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 */ 21 22 /* 23 * This file contains a high-performance replacement for the socket-based 24 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 25 * all features of sockets, but does do everything that pipes normally 26 * do. 27 */ 28 #include <sys/param.h> 29 #include <sys/systm.h> 30 #include <sys/kernel.h> 31 #include <sys/proc.h> 32 #include <sys/fcntl.h> 33 #include <sys/file.h> 34 #include <sys/filedesc.h> 35 #include <sys/filio.h> 36 #include <sys/ttycom.h> 37 #include <sys/stat.h> 38 #include <sys/signalvar.h> 39 #include <sys/sysproto.h> 40 #include <sys/pipe.h> 41 #include <sys/vnode.h> 42 #include <sys/uio.h> 43 #include <sys/event.h> 44 #include <sys/globaldata.h> 45 #include <sys/module.h> 46 #include <sys/malloc.h> 47 #include <sys/sysctl.h> 48 #include <sys/socket.h> 49 50 #include <vm/vm.h> 51 #include <vm/vm_param.h> 52 #include <sys/lock.h> 53 #include <vm/vm_object.h> 54 #include <vm/vm_kern.h> 55 #include <vm/vm_extern.h> 56 #include <vm/pmap.h> 57 #include <vm/vm_map.h> 58 #include <vm/vm_page.h> 59 #include <vm/vm_zone.h> 60 61 #include <sys/file2.h> 62 #include <sys/signal2.h> 63 64 #include <machine/cpufunc.h> 65 66 /* 67 * interfaces to the outside world 68 */ 69 static int pipe_read (struct file *fp, struct uio *uio, 70 struct ucred *cred, int flags); 71 static int pipe_write (struct file *fp, struct uio *uio, 72 struct ucred *cred, int flags); 73 static int pipe_close (struct file *fp); 74 static int pipe_shutdown (struct file *fp, int how); 75 static int pipe_kqfilter (struct file *fp, struct knote *kn); 76 static int pipe_stat (struct file *fp, struct stat *sb, struct ucred *cred); 77 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, 78 struct ucred *cred, struct sysmsg *msg); 79 80 static struct fileops pipeops = { 81 .fo_read = pipe_read, 82 .fo_write = pipe_write, 83 .fo_ioctl = pipe_ioctl, 84 .fo_kqfilter = pipe_kqfilter, 85 .fo_stat = pipe_stat, 86 .fo_close = pipe_close, 87 .fo_shutdown = pipe_shutdown 88 }; 89 90 static void filt_pipedetach(struct knote *kn); 91 static int filt_piperead(struct knote *kn, long hint); 92 static int filt_pipewrite(struct knote *kn, long hint); 93 94 static struct filterops pipe_rfiltops = 95 { FILTEROP_ISFD|FILTEROP_MPSAFE, NULL, filt_pipedetach, filt_piperead }; 96 static struct filterops pipe_wfiltops = 97 { FILTEROP_ISFD|FILTEROP_MPSAFE, NULL, filt_pipedetach, filt_pipewrite }; 98 99 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures"); 100 101 /* 102 * Default pipe buffer size(s), this can be kind-of large now because pipe 103 * space is pageable. The pipe code will try to maintain locality of 104 * reference for performance reasons, so small amounts of outstanding I/O 105 * will not wipe the cache. 106 */ 107 #define MINPIPESIZE (PIPE_SIZE/3) 108 #define MAXPIPESIZE (2*PIPE_SIZE/3) 109 110 /* 111 * Limit the number of "big" pipes 112 */ 113 #define LIMITBIGPIPES 64 114 #define PIPEQ_MAX_CACHE 16 /* per-cpu pipe structure cache */ 115 116 static int pipe_maxbig = LIMITBIGPIPES; 117 static int pipe_maxcache = PIPEQ_MAX_CACHE; 118 static int pipe_bigcount; 119 static int pipe_nbig; 120 static int pipe_bcache_alloc; 121 static int pipe_bkmem_alloc; 122 static int pipe_rblocked_count; 123 static int pipe_wblocked_count; 124 125 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation"); 126 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig, 127 CTLFLAG_RD, &pipe_nbig, 0, "number of big pipes allocated"); 128 SYSCTL_INT(_kern_pipe, OID_AUTO, bigcount, 129 CTLFLAG_RW, &pipe_bigcount, 0, "number of times pipe expanded"); 130 SYSCTL_INT(_kern_pipe, OID_AUTO, rblocked, 131 CTLFLAG_RW, &pipe_rblocked_count, 0, "number of times pipe expanded"); 132 SYSCTL_INT(_kern_pipe, OID_AUTO, wblocked, 133 CTLFLAG_RW, &pipe_wblocked_count, 0, "number of times pipe expanded"); 134 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache, 135 CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu"); 136 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig, 137 CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes"); 138 static int pipe_delay = 5000; /* 5uS default */ 139 SYSCTL_INT(_kern_pipe, OID_AUTO, delay, 140 CTLFLAG_RW, &pipe_delay, 0, "SMP delay optimization in ns"); 141 #if !defined(NO_PIPE_SYSCTL_STATS) 142 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc, 143 CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache"); 144 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc, 145 CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem"); 146 #endif 147 148 /* 149 * Auto-size pipe cache to reduce kmem allocations and frees. 