk", 0); 652 cpipe->pipe_waiters--; 653 if (error != 0) 654 return (error); 655 } 656 cpipe->pipe_state |= PIPE_LOCKFL; 657 return (0); 658} 659 660/* 661 * unlock a pipe I/O lock 662 */ 663static __inline void 664pipeunlock(struct pipe *cpipe) 665{ 666 667 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 668 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 669 ("Unlocked pipe passed to pipeunlock")); 670 KASSERT(cpipe->pipe_waiters >= 0, 671 ("%s: bad waiter count %d", __func__, 672 cpipe->pipe_waiters)); 673 cpipe->pipe_state &= ~PIPE_LOCKFL; 674 if (cpipe->pipe_waiters > 0) 675 wakeup_one(&cpipe->pipe_waiters); 676} 677 678void 679pipeselwakeup(struct pipe *cpipe) 680{ 681 682 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 683 if (cpipe->pipe_state & PIPE_SEL) { 684 selwakeuppri(&cpipe->pipe_sel, PSOCK); 685 if (!SEL_WAITING(&cpipe->pipe_sel)) 686 cpipe->pipe_state &= ~PIPE_SEL; 687 } 688 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 689 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 690 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 691} 692 693/* 694 * Initialize and allocate VM and memory for pipe. The structure 695 * will start out zero'd from the ctor, so we just manage the kmem. 696 */ 697static int 698pipe_create(struct pipe *pipe, bool large_backing) 699{ 700 int error; 701 702 error = pipespace_new(pipe, !large_backing || amountpipekva > 703 maxpipekva / 2 ? SMALL_PIPE_SIZE : PIPE_SIZE); 704 if (error == 0) 705 pipe->pipe_ino = alloc_unr64(&pipeino_unr); 706 return (error); 707} 708 709/* ARGSUSED */ 710static int 711pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 712 int flags, struct thread *td) 713{ 714 struct pipe *rpipe; 715 int error; 716 int nread = 0; 717 int size; 718 719 rpipe = fp->f_data; 720 721 /* 722 * Try to avoid locking the pipe if we have nothing to do. 723 * 724 * There are programs which share one pipe amongst multiple processes 725 * and perform non-blocking reads in parallel, even if the pipe is 726 * empty. This in particular is the case with BSD make, which when 727 * spawned with a high -j number can find itself with over half of the 728 * calls failing to find anything. 729 */ 730 if ((fp->f_flag & FNONBLOCK) != 0 && !mac_pipe_check_read_enabled()) { 731 if (__predict_false(uio->uio_resid == 0)) 732 return (0); 733 if ((atomic_load_short(&rpipe->pipe_state) & PIPE_EOF) == 0 && 734 atomic_load_int(&rpipe->pipe_buffer.cnt) == 0 && 735 atomic_load_int(&rpipe->pipe_pages.cnt) == 0) 736 return (EAGAIN); 737 } 738 739 PIPE_LOCK(rpipe); 740 ++rpipe->pipe_busy; 741 error = pipelock(rpipe, 1); 742 if (error) 743 goto unlocked_error; 744 745#ifdef MAC 746 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 747 if (error) 748 goto locked_error; 749#endif 750 if (amountpipekva > (3 * maxpipekva) / 4) { 751 if ((rpipe->pipe_state & PIPE_DIRECTW) == 0 && 752 rpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 753 rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 754 piperesizeallowed == 1) { 755 PIPE_UNLOCK(rpipe); 756 pipespace(rpipe, SMALL_PIPE_SIZE); 757 PIPE_LOCK(rpipe); 758 } 759 } 760 761 while (uio->uio_resid) { 762 /* 763 * normal pipe buffer receive 764 */ 765 if (rpipe->pipe_buffer.cnt > 0) { 766 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 767 if (size > rpipe->pipe_buffer.cnt) 768 size = rpipe->pipe_buffer.cnt; 769 if (size > uio->uio_resid) 770 size = uio->uio_resid; 771 772 PIPE_UNLOCK(rpipe); 773 error = uiomove( 774 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 775 size, uio); 776 PIPE_LOCK(rpipe); 777 if (error) 778 break; 779 780 rpipe->pipe_buffer.out += size; 781 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 782 rpipe->pipe_buffer.out = 0; 783 784 rpipe->pipe_buffer.cnt -= size; 785 786 /* 787 * If there is no more to read in the pipe, reset 788 * its pointers to the beginning. This improves 789 * cache hit stats. 790 */ 791 if (rpipe->pipe_buffer.cnt == 0) { 792 rpipe->pipe_buffer.in = 0; 793 rpipe->pipe_buffer.out = 0; 794 } 795 nread += size; 796#ifndef PIPE_NODIRECT 797 /* 798 * Direct copy, bypassing a kernel buffer. 