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 #include <sys/kern_syscall.h> 50 #include <sys/lock.h> 51 #include <sys/mutex.h> 52 53 #include <vm/vm.h> 54 #include <vm/vm_param.h> 55 #include <vm/vm_object.h> 56 #include <vm/vm_kern.h> 57 #include <vm/vm_extern.h> 58 #include <vm/pmap.h> 59 #include <vm/vm_map.h> 60 #include <vm/vm_page.h> 61 #include <vm/vm_zone.h> 62 63 #include <sys/file2.h> 64 #include <sys/signal2.h> 65 #include <sys/mutex2.h> 66 67 #include <machine/cpufunc.h> 68 69 /* 70 * interfaces to the outside world 71 */ 72 static int pipe_read (struct file *fp, struct uio *uio, 73 struct ucred *cred, int flags); 74 static int pipe_write (struct file *fp, struct uio *uio, 75 struct ucred *cred, int flags); 76 static int pipe_close (struct file *fp); 77 static int pipe_shutdown (struct file *fp, int how); 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, 81 struct ucred *cred, struct sysmsg *msg); 82 83 static struct fileops pipeops = { 84 .fo_read = pipe_read, 85 .fo_write = pipe_write, 86 .fo_ioctl = pipe_ioctl, 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 { FILTEROP_ISFD|FILTEROP_MPSAFE, NULL, filt_pipedetach, filt_piperead }; 99 static struct filterops pipe_wfiltops = 100 { FILTEROP_ISFD|FILTEROP_MPSAFE, 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 static struct mtx *pipe_gdlocks; 128 129 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation"); 130 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig, 131 CTLFLAG_RD, &pipe_nbig, 0, "number of big pipes allocated"); 132 SYSCTL_INT(_kern_pipe, OID_AUTO, bigcount, 133 CTLFLAG_RW, &pipe_bigcount, 0, "number of times pipe expanded"); 134 SYSCTL_INT(_kern_pipe, OID_AUTO, rblocked, 135 CTLFLAG_RW, &pipe_rblocked_count, 0, "number of times pipe expanded"); 136 SYSCTL_INT(_kern_pipe, OID_AUTO, wblocked, 137 CTLFLAG_RW, &pipe_wblocked_count, 0, "number of times pipe expanded"); 138 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache, 139 CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu"); 140 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig, 141 CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes"); 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 #if !defined(NO_PIPE_SYSCTL_STATS) 146 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc, 147 CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache"); 148 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc, 149 CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem"); 150 #endif 151 152 /* 153 * Auto-size pipe cache to reduce kmem allocations and frees. 154 */ 155 static 156 void 157 pipeinit(void *dummy) 158 { 159 size_t mbytes = kmem_lim_size(); 160 int n; 161 162 if (pipe_maxbig == LIMITBIGPIPES) { 163 if (mbytes >= 7 * 1024) 164 pipe_maxbig *= 2; 165 if (mbytes >= 15 * 1024) 166 pipe_maxbig *= 2; 167 } 168 if (pipe_maxcache == PIPEQ_MAX_CACHE) { 169 if (mbytes >= 7 * 1024) 170 pipe_maxcache *= 2; 171 if (mbytes >= 15 * 1024) 172 pipe_maxcache *= 2; 173 } 174 pipe_gdlocks = kmalloc(sizeof(*pipe_gdlocks) * ncpus, 175 M_PIPE, M_WAITOK | M_ZERO); 176 for (n = 0; n < ncpus; ++n) 177 mtx_init(&pipe_gdlocks[n], "pipekm"); 178 } 179 SYSINIT(kmem, SI_BOOT2_MACHDEP, SI_ORDER_ANY, pipeinit, NULL); 180 181 static void pipeclose (struct pipe *cpipe); 182 static void pipe_free_kmem (struct pipe *cpipe); 183 static int pipe_create (struct pipe **cpipep); 184 static int pipespace (struct pipe *cpipe, int size); 185 186 static __inline void 187 pipewakeup(struct pipe *cpipe, int dosigio) 188 { 189 if (dosigio && (cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) { 190 lwkt_gettoken(&sigio_token); 191 pgsigio(cpipe->pipe_sigio, SIGIO, 0); 192 lwkt_reltoken(&sigio_token); 193 } 194 KNOTE(&cpipe->pipe_kq.ki_note, 0); 195 } 196 197 /* 198 * These routines are called before and after a UIO. The UIO 199 * may block, causing our held tokens to be lost temporarily. 200 * 201 * We use these routines to serialize reads against other reads 202 * and writes against other writes. 