150 */ 151 static 152 void 153 pipeinit(void *dummy) 154 { 155 size_t mbytes = kmem_lim_size(); 156 157 if (pipe_maxbig == LIMITBIGPIPES) { 158 if (mbytes >= 7 * 1024) 159 pipe_maxbig *= 2; 160 if (mbytes >= 15 * 1024) 161 pipe_maxbig *= 2; 162 } 163 if (pipe_maxcache == PIPEQ_MAX_CACHE) { 164 if (mbytes >= 7 * 1024) 165 pipe_maxcache *= 2; 166 if (mbytes >= 15 * 1024) 167 pipe_maxcache *= 2; 168 } 169 } 170 SYSINIT(kmem, SI_BOOT2_MACHDEP, SI_ORDER_ANY, pipeinit, NULL); 171 172 static void pipeclose (struct pipe *cpipe); 173 static void pipe_free_kmem (struct pipe *cpipe); 174 static int pipe_create (struct pipe **cpipep); 175 static int pipespace (struct pipe *cpipe, int size); 176 177 static __inline void 178 pipewakeup(struct pipe *cpipe, int dosigio) 179 { 180 if (dosigio && (cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) { 181 lwkt_gettoken(&sigio_token); 182 pgsigio(cpipe->pipe_sigio, SIGIO, 0); 183 lwkt_reltoken(&sigio_token); 184 } 185 KNOTE(&cpipe->pipe_kq.ki_note, 0); 186 } 187 188 /* 189 * These routines are called before and after a UIO. The UIO 190 * may block, causing our held tokens to be lost temporarily. 191 * 192 * We use these routines to serialize reads against other reads 193 * and writes against other writes. 194 * 195 * The read token is held on entry so *ipp does not race. 196 */ 197 static __inline int 198 pipe_start_uio(struct pipe *cpipe, int *ipp) 199 { 200 int error; 201 202 while (*ipp) { 203 *ipp = -1; 204 error = tsleep(ipp, PCATCH, "pipexx", 0); 205 if (error) 206 return (error); 207 } 208 *ipp = 1; 209 return (0); 210 } 211 212 static __inline void 213 pipe_end_uio(struct pipe *cpipe, int *ipp) 214 { 215 if (*ipp < 0) { 216 *ipp = 0; 217 wakeup(ipp); 218 } else { 219 KKASSERT(*ipp > 0); 220 *ipp = 0; 221 } 222 } 223 224 /* 225 * The pipe system call for the DTYPE_PIPE type of pipes 226 * 227 * pipe_args(int dummy) 228 * 229 * MPSAFE 230 */ 231 int 232 sys_pipe(struct pipe_args *uap) 233 { 234 struct thread *td = curthread; 235 struct filedesc *fdp = td->td_proc->p_fd; 236 struct file *rf, *wf; 237 struct pipe *rpipe, *wpipe; 238 int fd1, fd2, error; 239 240 rpipe = wpipe = NULL; 241 if (pipe_create(&rpipe) || pipe_create(&wpipe)) { 242 pipeclose(rpipe); 243 pipeclose(wpipe); 244 return (ENFILE); 245 } 246 247 error = falloc(td->td_lwp, &rf, &fd1); 248 if (error) { 249 pipeclose(rpipe); 250 pipeclose(wpipe); 251 return (error); 252 } 253 uap->sysmsg_fds[0] = fd1; 254 255 /* 256 * Warning: once we've gotten past allocation of the fd for the 257 * read-side, we can only drop the read side via fdrop() in order 258 * to avoid races against processes which manage to dup() the read 259 * side while we are blocked trying to allocate the write side. 260 */ 261 rf->f_type = DTYPE_PIPE; 262 rf->f_flag = FREAD | FWRITE; 263 rf->f_ops = &pipeops; 264 rf->f_data = rpipe; 265 error = falloc(td->td_lwp, &wf, &fd2); 266 if (error) { 267 fsetfd(fdp, NULL, fd1); 268 fdrop(rf); 269 /* rpipe has been closed by fdrop(). */ 270 pipeclose(wpipe); 271 return (error); 272 } 273 wf->f_type = DTYPE_PIPE; 274 wf->f_flag = FREAD | FWRITE; 275 wf->f_ops = &pipeops; 276 wf->f_data = wpipe; 277 uap->sysmsg_fds[1] = fd2; 278 279 rpipe->pipe_slock = kmalloc(sizeof(struct lock), 280 M_PIPE, M_WAITOK|M_ZERO); 281 wpipe->pipe_slock = rpipe->pipe_slock; 282 rpipe->pipe_peer = wpipe; 283 wpipe->pipe_peer = rpipe; 284 lockinit(rpipe->pipe_slock, "pipecl", 0, 0); 285 286 /* 287 * Once activated the peer relationship remains valid until 288 * both sides are closed. 289 */ 290 fsetfd(fdp, rf, fd1); 291 fsetfd(fdp, wf, fd2); 292 fdrop(rf); 293 fdrop(wf); 294 295 return (0); 296 } 297 298 /* 299 * Allocate kva for pipe circular buffer, the space is pageable 300 * This routine will 'realloc' the size of a pipe safely, if it fails 301 * it will retain the old buffer. 302 * If it fails it will return ENOMEM. 