1 /* 2 * Copyright (c) 1996 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Absolutely no warranty of function or purpose is made by the author 15 * John S. Dyson. 16 * 4. Modifications may be freely made to this file if the above conditions 17 * are met. 18 * 19 * $FreeBSD: src/sys/kern/sys_pipe.c,v 1.60.2.13 2002/08/05 15:05:15 des Exp $ 20 * $DragonFly: src/sys/kern/sys_pipe.c,v 1.50 2008/09/09 04:06:13 dillon Exp $ 21 */ 22 23 /* 24 * This file contains a high-performance replacement for the socket-based 25 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 26 * all features of sockets, but does do everything that pipes normally 27 * do. 28 */ 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/kernel.h> 32 #include <sys/proc.h> 33 #include <sys/fcntl.h> 34 #include <sys/file.h> 35 #include <sys/filedesc.h> 36 #include <sys/filio.h> 37 #include <sys/ttycom.h> 38 #include <sys/stat.h> 39 #include <sys/poll.h> 40 #include <sys/select.h> 41 #include <sys/signalvar.h> 42 #include <sys/sysproto.h> 43 #include <sys/pipe.h> 44 #include <sys/vnode.h> 45 #include <sys/uio.h> 46 #include <sys/event.h> 47 #include <sys/globaldata.h> 48 #include <sys/module.h> 49 #include <sys/malloc.h> 50 #include <sys/sysctl.h> 51 #include <sys/socket.h> 52 53 #include <vm/vm.h> 54 #include <vm/vm_param.h> 55 #include <sys/lock.h> 56 #include <vm/vm_object.h> 57 #include <vm/vm_kern.h> 58 #include <vm/vm_extern.h> 59 #include <vm/pmap.h> 60 #include <vm/vm_map.h> 61 #include <vm/vm_page.h> 62 #include <vm/vm_zone.h> 63 64 #include <sys/file2.h> 65 66 #include <machine/cpufunc.h> 67 68 /* 69 * interfaces to the outside world 70 */ 71 static int pipe_read (struct file *fp, struct uio *uio, 72 struct ucred *cred, int flags); 73 static int pipe_write (struct file *fp, struct uio *uio, 74 struct ucred *cred, int flags); 75 static int pipe_close (struct file *fp); 76 static int pipe_shutdown (struct file *fp, int how); 77 static int pipe_poll (struct file *fp, int events, struct ucred *cred); 78 static int pipe_kqfilter (struct file *fp, struct knote *kn); 79 static int pipe_stat (struct file *fp, struct stat *sb, struct ucred *cred); 80 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, struct ucred *cred); 81 82 static struct fileops pipeops = { 83 .fo_read = pipe_read, 84 .fo_write = pipe_write, 85 .fo_ioctl = pipe_ioctl, 86 .fo_poll = pipe_poll, 87 .fo_kqfilter = pipe_kqfilter, 88 .fo_stat = pipe_stat, 89 .fo_close = pipe_close, 90 .fo_shutdown = pipe_shutdown 91 }; 92 93 static void filt_pipedetach(struct knote *kn); 94 static int filt_piperead(struct knote *kn, long hint); 95 static int filt_pipewrite(struct knote *kn, long hint); 96 97 static struct filterops pipe_rfiltops = 98 { 1, NULL, filt_pipedetach, filt_piperead }; 99 static struct filterops pipe_wfiltops = 100 { 1, NULL, filt_pipedetach, filt_pipewrite }; 101 102 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures"); 103 104 /* 105 * Default pipe buffer size(s), this can be kind-of large now because pipe 106 * space is pageable. The pipe code will try to maintain locality of 107 * reference for performance reasons, so small amounts of outstanding I/O 108 * will not wipe the cache. 109 */ 110 #define MINPIPESIZE (PIPE_SIZE/3) 111 #define MAXPIPESIZE (2*PIPE_SIZE/3) 112 113 /* 114 * Limit the number of "big" pipes 115 */ 116 #define LIMITBIGPIPES 64 117 #define PIPEQ_MAX_CACHE 16 /* per-cpu pipe structure cache */ 118 119 static int pipe_maxbig = LIMITBIGPIPES; 120 static int pipe_maxcache = PIPEQ_MAX_CACHE; 121 static int pipe_bigcount; 122 static int pipe_nbig; 123 static int pipe_bcache_alloc; 124 static int pipe_bkmem_alloc; 125 static int pipe_rblocked_count; 126 static int pipe_wblocked_count; 127 128 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation"); 129 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig, 130 CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated"); 131 SYSCTL_INT(_kern_pipe, OID_AUTO, bigcount, 132 CTLFLAG_RW, &pipe_bigcount, 0, "number of times pipe expanded"); 133 SYSCTL_INT(_kern_pipe, OID_AUTO, rblocked, 134 CTLFLAG_RW, &pipe_rblocked_count, 0, "number of times pipe expanded"); 135 SYSCTL_INT(_kern_pipe, OID_AUTO, wblocked, 136 CTLFLAG_RW, &pipe_wblocked_count, 0, "number of times pipe expanded"); 137 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache, 138 CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu"); 139 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig, 140 CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes"); 141 #ifdef SMP 142 static int pipe_delay = 5000; /* 5uS default */ 143 SYSCTL_INT(_kern_pipe, OID_AUTO, delay, 144 CTLFLAG_RW, &pipe_delay, 0, "SMP delay optimization in ns"); 145 static int pipe_mpsafe = 1; 146 SYSCTL_INT(_kern_pipe, OID_AUTO, mpsafe, 147 CTLFLAG_RW, &pipe_mpsafe, 0, ""); 148 #endif 149 #if !defined(NO_PIPE_SYSCTL_STATS) 150 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc, 151 CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache"); 152 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc, 153 CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem"); 154 #endif 155 156 static void pipeclose (struct pipe *cpipe); 157 static void pipe_free_kmem (struct pipe *cpipe); 158 static int pipe_create (struct pipe **cpipep); 159 static __inline void pipeselwakeup (struct pipe *cpipe); 160 static int pipespace (struct pipe *cpipe, int size); 161 162 static __inline void 163 pipeselwakeup(struct pipe *cpipe) 164 { 165 if (cpipe->pipe_state & PIPE_SEL) { 166 get_mplock(); 167 cpipe->pipe_state &= ~PIPE_SEL; 168 selwakeup(&cpipe->pipe_sel); 169 rel_mplock(); 170 } 171 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) { 172 get_mplock(); 173 pgsigio(cpipe->pipe_sigio, SIGIO, 0); 174 rel_mplock(); 175 } 176 if (SLIST_FIRST(&cpipe->pipe_sel.si_note)) { 177 get_mplock(); 178 KNOTE(&cpipe->pipe_sel.si_note, 0); 179 rel_mplock(); 180 } 181 } 182 183 /* 184 * These routines are called before and after a UIO. The UIO 185 * may block, causing our held tokens to be lost temporarily. 186 * 187 * We use these routines to serialize reads against other reads 188 * and writes against other writes. 189 * 190 * The read token is held on entry so *ipp does not race. 191 */ 192 static __inline int 193 pipe_start_uio(struct pipe *cpipe, int *ipp) 194 { 195 int error; 196 197 while (*ipp) { 198 *ipp = -1; 199 error = tsleep(ipp, PCATCH, "pipexx", 0); 200 if (error) 201 return (error); 202 } 203 *ipp = 1; 204 return (0); 205 } 206 207 static __inline void 208 pipe_end_uio(struct pipe *cpipe, int *ipp) 209 { 210 if (*ipp < 0) { 211 *ipp = 0; 212 wakeup(ipp); 213 } else { 214 KKASSERT(*ipp > 0); 215 *ipp = 0; 216 } 217 } 218 219 static __inline void 220 pipe_get_mplock(int *save) 221 { 222 #ifdef SMP 223 if (pipe_mpsafe == 0) { 224 get_mplock(); 225 *save = 1; 226 } else 227 #endif 228 { 229 *save = 0; 230 } 231 } 232 233 static __inline void 234 pipe_rel_mplock(int *save) 235 { 236 #ifdef SMP 237 if (*save) 238 rel_mplock(); 239 #endif 240 } 241 242 243 /* 244 * The pipe system call for the DTYPE_PIPE type of pipes 245 * 246 * pipe_ARgs(int dummy) 247 */ 248 249 /* ARGSUSED */ 250 int 251 sys_pipe(struct pipe_args *uap) 252 { 253 struct thread *td = curthread; 254 struct proc *p = td->td_proc; 255 struct file *rf, *wf; 256 struct pipe *rpipe, *wpipe; 257 int fd1, fd2, error; 258 259 KKASSERT(p); 260 261 rpipe = wpipe = NULL; 262 if (pipe_create(&rpipe) || pipe_create(&wpipe)) { 263 pipeclose(rpipe); 264 pipeclose(wpipe); 265 return (ENFILE); 266 } 267 268 error = falloc(p, &rf, &fd1); 269 if (error) { 270 pipeclose(rpipe); 271 pipeclose(wpipe); 272 return (error); 273 } 274 uap->sysmsg_fds[0] = fd1; 275 276 /* 277 * Warning: once we've gotten past allocation of the fd for the 278 * read-side, we can only drop the read side via fdrop() in order 279 * to avoid races against processes which manage to dup() the read 280 * side while we are blocked trying to allocate the write side. 281 */ 282 rf->f_type = DTYPE_PIPE; 283 rf->f_flag = FREAD | FWRITE; 284 rf->f_ops = &pipeops; 285 rf->f_data = rpipe; 286 error = falloc(p, &wf, &fd2); 287 if (error) { 288 fsetfd(p, NULL, fd1); 289 fdrop(rf); 290 /* rpipe has been closed by fdrop(). */ 291 pipeclose(wpipe); 292 return (error); 293 } 294 wf->f_type = DTYPE_PIPE; 295 wf->f_flag = FREAD | FWRITE; 296 wf->f_ops = &pipeops; 297 wf->f_data = wpipe; 298 uap->sysmsg_fds[1] = fd2; 299 300 rpipe->pipe_slock = kmalloc(sizeof(struct lock), 301 M_PIPE, M_WAITOK|M_ZERO); 302 wpipe->pipe_slock = rpipe->pipe_slock; 303 rpipe->pipe_peer = wpipe; 304 wpipe->pipe_peer = rpipe; 305 lockinit(rpipe->pipe_slock, "pipecl", 0, 0); 306 307 /* 308 * Once activated the peer relationship remains valid until 309 * both sides are closed. 310 */ 311 fsetfd(p, rf, fd1); 312 fsetfd(p, wf, fd2); 313 fdrop(rf); 314 fdrop(wf); 315 316 return (0); 317 } 318 319 /* 320 * Allocate kva for pipe circular buffer, the space is pageable 321 * This routine will 'realloc' the size of a pipe safely, if it fails 322 * it will retain the old buffer. 323 * If it fails it will return ENOMEM. 