203 * 204 * The read token is held on entry so *ipp does not race. 205 */ 206 static __inline int 207 pipe_start_uio(struct pipe *cpipe, int *ipp) 208 { 209 int error; 210 211 while (*ipp) { 212 *ipp = -1; 213 error = tsleep(ipp, PCATCH, "pipexx", 0); 214 if (error) 215 return (error); 216 } 217 *ipp = 1; 218 return (0); 219 } 220 221 static __inline void 222 pipe_end_uio(struct pipe *cpipe, int *ipp) 223 { 224 if (*ipp < 0) { 225 *ipp = 0; 226 wakeup(ipp); 227 } else { 228 KKASSERT(*ipp > 0); 229 *ipp = 0; 230 } 231 } 232 233 /* 234 * The pipe system call for the DTYPE_PIPE type of pipes 235 * 236 * pipe_args(int dummy) 237 * 238 * MPSAFE 239 */ 240 int 241 sys_pipe(struct pipe_args *uap) 242 { 243 return kern_pipe(uap->sysmsg_fds, 0); 244 } 245 246 int 247 sys_pipe2(struct pipe2_args *uap) 248 { 249 return kern_pipe(uap->sysmsg_fds, uap->flags); 250 } 251 252 int 253 kern_pipe(long *fds, int flags) 254 { 255 struct thread *td = curthread; 256 struct filedesc *fdp = td->td_proc->p_fd; 257 struct file *rf, *wf; 258 struct pipe *rpipe, *wpipe; 259 int fd1, fd2, error; 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(td->td_lwp, &rf, &fd1); 269 if (error) { 270 pipeclose(rpipe); 271 pipeclose(wpipe); 272 return (error); 273 } 274 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 if (flags & O_NONBLOCK) 287 rf->f_flag |= O_NONBLOCK; 288 if (flags & O_CLOEXEC) 289 fdp->fd_files[fd1].fileflags |= UF_EXCLOSE; 290 291 error = falloc(td->td_lwp, &wf, &fd2); 292 if (error) { 293 fsetfd(fdp, NULL, fd1); 294 fdrop(rf); 295 /* rpipe has been closed by fdrop(). */ 296 pipeclose(wpipe); 297 return (error); 298 } 299 wf->f_type = DTYPE_PIPE; 300 wf->f_flag = FREAD | FWRITE; 301 wf->f_ops = &pipeops; 302 wf->f_data = wpipe; 303 if (flags & O_NONBLOCK) 304 wf->f_flag |= O_NONBLOCK; 305 if (flags & O_CLOEXEC) 306 fdp->fd_files[fd2].fileflags |= UF_EXCLOSE; 307 308 fds[1] = fd2; 309 310 rpipe->pipe_slock = kmalloc(sizeof(struct lock), 311 M_PIPE, M_WAITOK|M_ZERO); 312 wpipe->pipe_slock = rpipe->pipe_slock; 313 rpipe->pipe_peer = wpipe; 314 wpipe->pipe_peer = rpipe; 315 lockinit(rpipe->pipe_slock, "pipecl", 0, 0); 316 317 /* 318 * Once activated the peer relationship remains valid until 319 * both sides are closed. 320 */ 321 fsetfd(fdp, rf, fd1); 322 fsetfd(fdp, wf, fd2); 323 fdrop(rf); 324 fdrop(wf); 325 326 return (0); 327 } 328 329 /* 330 * Allocate kva for pipe circular buffer, the space is pageable 331 * This routine will 'realloc' the size of a pipe safely, if it fails 332 * it will retain the old buffer. 333 * If it fails it will return ENOMEM. 334 */ 335 static int 336 pipespace(struct pipe *cpipe, int size) 337 { 338 struct vm_object *object; 339 caddr_t buffer; 340 int npages, error; 341 342 npages = round_page(size) / PAGE_SIZE; 343 object = cpipe->pipe_buffer.object; 344 345 /* 346 * [re]create the object if necessary and reserve space for it 347 * in the kernel_map. The object and memory are pageable. On 348 * success, free the old resources before assigning the new 349 * ones. 350 */ 351 if (object == NULL || object->size != npages) { 352 object = vm_object_allocate(OBJT_DEFAULT, npages); 353 buffer = (caddr_t)vm_map_min(&kernel_map); 354 355 error = vm_map_find(&kernel_map, object, NULL, 356 0, (vm_offset_t *)&buffer, size, 357 PAGE_SIZE, TRUE, 358 VM_MAPTYPE_NORMAL, VM_SUBSYS_PIPE, 359 VM_PROT_ALL, VM_PROT_ALL, 0); 360 361 if (error != KERN_SUCCESS) { 362 vm_object_deallocate(object); 363 return (ENOMEM); 364 } 365 pipe_free_kmem(cpipe); 366 cpipe->pipe_buffer.object = object; 367 cpipe->pipe_buffer.buffer = buffer; 368 cpipe->pipe_buffer.size = size; 369 ++pipe_bkmem_alloc; 370 } else { 371 ++pipe_bcache_alloc; 372 } 373 cpipe->pipe_buffer.rindex = 0; 374 cpipe->pipe_buffer.windex = 0; 375 return (0); 376 } 377 378 /* 379 * Initialize and allocate VM and memory for pipe, pulling the pipe from 380 * our per-cpu cache if possible. For now make sure it is sized for the 381 * smaller PIPE_SIZE default. 