799 */ 800 } else if ((size = rpipe->pipe_pages.cnt) != 0) { 801 if (size > uio->uio_resid) 802 size = (u_int) uio->uio_resid; 803 PIPE_UNLOCK(rpipe); 804 error = uiomove_fromphys(rpipe->pipe_pages.ms, 805 rpipe->pipe_pages.pos, size, uio); 806 PIPE_LOCK(rpipe); 807 if (error) 808 break; 809 nread += size; 810 rpipe->pipe_pages.pos += size; 811 rpipe->pipe_pages.cnt -= size; 812 if (rpipe->pipe_pages.cnt == 0) { 813 rpipe->pipe_state &= ~PIPE_WANTW; 814 wakeup(rpipe); 815 } 816#endif 817 } else { 818 /* 819 * detect EOF condition 820 * read returns 0 on EOF, no need to set error 821 */ 822 if (rpipe->pipe_state & PIPE_EOF) 823 break; 824 825 /* 826 * If the "write-side" has been blocked, wake it up now. 827 */ 828 if (rpipe->pipe_state & PIPE_WANTW) { 829 rpipe->pipe_state &= ~PIPE_WANTW; 830 wakeup(rpipe); 831 } 832 833 /* 834 * Break if some data was read. 835 */ 836 if (nread > 0) 837 break; 838 839 /* 840 * Unlock the pipe buffer for our remaining processing. 841 * We will either break out with an error or we will 842 * sleep and relock to loop. 843 */ 844 pipeunlock(rpipe); 845 846 /* 847 * Handle non-blocking mode operation or 848 * wait for more data. 849 */ 850 if (fp->f_flag & FNONBLOCK) { 851 error = EAGAIN; 852 } else { 853 rpipe->pipe_state |= PIPE_WANTR; 854 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 855 PRIBIO | PCATCH, 856 "piperd", 0)) == 0) 857 error = pipelock(rpipe, 1); 858 } 859 if (error) 860 goto unlocked_error; 861 } 862 } 863#ifdef MAC 864locked_error: 865#endif 866 pipeunlock(rpipe); 867 868 /* XXX: should probably do this before getting any locks. */ 869 if (error == 0) 870 pipe_timestamp(&rpipe->pipe_atime); 871unlocked_error: 872 --rpipe->pipe_busy; 873 874 /* 875 * PIPE_WANT processing only makes sense if pipe_busy is 0. 876 */ 877 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 878 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 879 wakeup(rpipe); 880 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 881 /* 882 * Handle write blocking hysteresis. 883 */ 884 if (rpipe->pipe_state & PIPE_WANTW) { 885 rpipe->pipe_state &= ~PIPE_WANTW; 886 wakeup(rpipe); 887 } 888 } 889 890 /* 891 * Only wake up writers if there was actually something read. 892 * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs. 893 */ 894 if (nread > 0 && 895 rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF) 896 pipeselwakeup(rpipe); 897 898 PIPE_UNLOCK(rpipe); 899 if (nread > 0) 900 td->td_ru.ru_msgrcv++; 901 return (error); 902} 903 904#ifndef PIPE_NODIRECT 905/* 906 * Map the sending processes' buffer into kernel space and wire it. 907 * This is similar to a physical write operation. 908 */ 909static int 910pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio) 911{ 912 u_int size; 913 int i; 914 915 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 916 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 917 ("%s: PIPE_DIRECTW set on %p", __func__, wpipe)); 918 KASSERT(wpipe->pipe_pages.cnt == 0, 919 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 920 921 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 922 size = wpipe->pipe_buffer.size; 923 else 924 size = uio->uio_iov->iov_len; 925 926 wpipe->pipe_state |= PIPE_DIRECTW; 927 PIPE_UNLOCK(wpipe); 928 i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 929 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 930 wpipe->pipe_pages.ms, PIPENPAGES); 931 PIPE_LOCK(wpipe); 932 if (i < 0) { 933 wpipe->pipe_state &= ~PIPE_DIRECTW; 934 return (EFAULT); 935 } 936 937 wpipe->pipe_pages.npages = i; 938 wpipe->pipe_pages.pos = 939 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 940 wpipe->pipe_pages.cnt = size; 941 942 uio->uio_iov->iov_len -= size; 943 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 944 if (uio->uio_iov->iov_len == 0) 945 uio->uio_iov++; 946 uio->uio_resid -= size; 947 uio->uio_offset += size; 948 return (0); 949} 950 951/* 952 * Unwire the process buffer. 