324 */ 325 static int 326 pipespace(struct pipe *cpipe, int size) 327 { 328 struct vm_object *object; 329 caddr_t buffer; 330 int npages, error; 331 332 npages = round_page(size) / PAGE_SIZE; 333 object = cpipe->pipe_buffer.object; 334 335 /* 336 * [re]create the object if necessary and reserve space for it 337 * in the kernel_map. The object and memory are pageable. On 338 * success, free the old resources before assigning the new 339 * ones. 340 */ 341 if (object == NULL || object->size != npages) { 342 get_mplock(); 343 object = vm_object_allocate(OBJT_DEFAULT, npages); 344 buffer = (caddr_t)vm_map_min(&kernel_map); 345 346 error = vm_map_find(&kernel_map, object, 0, 347 (vm_offset_t *)&buffer, size, 348 1, 349 VM_MAPTYPE_NORMAL, 350 VM_PROT_ALL, VM_PROT_ALL, 351 0); 352 353 if (error != KERN_SUCCESS) { 354 vm_object_deallocate(object); 355 rel_mplock(); 356 return (ENOMEM); 357 } 358 pipe_free_kmem(cpipe); 359 rel_mplock(); 360 cpipe->pipe_buffer.object = object; 361 cpipe->pipe_buffer.buffer = buffer; 362 cpipe->pipe_buffer.size = size; 363 ++pipe_bkmem_alloc; 364 } else { 365 ++pipe_bcache_alloc; 366 } 367 cpipe->pipe_buffer.rindex = 0; 368 cpipe->pipe_buffer.windex = 0; 369 return (0); 370 } 371 372 /* 373 * Initialize and allocate VM and memory for pipe, pulling the pipe from 374 * our per-cpu cache if possible. For now make sure it is sized for the 375 * smaller PIPE_SIZE default. 376 */ 377 static int 378 pipe_create(struct pipe **cpipep) 379 { 380 globaldata_t gd = mycpu; 381 struct pipe *cpipe; 382 int error; 383 384 if ((cpipe = gd->gd_pipeq) != NULL) { 385 gd->gd_pipeq = cpipe->pipe_peer; 386 --gd->gd_pipeqcount; 387 cpipe->pipe_peer = NULL; 388 cpipe->pipe_wantwcnt = 0; 389 } else { 390 cpipe = kmalloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO); 391 } 392 *cpipep = cpipe; 393 if ((error = pipespace(cpipe, PIPE_SIZE)) != 0) 394 return (error); 395 vfs_timestamp(&cpipe->pipe_ctime); 396 cpipe->pipe_atime = cpipe->pipe_ctime; 397 cpipe->pipe_mtime = cpipe->pipe_ctime; 398 lwkt_token_init(&cpipe->pipe_rlock); 399 lwkt_token_init(&cpipe->pipe_wlock); 400 return (0); 401 } 402 403 /* 404 * MPALMOSTSAFE (acquires mplock) 405 */ 406 static int 407 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags) 408 { 409 struct pipe *rpipe; 410 int error; 411 int orig_resid; 412 int nread = 0; 413 int nbio; 414 u_int size; /* total bytes available */ 415 u_int nsize; /* total bytes to read */ 416 u_int rindex; /* contiguous bytes available */ 417 int notify_writer; 418 lwkt_tokref rlock; 419 lwkt_tokref wlock; 420 int mpsave; 421 422 /* 423 * Degenerate case 424 */ 425 orig_resid = uio->uio_resid; 426 if (orig_resid == 0) 427 return(0); 428 429 /* 430 * Setup locks, calculate nbio 431 */ 432 pipe_get_mplock(&mpsave); 433 rpipe = (struct pipe *)fp->f_data; 434 lwkt_gettoken(&rlock, &rpipe->pipe_rlock); 435 436 if (fflags & O_FBLOCKING) 437 nbio = 0; 438 else if (fflags & O_FNONBLOCKING) 439 nbio = 1; 440 else if (fp->f_flag & O_NONBLOCK) 441 nbio = 1; 442 else 443 nbio = 0; 444 445 /* 446 * Reads are serialized. Note howeverthat pipe_buffer.buffer and 447 * pipe_buffer.size can change out from under us when the number 448 * of bytes in the buffer are zero due to the write-side doing a 449 * pipespace(). 450 */ 451 error = pipe_start_uio(rpipe, &rpipe->pipe_rip); 452 if (error) { 453 pipe_rel_mplock(&mpsave); 454 lwkt_reltoken(&rlock); 455 return (error); 456 } 457 notify_writer = 0; 458 while (uio->uio_resid) { 459 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 460 cpu_lfence(); 461 if (size) { 462 rindex = rpipe->pipe_buffer.rindex & 463 (rpipe->pipe_buffer.size - 1); 464 nsize = size; 465 if (nsize > rpipe->pipe_buffer.size - rindex) 466 nsize = rpipe->pipe_buffer.size - rindex; 467 if (nsize > (u_int)uio->uio_resid) 468 nsize = (u_int)uio->uio_resid; 469 470 error = uiomove(&rpipe->pipe_buffer.buffer[rindex], 471 nsize, uio); 472 if (error) 473 break; 474 cpu_mfence(); 475 rpipe->pipe_buffer.rindex += nsize; 476 nread += nsize; 477 478 /* 479 * If the FIFO is still over half full just continue 480 * and do not try to notify the writer yet. 481 */ 482 if (size - nsize >= (rpipe->pipe_buffer.size >> 1)) { 483 notify_writer = 0; 484 continue; 485 } 486 487 /* 488 * When the FIFO is less then half full notify any 489 * waiting writer. WANTW can be checked while 490 * holding just the rlock. 491 */ 492 notify_writer = 1; 493 if ((rpipe->pipe_state & PIPE_WANTW) == 0) 494 continue; 495 } 496 497 /* 498 * If the "write-side" was blocked we wake it up. This code 499 * is reached either when the buffer is completely emptied 500 * or if it becomes more then half-empty. 