303 */ 304 static int 305 pipespace(struct pipe *cpipe, int size) 306 { 307 struct vm_object *object; 308 caddr_t buffer; 309 int npages, error; 310 311 npages = round_page(size) / PAGE_SIZE; 312 object = cpipe->pipe_buffer.object; 313 314 /* 315 * [re]create the object if necessary and reserve space for it 316 * in the kernel_map. The object and memory are pageable. On 317 * success, free the old resources before assigning the new 318 * ones. 319 */ 320 if (object == NULL || object->size != npages) { 321 object = vm_object_allocate(OBJT_DEFAULT, npages); 322 buffer = (caddr_t)vm_map_min(&kernel_map); 323 324 error = vm_map_find(&kernel_map, object, NULL, 325 0, (vm_offset_t *)&buffer, size, 326 PAGE_SIZE, 327 1, VM_MAPTYPE_NORMAL, 328 VM_PROT_ALL, VM_PROT_ALL, 0); 329 330 if (error != KERN_SUCCESS) { 331 vm_object_deallocate(object); 332 return (ENOMEM); 333 } 334 pipe_free_kmem(cpipe); 335 cpipe->pipe_buffer.object = object; 336 cpipe->pipe_buffer.buffer = buffer; 337 cpipe->pipe_buffer.size = size; 338 ++pipe_bkmem_alloc; 339 } else { 340 ++pipe_bcache_alloc; 341 } 342 cpipe->pipe_buffer.rindex = 0; 343 cpipe->pipe_buffer.windex = 0; 344 return (0); 345 } 346 347 /* 348 * Initialize and allocate VM and memory for pipe, pulling the pipe from 349 * our per-cpu cache if possible. For now make sure it is sized for the 350 * smaller PIPE_SIZE default. 351 */ 352 static int 353 pipe_create(struct pipe **cpipep) 354 { 355 globaldata_t gd = mycpu; 356 struct pipe *cpipe; 357 int error; 358 359 if ((cpipe = gd->gd_pipeq) != NULL) { 360 gd->gd_pipeq = cpipe->pipe_peer; 361 --gd->gd_pipeqcount; 362 cpipe->pipe_peer = NULL; 363 cpipe->pipe_wantwcnt = 0; 364 } else { 365 cpipe = kmalloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO); 366 } 367 *cpipep = cpipe; 368 if ((error = pipespace(cpipe, PIPE_SIZE)) != 0) 369 return (error); 370 vfs_timestamp(&cpipe->pipe_ctime); 371 cpipe->pipe_atime = cpipe->pipe_ctime; 372 cpipe->pipe_mtime = cpipe->pipe_ctime; 373 lwkt_token_init(&cpipe->pipe_rlock, "piper"); 374 lwkt_token_init(&cpipe->pipe_wlock, "pipew"); 375 return (0); 376 } 377 378 static int 379 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags) 380 { 381 struct pipe *rpipe; 382 struct pipe *wpipe; 383 int error; 384 size_t nread = 0; 385 int nbio; 386 u_int size; /* total bytes available */ 387 u_int nsize; /* total bytes to read */ 388 u_int rindex; /* contiguous bytes available */ 389 int notify_writer; 390 int bigread; 391 int bigcount; 392 393 atomic_set_int(&curthread->td_mpflags, TDF_MP_BATCH_DEMARC); 394 395 if (uio->uio_resid == 0) 396 return(0); 397 398 /* 399 * Setup locks, calculate nbio 400 */ 401 rpipe = (struct pipe *)fp->f_data; 402 wpipe = rpipe->pipe_peer; 403 lwkt_gettoken(&rpipe->pipe_rlock); 404 405 if (fflags & O_FBLOCKING) 406 nbio = 0; 407 else if (fflags & O_FNONBLOCKING) 408 nbio = 1; 409 else if (fp->f_flag & O_NONBLOCK) 410 nbio = 1; 411 else 412 nbio = 0; 413 414 /* 415 * Reads are serialized. Note however that pipe_buffer.buffer and 416 * pipe_buffer.size can change out from under us when the number 417 * of bytes in the buffer are zero due to the write-side doing a 418 * pipespace(). 419 */ 420 error = pipe_start_uio(rpipe, &rpipe->pipe_rip); 421 if (error) { 422 lwkt_reltoken(&rpipe->pipe_rlock); 423 return (error); 424 } 425 notify_writer = 0; 426 427 bigread = (uio->uio_resid > 10 * 1024 * 1024); 428 bigcount = 10; 429 430 while (uio->uio_resid) { 431 /* 432 * Don't hog the cpu. 433 */ 434 if (bigread && --bigcount == 0) { 435 lwkt_user_yield(); 436 bigcount = 10; 437 if (CURSIG(curthread->td_lwp)) { 438 error = EINTR; 439 break; 440 } 441 } 442 443 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 444 cpu_lfence(); 445 if (size) { 446 rindex = rpipe->pipe_buffer.rindex & 447 (rpipe->pipe_buffer.size - 1); 448 nsize = size; 449 if (nsize > rpipe->pipe_buffer.size - rindex) 450 nsize = rpipe->pipe_buffer.size - rindex; 451 nsize = szmin(nsize, uio->uio_resid); 452 453 error = uiomove(&rpipe->pipe_buffer.buffer[rindex], 454 nsize, uio); 455 if (error) 456 break; 457 cpu_mfence(); 458 rpipe->pipe_buffer.rindex += nsize; 459 nread += nsize; 460 461 /* 462 * If the FIFO is still over half full just continue 463 * and do not try to notify the writer yet. 464 */ 465 if (size - nsize >= (rpipe->pipe_buffer.size >> 1)) { 466 notify_writer = 0; 467 continue; 468 } 469 470 /* 471 * When the FIFO is less then half full notify any 472 * waiting writer. WANTW can be checked while 473 * holding just the rlock. 