sys/kern/sys_pipe.c

   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/signalvar.h>
  40 #include <sys/sysproto.h>
  41 #include <sys/pipe.h>
  42 #include <sys/vnode.h>
  43 #include <sys/uio.h>
  44 #include <sys/event.h>
  45 #include <sys/globaldata.h>
  46 #include <sys/module.h>
  47 #include <sys/malloc.h>
  48 #include <sys/sysctl.h>
  49 #include <sys/socket.h>
  50
  51 #include <vm/vm.h>
  52 #include <vm/vm_param.h>
  53 #include <sys/lock.h>
  54 #include <vm/vm_object.h>
  55 #include <vm/vm_kern.h>
  56 #include <vm/vm_extern.h>
  57 #include <vm/pmap.h>
  58 #include <vm/vm_map.h>
  59 #include <vm/vm_page.h>
  60 #include <vm/vm_zone.h>
  61
  62 #include <sys/file2.h>
  63 #include <sys/signal2.h>
  64 #include <sys/mplock2.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_kqfilter (struct file *fp, struct knote *kn);
  78 static int pipe_stat (struct file *fp, struct stat *sb, struct ucred *cred);
  79 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data,
  80                 struct ucred *cred, struct sysmsg *msg);
  81
  82 static struct fileops pipeops = {
  83         .fo_read = pipe_read,
  84         .fo_write = pipe_write,
  85         .fo_ioctl = pipe_ioctl,
  86         .fo_kqfilter = pipe_kqfilter,
  87         .fo_stat = pipe_stat,
  88         .fo_close = pipe_close,
  89         .fo_shutdown = pipe_shutdown
  90 };
  91
  92 static void     filt_pipedetach(struct knote *kn);
  93 static int      filt_piperead(struct knote *kn, long hint);
  94 static int      filt_pipewrite(struct knote *kn, long hint);
  95
  96 static struct filterops pipe_rfiltops =
  97         { 1, NULL, filt_pipedetach, filt_piperead };
  98 static struct filterops pipe_wfiltops =
  99         { 1, NULL, filt_pipedetach, filt_pipewrite };
 100
 101 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures");
 102
 103 /*
 104  * Default pipe buffer size(s), this can be kind-of large now because pipe
 105  * space is pageable.  The pipe code will try to maintain locality of
 106  * reference for performance reasons, so small amounts of outstanding I/O
 107  * will not wipe the cache.
 108  */
 109 #define MINPIPESIZE (PIPE_SIZE/3)
 110 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 111
 112 /*
 113  * Limit the number of "big" pipes
 114  */
 115 #define LIMITBIGPIPES   64
 116 #define PIPEQ_MAX_CACHE 16      /* per-cpu pipe structure cache */
 117
 118 static int pipe_maxbig = LIMITBIGPIPES;
 119 static int pipe_maxcache = PIPEQ_MAX_CACHE;
 120 static int pipe_bigcount;
 121 static int pipe_nbig;
 122 static int pipe_bcache_alloc;
 123 static int pipe_bkmem_alloc;
 124 static int pipe_rblocked_count;
 125 static int pipe_wblocked_count;
 126
 127 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation");
 128 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig,
 129         CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated");
 130 SYSCTL_INT(_kern_pipe, OID_AUTO, bigcount,
 131         CTLFLAG_RW, &pipe_bigcount, 0, "number of times pipe expanded");
 132 SYSCTL_INT(_kern_pipe, OID_AUTO, rblocked,
 133         CTLFLAG_RW, &pipe_rblocked_count, 0, "number of times pipe expanded");
 134 SYSCTL_INT(_kern_pipe, OID_AUTO, wblocked,
 135         CTLFLAG_RW, &pipe_wblocked_count, 0, "number of times pipe expanded");
 136 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache,
 137         CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu");
 138 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig,
 139         CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes");
 140 #ifdef SMP
 141 static int pipe_delay = 5000;   /* 5uS default */
 142 SYSCTL_INT(_kern_pipe, OID_AUTO, delay,
 143         CTLFLAG_RW, &pipe_delay, 0, "SMP delay optimization in ns");
 144 static int pipe_mpsafe = 1;
 145 SYSCTL_INT(_kern_pipe, OID_AUTO, mpsafe,
 146         CTLFLAG_RW, &pipe_mpsafe, 0, "");
 147 #endif
 148 #if !defined(NO_PIPE_SYSCTL_STATS)
 149 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc,
 150         CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache");
 151 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc,
 152         CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem");
 153 #endif
 154
 155 static void pipeclose (struct pipe *cpipe);
 156 static void pipe_free_kmem (struct pipe *cpipe);
 157 static int pipe_create (struct pipe **cpipep);
 158 static __inline void pipewakeup (struct pipe *cpipe);
 159 static int pipespace (struct pipe *cpipe, int size);
 160
 161 static __inline void
 162 pipewakeup(struct pipe *cpipe)
 163 {
 164         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) {
 165                 get_mplock();
 166                 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
 167                 rel_mplock();
 168         }
 169         if (SLIST_FIRST(&cpipe->pipe_kq.ki_note))
 170                 KNOTE(&cpipe->pipe_kq.ki_note, 0);
 171 }
 172
 173 /*
 174  * These routines are called before and after a UIO.  The UIO
 175  * may block, causing our held tokens to be lost temporarily.