501 * 502 * Pipe_state can only be modified if both the rlock and 503 * wlock are held. 504 */ 505 if (rpipe->pipe_state & PIPE_WANTW) { 506 lwkt_gettoken(&wlock, &rpipe->pipe_wlock); 507 if (rpipe->pipe_state & PIPE_WANTW) { 508 notify_writer = 0; 509 rpipe->pipe_state &= ~PIPE_WANTW; 510 lwkt_reltoken(&wlock); 511 wakeup(rpipe); 512 } else { 513 lwkt_reltoken(&wlock); 514 } 515 } 516 517 /* 518 * Pick up our copy loop again if the writer sent data to 519 * us while we were messing around. 520 * 521 * On a SMP box poll up to pipe_delay nanoseconds for new 522 * data. Typically a value of 2000 to 4000 is sufficient 523 * to eradicate most IPIs/tsleeps/wakeups when a pipe 524 * is used for synchronous communications with small packets, 525 * and 8000 or so (8uS) will pipeline large buffer xfers 526 * between cpus over a pipe. 527 * 528 * For synchronous communications a hit means doing a 529 * full Awrite-Bread-Bwrite-Aread cycle in less then 2uS, 530 * where as miss requiring a tsleep/wakeup sequence 531 * will take 7uS or more. 532 */ 533 if (rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex) 534 continue; 535 536 #if defined(SMP) && defined(_RDTSC_SUPPORTED_) 537 if (pipe_delay) { 538 int64_t tsc_target; 539 int good = 0; 540 541 tsc_target = tsc_get_target(pipe_delay); 542 while (tsc_test_target(tsc_target) == 0) { 543 if (rpipe->pipe_buffer.windex != 544 rpipe->pipe_buffer.rindex) { 545 good = 1; 546 break; 547 } 548 } 549 if (good) 550 continue; 551 } 552 #endif 553 554 /* 555 * Detect EOF condition, do not set error. 556 */ 557 if (rpipe->pipe_state & PIPE_REOF) 558 break; 559 560 /* 561 * Break if some data was read, or if this was a non-blocking 562 * read. 563 */ 564 if (nread > 0) 565 break; 566 567 if (nbio) { 568 error = EAGAIN; 569 break; 570 } 571 572 /* 573 * Last chance, interlock with WANTR. 574 */ 575 lwkt_gettoken(&wlock, &rpipe->pipe_wlock); 576 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 577 if (size) { 578 lwkt_reltoken(&wlock); 579 continue; 580 } 581 582 /* 583 * If there is no more to read in the pipe, reset its 584 * pointers to the beginning. This improves cache hit 585 * stats. 586 * 587 * We need both locks to modify both pointers, and there 588 * must also not be a write in progress or the uiomove() 589 * in the write might block and temporarily release 590 * its wlock, then reacquire and update windex. We are 591 * only serialized against reads, not writes. 592 * 593 * XXX should we even bother resetting the indices? It 594 * might actually be more cache efficient not to. 595 */ 596 if (rpipe->pipe_buffer.rindex == rpipe->pipe_buffer.windex && 597 rpipe->pipe_wip == 0) { 598 rpipe->pipe_buffer.rindex = 0; 599 rpipe->pipe_buffer.windex = 0; 600 } 601 602 /* 603 * Wait for more data. 604 * 605 * Pipe_state can only be set if both the rlock and wlock 606 * are held. 607 */ 608 rpipe->pipe_state |= PIPE_WANTR; 609 tsleep_interlock(rpipe, PCATCH); 610 lwkt_reltoken(&wlock); 611 error = tsleep(rpipe, PCATCH | PINTERLOCKED, "piperd", 0); 612 ++pipe_rblocked_count; 613 if (error) 614 break; 615 } 616 pipe_end_uio(rpipe, &rpipe->pipe_rip); 617 618 /* 619 * Uptime last access time 620 */ 621 if (error == 0 && nread) 622 vfs_timestamp(&rpipe->pipe_atime); 623 624 /* 625 * If we drained the FIFO more then half way then handle 626 * write blocking hysteresis. 627 * 628 * Note that PIPE_WANTW cannot be set by the writer without 629 * it holding both rlock and wlock, so we can test it 630 * while holding just rlock. 631 */ 632 if (notify_writer) { 633 if (rpipe->pipe_state & PIPE_WANTW) { 634 lwkt_gettoken(&wlock, &rpipe->pipe_wlock); 635 if (rpipe->pipe_state & PIPE_WANTW) { 636 rpipe->pipe_state &= ~PIPE_WANTW; 637 lwkt_reltoken(&wlock); 638 wakeup(rpipe); 639 } else { 640 lwkt_reltoken(&wlock); 641 } 642 } 643 } 644 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 645 lwkt_reltoken(&rlock); 646 647 /* 648 * If enough space is available in buffer then wakeup sel writers? 649 */ 650 if ((rpipe->pipe_buffer.size - size) >= PIPE_BUF) 651 pipeselwakeup(rpipe); 652 pipe_rel_mplock(&mpsave); 653 return (error); 654 } 655 656 /* 657 * MPALMOSTSAFE - acquires mplock 658 */ 659 static int 660 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags) 661 { 662 int error; 663 int orig_resid; 664 int nbio; 665 struct pipe *wpipe, *rpipe; 666 lwkt_tokref rlock; 667 lwkt_tokref wlock; 668 u_int windex; 669 u_int space; 670 u_int wcount; 671 int mpsave; 672 673 pipe_get_mplock(&mpsave); 674 675 /* 676 * Writes go to the peer. The peer will always exist. 