382 */ 383 static int 384 pipe_create(struct pipe **cpipep) 385 { 386 globaldata_t gd = mycpu; 387 struct pipe *cpipe; 388 int error; 389 390 if ((cpipe = gd->gd_pipeq) != NULL) { 391 gd->gd_pipeq = cpipe->pipe_peer; 392 --gd->gd_pipeqcount; 393 cpipe->pipe_peer = NULL; 394 cpipe->pipe_wantwcnt = 0; 395 } else { 396 cpipe = kmalloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO); 397 } 398 *cpipep = cpipe; 399 if ((error = pipespace(cpipe, PIPE_SIZE)) != 0) 400 return (error); 401 vfs_timestamp(&cpipe->pipe_ctime); 402 cpipe->pipe_atime = cpipe->pipe_ctime; 403 cpipe->pipe_mtime = cpipe->pipe_ctime; 404 lwkt_token_init(&cpipe->pipe_rlock, "piper"); 405 lwkt_token_init(&cpipe->pipe_wlock, "pipew"); 406 return (0); 407 } 408 409 static int 410 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags) 411 { 412 struct pipe *rpipe; 413 struct pipe *wpipe; 414 int error; 415 size_t nread = 0; 416 int nbio; 417 u_int size; /* total bytes available */ 418 u_int nsize; /* total bytes to read */ 419 u_int rindex; /* contiguous bytes available */ 420 int notify_writer; 421 int bigread; 422 int bigcount; 423 424 atomic_set_int(&curthread->td_mpflags, TDF_MP_BATCH_DEMARC); 425 426 if (uio->uio_resid == 0) 427 return(0); 428 429 /* 430 * Setup locks, calculate nbio 431 */ 432 rpipe = (struct pipe *)fp->f_data; 433 wpipe = rpipe->pipe_peer; 434 lwkt_gettoken(&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 however that 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 lwkt_reltoken(&rpipe->pipe_rlock); 454 return (error); 455 } 456 notify_writer = 0; 457 458 bigread = (uio->uio_resid > 10 * 1024 * 1024); 459 bigcount = 10; 460 461 while (uio->uio_resid) { 462 /* 463 * Don't hog the cpu. 464 */ 465 if (bigread && --bigcount == 0) { 466 lwkt_user_yield(); 467 bigcount = 10; 468 if (CURSIG(curthread->td_lwp)) { 469 error = EINTR; 470 break; 471 } 472 } 473 474 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 475 cpu_lfence(); 476 if (size) { 477 rindex = rpipe->pipe_buffer.rindex & 478 (rpipe->pipe_buffer.size - 1); 479 nsize = size; 480 if (nsize > rpipe->pipe_buffer.size - rindex) 481 nsize = rpipe->pipe_buffer.size - rindex; 482 nsize = szmin(nsize, uio->uio_resid); 483 484 error = uiomove(&rpipe->pipe_buffer.buffer[rindex], 485 nsize, uio); 486 if (error) 487 break; 488 cpu_mfence(); 489 rpipe->pipe_buffer.rindex += nsize; 490 nread += nsize; 491 492 /* 493 * If the FIFO is still over half full just continue 494 * and do not try to notify the writer yet. 495 */ 496 if (size - nsize >= (rpipe->pipe_buffer.size >> 1)) { 497 notify_writer = 0; 498 continue; 499 } 500 501 /* 502 * When the FIFO is less then half full notify any 503 * waiting writer. WANTW can be checked while 504 * holding just the rlock. 505 */ 506 notify_writer = 1; 507 if ((rpipe->pipe_state & PIPE_WANTW) == 0) 508 continue; 509 } 510 511 /* 512 * If the "write-side" was blocked we wake it up. This code 513 * is reached either when the buffer is completely emptied 514 * or if it becomes more then half-empty. 515 * 516 * Pipe_state can only be modified if both the rlock and 517 * wlock are held. 518 */ 519 if (rpipe->pipe_state & PIPE_WANTW) { 520 lwkt_gettoken(&rpipe->pipe_wlock); 521 if (rpipe->pipe_state & PIPE_WANTW) { 522 rpipe->pipe_state &= ~PIPE_WANTW; 523 lwkt_reltoken(&rpipe->pipe_wlock); 524 wakeup(rpipe); 525 } else { 526 lwkt_reltoken(&rpipe->pipe_wlock); 527 } 528 } 529 530 /* 531 * Pick up our copy loop again if the writer sent data to 532 * us while we were messing around. 533 * 534 * On a SMP box poll up to pipe_delay nanoseconds for new 535 * data. Typically a value of 2000 to 4000 is sufficient 536 * to eradicate most IPIs/tsleeps/wakeups when a pipe 537 * is used for synchronous communications with small packets, 538 * and 8000 or so (8uS) will pipeline large buffer xfers 539 * between cpus over a pipe. 540 * 541 * For synchronous communications a hit means doing a 542 * full Awrite-Bread-Bwrite-Aread cycle in less then 2uS, 543 * where as miss requiring a tsleep/wakeup sequence 544 * will take 7uS or more. 545 */ 546 if (rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex) 547 continue; 548 549 #ifdef _RDTSC_SUPPORTED_ 550 if (pipe_delay) { 551 int64_t tsc_target; 552 int good = 0; 553 554 tsc_target = tsc_get_target(pipe_delay); 555 while (tsc_test_target(tsc_target) == 0) { 556 if (rpipe->pipe_buffer.windex != 557 rpipe->pipe_buffer.rindex) { 558 good = 1; 559 break; 560 } 561 } 562 if (good) 563 continue; 564 } 565 #endif 566 567 /* 568 * Detect EOF condition, do not set error. 