 176  *
 177  * We use these routines to serialize reads against other reads
 178  * and writes against other writes.
 179  *
 180  * The read token is held on entry so *ipp does not race.
 181  */
 182 static __inline int
 183 pipe_start_uio(struct pipe *cpipe, int *ipp)
 184 {
 185         int error;
 186
 187         while (*ipp) {
 188                 *ipp = -1;
 189                 error = tsleep(ipp, PCATCH, "pipexx", 0);
 190                 if (error)
 191                         return (error);
 192         }
 193         *ipp = 1;
 194         return (0);
 195 }
 196
 197 static __inline void
 198 pipe_end_uio(struct pipe *cpipe, int *ipp)
 199 {
 200         if (*ipp < 0) {
 201                 *ipp = 0;
 202                 wakeup(ipp);
 203         } else {
 204                 KKASSERT(*ipp > 0);
 205                 *ipp = 0;
 206         }
 207 }
 208
 209 static __inline void
 210 pipe_get_mplock(int *save)
 211 {
 212 #ifdef SMP
 213         if (pipe_mpsafe == 0) {
 214                 get_mplock();
 215                 *save = 1;
 216         } else
 217 #endif
 218         {
 219                 *save = 0;
 220         }
 221 }
 222
 223 static __inline void
 224 pipe_rel_mplock(int *save)
 225 {
 226 #ifdef SMP
 227         if (*save)
 228                 rel_mplock();
 229 #endif
 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         struct thread *td = curthread;
 244         struct filedesc *fdp = td->td_proc->p_fd;
 245         struct file *rf, *wf;
 246         struct pipe *rpipe, *wpipe;
 247         int fd1, fd2, error;
 248
 249         rpipe = wpipe = NULL;
 250         if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
 251                 pipeclose(rpipe);
 252                 pipeclose(wpipe);
 253                 return (ENFILE);
 254         }
 255
 256         error = falloc(td->td_lwp, &rf, &fd1);
 257         if (error) {
 258                 pipeclose(rpipe);
 259                 pipeclose(wpipe);
 260                 return (error);
 261         }
 262         uap->sysmsg_fds[0] = fd1;
 263
 264         /*
 265          * Warning: once we've gotten past allocation of the fd for the
 266          * read-side, we can only drop the read side via fdrop() in order
 267          * to avoid races against processes which manage to dup() the read
 268          * side while we are blocked trying to allocate the write side.
 269          */
 270         rf->f_type = DTYPE_PIPE;
 271         rf->f_flag = FREAD | FWRITE;
 272         rf->f_ops = &pipeops;
 273         rf->f_data = rpipe;
 274         error = falloc(td->td_lwp, &wf, &fd2);
 275         if (error) {
 276                 fsetfd(fdp, NULL, fd1);
 277                 fdrop(rf);
 278                 /* rpipe has been closed by fdrop(). */
 279                 pipeclose(wpipe);
 280                 return (error);
 281         }
 282         wf->f_type = DTYPE_PIPE;
 283         wf->f_flag = FREAD | FWRITE;
 284         wf->f_ops = &pipeops;
 285         wf->f_data = wpipe;
 286         uap->sysmsg_fds[1] = fd2;
 287
 288         rpipe->pipe_slock = kmalloc(sizeof(struct lock),
 289                                     M_PIPE, M_WAITOK|M_ZERO);
 290         wpipe->pipe_slock = rpipe->pipe_slock;
 291         rpipe->pipe_peer = wpipe;
 292         wpipe->pipe_peer = rpipe;
 293         lockinit(rpipe->pipe_slock, "pipecl", 0, 0);
 294
 295         /*
 296          * Once activated the peer relationship remains valid until
 297          * both sides are closed.