677 */ 678 rpipe = (struct pipe *) fp->f_data; 679 wpipe = rpipe->pipe_peer; 680 lwkt_gettoken(&wlock, &wpipe->pipe_wlock); 681 if (wpipe->pipe_state & PIPE_WEOF) { 682 pipe_rel_mplock(&mpsave); 683 lwkt_reltoken(&wlock); 684 return (EPIPE); 685 } 686 687 /* 688 * Degenerate case (EPIPE takes prec) 689 */ 690 if (uio->uio_resid == 0) { 691 pipe_rel_mplock(&mpsave); 692 lwkt_reltoken(&wlock); 693 return(0); 694 } 695 696 /* 697 * Writes are serialized (start_uio must be called with wlock) 698 */ 699 error = pipe_start_uio(wpipe, &wpipe->pipe_wip); 700 if (error) { 701 pipe_rel_mplock(&mpsave); 702 lwkt_reltoken(&wlock); 703 return (error); 704 } 705 706 if (fflags & O_FBLOCKING) 707 nbio = 0; 708 else if (fflags & O_FNONBLOCKING) 709 nbio = 1; 710 else if (fp->f_flag & O_NONBLOCK) 711 nbio = 1; 712 else 713 nbio = 0; 714 715 /* 716 * If it is advantageous to resize the pipe buffer, do 717 * so. We are write-serialized so we can block safely. 718 */ 719 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) && 720 (pipe_nbig < pipe_maxbig) && 721 wpipe->pipe_wantwcnt > 4 && 722 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) { 723 /* 724 * Recheck after lock. 725 */ 726 lwkt_gettoken(&rlock, &wpipe->pipe_rlock); 727 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) && 728 (pipe_nbig < pipe_maxbig) && 729 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) { 730 atomic_add_int(&pipe_nbig, 1); 731 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) 732 ++pipe_bigcount; 733 else 734 atomic_subtract_int(&pipe_nbig, 1); 735 } 736 lwkt_reltoken(&rlock); 737 } 738 739 orig_resid = uio->uio_resid; 740 wcount = 0; 741 742 while (uio->uio_resid) { 743 if (wpipe->pipe_state & PIPE_WEOF) { 744 error = EPIPE; 745 break; 746 } 747 748 windex = wpipe->pipe_buffer.windex & 749 (wpipe->pipe_buffer.size - 1); 750 space = wpipe->pipe_buffer.size - 751 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex); 752 cpu_lfence(); 753 754 /* Writes of size <= PIPE_BUF must be atomic. */ 755 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 756 space = 0; 757 758 /* 759 * Write to fill, read size handles write hysteresis. Also 760 * additional restrictions can cause select-based non-blocking 761 * writes to spin. 762 */ 763 if (space > 0) { 764 u_int segsize; 765 766 /* 767 * Transfer size is minimum of uio transfer 768 * and free space in pipe buffer. 769 * 770 * Limit each uiocopy to no more then PIPE_SIZE 771 * so we can keep the gravy train going on a 772 * SMP box. This doubles the performance for 773 * write sizes > 16K. Otherwise large writes 774 * wind up doing an inefficient synchronous 775 * ping-pong. 776 */ 777 if (space > (u_int)uio->uio_resid) 778 space = (u_int)uio->uio_resid; 779 if (space > PIPE_SIZE) 780 space = PIPE_SIZE; 781 782 /* 783 * First segment to transfer is minimum of 784 * transfer size and contiguous space in 785 * pipe buffer. If first segment to transfer 786 * is less than the transfer size, we've got 787 * a wraparound in the buffer. 788 */ 789 segsize = wpipe->pipe_buffer.size - windex; 790 if (segsize > space) 791 segsize = space; 792 793 #ifdef SMP 794 /* 795 * If this is the first loop and the reader is 796 * blocked, do a preemptive wakeup of the reader. 797 * 798 * On SMP the IPI latency plus the wlock interlock 799 * on the reader side is the fastest way to get the 800 * reader going. (The scheduler will hard loop on 801 * lock tokens). 802 * 803 * NOTE: We can't clear WANTR here without acquiring 804 * the rlock, which we don't want to do here! 805 */ 806 if ((wpipe->pipe_state & PIPE_WANTR) && pipe_mpsafe > 1) 807 wakeup(wpipe); 808 #endif 809 810 /* 811 * Transfer segment, which may include a wrap-around. 812 * Update windex to account for both all in one go 813 * so the reader can read() the data atomically. 814 */ 815 error = uiomove(&wpipe->pipe_buffer.buffer[windex], 816 segsize, uio); 817 if (error == 0 && segsize < space) { 818 segsize = space - segsize; 819 error = uiomove(&wpipe->pipe_buffer.buffer[0], 820 segsize, uio); 821 } 822 if (error) 823 break; 824 cpu_mfence(); 825 wpipe->pipe_buffer.windex += space; 826 wcount += space; 827 continue; 828 } 829 830 /* 831 * We need both the rlock and the wlock to interlock against 832 * the EOF, WANTW, and size checks, and to modify pipe_state. 833 * 834 * These are token locks so we do not have to worry about 835 * deadlocks. 836 */ 837 lwkt_gettoken(&rlock, &wpipe->pipe_rlock); 838 839 /* 840 * If the "read-side" has been blocked, wake it up now 841 * and yield to let it drain synchronously rather 842 * then block. 