474 */ 475 notify_writer = 1; 476 if ((rpipe->pipe_state & PIPE_WANTW) == 0) 477 continue; 478 } 479 480 /* 481 * If the "write-side" was blocked we wake it up. This code 482 * is reached either when the buffer is completely emptied 483 * or if it becomes more then half-empty. 484 * 485 * Pipe_state can only be modified if both the rlock and 486 * wlock are held. 487 */ 488 if (rpipe->pipe_state & PIPE_WANTW) { 489 lwkt_gettoken(&rpipe->pipe_wlock); 490 if (rpipe->pipe_state & PIPE_WANTW) { 491 rpipe->pipe_state &= ~PIPE_WANTW; 492 lwkt_reltoken(&rpipe->pipe_wlock); 493 wakeup(rpipe); 494 } else { 495 lwkt_reltoken(&rpipe->pipe_wlock); 496 } 497 } 498 499 /* 500 * Pick up our copy loop again if the writer sent data to 501 * us while we were messing around. 502 * 503 * On a SMP box poll up to pipe_delay nanoseconds for new 504 * data. Typically a value of 2000 to 4000 is sufficient 505 * to eradicate most IPIs/tsleeps/wakeups when a pipe 506 * is used for synchronous communications with small packets, 507 * and 8000 or so (8uS) will pipeline large buffer xfers 508 * between cpus over a pipe. 509 * 510 * For synchronous communications a hit means doing a 511 * full Awrite-Bread-Bwrite-Aread cycle in less then 2uS, 512 * where as miss requiring a tsleep/wakeup sequence 513 * will take 7uS or more. 514 */ 515 if (rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex) 516 continue; 517 518 #ifdef _RDTSC_SUPPORTED_ 519 if (pipe_delay) { 520 int64_t tsc_target; 521 int good = 0; 522 523 tsc_target = tsc_get_target(pipe_delay); 524 while (tsc_test_target(tsc_target) == 0) { 525 if (rpipe->pipe_buffer.windex != 526 rpipe->pipe_buffer.rindex) { 527 good = 1; 528 break; 529 } 530 } 531 if (good) 532 continue; 533 } 534 #endif 535 536 /* 537 * Detect EOF condition, do not set error. 538 */ 539 if (rpipe->pipe_state & PIPE_REOF) 540 break; 541 542 /* 543 * Break if some data was read, or if this was a non-blocking 544 * read. 545 */ 546 if (nread > 0) 547 break; 548 549 if (nbio) { 550 error = EAGAIN; 551 break; 552 } 553 554 /* 555 * Last chance, interlock with WANTR. 556 */ 557 lwkt_gettoken(&rpipe->pipe_wlock); 558 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 559 if (size) { 560 lwkt_reltoken(&rpipe->pipe_wlock); 561 continue; 562 } 563 564 /* 565 * Retest EOF - acquiring a new token can temporarily release 566 * tokens already held. 567 */ 568 if (rpipe->pipe_state & PIPE_REOF) { 569 lwkt_reltoken(&rpipe->pipe_wlock); 570 break; 571 } 572 573 /* 574 * If there is no more to read in the pipe, reset its 575 * pointers to the beginning. This improves cache hit 576 * stats. 577 * 578 * We need both locks to modify both pointers, and there 579 * must also not be a write in progress or the uiomove() 580 * in the write might block and temporarily release 581 * its wlock, then reacquire and update windex. We are 582 * only serialized against reads, not writes. 583 * 584 * XXX should we even bother resetting the indices? It 585 * might actually be more cache efficient not to. 586 */ 587 if (rpipe->pipe_buffer.rindex == rpipe->pipe_buffer.windex && 588 rpipe->pipe_wip == 0) { 589 rpipe->pipe_buffer.rindex = 0; 590 rpipe->pipe_buffer.windex = 0; 591 } 592 593 /* 594 * Wait for more data. 595 * 596 * Pipe_state can only be set if both the rlock and wlock 597 * are held. 598 */ 599 rpipe->pipe_state |= PIPE_WANTR; 600 tsleep_interlock(rpipe, PCATCH); 601 lwkt_reltoken(&rpipe->pipe_wlock); 602 error = tsleep(rpipe, PCATCH | PINTERLOCKED, "piperd", 0); 603 ++pipe_rblocked_count; 604 if (error) 605 break; 606 } 607 pipe_end_uio(rpipe, &rpipe->pipe_rip); 608 609 /* 610 * Uptime last access time 611 */ 612 if (error == 0 && nread) 613 vfs_timestamp(&rpipe->pipe_atime); 614 615 /* 616 * If we drained the FIFO more then half way then handle 617 * write blocking hysteresis. 618 * 619 * Note that PIPE_WANTW cannot be set by the writer without 620 * it holding both rlock and wlock, so we can test it 621 * while holding just rlock. 