953 */ 954static void 955pipe_destroy_write_buffer(struct pipe *wpipe) 956{ 957 958 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 959 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 960 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 961 KASSERT(wpipe->pipe_pages.cnt == 0, 962 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 963 964 wpipe->pipe_state &= ~PIPE_DIRECTW; 965 vm_page_unhold_pages(wpipe->pipe_pages.ms, wpipe->pipe_pages.npages); 966 wpipe->pipe_pages.npages = 0; 967} 968 969/* 970 * In the case of a signal, the writing process might go away. This 971 * code copies the data into the circular buffer so that the source 972 * pages can be freed without loss of data. 973 */ 974static void 975pipe_clone_write_buffer(struct pipe *wpipe) 976{ 977 struct uio uio; 978 struct iovec iov; 979 int size; 980 int pos; 981 982 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 983 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 984 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 985 986 size = wpipe->pipe_pages.cnt; 987 pos = wpipe->pipe_pages.pos; 988 wpipe->pipe_pages.cnt = 0; 989 990 wpipe->pipe_buffer.in = size; 991 wpipe->pipe_buffer.out = 0; 992 wpipe->pipe_buffer.cnt = size; 993 994 PIPE_UNLOCK(wpipe); 995 iov.iov_base = wpipe->pipe_buffer.buffer; 996 iov.iov_len = size; 997 uio.uio_iov = &iov; 998 uio.uio_iovcnt = 1; 999 uio.uio_offset = 0; 1000 uio.uio_resid = size; 1001 uio.uio_segflg = UIO_SYSSPACE; 1002 uio.uio_rw = UIO_READ; 1003 uio.uio_td = curthread; 1004 uiomove_fromphys(wpipe->pipe_pages.ms, pos, size, &uio); 1005 PIPE_LOCK(wpipe); 1006 pipe_destroy_write_buffer(wpipe); 1007} 1008 1009/* 1010 * This implements the pipe buffer write mechanism. Note that only 1011 * a direct write OR a normal pipe write can be pending at any given time. 1012 * If there are any characters in the pipe buffer, the direct write will 1013 * be deferred until the receiving process grabs all of the bytes from 1014 * the pipe buffer. Then the direct mapping write is set-up. 1015 */ 1016static int 1017pipe_direct_write(struct pipe *wpipe, struct uio *uio) 1018{ 1019 int error; 1020 1021retry: 1022 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1023 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 1024 error = EPIPE; 1025 goto error1; 1026 } 1027 if (wpipe->pipe_state & PIPE_DIRECTW) { 1028 if (wpipe->pipe_state & PIPE_WANTR) { 1029 wpipe->pipe_state &= ~PIPE_WANTR; 1030 wakeup(wpipe); 1031 } 1032 pipeselwakeup(wpipe); 1033 wpipe->pipe_state |= PIPE_WANTW; 1034 pipeunlock(wpipe); 1035 error = msleep(wpipe, PIPE_MTX(wpipe), 1036 PRIBIO | PCATCH, "pipdww", 0); 1037 pipelock(wpipe, 0); 1038 if (error != 0) 1039 goto error1; 1040 goto retry; 1041 } 1042 if (wpipe->pipe_buffer.cnt > 0) { 1043 if (wpipe->pipe_state & PIPE_WANTR) { 1044 wpipe->pipe_state &= ~PIPE_WANTR; 1045 wakeup(wpipe); 1046 } 1047 pipeselwakeup(wpipe); 1048 wpipe->pipe_state |= PIPE_WANTW; 1049 pipeunlock(wpipe); 1050 error = msleep(wpipe, PIPE_MTX(wpipe), 1051 PRIBIO | PCATCH, "pipdwc", 0); 1052 pipelock(wpipe, 0); 1053 if (error != 0) 1054 goto error1; 1055 goto retry; 1056 } 1057 1058 error = pipe_build_write_buffer(wpipe, uio); 1059 if (error) { 1060 goto error1; 1061 } 1062 1063 while (wpipe->pipe_pages.cnt != 0 && 1064 (wpipe->pipe_state & PIPE_EOF) == 0) { 1065 if (wpipe->pipe_state & PIPE_WANTR) { 1066 wpipe->pipe_state &= ~PIPE_WANTR; 1067 wakeup(wpipe); 1068 } 1069 pipeselwakeup(wpipe); 1070 wpipe->pipe_state |= PIPE_WANTW; 1071 pipeunlock(wpipe); 1072 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1073 "pipdwt", 0); 1074 pipelock(wpipe, 0); 1075 if (error != 0) 1076 break; 1077 } 1078 1079 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 1080 wpipe->pipe_pages.cnt = 0; 1081 pipe_destroy_write_buffer(wpipe); 1082 pipeselwakeup(wpipe); 1083 error = EPIPE; 1084 } else if (error == EINTR || error == ERESTART) { 1085 pipe_clone_write_buffer(wpipe); 1086 } else { 1087 pipe_destroy_write_buffer(wpipe); 1088 } 1089 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 