 298          */
 299         fsetfd(fdp, rf, fd1);
 300         fsetfd(fdp, wf, fd2);
 301         fdrop(rf);
 302         fdrop(wf);
 303
 304         return (0);
 305 }
 306
 307 /*
 308  * Allocate kva for pipe circular buffer, the space is pageable
 309  * This routine will 'realloc' the size of a pipe safely, if it fails
 310  * it will retain the old buffer.
 311  * If it fails it will return ENOMEM.
 312  */
 313 static int
 314 pipespace(struct pipe *cpipe, int size)
 315 {
 316         struct vm_object *object;
 317         caddr_t buffer;
 318         int npages, error;
 319
 320         npages = round_page(size) / PAGE_SIZE;
 321         object = cpipe->pipe_buffer.object;
 322
 323         /*
 324          * [re]create the object if necessary and reserve space for it
 325          * in the kernel_map.  The object and memory are pageable.  On
 326          * success, free the old resources before assigning the new
 327          * ones.
 328          */
 329         if (object == NULL || object->size != npages) {
 330                 get_mplock();
 331                 object = vm_object_allocate(OBJT_DEFAULT, npages);
 332                 buffer = (caddr_t)vm_map_min(&kernel_map);
 333
 334                 error = vm_map_find(&kernel_map, object, 0,
 335                                     (vm_offset_t *)&buffer,
 336                                     size, PAGE_SIZE,
 337                                     1, VM_MAPTYPE_NORMAL,
 338                                     VM_PROT_ALL, VM_PROT_ALL,
 339                                     0);
 340
 341                 if (error != KERN_SUCCESS) {
 342                         vm_object_deallocate(object);
 343                         rel_mplock();
 344                         return (ENOMEM);
 345                 }
 346                 pipe_free_kmem(cpipe);
 347                 rel_mplock();
 348                 cpipe->pipe_buffer.object = object;
 349                 cpipe->pipe_buffer.buffer = buffer;
 350                 cpipe->pipe_buffer.size = size;
 351                 ++pipe_bkmem_alloc;
 352         } else {
 353                 ++pipe_bcache_alloc;
 354         }
 355         cpipe->pipe_buffer.rindex = 0;
 356         cpipe->pipe_buffer.windex = 0;
 357         return (0);
 358 }
 359
 360 /*
 361  * Initialize and allocate VM and memory for pipe, pulling the pipe from
 362  * our per-cpu cache if possible.  For now make sure it is sized for the
 363  * smaller PIPE_SIZE default.
 364  */
 365 static int
 366 pipe_create(struct pipe **cpipep)
 367 {
 368         globaldata_t gd = mycpu;
 369         struct pipe *cpipe;
 370         int error;
 371
 372         if ((cpipe = gd->gd_pipeq) != NULL) {
 373                 gd->gd_pipeq = cpipe->pipe_peer;
 374                 --gd->gd_pipeqcount;
 375                 cpipe->pipe_peer = NULL;
 376                 cpipe->pipe_wantwcnt = 0;
 377         } else {
 378                 cpipe = kmalloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
 379         }
 380         *cpipep = cpipe;
 381         if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
 382                 return (error);
 383         vfs_timestamp(&cpipe->pipe_ctime);
 384         cpipe->pipe_atime = cpipe->pipe_ctime;
 385         cpipe->pipe_mtime = cpipe->pipe_ctime;
 386         lwkt_token_init(&cpipe->pipe_rlock, 1);
 387         lwkt_token_init(&cpipe->pipe_wlock, 1);
 388         return (0);
 389 }
 390
 391 /*
 392  * MPALMOSTSAFE (acquires mplock)
 393  */
 394 static int
 395 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
 396 {
 397         struct pipe *rpipe;
 398         int error;
 399         size_t nread = 0;
 400         int nbio;
 401         u_int size;     /* total bytes available */
 402         u_int nsize;    /* total bytes to read */
 403         u_int rindex;   /* contiguous bytes available */
 404         int notify_writer;
 405         int mpsave;
 406         int bigread;
 407         int bigcount;
 408
 409         if (uio->uio_resid == 0)
 410                 return(0);
 411
 412         /*
 413          * Setup locks, calculate nbio
 414          */
 415         pipe_get_mplock(&mpsave);
 416         rpipe = (struct pipe *)fp->f_data;
 417         lwkt_gettoken(&rpipe->pipe_rlock);
 418
 419         if (fflags & O_FBLOCKING)
 420                 nbio = 0;
 421         else if (fflags & O_FNONBLOCKING)
 422                 nbio = 1;
 423         else if (fp->f_flag & O_NONBLOCK)
 424                 nbio = 1;
 425         else
 426                 nbio = 0;
 427
 428         /*
 429          * Reads are serialized.  Note however that pipe_buffer.buffer and
 430          * pipe_buffer.size can change out from under us when the number
 431          * of bytes in the buffer are zero due to the write-side doing a
 432          * pipespace().