843 */ 844 if (wpipe->pipe_state & PIPE_WANTR) { 845 wpipe->pipe_state &= ~PIPE_WANTR; 846 wakeup(wpipe); 847 } 848 849 /* 850 * don't block on non-blocking I/O 851 */ 852 if (nbio) { 853 lwkt_reltoken(&rlock); 854 error = EAGAIN; 855 break; 856 } 857 858 /* 859 * re-test whether we have to block in the writer after 860 * acquiring both locks, in case the reader opened up 861 * some space. 862 */ 863 space = wpipe->pipe_buffer.size - 864 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex); 865 cpu_lfence(); 866 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 867 space = 0; 868 869 /* 870 * We have no more space and have something to offer, 871 * wake up select/poll. 872 */ 873 if (space == 0) { 874 wpipe->pipe_state |= PIPE_WANTW; 875 ++wpipe->pipe_wantwcnt; 876 pipeselwakeup(wpipe); 877 if (wpipe->pipe_state & PIPE_WANTW) 878 error = tsleep(wpipe, PCATCH, "pipewr", 0); 879 ++pipe_wblocked_count; 880 } 881 lwkt_reltoken(&rlock); 882 883 /* 884 * Break out if we errored or the read side wants us to go 885 * away. 886 */ 887 if (error) 888 break; 889 if (wpipe->pipe_state & PIPE_WEOF) { 890 error = EPIPE; 891 break; 892 } 893 } 894 pipe_end_uio(wpipe, &wpipe->pipe_wip); 895 896 /* 897 * If we have put any characters in the buffer, we wake up 898 * the reader. 899 * 900 * Both rlock and wlock are required to be able to modify pipe_state. 901 */ 902 if (wpipe->pipe_buffer.windex != wpipe->pipe_buffer.rindex) { 903 if (wpipe->pipe_state & PIPE_WANTR) { 904 lwkt_gettoken(&rlock, &wpipe->pipe_rlock); 905 if (wpipe->pipe_state & PIPE_WANTR) { 906 wpipe->pipe_state &= ~PIPE_WANTR; 907 lwkt_reltoken(&rlock); 908 wakeup(wpipe); 909 } else { 910 lwkt_reltoken(&rlock); 911 } 912 } 913 } 914 915 /* 916 * Don't return EPIPE if I/O was successful 917 */ 918 if ((wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex) && 919 (uio->uio_resid == 0) && 920 (error == EPIPE)) { 921 error = 0; 922 } 923 924 if (error == 0) 925 vfs_timestamp(&wpipe->pipe_mtime); 926 927 /* 928 * We have something to offer, 929 * wake up select/poll. 930 */ 931 space = wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex; 932 lwkt_reltoken(&wlock); 933 if (space) 934 pipeselwakeup(wpipe); 935 pipe_rel_mplock(&mpsave); 936 return (error); 937 } 938 939 /* 940 * MPALMOSTSAFE - acquires mplock 941 * 942 * we implement a very minimal set of ioctls for compatibility with sockets. 943 */ 944 int 945 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct ucred *cred) 946 { 947 struct pipe *mpipe; 948 lwkt_tokref rlock; 949 lwkt_tokref wlock; 950 int error; 951 int mpsave; 952 953 pipe_get_mplock(&mpsave); 954 mpipe = (struct pipe *)fp->f_data; 955 956 lwkt_gettoken(&rlock, &mpipe->pipe_rlock); 957 lwkt_gettoken(&wlock, &mpipe->pipe_wlock); 958 959 switch (cmd) { 960 case FIOASYNC: 961 if (*(int *)data) { 962 mpipe->pipe_state |= PIPE_ASYNC; 963 } else { 964 mpipe->pipe_state &= ~PIPE_ASYNC; 965 } 966 error = 0; 967 break; 968 case FIONREAD: 969 *(int *)data = mpipe->pipe_buffer.windex - 970 mpipe->pipe_buffer.rindex; 971 error = 0; 972 break; 973 case FIOSETOWN: 974 get_mplock(); 975 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 976 rel_mplock(); 977 break; 978 case FIOGETOWN: 979 *(int *)data = fgetown(mpipe->pipe_sigio); 980 error = 0; 981 break; 982 case TIOCSPGRP: 983 /* This is deprecated, FIOSETOWN should be used instead. */ 984 get_mplock(); 985 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 986 rel_mplock(); 987 break; 988 989 case TIOCGPGRP: 990 /* This is deprecated, FIOGETOWN should be used instead. */ 991 *(int *)data = -fgetown(mpipe->pipe_sigio); 992 error = 0; 993 break; 994 default: 995 error = ENOTTY; 996 break; 997 } 998 lwkt_reltoken(&rlock); 999 lwkt_reltoken(&wlock); 1000 pipe_rel_mplock(&mpsave); 1001 1002 return (error); 1003 } 1004 1005 /* 1006 * MPALMOSTSAFE - acquires mplock 1007 */ 1008 int 1009 pipe_poll(struct file *fp, int events, struct ucred *cred) 1010 { 1011 struct pipe *rpipe; 1012 struct pipe *wpipe; 1013 int revents = 0; 1014 u_int space; 1015 int mpsave; 1016 1017 pipe_get_mplock(&mpsave); 1018 rpipe = (struct pipe *)fp->f_data; 1019 wpipe = rpipe->pipe_peer; 1020 if (events & (POLLIN | POLLRDNORM)) { 1021 if ((rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex) || 1022 (rpipe->pipe_state & PIPE_REOF)) { 1023 revents |= events & (POLLIN | POLLRDNORM); 1024 } 1025 } 1026 1027 if (events & (POLLOUT | POLLWRNORM)) { 1028 if (wpipe == NULL || (wpipe->pipe_state & PIPE_WEOF)) { 1029 