1090 ("pipe %p leaked PIPE_DIRECTW", wpipe)); 1091 return (error); 1092 1093error1: 1094 wakeup(wpipe); 1095 return (error); 1096} 1097#endif 1098 1099static int 1100pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 1101 int flags, struct thread *td) 1102{ 1103 struct pipe *wpipe, *rpipe; 1104 ssize_t orig_resid; 1105 int desiredsize, error; 1106 1107 rpipe = fp->f_data; 1108 wpipe = PIPE_PEER(rpipe); 1109 PIPE_LOCK(rpipe); 1110 error = pipelock(wpipe, 1); 1111 if (error) { 1112 PIPE_UNLOCK(rpipe); 1113 return (error); 1114 } 1115 /* 1116 * detect loss of pipe read side, issue SIGPIPE if lost. 1117 */ 1118 if (wpipe->pipe_present != PIPE_ACTIVE || 1119 (wpipe->pipe_state & PIPE_EOF)) { 1120 pipeunlock(wpipe); 1121 PIPE_UNLOCK(rpipe); 1122 return (EPIPE); 1123 } 1124#ifdef MAC 1125 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1126 if (error) { 1127 pipeunlock(wpipe); 1128 PIPE_UNLOCK(rpipe); 1129 return (error); 1130 } 1131#endif 1132 ++wpipe->pipe_busy; 1133 1134 /* Choose a larger size if it's advantageous */ 1135 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1136 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1137 if (piperesizeallowed != 1) 1138 break; 1139 if (amountpipekva > maxpipekva / 2) 1140 break; 1141 if (desiredsize == BIG_PIPE_SIZE) 1142 break; 1143 desiredsize = desiredsize * 2; 1144 } 1145 1146 /* Choose a smaller size if we're in a OOM situation */ 1147 if (amountpipekva > (3 * maxpipekva) / 4 && 1148 wpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 1149 wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 1150 piperesizeallowed == 1) 1151 desiredsize = SMALL_PIPE_SIZE; 1152 1153 /* Resize if the above determined that a new size was necessary */ 1154 if (desiredsize != wpipe->pipe_buffer.size && 1155 (wpipe->pipe_state & PIPE_DIRECTW) == 0) { 1156 PIPE_UNLOCK(wpipe); 1157 pipespace(wpipe, desiredsize); 1158 PIPE_LOCK(wpipe); 1159 } 1160 MPASS(wpipe->pipe_buffer.size != 0); 1161 1162 orig_resid = uio->uio_resid; 1163 1164 while (uio->uio_resid) { 1165 int space; 1166 1167 if (wpipe->pipe_state & PIPE_EOF) { 1168 error = EPIPE; 1169 break; 1170 } 1171#ifndef PIPE_NODIRECT 1172 /* 1173 * If the transfer is large, we can gain performance if 1174 * we do process-to-process copies directly. 1175 * If the write is non-blocking, we don't use the 1176 * direct write mechanism. 1177 * 1178 * The direct write mechanism will detect the reader going 1179 * away on us. 1180 */ 1181 if (uio->uio_segflg == UIO_USERSPACE && 1182 uio->uio_iov->iov_len >= pipe_mindirect && 1183 wpipe->pipe_buffer.size >= pipe_mindirect && 1184 (fp->f_flag & FNONBLOCK) == 0) { 1185 error = pipe_direct_write(wpipe, uio); 1186 if (error != 0) 1187 break; 1188 continue; 1189 } 1190#endif 1191 1192 /* 1193 * Pipe buffered writes cannot be coincidental with 1194 * direct writes. We wait until the currently executing 1195 * direct write is completed before we start filling the 1196 * pipe buffer. We break out if a signal occurs or the 1197 * reader goes away. 1198 */ 1199 if (wpipe->pipe_pages.cnt != 0) { 1200 if (wpipe->pipe_state & PIPE_WANTR) { 1201 wpipe->pipe_state &= ~PIPE_WANTR; 1202 wakeup(wpipe); 1203 } 1204 pipeselwakeup(wpipe); 1205 wpipe->pipe_state |= PIPE_WANTW; 1206 pipeunlock(wpipe); 1207 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1208 "pipbww", 0); 1209 pipelock(wpipe, 0); 1210 if (error != 0) 1211 break; 1212 continue; 1213 } 1214 1215 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1216 1217 /* Writes of size <= PIPE_BUF must be atomic. */ 1218 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1219 space = 0; 1220 1221 if (space > 0) { 1222 int size; /* Transfer size */ 1223 int segsize; /* first segment to transfer */ 1224 1225 /* 1226 * Transfer size is minimum of uio transfer 1227 * and free space in pipe buffer. 1228 */ 1229 if (space > uio->uio_resid) 1230 size = uio->uio_resid; 1231 else 1232 size = space; 1233 /* 1234 * First segment to transfer is minimum of 1235 * transfer size and contiguous space in 1236 * pipe buffer. If first segment to transfer 1237 * is less than the transfer size, we've got 1238 * a wraparound in the buffer. 