622 */ 623 if (notify_writer) { 624 /* 625 * Synchronous blocking is done on the pipe involved 626 */ 627 if (rpipe->pipe_state & PIPE_WANTW) { 628 lwkt_gettoken(&rpipe->pipe_wlock); 629 if (rpipe->pipe_state & PIPE_WANTW) { 630 rpipe->pipe_state &= ~PIPE_WANTW; 631 lwkt_reltoken(&rpipe->pipe_wlock); 632 wakeup(rpipe); 633 } else { 634 lwkt_reltoken(&rpipe->pipe_wlock); 635 } 636 } 637 638 /* 639 * But we may also have to deal with a kqueue which is 640 * stored on the same pipe as its descriptor, so a 641 * EVFILT_WRITE event waiting for our side to drain will 642 * be on the other side. 643 */ 644 lwkt_gettoken(&wpipe->pipe_wlock); 645 pipewakeup(wpipe, 0); 646 lwkt_reltoken(&wpipe->pipe_wlock); 647 } 648 /*size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;*/ 649 lwkt_reltoken(&rpipe->pipe_rlock); 650 651 return (error); 652 } 653 654 static int 655 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags) 656 { 657 int error; 658 int orig_resid; 659 int nbio; 660 struct pipe *wpipe; 661 struct pipe *rpipe; 662 u_int windex; 663 u_int space; 664 u_int wcount; 665 int bigwrite; 666 int bigcount; 667 668 /* 669 * Writes go to the peer. The peer will always exist. 670 */ 671 rpipe = (struct pipe *) fp->f_data; 672 wpipe = rpipe->pipe_peer; 673 lwkt_gettoken(&wpipe->pipe_wlock); 674 if (wpipe->pipe_state & PIPE_WEOF) { 675 lwkt_reltoken(&wpipe->pipe_wlock); 676 return (EPIPE); 677 } 678 679 /* 680 * Degenerate case (EPIPE takes prec) 681 */ 682 if (uio->uio_resid == 0) { 683 lwkt_reltoken(&wpipe->pipe_wlock); 684 return(0); 685 } 686 687 /* 688 * Writes are serialized (start_uio must be called with wlock) 689 */ 690 error = pipe_start_uio(wpipe, &wpipe->pipe_wip); 691 if (error) { 692 lwkt_reltoken(&wpipe->pipe_wlock); 693 return (error); 694 } 695 696 if (fflags & O_FBLOCKING) 697 nbio = 0; 698 else if (fflags & O_FNONBLOCKING) 699 nbio = 1; 700 else if (fp->f_flag & O_NONBLOCK) 701 nbio = 1; 702 else 703 nbio = 0; 704 705 /* 706 * If it is advantageous to resize the pipe buffer, do 707 * so. We are write-serialized so we can block safely. 708 */ 709 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) && 710 (pipe_nbig < pipe_maxbig) && 711 wpipe->pipe_wantwcnt > 4 && 712 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) { 713 /* 714 * Recheck after lock. 715 */ 716 lwkt_gettoken(&wpipe->pipe_rlock); 717 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) && 718 (pipe_nbig < pipe_maxbig) && 719 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) { 720 atomic_add_int(&pipe_nbig, 1); 721 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) 722 ++pipe_bigcount; 723 else 724 atomic_subtract_int(&pipe_nbig, 1); 725 } 726 lwkt_reltoken(&wpipe->pipe_rlock); 727 } 728 729 orig_resid = uio->uio_resid; 730 wcount = 0; 731 732 bigwrite = (uio->uio_resid > 10 * 1024 * 1024); 733 bigcount = 10; 734 735 while (uio->uio_resid) { 736 if (wpipe->pipe_state & PIPE_WEOF) { 737 error = EPIPE; 738 break; 739 } 740 741 /* 742 * Don't hog the cpu. 743 */ 744 if (bigwrite && --bigcount == 0) { 745 lwkt_user_yield(); 746 bigcount = 10; 747 if (CURSIG(curthread->td_lwp)) { 748 error = EINTR; 749 break; 750 } 751 } 752 753 windex = wpipe->pipe_buffer.windex & 754 (wpipe->pipe_buffer.size - 1); 755 space = wpipe->pipe_buffer.size - 756 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex); 757 cpu_lfence(); 758 759 /* Writes of size <= PIPE_BUF must be atomic. */ 760 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 761 space = 0; 762 763 /* 764 * Write to fill, read size handles write hysteresis. Also 765 * additional restrictions can cause select-based non-blocking 766 * writes to spin. 767 */ 768 if (space > 0) { 769 u_int segsize; 770 771 /* 772 * Transfer size is minimum of uio transfer 773 * and free space in pipe buffer. 774 * 775 * Limit each uiocopy to no more then PIPE_SIZE 776 * so we can keep the gravy train going on a 777 * SMP box. This doubles the performance for 778 * write sizes > 16K. Otherwise large writes 779 * wind up doing an inefficient synchronous 780 * ping-pong. 781 */ 782 space = szmin(space, uio->uio_resid); 783 if (space > PIPE_SIZE) 784 space = PIPE_SIZE; 785 786 /* 787 * First segment to transfer is minimum of 788 * transfer size and contiguous space in 789 * pipe buffer. If first segment to transfer 790 * is less than the transfer size, we've got 791 * a wraparound in the buffer. 792 */ 793 segsize = wpipe->pipe_buffer.size - windex; 794 if (segsize > space) 795 segsize = space; 796 797 /* 798 * If this is the first loop and the reader is 799 * blocked, do a preemptive wakeup of the reader. 800 * 801 * On SMP the IPI latency plus the wlock interlock 802 * on the reader side is the fastest way to get the 803 * reader going. (The scheduler will hard loop on 804 * lock tokens). 