569 */ 570 if (rpipe->pipe_state & PIPE_REOF) 571 break; 572 573 /* 574 * Break if some data was read, or if this was a non-blocking 575 * read. 576 */ 577 if (nread > 0) 578 break; 579 580 if (nbio) { 581 error = EAGAIN; 582 break; 583 } 584 585 /* 586 * Last chance, interlock with WANTR. 587 */ 588 lwkt_gettoken(&rpipe->pipe_wlock); 589 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 590 if (size) { 591 lwkt_reltoken(&rpipe->pipe_wlock); 592 continue; 593 } 594 595 /* 596 * Retest EOF - acquiring a new token can temporarily release 597 * tokens already held. 598 */ 599 if (rpipe->pipe_state & PIPE_REOF) { 600 lwkt_reltoken(&rpipe->pipe_wlock); 601 break; 602 } 603 604 /* 605 * If there is no more to read in the pipe, reset its 606 * pointers to the beginning. This improves cache hit 607 * stats. 608 * 609 * We need both locks to modify both pointers, and there 610 * must also not be a write in progress or the uiomove() 611 * in the write might block and temporarily release 612 * its wlock, then reacquire and update windex. We are 613 * only serialized against reads, not writes. 614 * 615 * XXX should we even bother resetting the indices? It 616 * might actually be more cache efficient not to. 617 */ 618 if (rpipe->pipe_buffer.rindex == rpipe->pipe_buffer.windex && 619 rpipe->pipe_wip == 0) { 620 rpipe->pipe_buffer.rindex = 0; 621 rpipe->pipe_buffer.windex = 0; 622 } 623 624 /* 625 * Wait for more data. 626 * 627 * Pipe_state can only be set if both the rlock and wlock 628 * are held. 629 */ 630 rpipe->pipe_state |= PIPE_WANTR; 631 tsleep_interlock(rpipe, PCATCH); 632 lwkt_reltoken(&rpipe->pipe_wlock); 633 error = tsleep(rpipe, PCATCH | PINTERLOCKED, "piperd", 0); 634 ++pipe_rblocked_count; 635 if (error) 636 break; 637 } 638 pipe_end_uio(rpipe, &rpipe->pipe_rip); 639 640 /* 641 * Uptime last access time 642 */ 643 if (error == 0 && nread) 644 vfs_timestamp(&rpipe->pipe_atime); 645 646 /* 647 * If we drained the FIFO more then half way then handle 648 * write blocking hysteresis. 649 * 650 * Note that PIPE_WANTW cannot be set by the writer without 651 * it holding both rlock and wlock, so we can test it 652 * while holding just rlock. 653 */ 654 if (notify_writer) { 655 /* 656 * Synchronous blocking is done on the pipe involved 657 */ 658 if (rpipe->pipe_state & PIPE_WANTW) { 659 lwkt_gettoken(&rpipe->pipe_wlock); 660 if (rpipe->pipe_state & PIPE_WANTW) { 661 rpipe->pipe_state &= ~PIPE_WANTW; 662 lwkt_reltoken(&rpipe->pipe_wlock); 663 wakeup(rpipe); 664 } else { 665 lwkt_reltoken(&rpipe->pipe_wlock); 666 } 667 } 668 669 /* 670 * But we may also have to deal with a kqueue which is 671 * stored on the same pipe as its descriptor, so a 672 * EVFILT_WRITE event waiting for our side to drain will 673 * be on the other side. 674 */ 675 lwkt_gettoken(&wpipe->pipe_wlock); 676 pipewakeup(wpipe, 0); 677 lwkt_reltoken(&wpipe->pipe_wlock); 678 } 679 /*size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;*/ 680 lwkt_reltoken(&rpipe->pipe_rlock); 681 682 return (error); 683 } 684 685 static int 686 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags) 687 { 688 int error; 689 int orig_resid; 690 int nbio; 691 struct pipe *wpipe; 692 struct pipe *rpipe; 693 u_int windex; 694 u_int space; 695 u_int wcount; 696 int bigwrite; 697 int bigcount; 698 699 /* 700 * Writes go to the peer. The peer will always exist. 701 */ 702 rpipe = (struct pipe *) fp->f_data; 703 wpipe = rpipe->pipe_peer; 704 lwkt_gettoken(&wpipe->pipe_wlock); 705 if (wpipe->pipe_state & PIPE_WEOF) { 706 lwkt_reltoken(&wpipe->pipe_wlock); 707 return (EPIPE); 708 } 709 710 /* 711 * Degenerate case (EPIPE takes prec) 712 */ 713 if (uio->uio_resid == 0) { 714 lwkt_reltoken(&wpipe->pipe_wlock); 715 return(0); 716 } 717 718 /* 719 * Writes are serialized (start_uio must be called with wlock) 720 */ 721 error = pipe_start_uio(wpipe, &wpipe->pipe_wip); 722 if (error) { 723 lwkt_reltoken(&wpipe->pipe_wlock); 724 return (error); 725 } 726 727 if (fflags & O_FBLOCKING) 728 nbio = 0; 729 else if (fflags & O_FNONBLOCKING) 730 nbio = 1; 731 else if (fp->f_flag & O_NONBLOCK) 732 nbio = 1; 733 else 734 nbio = 0; 735 736 /* 737 * If it is advantageous to resize the pipe buffer, do 738 * so. We are write-serialized so we can block safely. 