1239 */ 1240 segsize = wpipe->pipe_buffer.size - 1241 wpipe->pipe_buffer.in; 1242 if (segsize > size) 1243 segsize = size; 1244 1245 /* Transfer first segment */ 1246 1247 PIPE_UNLOCK(rpipe); 1248 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1249 segsize, uio); 1250 PIPE_LOCK(rpipe); 1251 1252 if (error == 0 && segsize < size) { 1253 KASSERT(wpipe->pipe_buffer.in + segsize == 1254 wpipe->pipe_buffer.size, 1255 ("Pipe buffer wraparound disappeared")); 1256 /* 1257 * Transfer remaining part now, to 1258 * support atomic writes. Wraparound 1259 * happened. 1260 */ 1261 1262 PIPE_UNLOCK(rpipe); 1263 error = uiomove( 1264 &wpipe->pipe_buffer.buffer[0], 1265 size - segsize, uio); 1266 PIPE_LOCK(rpipe); 1267 } 1268 if (error == 0) { 1269 wpipe->pipe_buffer.in += size; 1270 if (wpipe->pipe_buffer.in >= 1271 wpipe->pipe_buffer.size) { 1272 KASSERT(wpipe->pipe_buffer.in == 1273 size - segsize + 1274 wpipe->pipe_buffer.size, 1275 ("Expected wraparound bad")); 1276 wpipe->pipe_buffer.in = size - segsize; 1277 } 1278 1279 wpipe->pipe_buffer.cnt += size; 1280 KASSERT(wpipe->pipe_buffer.cnt <= 1281 wpipe->pipe_buffer.size, 1282 ("Pipe buffer overflow")); 1283 } 1284 if (error != 0) 1285 break; 1286 continue; 1287 } else { 1288 /* 1289 * If the "read-side" has been blocked, wake it up now. 1290 */ 1291 if (wpipe->pipe_state & PIPE_WANTR) { 1292 wpipe->pipe_state &= ~PIPE_WANTR; 1293 wakeup(wpipe); 1294 } 1295 1296 /* 1297 * don't block on non-blocking I/O 1298 */ 1299 if (fp->f_flag & FNONBLOCK) { 1300 error = EAGAIN; 1301 break; 1302 } 1303 1304 /* 1305 * We have no more space and have something to offer, 1306 * wake up select/poll. 1307 */ 1308 pipeselwakeup(wpipe); 1309 1310 wpipe->pipe_state |= PIPE_WANTW; 1311 pipeunlock(wpipe); 1312 error = msleep(wpipe, PIPE_MTX(rpipe), 1313 PRIBIO | PCATCH, "pipewr", 0); 1314 pipelock(wpipe, 0); 1315 if (error != 0) 1316 break; 1317 continue; 1318 } 1319 } 1320 1321 --wpipe->pipe_busy; 1322 1323 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1324 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1325 wakeup(wpipe); 1326 } else if (wpipe->pipe_buffer.cnt > 0) { 1327 /* 1328 * If we have put any characters in the buffer, we wake up 1329 * the reader. 1330 */ 1331 if (wpipe->pipe_state & PIPE_WANTR) { 1332 wpipe->pipe_state &= ~PIPE_WANTR; 1333 wakeup(wpipe); 1334 } 1335 } 1336 1337 /* 1338 * Don't return EPIPE if any byte was written. 1339 * EINTR and other interrupts are handled by generic I/O layer. 1340 * Do not pretend that I/O succeeded for obvious user error 1341 * like EFAULT. 1342 */ 1343 if (uio->uio_resid != orig_resid && error == EPIPE) 1344 error = 0; 1345 1346 if (error == 0) 1347 pipe_timestamp(&wpipe->pipe_mtime); 1348 1349 /* 1350 * We have something to offer, 1351 * wake up select/poll. 1352 */ 1353 if (wpipe->pipe_buffer.cnt) 1354 pipeselwakeup(wpipe); 1355 1356 pipeunlock(wpipe); 1357 PIPE_UNLOCK(rpipe); 1358 if (uio->uio_resid != orig_resid) 1359 td->td_ru.ru_msgsnd++; 1360 return (error); 1361} 1362 1363/* ARGSUSED */ 1364static int 1365pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred, 1366 struct thread *td) 1367{ 1368 struct pipe *cpipe; 1369 int error; 1370 1371 cpipe = fp->f_data; 1372 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1373 error = vnops.fo_truncate(fp, length, active_cred, td); 1374 else 1375 error = invfo_truncate(fp, length, active_cred, td); 1376 return (error); 1377} 1378 1379/* 1380 * we implement a very minimal set of ioctls for compatibility with sockets. 1381 */ 1382static int 1383pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred, 1384 struct thread *td) 1385{ 1386 struct pipe *mpipe = fp->f_data; 1387 int error; 1388 1389 PIPE_LOCK(mpipe); 1390 1391#ifdef MAC 1392 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1393 if (error) { 1394 PIPE_UNLOCK(mpipe); 1395 return (error); 1396 } 1397#endif 1398 1399 error = 0; 1400 switch (cmd) { 1401 case FIONBIO: 1402 break; 1403 1404 case FIOASYNC: 1405 if (*(int *)data) { 1406 mpipe->pipe_state |= PIPE_ASYNC; 1407 } else { 1408 mpipe->pipe_state &= ~PIPE_ASYNC; 1409 } 1410 break; 1411 1412 case FIONREAD: 1413 if (!