805 * 806 * NOTE: We can't clear WANTR here without acquiring 807 * the rlock, which we don't want to do here! 808 */ 809 if ((wpipe->pipe_state & PIPE_WANTR)) 810 wakeup(wpipe); 811 812 /* 813 * Transfer segment, which may include a wrap-around. 814 * Update windex to account for both all in one go 815 * so the reader can read() the data atomically. 816 */ 817 error = uiomove(&wpipe->pipe_buffer.buffer[windex], 818 segsize, uio); 819 if (error == 0 && segsize < space) { 820 segsize = space - segsize; 821 error = uiomove(&wpipe->pipe_buffer.buffer[0], 822 segsize, uio); 823 } 824 if (error) 825 break; 826 cpu_mfence(); 827 wpipe->pipe_buffer.windex += space; 828 wcount += space; 829 continue; 830 } 831 832 /* 833 * We need both the rlock and the wlock to interlock against 834 * the EOF, WANTW, and size checks, and to modify pipe_state. 835 * 836 * These are token locks so we do not have to worry about 837 * deadlocks. 838 */ 839 lwkt_gettoken(&wpipe->pipe_rlock); 840 841 /* 842 * If the "read-side" has been blocked, wake it up now 843 * and yield to let it drain synchronously rather 844 * then block. 845 */ 846 if (wpipe->pipe_state & PIPE_WANTR) { 847 wpipe->pipe_state &= ~PIPE_WANTR; 848 wakeup(wpipe); 849 } 850 851 /* 852 * don't block on non-blocking I/O 853 */ 854 if (nbio) { 855 lwkt_reltoken(&wpipe->pipe_rlock); 856 error = EAGAIN; 857 break; 858 } 859 860 /* 861 * re-test whether we have to block in the writer after 862 * acquiring both locks, in case the reader opened up 863 * some space. 864 */ 865 space = wpipe->pipe_buffer.size - 866 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex); 867 cpu_lfence(); 868 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 869 space = 0; 870 871 /* 872 * Retest EOF - acquiring a new token can temporarily release 873 * tokens already held. 874 */ 875 if (wpipe->pipe_state & PIPE_WEOF) { 876 lwkt_reltoken(&wpipe->pipe_rlock); 877 error = EPIPE; 878 break; 879 } 880 881 /* 882 * We have no more space and have something to offer, 883 * wake up select/poll/kq. 884 */ 885 if (space == 0) { 886 wpipe->pipe_state |= PIPE_WANTW; 887 ++wpipe->pipe_wantwcnt; 888 pipewakeup(wpipe, 1); 889 if (wpipe->pipe_state & PIPE_WANTW) 890 error = tsleep(wpipe, PCATCH, "pipewr", 0); 891 ++pipe_wblocked_count; 892 } 893 lwkt_reltoken(&wpipe->pipe_rlock); 894 895 /* 896 * Break out if we errored or the read side wants us to go 897 * away. 898 */ 899 if (error) 900 break; 901 if (wpipe->pipe_state & PIPE_WEOF) { 902 error = EPIPE; 903 break; 904 } 905 } 906 pipe_end_uio(wpipe, &wpipe->pipe_wip); 907 908 /* 909 * If we have put any characters in the buffer, we wake up 910 * the reader. 911 * 912 * Both rlock and wlock are required to be able to modify pipe_state. 913 */ 914 if (wpipe->pipe_buffer.windex != wpipe->pipe_buffer.rindex) { 915 if (wpipe->pipe_state & PIPE_WANTR) { 916 lwkt_gettoken(&wpipe->pipe_rlock); 917 if (wpipe->pipe_state & PIPE_WANTR) { 918 wpipe->pipe_state &= ~PIPE_WANTR; 919 lwkt_reltoken(&wpipe->pipe_rlock); 920 wakeup(wpipe); 921 } else { 922 lwkt_reltoken(&wpipe->pipe_rlock); 923 } 924 } 925 lwkt_gettoken(&wpipe->pipe_rlock); 926 pipewakeup(wpipe, 1); 927 lwkt_reltoken(&wpipe->pipe_rlock); 928 } 929 930 /* 931 * Don't return EPIPE if I/O was successful 932 */ 933 if ((wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex) && 934 (uio->uio_resid == 0) && 935 (error == EPIPE)) { 936 error = 0; 937 } 938 939 if (error == 0) 940 vfs_timestamp(&wpipe->pipe_mtime); 941 942 /* 943 * We have something to offer, 944 * wake up select/poll/kq. 945 */ 946 /*space = wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex;*/ 947 lwkt_reltoken(&wpipe->pipe_wlock); 948 return (error); 949 } 950 951 /* 952 * we implement a very minimal set of ioctls for compatibility with sockets. 953 */ 954 static int 955 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, 956 struct ucred *cred, struct sysmsg *msg) 957 { 958 struct pipe *mpipe; 959 int error; 960 961 mpipe = (struct pipe *)fp->f_data; 962 963 lwkt_gettoken(&mpipe->pipe_rlock); 964 lwkt_gettoken(&mpipe->pipe_wlock); 965 966 switch (cmd) { 967 case FIOASYNC: 968 if (*(int *)data) { 969 mpipe->pipe_state |= PIPE_ASYNC; 970 } else { 971 mpipe->pipe_state &= ~PIPE_ASYNC; 972 } 973 error = 0; 974 break; 975 case FIONREAD: 976 *(int *)data = mpipe->pipe_buffer.windex - 977 mpipe->pipe_buffer.rindex; 978 error = 0; 979 break; 980 case FIOSETOWN: 981 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 982 