revents |= events & (POLLOUT | POLLWRNORM); 1030 } else { 1031 space = wpipe->pipe_buffer.windex - 1032 wpipe->pipe_buffer.rindex; 1033 space = wpipe->pipe_buffer.size - space; 1034 if (space >= PIPE_BUF) 1035 revents |= events & (POLLOUT | POLLWRNORM); 1036 } 1037 } 1038 1039 if ((rpipe->pipe_state & PIPE_REOF) || 1040 (wpipe == NULL) || 1041 (wpipe->pipe_state & PIPE_WEOF)) 1042 revents |= POLLHUP; 1043 1044 if (revents == 0) { 1045 if (events & (POLLIN | POLLRDNORM)) { 1046 selrecord(curthread, &rpipe->pipe_sel); 1047 rpipe->pipe_state |= PIPE_SEL; 1048 } 1049 1050 if (events & (POLLOUT | POLLWRNORM)) { 1051 selrecord(curthread, &wpipe->pipe_sel); 1052 wpipe->pipe_state |= PIPE_SEL; 1053 } 1054 } 1055 pipe_rel_mplock(&mpsave); 1056 return (revents); 1057 } 1058 1059 /* 1060 * MPSAFE 1061 */ 1062 static int 1063 pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred) 1064 { 1065 struct pipe *pipe; 1066 int mpsave; 1067 1068 pipe_get_mplock(&mpsave); 1069 pipe = (struct pipe *)fp->f_data; 1070 1071 bzero((caddr_t)ub, sizeof(*ub)); 1072 ub->st_mode = S_IFIFO; 1073 ub->st_blksize = pipe->pipe_buffer.size; 1074 ub->st_size = pipe->pipe_buffer.windex - pipe->pipe_buffer.rindex; 1075 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1076 ub->st_atimespec = pipe->pipe_atime; 1077 ub->st_mtimespec = pipe->pipe_mtime; 1078 ub->st_ctimespec = pipe->pipe_ctime; 1079 /* 1080 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev, 1081 * st_flags, st_gen. 1082 * XXX (st_dev, st_ino) should be unique. 1083 */ 1084 pipe_rel_mplock(&mpsave); 1085 return (0); 1086 } 1087 1088 /* 1089 * MPALMOSTSAFE - acquires mplock 1090 */ 1091 static int 1092 pipe_close(struct file *fp) 1093 { 1094 struct pipe *cpipe; 1095 1096 get_mplock(); 1097 cpipe = (struct pipe *)fp->f_data; 1098 fp->f_ops = &badfileops; 1099 fp->f_data = NULL; 1100 funsetown(cpipe->pipe_sigio); 1101 pipeclose(cpipe); 1102 rel_mplock(); 1103 return (0); 1104 } 1105 1106 /* 1107 * Shutdown one or both directions of a full-duplex pipe. 1108 * 1109 * MPALMOSTSAFE - acquires mplock 1110 */ 1111 static int 1112 pipe_shutdown(struct file *fp, int how) 1113 { 1114 struct pipe *rpipe; 1115 struct pipe *wpipe; 1116 int error = EPIPE; 1117 lwkt_tokref rpipe_rlock; 1118 lwkt_tokref rpipe_wlock; 1119 lwkt_tokref wpipe_rlock; 1120 lwkt_tokref wpipe_wlock; 1121 int mpsave; 1122 1123 pipe_get_mplock(&mpsave); 1124 rpipe = (struct pipe *)fp->f_data; 1125 wpipe = rpipe->pipe_peer; 1126 1127 /* 1128 * We modify pipe_state on both pipes, which means we need 1129 * all four tokens! 1130 */ 1131 lwkt_gettoken(&rpipe_rlock, &rpipe->pipe_rlock); 1132 lwkt_gettoken(&rpipe_wlock, &rpipe->pipe_wlock); 1133 lwkt_gettoken(&wpipe_rlock, &wpipe->pipe_rlock); 1134 lwkt_gettoken(&wpipe_wlock, &wpipe->pipe_wlock); 1135 1136 switch(how) { 1137 case SHUT_RDWR: 1138 case SHUT_RD: 1139 rpipe->pipe_state |= PIPE_REOF; /* my reads */ 1140 rpipe->pipe_state |= PIPE_WEOF; /* peer writes */ 1141 if (rpipe->pipe_state & PIPE_WANTR) { 1142 rpipe->pipe_state &= ~PIPE_WANTR; 1143 wakeup(rpipe); 1144 } 1145 if (rpipe->pipe_state & PIPE_WANTW) { 1146 rpipe->pipe_state &= ~PIPE_WANTW; 1147 wakeup(rpipe); 1148 } 1149 error = 0; 1150 if (how == SHUT_RD) 1151 break; 1152 /* fall through */ 1153 case SHUT_WR: 1154 wpipe->pipe_state |= PIPE_REOF; /* peer reads */ 1155 wpipe->pipe_state |= PIPE_WEOF; /* my writes */ 1156 if (wpipe->pipe_state & PIPE_WANTR) { 1157 wpipe->pipe_state &= ~PIPE_WANTR; 1158 wakeup(wpipe); 1159 } 1160 if (wpipe->pipe_state & PIPE_WANTW) { 1161 wpipe->pipe_state &= ~PIPE_WANTW; 1162 wakeup(wpipe); 1163 } 1164 error = 0; 1165 break; 1166 } 1167 pipeselwakeup(rpipe); 1168 pipeselwakeup(wpipe); 1169 1170 lwkt_reltoken(&rpipe_rlock); 1171 lwkt_reltoken(&rpipe_wlock); 1172 lwkt_reltoken(&wpipe_rlock); 1173 lwkt_reltoken(&wpipe_wlock); 1174 1175 pipe_rel_mplock(&mpsave); 1176 return (error); 1177 } 1178 1179 static void 1180 pipe_free_kmem(struct pipe *cpipe) 1181 { 1182 if (cpipe->pipe_buffer.buffer != NULL) { 1183 if (cpipe->pipe_buffer.size > PIPE_SIZE) 1184 atomic_subtract_int(&pipe_nbig, 1); 1185 kmem_free(&kernel_map, 1186 (vm_offset_t)cpipe->pipe_buffer.buffer, 1187 cpipe->pipe_buffer.size); 1188 cpipe->pipe_buffer.buffer = NULL; 1189 cpipe->pipe_buffer.object = NULL; 1190 } 1191 } 1192 1193 /* 1194 * Close the pipe. The slock must be held to interlock against simultanious 1195 * closes. The rlock and wlock must be held to adjust the pipe_state. 