 433          */
 434         error = pipe_start_uio(rpipe, &rpipe->pipe_rip);
 435         if (error) {
 436                 pipe_rel_mplock(&mpsave);
 437                 lwkt_reltoken(&rpipe->pipe_rlock);
 438                 return (error);
 439         }
 440         notify_writer = 0;
 441
 442         bigread = (uio->uio_resid > 10 * 1024 * 1024);
 443         bigcount = 10;
 444
 445         while (uio->uio_resid) {
 446                 /*
 447                  * Don't hog the cpu.
 448                  */
 449                 if (bigread && --bigcount == 0) {
 450                         lwkt_user_yield();
 451                         bigcount = 10;
 452                         if (CURSIG(curthread->td_lwp)) {
 453                                 error = EINTR;
 454                                 break;
 455                         }
 456                 }
 457
 458                 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
 459                 cpu_lfence();
 460                 if (size) {
 461                         rindex = rpipe->pipe_buffer.rindex &
 462                                  (rpipe->pipe_buffer.size - 1);
 463                         nsize = size;
 464                         if (nsize > rpipe->pipe_buffer.size - rindex)
 465                                 nsize = rpipe->pipe_buffer.size - rindex;
 466                         nsize = szmin(nsize, uio->uio_resid);
 467
 468                         error = uiomove(&rpipe->pipe_buffer.buffer[rindex],
 469                                         nsize, uio);
 470                         if (error)
 471                                 break;
 472                         cpu_mfence();
 473                         rpipe->pipe_buffer.rindex += nsize;
 474                         nread += nsize;
 475
 476                         /*
 477                          * If the FIFO is still over half full just continue
 478                          * and do not try to notify the writer yet.
 479                          */
 480                         if (size - nsize >= (rpipe->pipe_buffer.size >> 1)) {
 481                                 notify_writer = 0;
 482                                 continue;
 483                         }
 484
 485                         /*
 486                          * When the FIFO is less then half full notify any
 487                          * waiting writer.  WANTW can be checked while
 488                          * holding just the rlock.
 489                          */
 490                         notify_writer = 1;
 491                         if ((rpipe->pipe_state & PIPE_WANTW) == 0)
 492                                 continue;
 493                 }
 494
 495                 /*
 496                  * If the "write-side" was blocked we wake it up.  This code
 497                  * is reached either when the buffer is completely emptied
 498                  * or if it becomes more then half-empty.
 499                  *
 500                  * Pipe_state can only be modified if both the rlock and
 501                  * wlock are held.
 502                  */
 503                 if (rpipe->pipe_state & PIPE_WANTW) {
 504                         lwkt_gettoken(&rpipe->pipe_wlock);
 505                         if (rpipe->pipe_state & PIPE_WANTW) {
 506                                 notify_writer = 0;
 507                                 rpipe->pipe_state &= ~PIPE_WANTW;
 508                                 lwkt_reltoken(&rpipe->pipe_wlock);
 509                                 wakeup(rpipe);
 510                         } else {
 511                                 lwkt_reltoken(&rpipe->pipe_wlock);
 512                         }
 513                 }
 514
 515                 /*
 516                  * Pick up our copy loop again if the writer sent data to
 517                  * us while we were messing around.
 518                  *
 519                  * On a SMP box poll up to pipe_delay nanoseconds for new
 520                  * data.  Typically a value of 2000 to 4000 is sufficient
 521                  * to eradicate most IPIs/tsleeps/wakeups when a pipe
 522                  * is used for synchronous communications with small packets,
 523                  * and 8000 or so (8uS) will pipeline large buffer xfers
 524                  * between cpus over a pipe.
 525                  *
 526                  * For synchronous communications a hit means doing a
 527                  * full Awrite-Bread-Bwrite-Aread cycle in less then 2uS,
 528                  * where as miss requiring a tsleep/wakeup sequence
 529                  * will take 7uS or more.