break; 983 case FIOGETOWN: 984 *(int *)data = fgetown(&mpipe->pipe_sigio); 985 error = 0; 986 break; 987 case TIOCSPGRP: 988 /* This is deprecated, FIOSETOWN should be used instead. */ 989 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 990 break; 991 992 case TIOCGPGRP: 993 /* This is deprecated, FIOGETOWN should be used instead. */ 994 *(int *)data = -fgetown(&mpipe->pipe_sigio); 995 error = 0; 996 break; 997 default: 998 error = ENOTTY; 999 break; 1000 } 1001 lwkt_reltoken(&mpipe->pipe_wlock); 1002 lwkt_reltoken(&mpipe->pipe_rlock); 1003 1004 return (error); 1005 } 1006 1007 /* 1008 * MPSAFE 1009 */ 1010 static int 1011 pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred) 1012 { 1013 struct pipe *pipe; 1014 1015 pipe = (struct pipe *)fp->f_data; 1016 1017 bzero((caddr_t)ub, sizeof(*ub)); 1018 ub->st_mode = S_IFIFO; 1019 ub->st_blksize = pipe->pipe_buffer.size; 1020 ub->st_size = pipe->pipe_buffer.windex - pipe->pipe_buffer.rindex; 1021 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1022 ub->st_atimespec = pipe->pipe_atime; 1023 ub->st_mtimespec = pipe->pipe_mtime; 1024 ub->st_ctimespec = pipe->pipe_ctime; 1025 /* 1026 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev, 1027 * st_flags, st_gen. 1028 * XXX (st_dev, st_ino) should be unique. 1029 */ 1030 return (0); 1031 } 1032 1033 static int 1034 pipe_close(struct file *fp) 1035 { 1036 struct pipe *cpipe; 1037 1038 cpipe = (struct pipe *)fp->f_data; 1039 fp->f_ops = &badfileops; 1040 fp->f_data = NULL; 1041 funsetown(&cpipe->pipe_sigio); 1042 pipeclose(cpipe); 1043 return (0); 1044 } 1045 1046 /* 1047 * Shutdown one or both directions of a full-duplex pipe. 1048 */ 1049 static int 1050 pipe_shutdown(struct file *fp, int how) 1051 { 1052 struct pipe *rpipe; 1053 struct pipe *wpipe; 1054 int error = EPIPE; 1055 1056 rpipe = (struct pipe *)fp->f_data; 1057 wpipe = rpipe->pipe_peer; 1058 1059 /* 1060 * We modify pipe_state on both pipes, which means we need 1061 * all four tokens! 1062 */ 1063 lwkt_gettoken(&rpipe->pipe_rlock); 1064 lwkt_gettoken(&rpipe->pipe_wlock); 1065 lwkt_gettoken(&wpipe->pipe_rlock); 1066 lwkt_gettoken(&wpipe->pipe_wlock); 1067 1068 switch(how) { 1069 case SHUT_RDWR: 1070 case SHUT_RD: 1071 rpipe->pipe_state |= PIPE_REOF; /* my reads */ 1072 rpipe->pipe_state |= PIPE_WEOF; /* peer writes */ 1073 if (rpipe->pipe_state & PIPE_WANTR) { 1074 rpipe->pipe_state &= ~PIPE_WANTR; 1075 wakeup(rpipe); 1076 } 1077 if (rpipe->pipe_state & PIPE_WANTW) { 1078 rpipe->pipe_state &= ~PIPE_WANTW; 1079 wakeup(rpipe); 1080 } 1081 error = 0; 1082 if (how == SHUT_RD) 1083 break; 1084 /* fall through */ 1085 case SHUT_WR: 1086 wpipe->pipe_state |= PIPE_REOF; /* peer reads */ 1087 wpipe->pipe_state |= PIPE_WEOF; /* my writes */ 1088 if (wpipe->pipe_state & PIPE_WANTR) { 1089 wpipe->pipe_state &= ~PIPE_WANTR; 1090 wakeup(wpipe); 1091 } 1092 if (wpipe->pipe_state & PIPE_WANTW) { 1093 wpipe->pipe_state &= ~PIPE_WANTW; 1094 wakeup(wpipe); 1095 } 1096 error = 0; 1097 break; 1098 } 1099 pipewakeup(rpipe, 1); 1100 pipewakeup(wpipe, 1); 1101 1102 lwkt_reltoken(&wpipe->pipe_wlock); 1103 lwkt_reltoken(&wpipe->pipe_rlock); 1104 lwkt_reltoken(&rpipe->pipe_wlock); 1105 lwkt_reltoken(&rpipe->pipe_rlock); 1106 1107 return (error); 1108 } 1109 1110 static void 1111 pipe_free_kmem(struct pipe *cpipe) 1112 { 1113 if (cpipe->pipe_buffer.buffer != NULL) { 1114 if (cpipe->pipe_buffer.size > PIPE_SIZE) 1115 atomic_subtract_int(&pipe_nbig, 1); 1116 kmem_free(&kernel_map, 1117 (vm_offset_t)cpipe->pipe_buffer.buffer, 1118 cpipe->pipe_buffer.size); 1119 cpipe->pipe_buffer.buffer = NULL; 1120 cpipe->pipe_buffer.object = NULL; 1121 } 1122 } 1123 1124 /* 1125 * Close the pipe. The slock must be held to interlock against simultanious 1126 * closes. The rlock and wlock must be held to adjust the pipe_state. 1127 */ 1128 static void 1129 pipeclose(struct pipe *cpipe) 1130 { 1131 globaldata_t gd; 1132 struct pipe *ppipe; 1133 1134 if (cpipe == NULL) 1135 return; 1136 1137 /* 1138 * The slock may not have been allocated yet (close during 1139 * initialization) 1140 * 1141 * We need both the read and write tokens to modify pipe_state. 