1196 */ 1197 static void 1198 pipeclose(struct pipe *cpipe) 1199 { 1200 globaldata_t gd; 1201 struct pipe *ppipe; 1202 lwkt_tokref cpipe_rlock; 1203 lwkt_tokref cpipe_wlock; 1204 lwkt_tokref ppipe_rlock; 1205 lwkt_tokref ppipe_wlock; 1206 1207 if (cpipe == NULL) 1208 return; 1209 1210 /* 1211 * The slock may not have been allocated yet (close during 1212 * initialization) 1213 * 1214 * We need both the read and write tokens to modify pipe_state. 1215 */ 1216 if (cpipe->pipe_slock) 1217 lockmgr(cpipe->pipe_slock, LK_EXCLUSIVE); 1218 lwkt_gettoken(&cpipe_rlock, &cpipe->pipe_rlock); 1219 lwkt_gettoken(&cpipe_wlock, &cpipe->pipe_wlock); 1220 1221 /* 1222 * Set our state, wakeup anyone waiting in select, and 1223 * wakeup anyone blocked on our pipe. 1224 */ 1225 cpipe->pipe_state |= PIPE_CLOSED | PIPE_REOF | PIPE_WEOF; 1226 pipeselwakeup(cpipe); 1227 if (cpipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) { 1228 cpipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW); 1229 wakeup(cpipe); 1230 } 1231 1232 /* 1233 * Disconnect from peer. 1234 */ 1235 if ((ppipe = cpipe->pipe_peer) != NULL) { 1236 lwkt_gettoken(&ppipe_rlock, &ppipe->pipe_rlock); 1237 lwkt_gettoken(&ppipe_wlock, &ppipe->pipe_wlock); 1238 ppipe->pipe_state |= PIPE_REOF | PIPE_WEOF; 1239 pipeselwakeup(ppipe); 1240 if (ppipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) { 1241 ppipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW); 1242 wakeup(ppipe); 1243 } 1244 if (SLIST_FIRST(&ppipe->pipe_sel.si_note)) { 1245 get_mplock(); 1246 KNOTE(&ppipe->pipe_sel.si_note, 0); 1247 rel_mplock(); 1248 } 1249 lwkt_reltoken(&ppipe_rlock); 1250 lwkt_reltoken(&ppipe_wlock); 1251 } 1252 1253 /* 1254 * If the peer is also closed we can free resources for both 1255 * sides, otherwise we leave our side intact to deal with any 1256 * races (since we only have the slock). 1257 */ 1258 if (ppipe && (ppipe->pipe_state & PIPE_CLOSED)) { 1259 cpipe->pipe_peer = NULL; 1260 ppipe->pipe_peer = NULL; 1261 ppipe->pipe_slock = NULL; /* we will free the slock */ 1262 pipeclose(ppipe); 1263 ppipe = NULL; 1264 } 1265 1266 lwkt_reltoken(&cpipe_rlock); 1267 lwkt_reltoken(&cpipe_wlock); 1268 if (cpipe->pipe_slock) 1269 lockmgr(cpipe->pipe_slock, LK_RELEASE); 1270 1271 /* 1272 * If we disassociated from our peer we can free resources 1273 */ 1274 if (ppipe == NULL) { 1275 gd = mycpu; 1276 if (cpipe->pipe_slock) { 1277 kfree(cpipe->pipe_slock, M_PIPE); 1278 cpipe->pipe_slock = NULL; 1279 } 1280 if (gd->gd_pipeqcount >= pipe_maxcache || 1281 cpipe->pipe_buffer.size != PIPE_SIZE 1282 ) { 1283 pipe_free_kmem(cpipe); 1284 kfree(cpipe, M_PIPE); 1285 } else { 1286 cpipe->pipe_state = 0; 1287 cpipe->pipe_peer = gd->gd_pipeq; 1288 gd->gd_pipeq = cpipe; 1289 ++gd->gd_pipeqcount; 1290 } 1291 } 1292 } 1293 1294 /* 1295 * MPALMOSTSAFE - acquires mplock 1296 */ 1297 static int 1298 pipe_kqfilter(struct file *fp, struct knote *kn) 1299 { 1300 struct pipe *cpipe; 1301 1302 get_mplock(); 1303 cpipe = (struct pipe *)kn->kn_fp->f_data; 1304 1305 switch (kn->kn_filter) { 1306 case EVFILT_READ: 1307 kn->kn_fop = &pipe_rfiltops; 1308 break; 1309 case EVFILT_WRITE: 1310 kn->kn_fop = &pipe_wfiltops; 1311 cpipe = cpipe->pipe_peer; 1312 if (cpipe == NULL) { 1313 /* other end of pipe has been closed */ 1314 rel_mplock(); 1315 return (EPIPE); 1316 } 1317 break; 1318 default: 1319 return (1); 1320 } 1321 kn->kn_hook = (caddr_t)cpipe; 1322 1323 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext); 1324 rel_mplock(); 1325 return (0); 1326 } 1327 1328 static void 1329 filt_pipedetach(struct knote *kn) 1330 { 1331 struct pipe *cpipe = (struct pipe *)kn->kn_hook; 1332 1333 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext); 1334 } 1335 1336 /*ARGSUSED*/ 1337 static int 1338 filt_piperead(struct knote *kn, long hint) 1339 { 1340 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1341 1342 kn->kn_data = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 1343 1344 /* XXX RACE */ 1345 if (rpipe->pipe_state & PIPE_REOF) { 1346 kn->kn_flags |= EV_EOF; 1347 return (1); 1348 } 1349 return (kn->kn_data > 0); 1350 } 1351 1352 /*ARGSUSED*/ 1353 static int 1354 filt_pipewrite(struct knote *kn, long hint) 1355 { 1356 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1357 struct pipe *wpipe = rpipe->pipe_peer; 1358 u_int32_t space; 1359 1360 /* XXX RACE */ 1361 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_WEOF)) { 1362 kn->kn_data = 0; 1363 kn->kn_flags |= EV_EOF; 1364 return (1); 1365 } 1366 space = wpipe->pipe_buffer.windex - 1367 wpipe->pipe_buffer.rindex; 1368 space = wpipe->pipe_buffer.size - space; 1369 kn->kn_data = space; 1370 return (kn->kn_data >= PIPE_BUF); 1371 } 1372