739 */ 740 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) && 741 (pipe_nbig < pipe_maxbig) && 742 wpipe->pipe_wantwcnt > 4 && 743 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) { 744 /* 745 * Recheck after lock. 746 */ 747 lwkt_gettoken(&wpipe->pipe_rlock); 748 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) && 749 (pipe_nbig < pipe_maxbig) && 750 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) { 751 atomic_add_int(&pipe_nbig, 1); 752 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) 753 ++pipe_bigcount; 754 else 755 atomic_subtract_int(&pipe_nbig, 1); 756 } 757 lwkt_reltoken(&wpipe->pipe_rlock); 758 } 759 760 orig_resid = uio->uio_resid; 761 wcount = 0; 762 763 bigwrite = (uio->uio_resid > 10 * 1024 * 1024); 764 bigcount = 10; 765 766 while (uio->uio_resid) { 767 if (wpipe->pipe_state & PIPE_WEOF) { 768 error = EPIPE; 769 break; 770 } 771 772 /* 773 * Don't hog the cpu. 774 */ 775 if (bigwrite && --bigcount == 0) { 776 lwkt_user_yield(); 777 bigcount = 10; 778 if (CURSIG(curthread->td_lwp)) { 779 error = EINTR; 780 break; 781 } 782 } 783 784 windex = wpipe->pipe_buffer.windex & 785 (wpipe->pipe_buffer.size - 1); 786 space = wpipe->pipe_buffer.size - 787 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex); 788 cpu_lfence(); 789 790 /* Writes of size <= PIPE_BUF must be atomic. */ 791 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 792 space = 0; 793 794 /* 795 * Write to fill, read size handles write hysteresis. Also 796 * additional restrictions can cause select-based non-blocking 797 * writes to spin. 798 */ 799 if (space > 0) { 800 u_int segsize; 801 802 /* 803 * Transfer size is minimum of uio transfer 804 * and free space in pipe buffer. 805 * 806 * Limit each uiocopy to no more then PIPE_SIZE 807 * so we can keep the gravy train going on a 808 * SMP box. This doubles the performance for 809 * write sizes > 16K. Otherwise large writes 810 * wind up doing an inefficient synchronous 811 * ping-pong. 812 */ 813 space = szmin(space, uio->uio_resid); 814 if (space > PIPE_SIZE) 815 space = PIPE_SIZE; 816 817 /* 818 * First segment to transfer is minimum of 819 * transfer size and contiguous space in 820 * pipe buffer. If first segment to transfer 821 * is less than the transfer size, we've got 822 * a wraparound in the buffer. 823 */ 824 segsize = wpipe->pipe_buffer.size - windex; 825 if (segsize > space) 826 segsize = space; 827 828 /* 829 * If this is the first loop and the reader is 830 * blocked, do a preemptive wakeup of the reader. 831 * 832 * On SMP the IPI latency plus the wlock interlock 833 * on the reader side is the fastest way to get the 834 * reader going. (The scheduler will hard loop on 835 * lock tokens). 836 * 837 * NOTE: We can't clear WANTR here without acquiring 838 * the rlock, which we don't want to do here! 839 */ 840 if ((wpipe->pipe_state & PIPE_WANTR)) 841 wakeup(wpipe); 842 843 /* 844 * Transfer segment, which may include a wrap-around. 845 * Update windex to account for both all in one go 846 * so the reader can read() the data atomically. 847 */ 848 error = uiomove(&wpipe->pipe_buffer.buffer[windex], 849 segsize, uio); 850 if (error == 0 && segsize < space) { 851 segsize = space - segsize; 852 error = uiomove(&wpipe->pipe_buffer.buffer[0], 853 segsize, uio); 854 } 855 if (error) 856 break; 857 cpu_mfence(); 858 wpipe->pipe_buffer.windex += space; 859 wcount += space; 860 continue; 861 } 862 863 /* 864 * We need both the rlock and the wlock to interlock against 865 * the EOF, WANTW, and size checks, and to modify pipe_state. 866 * 867 * These are token locks so we do not have to worry about 868 * deadlocks. 869 */ 870 lwkt_gettoken(&wpipe->pipe_rlock); 871 872 /* 873 * If the "read-side" has been blocked, wake it up now 874 * and yield to let it drain synchronously rather 875 * then block. 876 */ 877 if (wpipe->pipe_state & PIPE_WANTR) { 878 wpipe->pipe_state &= ~PIPE_WANTR; 879 wakeup(wpipe); 880 } 881 882 /* 883 * don't block on non-blocking I/O 884 */ 885 if (nbio) { 886 lwkt_reltoken(&wpipe->pipe_rlock); 887 error = EAGAIN; 888 break; 889 } 890 891 /* 892 * re-test whether we have to block in the writer after 893 * acquiring both locks, in case the reader opened up 894 * some space. 