(fp->f_flag & FREAD)) { 1414 *(int *)data = 0; 1415 PIPE_UNLOCK(mpipe); 1416 return (0); 1417 } 1418 if (mpipe->pipe_pages.cnt != 0) 1419 *(int *)data = mpipe->pipe_pages.cnt; 1420 else 1421 *(int *)data = mpipe->pipe_buffer.cnt; 1422 break; 1423 1424 case FIOSETOWN: 1425 PIPE_UNLOCK(mpipe); 1426 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1427 goto out_unlocked; 1428 1429 case FIOGETOWN: 1430 *(int *)data = fgetown(&mpipe->pipe_sigio); 1431 break; 1432 1433 /* This is deprecated, FIOSETOWN should be used instead. */ 1434 case TIOCSPGRP: 1435 PIPE_UNLOCK(mpipe); 1436 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1437 goto out_unlocked; 1438 1439 /* This is deprecated, FIOGETOWN should be used instead. */ 1440 case TIOCGPGRP: 1441 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1442 break; 1443 1444 default: 1445 error = ENOTTY; 1446 break; 1447 } 1448 PIPE_UNLOCK(mpipe); 1449out_unlocked: 1450 return (error); 1451} 1452 1453static int 1454pipe_poll(struct file *fp, int events, struct ucred *active_cred, 1455 struct thread *td) 1456{ 1457 struct pipe *rpipe; 1458 struct pipe *wpipe; 1459 int levents, revents; 1460#ifdef MAC 1461 int error; 1462#endif 1463 1464 revents = 0; 1465 rpipe = fp->f_data; 1466 wpipe = PIPE_PEER(rpipe); 1467 PIPE_LOCK(rpipe); 1468#ifdef MAC 1469 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1470 if (error) 1471 goto locked_error; 1472#endif 1473 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1474 if (rpipe->pipe_pages.cnt > 0 || rpipe->pipe_buffer.cnt > 0) 1475 revents |= events & (POLLIN | POLLRDNORM); 1476 1477 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1478 if (wpipe->pipe_present != PIPE_ACTIVE || 1479 (wpipe->pipe_state & PIPE_EOF) || 1480 ((wpipe->pipe_state & PIPE_DIRECTW) == 0 && 1481 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1482 wpipe->pipe_buffer.size == 0))) 1483 revents |= events & (POLLOUT | POLLWRNORM); 1484 1485 levents = events & 1486 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1487 if (rpipe->pipe_type & PIPE_TYPE_NAMED && fp->f_flag & FREAD && levents && 1488 fp->f_pipegen == rpipe->pipe_wgen) 1489 events |= POLLINIGNEOF; 1490 1491 if ((events & POLLINIGNEOF) == 0) { 1492 if (rpipe->pipe_state & PIPE_EOF) { 1493 if (fp->f_flag & FREAD) 1494 revents |= (events & (POLLIN | POLLRDNORM)); 1495 if (wpipe->pipe_present != PIPE_ACTIVE || 1496 (wpipe->pipe_state & PIPE_EOF)) 1497 revents |= POLLHUP; 1498 } 1499 } 1500 1501 if (revents == 0) { 1502 /* 1503 * Add ourselves regardless of eventmask as we have to return 1504 * POLLHUP even if it was not asked for. 1505 */ 1506 if ((fp->f_flag & FREAD) != 0) { 1507 selrecord(td, &rpipe->pipe_sel); 1508 if (SEL_WAITING(&rpipe->pipe_sel)) 1509 rpipe->pipe_state |= PIPE_SEL; 1510 } 1511 1512 if ((fp->f_flag & FWRITE) != 0 && 1513 wpipe->pipe_present == PIPE_ACTIVE) { 1514 selrecord(td, &wpipe->pipe_sel); 1515 if (SEL_WAITING(&wpipe->pipe_sel)) 1516 wpipe->pipe_state |= PIPE_SEL; 1517 } 1518 } 1519#ifdef MAC 1520locked_error: 1521#endif 1522 PIPE_UNLOCK(rpipe); 1523 1524 return (revents); 1525} 1526 1527/* 1528 * We shouldn't need locks here as we're doing a read and this should 1529 * be a natural race. 1530 */ 1531static int 1532pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred) 1533{ 1534 struct pipe *pipe; 1535#ifdef MAC 1536 int error; 1537#endif 1538 1539 pipe = fp->f_data; 1540#ifdef MAC 1541 if (mac_pipe_check_stat_enabled()) { 1542 PIPE_LOCK(pipe); 1543 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1544 PIPE_UNLOCK(pipe); 1545 if (error) { 1546 return (error); 1547 } 1548 } 1549#endif 1550 1551 /* For named pipes ask the underlying filesystem. */ 1552 if (pipe->pipe_type & PIPE_TYPE_NAMED) { 1553 return (vnops.fo_stat(fp, ub, active_cred)); 1554 } 1555 1556 bzero(ub, sizeof(*ub)); 1557 