 530                  */
 531                 if (rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex)
 532                         continue;
 533
 534 #if defined(SMP) && defined(_RDTSC_SUPPORTED_)
 535                 if (pipe_delay) {
 536                         int64_t tsc_target;
 537                         int good = 0;
 538
 539                         tsc_target = tsc_get_target(pipe_delay);
 540                         while (tsc_test_target(tsc_target) == 0) {
 541                                 if (rpipe->pipe_buffer.windex !=
 542                                     rpipe->pipe_buffer.rindex) {
 543                                         good = 1;
 544                                         break;
 545                                 }
 546                         }
 547                         if (good)
 548                                 continue;
 549                 }
 550 #endif
 551
 552                 /*
 553                  * Detect EOF condition, do not set error.
 554                  */
 555                 if (rpipe->pipe_state & PIPE_REOF)
 556                         break;
 557
 558                 /*
 559                  * Break if some data was read, or if this was a non-blocking
 560                  * read.
 561                  */
 562                 if (nread > 0)
 563                         break;
 564
 565                 if (nbio) {
 566                         error = EAGAIN;
 567                         break;
 568                 }
 569
 570                 /*
 571                  * Last chance, interlock with WANTR.
 572                  */
 573                 lwkt_gettoken(&rpipe->pipe_wlock);
 574                 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
 575                 if (size) {
 576                         lwkt_reltoken(&rpipe->pipe_wlock);
 577                         continue;
 578                 }
 579
 580                 /*
 581                  * Retest EOF - acquiring a new token can temporarily release
 582                  * tokens already held.
 583                  */
 584                 if (rpipe->pipe_state & PIPE_REOF) {
 585                         lwkt_reltoken(&rpipe->pipe_wlock);
 586                         break;
 587                 }
 588
 589                 /*
 590                  * If there is no more to read in the pipe, reset its
 591                  * pointers to the beginning.  This improves cache hit
 592                  * stats.
 593                  *
 594                  * We need both locks to modify both pointers, and there
 595                  * must also not be a write in progress or the uiomove()
 596                  * in the write might block and temporarily release
 597                  * its wlock, then reacquire and update windex.  We are
 598                  * only serialized against reads, not writes.
 599                  *
 600                  * XXX should we even bother resetting the indices?  It
 601                  *     might actually be more cache efficient not to.
 602                  */
 603                 if (rpipe->pipe_buffer.rindex == rpipe->pipe_buffer.windex &&
 604                     rpipe->pipe_wip == 0) {
 605                         rpipe->pipe_buffer.rindex = 0;
 606                         rpipe->pipe_buffer.windex = 0;
 607                 }
 608
 609                 /*
 610                  * Wait for more data.
 611                  *
 612                  * Pipe_state can only be set if both the rlock and wlock
 613                  * are held.
 614                  */
 615                 rpipe->pipe_state |= PIPE_WANTR;
 616                 tsleep_interlock(rpipe, PCATCH);
 617                 lwkt_reltoken(&rpipe->pipe_wlock);
 618                 error = tsleep(rpipe, PCATCH | PINTERLOCKED, "piperd", 0);
 619                 ++pipe_rblocked_count;
 620                 if (error)
 621                         break;
 622         }
 623         pipe_end_uio(rpipe, &rpipe->pipe_rip);
 624
 625         /*
 626          * Uptime last access time
 627          */
 628         if (error == 0 && nread)
 629                 vfs_timestamp(&rpipe->pipe_atime);
 630
 631         /*
 632          * If we drained the FIFO more then half way then handle
 633          * write blocking hysteresis.
 634          *
 635          * Note that PIPE_WANTW cannot be set by the writer without
 636          * it holding both rlock and wlock, so we can test it
 637          * while holding just rlock.
 638          */
 639         if (notify_writer) {
 640                 if (rpipe->pipe_state & PIPE_WANTW) {
 641                         lwkt_gettoken(&rpipe->pipe_wlock);
 642                         if (rpipe->pipe_state & PIPE_WANTW) {
 643                                 rpipe->pipe_state &= ~PIPE_WANTW;
 644                                 lwkt_reltoken(&rpipe->pipe_wlock);
 645                                 wakeup(rpipe);
 646                         } else {
 647                                 lwkt_reltoken(&rpipe->pipe_wlock);
 648                         }
 649                 }
 650                 lwkt_gettoken(&rpipe->pipe_wlock);
 651                 pipewakeup(rpipe);
 652                 lwkt_reltoken(&rpipe->pipe_wlock);
 653         }
 654         /*size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;*/
 655         lwkt_reltoken(&rpipe->pipe_rlock);
 656
 657         pipe_rel_mplock(&mpsave);
 658         return (error);
 659 }
 660
 661 /*
 662  * MPALMOSTSAFE - acquires mplock
 663  */
 664 static int
 665 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
 666 {
 667         int error;
 668         int orig_resid;
 669         int nbio;
 670         struct pipe *wpipe, *rpipe;
 671         u_int windex;
 672         u_int space;
 673         u_int wcount;
 674         int mpsave;
 675         int bigwrite;
 676         int bigcount;
 677
 678         pipe_get_mplock(&mpsave);
 679
 680         /*
 681          * Writes go to the peer.  The peer will always exist.