895 */ 896 space = wpipe->pipe_buffer.size - 897 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex); 898 cpu_lfence(); 899 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 900 space = 0; 901 902 /* 903 * Retest EOF - acquiring a new token can temporarily release 904 * tokens already held. 905 */ 906 if (wpipe->pipe_state & PIPE_WEOF) { 907 lwkt_reltoken(&wpipe->pipe_rlock); 908 error = EPIPE; 909 break; 910 } 911 912 /* 913 * We have no more space and have something to offer, 914 * wake up select/poll/kq. 915 */ 916 if (space == 0) { 917 wpipe->pipe_state |= PIPE_WANTW; 918 ++wpipe->pipe_wantwcnt; 919 pipewakeup(wpipe, 1); 920 if (wpipe->pipe_state & PIPE_WANTW) 921 error = tsleep(wpipe, PCATCH, "pipewr", 0); 922 ++pipe_wblocked_count; 923 } 924 lwkt_reltoken(&wpipe->pipe_rlock); 925 926 /* 927 * Break out if we errored or the read side wants us to go 928 * away. 929 */ 930 if (error) 931 break; 932 if (wpipe->pipe_state & PIPE_WEOF) { 933 error = EPIPE; 934 break; 935 } 936 } 937 pipe_end_uio(wpipe, &wpipe->pipe_wip); 938 939 /* 940 * If we have put any characters in the buffer, we wake up 941 * the reader. 942 * 943 * Both rlock and wlock are required to be able to modify pipe_state. 944 */ 945 if (wpipe->pipe_buffer.windex != wpipe->pipe_buffer.rindex) { 946 if (wpipe->pipe_state & PIPE_WANTR) { 947 lwkt_gettoken(&wpipe->pipe_rlock); 948 if (wpipe->pipe_state & PIPE_WANTR) { 949 wpipe->pipe_state &= ~PIPE_WANTR; 950 lwkt_reltoken(&wpipe->pipe_rlock); 951 wakeup(wpipe); 952 } else { 953 lwkt_reltoken(&wpipe->pipe_rlock); 954 } 955 } 956 lwkt_gettoken(&wpipe->pipe_rlock); 957 pipewakeup(wpipe, 1); 958 lwkt_reltoken(&wpipe->pipe_rlock); 959 } 960 961 /* 962 * Don't return EPIPE if I/O was successful 963 */ 964 if ((wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex) && 965 (uio->uio_resid == 0) && 966 (error == EPIPE)) { 967 error = 0; 968 } 969 970 if (error == 0) 971 vfs_timestamp(&wpipe->pipe_mtime); 972 973 /* 974 * We have something to offer, 975 * wake up select/poll/kq. 976 */ 977 /*space = wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex;*/ 978 lwkt_reltoken(&wpipe->pipe_wlock); 979 return (error); 980 } 981 982 /* 983 * we implement a very minimal set of ioctls for compatibility with sockets. 984 */ 985 static int 986 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, 987 struct ucred *cred, struct sysmsg *msg) 988 { 989 struct pipe *mpipe; 990 int error; 991 992 mpipe = (struct pipe *)fp->f_data; 993 994 lwkt_gettoken(&mpipe->pipe_rlock); 995 lwkt_gettoken(&mpipe->pipe_wlock); 996 997 switch (cmd) { 998 case FIOASYNC: 999 if (*(int *)data) { 1000 mpipe->pipe_state |= PIPE_ASYNC; 1001 } else { 1002 mpipe->pipe_state &= ~PIPE_ASYNC; 1003 } 1004 error = 0; 1005 break; 1006 case FIONREAD: 1007 *(int *)data = mpipe->pipe_buffer.windex - 1008 mpipe->pipe_buffer.rindex; 1009 error = 0; 1010 break; 1011 case FIOSETOWN: 1012 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1013 break; 1014 case FIOGETOWN: 1015 *(int *)data = fgetown(&mpipe->pipe_sigio); 1016 error = 0; 1017 break; 1018 case TIOCSPGRP: 1019 /* This is deprecated, FIOSETOWN should be used instead. */ 1020 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1021 break; 1022 1023 case TIOCGPGRP: 1024 /* This is deprecated, FIOGETOWN should be used instead. */ 1025 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1026 error = 0; 1027 break; 1028 default: 1029 error = ENOTTY; 1030 break; 1031 } 1032 lwkt_reltoken(&mpipe->pipe_wlock); 1033 lwkt_reltoken(&mpipe->pipe_rlock); 1034 1035 return (error); 1036 } 1037 1038 /* 1039 * MPSAFE 1040 */ 1041 static int 1042 pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred) 1043 { 1044 struct pipe *pipe; 1045 1046 pipe = (struct pipe *)fp->f_data; 1047 1048 bzero((caddr_t)ub, sizeof(*ub)); 1049 ub->st_mode = S_IFIFO; 1050 ub->st_blksize = pipe->pipe_buffer.size; 1051 ub->st_size = pipe->pipe_buffer.windex - pipe->pipe_buffer.rindex; 1052 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1053 ub->st_atimespec = pipe->pipe_atime; 1054 ub->st_mtimespec = pipe->pipe_mtime; 1055 ub->st_ctimespec = pipe->pipe_ctime; 1056 /* 1057 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev, 1058 * st_flags, st_gen. 1059 * XXX (st_dev, st_ino) should be unique. 