1142 */ 1143 if (cpipe->pipe_slock) 1144 lockmgr(cpipe->pipe_slock, LK_EXCLUSIVE); 1145 lwkt_gettoken(&cpipe->pipe_rlock); 1146 lwkt_gettoken(&cpipe->pipe_wlock); 1147 1148 /* 1149 * Set our state, wakeup anyone waiting in select/poll/kq, and 1150 * wakeup anyone blocked on our pipe. 1151 */ 1152 cpipe->pipe_state |= PIPE_CLOSED | PIPE_REOF | PIPE_WEOF; 1153 pipewakeup(cpipe, 1); 1154 if (cpipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) { 1155 cpipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW); 1156 wakeup(cpipe); 1157 } 1158 1159 /* 1160 * Disconnect from peer. 1161 */ 1162 if ((ppipe = cpipe->pipe_peer) != NULL) { 1163 lwkt_gettoken(&ppipe->pipe_rlock); 1164 lwkt_gettoken(&ppipe->pipe_wlock); 1165 ppipe->pipe_state |= PIPE_REOF | PIPE_WEOF; 1166 pipewakeup(ppipe, 1); 1167 if (ppipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) { 1168 ppipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW); 1169 wakeup(ppipe); 1170 } 1171 if (SLIST_FIRST(&ppipe->pipe_kq.ki_note)) 1172 KNOTE(&ppipe->pipe_kq.ki_note, 0); 1173 lwkt_reltoken(&ppipe->pipe_wlock); 1174 lwkt_reltoken(&ppipe->pipe_rlock); 1175 } 1176 1177 /* 1178 * If the peer is also closed we can free resources for both 1179 * sides, otherwise we leave our side intact to deal with any 1180 * races (since we only have the slock). 1181 */ 1182 if (ppipe && (ppipe->pipe_state & PIPE_CLOSED)) { 1183 cpipe->pipe_peer = NULL; 1184 ppipe->pipe_peer = NULL; 1185 ppipe->pipe_slock = NULL; /* we will free the slock */ 1186 pipeclose(ppipe); 1187 ppipe = NULL; 1188 } 1189 1190 lwkt_reltoken(&cpipe->pipe_wlock); 1191 lwkt_reltoken(&cpipe->pipe_rlock); 1192 if (cpipe->pipe_slock) 1193 lockmgr(cpipe->pipe_slock, LK_RELEASE); 1194 1195 /* 1196 * If we disassociated from our peer we can free resources 1197 */ 1198 if (ppipe == NULL) { 1199 gd = mycpu; 1200 if (cpipe->pipe_slock) { 1201 kfree(cpipe->pipe_slock, M_PIPE); 1202 cpipe->pipe_slock = NULL; 1203 } 1204 if (gd->gd_pipeqcount >= pipe_maxcache || 1205 cpipe->pipe_buffer.size != PIPE_SIZE 1206 ) { 1207 pipe_free_kmem(cpipe); 1208 kfree(cpipe, M_PIPE); 1209 } else { 1210 cpipe->pipe_state = 0; 1211 cpipe->pipe_peer = gd->gd_pipeq; 1212 gd->gd_pipeq = cpipe; 1213 ++gd->gd_pipeqcount; 1214 } 1215 } 1216 } 1217 1218 static int 1219 pipe_kqfilter(struct file *fp, struct knote *kn) 1220 { 1221 struct pipe *cpipe; 1222 1223 cpipe = (struct pipe *)kn->kn_fp->f_data; 1224 1225 switch (kn->kn_filter) { 1226 case EVFILT_READ: 1227 kn->kn_fop = &pipe_rfiltops; 1228 break; 1229 case EVFILT_WRITE: 1230 kn->kn_fop = &pipe_wfiltops; 1231 if (cpipe->pipe_peer == NULL) { 1232 /* other end of pipe has been closed */ 1233 return (EPIPE); 1234 } 1235 break; 1236 default: 1237 return (EOPNOTSUPP); 1238 } 1239 kn->kn_hook = (caddr_t)cpipe; 1240 1241 knote_insert(&cpipe->pipe_kq.ki_note, kn); 1242 1243 return (0); 1244 } 1245 1246 static void 1247 filt_pipedetach(struct knote *kn) 1248 { 1249 struct pipe *cpipe = (struct pipe *)kn->kn_hook; 1250 1251 knote_remove(&cpipe->pipe_kq.ki_note, kn); 1252 } 1253 1254 /*ARGSUSED*/ 1255 static int 1256 filt_piperead(struct knote *kn, long hint) 1257 { 1258 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1259 int ready = 0; 1260 1261 lwkt_gettoken(&rpipe->pipe_rlock); 1262 lwkt_gettoken(&rpipe->pipe_wlock); 1263 1264 kn->kn_data = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 1265 1266 if (rpipe->pipe_state & PIPE_REOF) { 1267 /* 1268 * Only set NODATA if all data has been exhausted 1269 */ 1270 if (kn->kn_data == 0) 1271 kn->kn_flags |= EV_NODATA; 1272 kn->kn_flags |= EV_EOF; 1273 ready = 1; 1274 } 1275 1276 lwkt_reltoken(&rpipe->pipe_wlock); 1277 lwkt_reltoken(&rpipe->pipe_rlock); 1278 1279 if (!ready) 1280 ready = kn->kn_data > 0; 1281 1282 return (ready); 1283 } 1284 1285 /*ARGSUSED*/ 1286 static int 1287 filt_pipewrite(struct knote *kn, long hint) 1288 { 1289 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1290 struct pipe *wpipe = rpipe->pipe_peer; 1291 int ready = 0; 1292 1293 kn->kn_data = 0; 1294 if (wpipe == NULL) { 1295 kn->kn_flags |= (EV_EOF | EV_NODATA); 1296 return (1); 1297 } 1298 1299 lwkt_gettoken(&wpipe->pipe_rlock); 1300 lwkt_gettoken(&wpipe->pipe_wlock); 1301 1302 if (wpipe->pipe_state & PIPE_WEOF) { 1303 kn->kn_flags |= (EV_EOF | EV_NODATA); 1304 ready = 1; 1305 } 1306 1307 if (!ready) 1308 kn->kn_data = wpipe->pipe_buffer.size - 1309 (wpipe->pipe_buffer.windex - 1310 wpipe->pipe_buffer.rindex); 1311 1312 lwkt_reltoken(&wpipe->pipe_wlock); 1313 lwkt_reltoken(&wpipe->pipe_rlock); 1314 1315 if (!ready) 1316 ready = kn->kn_data >= PIPE_BUF; 1317 1318 return (ready); 1319 } 1320