 682          */
 683         rpipe = (struct pipe *) fp->f_data;
 684         wpipe = rpipe->pipe_peer;
 685         lwkt_gettoken(&wpipe->pipe_wlock);
 686         if (wpipe->pipe_state & PIPE_WEOF) {
 687                 pipe_rel_mplock(&mpsave);
 688                 lwkt_reltoken(&wpipe->pipe_wlock);
 689                 return (EPIPE);
 690         }
 691
 692         /*
 693          * Degenerate case (EPIPE takes prec)
 694          */
 695         if (uio->uio_resid == 0) {
 696                 pipe_rel_mplock(&mpsave);
 697                 lwkt_reltoken(&wpipe->pipe_wlock);
 698                 return(0);
 699         }
 700
 701         /*
 702          * Writes are serialized (start_uio must be called with wlock)
 703          */
 704         error = pipe_start_uio(wpipe, &wpipe->pipe_wip);
 705         if (error) {
 706                 pipe_rel_mplock(&mpsave);
 707                 lwkt_reltoken(&wpipe->pipe_wlock);
 708                 return (error);
 709         }
 710
 711         if (fflags & O_FBLOCKING)
 712                 nbio = 0;
 713         else if (fflags & O_FNONBLOCKING)
 714                 nbio = 1;
 715         else if (fp->f_flag & O_NONBLOCK)
 716                 nbio = 1;
 717         else
 718                 nbio = 0;
 719
 720         /*
 721          * If it is advantageous to resize the pipe buffer, do
 722          * so.  We are write-serialized so we can block safely.
 723          */
 724         if ((wpipe->pipe_buffer.size <= PIPE_SIZE) &&
 725             (pipe_nbig < pipe_maxbig) &&
 726             wpipe->pipe_wantwcnt > 4 &&
 727             (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) {
 728                 /*
 729                  * Recheck after lock.
 730                  */
 731                 lwkt_gettoken(&wpipe->pipe_rlock);
 732                 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) &&
 733                     (pipe_nbig < pipe_maxbig) &&
 734                     (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) {
 735                         atomic_add_int(&pipe_nbig, 1);
 736                         if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
 737                                 ++pipe_bigcount;
 738                         else
 739                                 atomic_subtract_int(&pipe_nbig, 1);
 740                 }
 741                 lwkt_reltoken(&wpipe->pipe_rlock);
 742         }
 743
 744         orig_resid = uio->uio_resid;
 745         wcount = 0;
 746
 747         bigwrite = (uio->uio_resid > 10 * 1024 * 1024);
 748         bigcount = 10;
 749
 750         while (uio->uio_resid) {
 751                 if (wpipe->pipe_state & PIPE_WEOF) {
 752                         error = EPIPE;
 753                         break;
 754                 }
 755
 756                 /*
 757                  * Don't hog the cpu.
 758                  */
 759                 if (bigwrite && --bigcount == 0) {
 760                         lwkt_user_yield();
 761                         bigcount = 10;
 762                         if (CURSIG(curthread->td_lwp)) {
 763                                 error = EINTR;
 764                                 break;
 765                         }
 766                 }
 767
 768                 windex = wpipe->pipe_buffer.windex &
 769                          (wpipe->pipe_buffer.size - 1);
 770                 space = wpipe->pipe_buffer.size -
 771                         (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex);
 772                 cpu_lfence();
 773
 774                 /* Writes of size <= PIPE_BUF must be atomic. */
 775                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
 776                         space = 0;
 777
 778                 /*
 779                  * Write to fill, read size handles write hysteresis.  Also
 780                  * additional restrictions can cause select-based non-blocking
 781                  * writes to spin.
 782                  */
 783                 if (space > 0) {
 784                         u_int segsize;
 785
 786                         /*
 787                          * Transfer size is minimum of uio transfer
 788                          * and free space in pipe buffer.