1060 */ 1061 return (0); 1062 } 1063 1064 static int 1065 pipe_close(struct file *fp) 1066 { 1067 struct pipe *cpipe; 1068 1069 cpipe = (struct pipe *)fp->f_data; 1070 fp->f_ops = &badfileops; 1071 fp->f_data = NULL; 1072 funsetown(&cpipe->pipe_sigio); 1073 pipeclose(cpipe); 1074 return (0); 1075 } 1076 1077 /* 1078 * Shutdown one or both directions of a full-duplex pipe. 1079 */ 1080 static int 1081 pipe_shutdown(struct file *fp, int how) 1082 { 1083 struct pipe *rpipe; 1084 struct pipe *wpipe; 1085 int error = EPIPE; 1086 1087 rpipe = (struct pipe *)fp->f_data; 1088 wpipe = rpipe->pipe_peer; 1089 1090 /* 1091 * We modify pipe_state on both pipes, which means we need 1092 * all four tokens! 1093 */ 1094 lwkt_gettoken(&rpipe->pipe_rlock); 1095 lwkt_gettoken(&rpipe->pipe_wlock); 1096 lwkt_gettoken(&wpipe->pipe_rlock); 1097 lwkt_gettoken(&wpipe->pipe_wlock); 1098 1099 switch(how) { 1100 case SHUT_RDWR: 1101 case SHUT_RD: 1102 rpipe->pipe_state |= PIPE_REOF; /* my reads */ 1103 rpipe->pipe_state |= PIPE_WEOF; /* peer writes */ 1104 if (rpipe->pipe_state & PIPE_WANTR) { 1105 rpipe->pipe_state &= ~PIPE_WANTR; 1106 wakeup(rpipe); 1107 } 1108 if (rpipe->pipe_state & PIPE_WANTW) { 1109 rpipe->pipe_state &= ~PIPE_WANTW; 1110 wakeup(rpipe); 1111 } 1112 error = 0; 1113 if (how == SHUT_RD) 1114 break; 1115 /* fall through */ 1116 case SHUT_WR: 1117 wpipe->pipe_state |= PIPE_REOF; /* peer reads */ 1118 wpipe->pipe_state |= PIPE_WEOF; /* my writes */ 1119 if (wpipe->pipe_state & PIPE_WANTR) { 1120 wpipe->pipe_state &= ~PIPE_WANTR; 1121 wakeup(wpipe); 1122 } 1123 if (wpipe->pipe_state & PIPE_WANTW) { 1124 wpipe->pipe_state &= ~PIPE_WANTW; 1125 wakeup(wpipe); 1126 } 1127 error = 0; 1128 break; 1129 } 1130 pipewakeup(rpipe, 1); 1131 pipewakeup(wpipe, 1); 1132 1133 lwkt_reltoken(&wpipe->pipe_wlock); 1134 lwkt_reltoken(&wpipe->pipe_rlock); 1135 lwkt_reltoken(&rpipe->pipe_wlock); 1136 lwkt_reltoken(&rpipe->pipe_rlock); 1137 1138 return (error); 1139 } 1140 1141 /* 1142 * Destroy the pipe buffer. 1143 */ 1144 static void 1145 pipe_free_kmem(struct pipe *cpipe) 1146 { 1147 if (cpipe->pipe_buffer.buffer != NULL) { 1148 if (cpipe->pipe_buffer.size > PIPE_SIZE) 1149 atomic_subtract_int(&pipe_nbig, 1); 1150 kmem_free(&kernel_map, 1151 (vm_offset_t)cpipe->pipe_buffer.buffer, 1152 cpipe->pipe_buffer.size); 1153 cpipe->pipe_buffer.buffer = NULL; 1154 cpipe->pipe_buffer.object = NULL; 1155 } 1156 } 1157 1158 /* 1159 * Close the pipe. The slock must be held to interlock against simultanious 1160 * closes. The rlock and wlock must be held to adjust the pipe_state. 1161 */ 1162 static void 1163 pipeclose(struct pipe *cpipe) 1164 { 1165 globaldata_t gd; 1166 struct pipe *ppipe; 1167 1168 if (cpipe == NULL) 1169 return; 1170 1171 /* 1172 * The slock may not have been allocated yet (close during 1173 * initialization) 1174 * 1175 * We need both the read and write tokens to modify pipe_state. 1176 */ 1177 if (cpipe->pipe_slock) 1178 lockmgr(cpipe->pipe_slock, LK_EXCLUSIVE); 1179 lwkt_gettoken(&cpipe->pipe_rlock); 1180 lwkt_gettoken(&cpipe->pipe_wlock); 1181 1182 /* 1183 * Set our state, wakeup anyone waiting in select/poll/kq, and 1184 * wakeup anyone blocked on our pipe. 1185 */ 1186 cpipe->pipe_state |= PIPE_CLOSED | PIPE_REOF | PIPE_WEOF; 1187 pipewakeup(cpipe, 1); 1188 if (cpipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) { 1189 cpipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW); 1190 wakeup(cpipe); 1191 } 1192 1193 /* 1194 * Disconnect from peer. 1195 */ 1196 if ((ppipe = cpipe->pipe_peer) != NULL) { 1197 lwkt_gettoken(&ppipe->pipe_rlock); 1198 lwkt_gettoken(&ppipe->pipe_wlock); 1199 ppipe->pipe_state |= PIPE_REOF | PIPE_WEOF; 1200 pipewakeup(ppipe, 1); 1201 if (ppipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) { 1202 ppipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW); 1203 wakeup(ppipe); 1204 } 1205 if (SLIST_FIRST(&ppipe->pipe_kq.ki_note)) 1206 KNOTE(&ppipe->pipe_kq.ki_note, 0); 1207 lwkt_reltoken(&ppipe->pipe_wlock); 1208 lwkt_reltoken(&ppipe->pipe_rlock); 1209 } 1210 1211 /* 1212 * If the peer is also closed we can free resources for both 1213 * sides, otherwise we leave our side intact to deal with any 1214 * races (since we only have the slock). 