ub->st_mode = S_IFIFO; 1558 ub->st_blksize = PAGE_SIZE; 1559 if (pipe->pipe_pages.cnt != 0) 1560 ub->st_size = pipe->pipe_pages.cnt; 1561 else 1562 ub->st_size = pipe->pipe_buffer.cnt; 1563 ub->st_blocks = howmany(ub->st_size, ub->st_blksize); 1564 ub->st_atim = pipe->pipe_atime; 1565 ub->st_mtim = pipe->pipe_mtime; 1566 ub->st_ctim = pipe->pipe_ctime; 1567 ub->st_uid = fp->f_cred->cr_uid; 1568 ub->st_gid = fp->f_cred->cr_gid; 1569 ub->st_dev = pipedev_ino; 1570 ub->st_ino = pipe->pipe_ino; 1571 /* 1572 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1573 */ 1574 return (0); 1575} 1576 1577/* ARGSUSED */ 1578static int 1579pipe_close(struct file *fp, struct thread *td) 1580{ 1581 1582 if (fp->f_vnode != NULL) 1583 return vnops.fo_close(fp, td); 1584 fp->f_ops = &badfileops; 1585 pipe_dtor(fp->f_data); 1586 fp->f_data = NULL; 1587 return (0); 1588} 1589 1590static int 1591pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1592{ 1593 struct pipe *cpipe; 1594 int error; 1595 1596 cpipe = fp->f_data; 1597 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1598 error = vn_chmod(fp, mode, active_cred, td); 1599 else 1600 error = invfo_chmod(fp, mode, active_cred, td); 1601 return (error); 1602} 1603 1604static int 1605pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1606 struct thread *td) 1607{ 1608 struct pipe *cpipe; 1609 int error; 1610 1611 cpipe = fp->f_data; 1612 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1613 error = vn_chown(fp, uid, gid, active_cred, td); 1614 else 1615 error = invfo_chown(fp, uid, gid, active_cred, td); 1616 return (error); 1617} 1618 1619static int 1620pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1621{ 1622 struct pipe *pi; 1623 1624 if (fp->f_type == DTYPE_FIFO) 1625 return (vn_fill_kinfo(fp, kif, fdp)); 1626 kif->kf_type = KF_TYPE_PIPE; 1627 pi = fp->f_data; 1628 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1629 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1630 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1631 kif->kf_un.kf_pipe.kf_pipe_buffer_in = pi->pipe_buffer.in; 1632 kif->kf_un.kf_pipe.kf_pipe_buffer_out = pi->pipe_buffer.out; 1633 kif->kf_un.kf_pipe.kf_pipe_buffer_size = pi->pipe_buffer.size; 1634 return (0); 1635} 1636 1637static void 1638pipe_free_kmem(struct pipe *cpipe) 1639{ 1640 1641 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1642 ("pipe_free_kmem: pipe mutex locked")); 1643 1644 if (cpipe->pipe_buffer.buffer != NULL) { 1645 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1646 vm_map_remove(pipe_map, 1647 (vm_offset_t)cpipe->pipe_buffer.buffer, 1648 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1649 cpipe->pipe_buffer.buffer = NULL; 1650 } 1651#ifndef PIPE_NODIRECT 1652 { 1653 cpipe->pipe_pages.cnt = 0; 1654 cpipe->pipe_pages.pos = 0; 1655 cpipe->pipe_pages.npages = 0; 1656 } 1657#endif 1658} 1659 1660/* 1661 * shutdown the pipe 1662 */ 1663static void 1664pipeclose(struct pipe *cpipe) 1665{ 1666#ifdef MAC 1667 struct pipepair *pp; 1668#endif 1669 struct pipe *ppipe; 1670 1671 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1672 1673 PIPE_LOCK(cpipe); 1674 pipelock(cpipe, 0); 1675#ifdef MAC 1676 pp = cpipe->pipe_pair; 1677#endif 1678 1679 /* 1680 * If the other side is blocked, wake it up saying that 1681 * we want to close it down. 1682 */ 1683 cpipe->pipe_state |= PIPE_EOF; 1684 while (cpipe->pipe_busy) { 1685 wakeup(cpipe); 1686 cpipe->pipe_state |= PIPE_WANT; 1687 pipeunlock(cpipe); 1688 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1689 pipelock(cpipe, 0); 1690 } 1691 1692 pipeselwakeup(cpipe); 1693 1694 /* 1695 * Disconnect from peer, if any. 1696 */ 1697 ppipe = cpipe->pipe_peer; 1698 if (ppipe->pipe_present == PIPE_ACTIVE) { 1699 ppipe->pipe_state |= PIPE_EOF; 1700 wakeup(ppipe); 1701 pipeselwakeup(ppipe); 1702 } 1703 1704 /* 1705 * Mark this endpoint as free. Release kmem resources. We 1706 * don't mark this endpoint as unused until we've finished 1707 * doing that, or the pipe might disappear out from under 1708 * us. 1709 */ 1710 PIPE_UNLOCK(cpipe); 1711 pipe_free_kmem(cpipe); 1712 PIPE_LOCK(cpipe); 1713 cpipe->pipe_present = PIPE_CLOSING; 1714 pipeunlock(cpipe); 1715 1716 /* 1717 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1718 * PIPE_FINALIZED, that allows other end to free the 1719 * pipe_pair, only after the knotes are completely dismantled. 