 789                          *
 790                          * Limit each uiocopy to no more then PIPE_SIZE
 791                          * so we can keep the gravy train going on a
 792                          * SMP box.  This doubles the performance for
 793                          * write sizes > 16K.  Otherwise large writes
 794                          * wind up doing an inefficient synchronous
 795                          * ping-pong.
 796                          */
 797                         space = szmin(space, uio->uio_resid);
 798                         if (space > PIPE_SIZE)
 799                                 space = PIPE_SIZE;
 800
 801                         /*
 802                          * First segment to transfer is minimum of
 803                          * transfer size and contiguous space in
 804                          * pipe buffer.  If first segment to transfer
 805                          * is less than the transfer size, we've got
 806                          * a wraparound in the buffer.
 807                          */
 808                         segsize = wpipe->pipe_buffer.size - windex;
 809                         if (segsize > space)
 810                                 segsize = space;
 811
 812 #ifdef SMP
 813                         /*
 814                          * If this is the first loop and the reader is
 815                          * blocked, do a preemptive wakeup of the reader.
 816                          *
 817                          * On SMP the IPI latency plus the wlock interlock
 818                          * on the reader side is the fastest way to get the
 819                          * reader going.  (The scheduler will hard loop on
 820                          * lock tokens).
 821                          *
 822                          * NOTE: We can't clear WANTR here without acquiring
 823                          * the rlock, which we don't want to do here!
 824                          */
 825                         if ((wpipe->pipe_state & PIPE_WANTR) && pipe_mpsafe > 1)
 826                                 wakeup(wpipe);
 827 #endif
 828
 829                         /*
 830                          * Transfer segment, which may include a wrap-around.
 831                          * Update windex to account for both all in one go
 832                          * so the reader can read() the data atomically.
 833                          */
 834                         error = uiomove(&wpipe->pipe_buffer.buffer[windex],
 835                                         segsize, uio);
 836                         if (error == 0 && segsize < space) {
 837                                 segsize = space - segsize;
 838                                 error = uiomove(&wpipe->pipe_buffer.buffer[0],
 839                                                 segsize, uio);
 840                         }
 841                         if (error)
 842                                 break;
 843                         cpu_mfence();
 844                         wpipe->pipe_buffer.windex += space;
 845                         wcount += space;
 846                         continue;
 847                 }
 848
 849                 /*
 850                  * We need both the rlock and the wlock to interlock against
 851                  * the EOF, WANTW, and size checks, and to modify pipe_state.
 852                  *
 853                  * These are token locks so we do not have to worry about
 854                  * deadlocks.
 855                  */
 856                 lwkt_gettoken(&wpipe->pipe_rlock);
 857
 858                 /*
 859                  * If the "read-side" has been blocked, wake it up now
 860                  * and yield to let it drain synchronously rather
 861                  * then block.
 862                  */
 863                 if (wpipe->pipe_state & PIPE_WANTR) {
 864                         wpipe->pipe_state &= ~PIPE_WANTR;
 865                         wakeup(wpipe);
 866                 }
 867
 868                 /*
 869                  * don't block on non-blocking I/O
 870                  */
 871                 if (nbio) {
 872                         lwkt_reltoken(&wpipe->pipe_rlock);
 873                         error = EAGAIN;
 874                         break;
 875                 }
 876
 877                 /*
 878                  * re-test whether we have to block in the writer after
 879                  * acquiring both locks, in case the reader opened up
 880                  * some space.
 881                  */
 882                 space = wpipe->pipe_buffer.size -
 883                         (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex);
 884                 cpu_lfence();
 885                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
 886                         space = 0;
 887
 888                 /*
 889                  * Retest EOF - acquiring a new token can temporarily release
 890                  * tokens already held.
 891                  */
 892                 if (wpipe->pipe_state & PIPE_WEOF) {
 893                         lwkt_reltoken(&wpipe->pipe_rlock);
 894                         error = EPIPE;
 895                         break;
 896                 }
 897
 898                 /*
 899                  * We have no more space and have something to offer,
 900                  * wake up select/poll/kq.
 901                  */
 902                 if (space == 0) {
 903                         wpipe->pipe_state |= PIPE_WANTW;
 904                         ++wpipe->pipe_wantwcnt;
 905                         pipewakeup(wpipe);
 906                         if (wpipe->pipe_state & PIPE_WANTW)
 907                                 error = tsleep(wpipe, PCATCH, "pipewr", 0);
 908                         ++pipe_wblocked_count;
 909                 }
 910                 lwkt_reltoken(&wpipe->pipe_rlock);
 911
 912                 /*
 913                  * Break out if we errored or the read side wants us to go
 914                  * away.