1215 */ 1216 if (ppipe && (ppipe->pipe_state & PIPE_CLOSED)) { 1217 cpipe->pipe_peer = NULL; 1218 ppipe->pipe_peer = NULL; 1219 ppipe->pipe_slock = NULL; /* we will free the slock */ 1220 pipeclose(ppipe); 1221 ppipe = NULL; 1222 } 1223 1224 lwkt_reltoken(&cpipe->pipe_wlock); 1225 lwkt_reltoken(&cpipe->pipe_rlock); 1226 if (cpipe->pipe_slock) 1227 lockmgr(cpipe->pipe_slock, LK_RELEASE); 1228 1229 /* 1230 * If we disassociated from our peer we can free resources. We 1231 * maintain a pcpu cache to improve performance, so the actual 1232 * tear-down case is limited to bulk situations. 1233 * 1234 * However, the bulk tear-down case can cause intense contention 1235 * on the kernel_map when, e.g. hundreds to hundreds of thousands 1236 * of processes are killed at the same time. To deal with this we 1237 * use a pcpu mutex to maintain concurrency but also limit the 1238 * number of threads banging on the map and pmap. 1239 * 1240 * We use the mtx mechanism instead of the lockmgr mechanism because 1241 * the mtx mechanism utilizes a queued design which will not break 1242 * down in the face of thousands to hundreds of thousands of 1243 * processes trying to free pipes simultaneously. The lockmgr 1244 * mechanism will wind up waking them all up each time a lock 1245 * cycles. 1246 */ 1247 if (ppipe == NULL) { 1248 gd = mycpu; 1249 if (cpipe->pipe_slock) { 1250 kfree(cpipe->pipe_slock, M_PIPE); 1251 cpipe->pipe_slock = NULL; 1252 } 1253 if (gd->gd_pipeqcount >= pipe_maxcache || 1254 cpipe->pipe_buffer.size != PIPE_SIZE 1255 ) { 1256 mtx_lock(&pipe_gdlocks[gd->gd_cpuid]); 1257 pipe_free_kmem(cpipe); 1258 mtx_unlock(&pipe_gdlocks[gd->gd_cpuid]); 1259 kfree(cpipe, M_PIPE); 1260 } else { 1261 cpipe->pipe_state = 0; 1262 cpipe->pipe_peer = gd->gd_pipeq; 1263 gd->gd_pipeq = cpipe; 1264 ++gd->gd_pipeqcount; 1265 } 1266 } 1267 } 1268 1269 static int 1270 pipe_kqfilter(struct file *fp, struct knote *kn) 1271 { 1272 struct pipe *cpipe; 1273 1274 cpipe = (struct pipe *)kn->kn_fp->f_data; 1275 1276 switch (kn->kn_filter) { 1277 case EVFILT_READ: 1278 kn->kn_fop = &pipe_rfiltops; 1279 break; 1280 case EVFILT_WRITE: 1281 kn->kn_fop = &pipe_wfiltops; 1282 if (cpipe->pipe_peer == NULL) { 1283 /* other end of pipe has been closed */ 1284 return (EPIPE); 1285 } 1286 break; 1287 default: 1288 return (EOPNOTSUPP); 1289 } 1290 kn->kn_hook = (caddr_t)cpipe; 1291 1292 knote_insert(&cpipe->pipe_kq.ki_note, kn); 1293 1294 return (0); 1295 } 1296 1297 static void 1298 filt_pipedetach(struct knote *kn) 1299 { 1300 struct pipe *cpipe = (struct pipe *)kn->kn_hook; 1301 1302 knote_remove(&cpipe->pipe_kq.ki_note, kn); 1303 } 1304 1305 /*ARGSUSED*/ 1306 static int 1307 filt_piperead(struct knote *kn, long hint) 1308 { 1309 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1310 int ready = 0; 1311 1312 lwkt_gettoken(&rpipe->pipe_rlock); 1313 lwkt_gettoken(&rpipe->pipe_wlock); 1314 1315 kn->kn_data = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex; 1316 1317 if (rpipe->pipe_state & PIPE_REOF) { 1318 /* 1319 * Only set NODATA if all data has been exhausted 1320 */ 1321 if (kn->kn_data == 0) 1322 kn->kn_flags |= EV_NODATA; 1323 kn->kn_flags |= EV_EOF; 1324 ready = 1; 1325 } 1326 1327 lwkt_reltoken(&rpipe->pipe_wlock); 1328 lwkt_reltoken(&rpipe->pipe_rlock); 1329 1330 if (!ready) 1331 ready = kn->kn_data > 0; 1332 1333 return (ready); 1334 } 1335 1336 /*ARGSUSED*/ 1337 static int 1338 filt_pipewrite(struct knote *kn, long hint) 1339 { 1340 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1341 struct pipe *wpipe = rpipe->pipe_peer; 1342 int ready = 0; 1343 1344 kn->kn_data = 0; 1345 if (wpipe == NULL) { 1346 kn->kn_flags |= (EV_EOF | EV_NODATA); 1347 return (1); 1348 } 1349 1350 lwkt_gettoken(&wpipe->pipe_rlock); 1351 lwkt_gettoken(&wpipe->pipe_wlock); 1352 1353 if (wpipe->pipe_state & PIPE_WEOF) { 1354 kn->kn_flags |= (EV_EOF | EV_NODATA); 1355 ready = 1; 1356 } 1357 1358 if (!ready) 1359 kn->kn_data = wpipe->pipe_buffer.size - 1360 (wpipe->pipe_buffer.windex - 1361 wpipe->pipe_buffer.rindex); 1362 1363 lwkt_reltoken(&wpipe->pipe_wlock); 1364 lwkt_reltoken(&wpipe->pipe_rlock); 1365 1366 if (!ready) 1367 ready = kn->kn_data >= PIPE_BUF; 1368 1369 return (ready); 1370 } 1371