1720 */ 1721 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1722 cpipe->pipe_present = PIPE_FINALIZED; 1723 seldrain(&cpipe->pipe_sel); 1724 knlist_destroy(&cpipe->pipe_sel.si_note); 1725 1726 /* 1727 * If both endpoints are now closed, release the memory for the 1728 * pipe pair. If not, unlock. 1729 */ 1730 if (ppipe->pipe_present == PIPE_FINALIZED) { 1731 PIPE_UNLOCK(cpipe); 1732#ifdef MAC 1733 mac_pipe_destroy(pp); 1734#endif 1735 uma_zfree(pipe_zone, cpipe->pipe_pair); 1736 } else 1737 PIPE_UNLOCK(cpipe); 1738} 1739 1740/*ARGSUSED*/ 1741static int 1742pipe_kqfilter(struct file *fp, struct knote *kn) 1743{ 1744 struct pipe *cpipe; 1745 1746 /* 1747 * If a filter is requested that is not supported by this file 1748 * descriptor, don't return an error, but also don't ever generate an 1749 * event. 1750 */ 1751 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1752 kn->kn_fop = &pipe_nfiltops; 1753 return (0); 1754 } 1755 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1756 kn->kn_fop = &pipe_nfiltops; 1757 return (0); 1758 } 1759 cpipe = fp->f_data; 1760 PIPE_LOCK(cpipe); 1761 switch (kn->kn_filter) { 1762 case EVFILT_READ: 1763 kn->kn_fop = &pipe_rfiltops; 1764 break; 1765 case EVFILT_WRITE: 1766 kn->kn_fop = &pipe_wfiltops; 1767 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1768 /* other end of pipe has been closed */ 1769 PIPE_UNLOCK(cpipe); 1770 return (EPIPE); 1771 } 1772 cpipe = PIPE_PEER(cpipe); 1773 break; 1774 default: 1775 if ((cpipe->pipe_type & PIPE_TYPE_NAMED) != 0) { 1776 PIPE_UNLOCK(cpipe); 1777 return (vnops.fo_kqfilter(fp, kn)); 1778 } 1779 PIPE_UNLOCK(cpipe); 1780 return (EINVAL); 1781 } 1782 1783 kn->kn_hook = cpipe; 1784 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1785 PIPE_UNLOCK(cpipe); 1786 return (0); 1787} 1788 1789static void 1790filt_pipedetach(struct knote *kn) 1791{ 1792 struct pipe *cpipe = kn->kn_hook; 1793 1794 PIPE_LOCK(cpipe); 1795 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1796 PIPE_UNLOCK(cpipe); 1797} 1798 1799/*ARGSUSED*/ 1800static int 1801filt_piperead(struct knote *kn, long hint) 1802{ 1803 struct file *fp = kn->kn_fp; 1804 struct pipe *rpipe = kn->kn_hook; 1805 1806 PIPE_LOCK_ASSERT(rpipe, MA_OWNED); 1807 kn->kn_data = rpipe->pipe_buffer.cnt; 1808 if (kn->kn_data == 0) 1809 kn->kn_data = rpipe->pipe_pages.cnt; 1810 1811 if ((rpipe->pipe_state & PIPE_EOF) != 0 && 1812 ((rpipe->pipe_type & PIPE_TYPE_NAMED) == 0 || 1813 fp->f_pipegen != rpipe->pipe_wgen)) { 1814 kn->kn_flags |= EV_EOF; 1815 return (1); 1816 } 1817 kn->kn_flags &= ~EV_EOF; 1818 return (kn->kn_data > 0); 1819} 1820 1821/*ARGSUSED*/ 1822static int 1823filt_pipewrite(struct knote *kn, long hint) 1824{ 1825 struct pipe *wpipe = kn->kn_hook; 1826 1827 /* 1828 * If this end of the pipe is closed, the knote was removed from the 1829 * knlist and the list lock (i.e., the pipe lock) is therefore not held. 1830 */ 1831 if (wpipe->pipe_present == PIPE_ACTIVE || 1832 (wpipe->pipe_type & PIPE_TYPE_NAMED) != 0) { 1833 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1834 1835 if (wpipe->pipe_state & PIPE_DIRECTW) { 1836 kn->kn_data = 0; 1837 } else if (wpipe->pipe_buffer.size > 0) { 1838 kn->kn_data = wpipe->pipe_buffer.size - 1839 wpipe->pipe_buffer.cnt; 1840 } else { 1841 kn->kn_data = PIPE_BUF; 1842 } 1843 } 1844 1845 if (wpipe->pipe_present != PIPE_ACTIVE || 1846 (wpipe->pipe_state & PIPE_EOF)) { 1847 kn->kn_flags |= EV_EOF; 1848 return (1); 1849 } 1850 kn->kn_flags &= ~EV_EOF; 1851 return (kn->kn_data >= PIPE_BUF); 1852} 1853 1854static void 1855filt_pipedetach_notsup(struct knote *kn) 1856{ 1857 1858} 1859 1860static int 1861filt_pipenotsup(struct knote *kn, long hint) 1862{ 1863 1864 return (0); 1865} 1866