 915                  */
 916                 if (error)
 917                         break;
 918                 if (wpipe->pipe_state & PIPE_WEOF) {
 919                         error = EPIPE;
 920                         break;
 921                 }
 922         }
 923         pipe_end_uio(wpipe, &wpipe->pipe_wip);
 924
 925         /*
 926          * If we have put any characters in the buffer, we wake up
 927          * the reader.
 928          *
 929          * Both rlock and wlock are required to be able to modify pipe_state.
 930          */
 931         if (wpipe->pipe_buffer.windex != wpipe->pipe_buffer.rindex) {
 932                 if (wpipe->pipe_state & PIPE_WANTR) {
 933                         lwkt_gettoken(&wpipe->pipe_rlock);
 934                         if (wpipe->pipe_state & PIPE_WANTR) {
 935                                 wpipe->pipe_state &= ~PIPE_WANTR;
 936                                 lwkt_reltoken(&wpipe->pipe_rlock);
 937                                 wakeup(wpipe);
 938                         } else {
 939                                 lwkt_reltoken(&wpipe->pipe_rlock);
 940                         }
 941                 }
 942                 lwkt_gettoken(&wpipe->pipe_rlock);
 943                 pipewakeup(wpipe);
 944                 lwkt_reltoken(&wpipe->pipe_rlock);
 945         }
 946
 947         /*
 948          * Don't return EPIPE if I/O was successful
 949          */
 950         if ((wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex) &&
 951             (uio->uio_resid == 0) &&
 952             (error == EPIPE)) {
 953                 error = 0;
 954         }
 955
 956         if (error == 0)
 957                 vfs_timestamp(&wpipe->pipe_mtime);
 958
 959         /*
 960          * We have something to offer,
 961          * wake up select/poll/kq.
 962          */
 963         /*space = wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex;*/
 964         lwkt_reltoken(&wpipe->pipe_wlock);
 965         pipe_rel_mplock(&mpsave);
 966         return (error);
 967 }
 968
 969 /*
 970  * MPALMOSTSAFE - acquires mplock
 971  *
 972  * we implement a very minimal set of ioctls for compatibility with sockets.
 973  */
 974 int
 975 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data,
 976            struct ucred *cred, struct sysmsg *msg)
 977 {
 978         struct pipe *mpipe;
 979         int error;
 980         int mpsave;
 981
 982         pipe_get_mplock(&mpsave);
 983         mpipe = (struct pipe *)fp->f_data;
 984
 985         lwkt_gettoken(&mpipe->pipe_rlock);
 986         lwkt_gettoken(&mpipe->pipe_wlock);
 987
 988         switch (cmd) {
 989         case FIOASYNC:
 990                 if (*(int *)data) {
 991                         mpipe->pipe_state |= PIPE_ASYNC;
 992                 } else {
 993                         mpipe->pipe_state &= ~PIPE_ASYNC;
 994                 }
 995                 error = 0;
 996                 break;
 997         case FIONREAD:
 998                 *(int *)data = mpipe->pipe_buffer.windex -
 999                                 mpipe->pipe_buffer.rindex;
1000                 error = 0;
1001                 break;
1002         case FIOSETOWN:
1003                 get_mplock();
1004                 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1005                 rel_mplock();
1006                 break;
1007         case FIOGETOWN:
1008                 *(int *)data = fgetown(mpipe->pipe_sigio);
1009                 error = 0;
1010                 break;
1011         case TIOCSPGRP:
1012                 /* This is deprecated, FIOSETOWN should be used instead. */
1013                 get_mplock();
1014                 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1015                 rel_mplock();
1016                 break;
1017
1018         case TIOCGPGRP:
1019                 /* This is deprecated, FIOGETOWN should be used instead. */
1020                 *(int *)data = -fgetown(mpipe->pipe_sigio);
1021                 error = 0;
1022                 break;
1023         default:
1024                 error = ENOTTY;
1025                 break;
1026         }
1027         lwkt_reltoken(&mpipe->pipe_wlock);
1028         lwkt_reltoken(&mpipe->pipe_rlock);
1029         pipe_rel_mplock(&mpsave);
1030
1031         return (error);
1032 }
1033
1034 /*
1035  * MPSAFE
1036  */
1037 static int
1038 pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred)
1039 {
1040         struct pipe *pipe;
1041         int mpsave;
1042
1043         pipe_get_mplock(&mpsave);
1044         pipe = (struct pipe *)fp->f_data;
1045
1046         bzero((caddr_t)ub, sizeof(*ub));
1047         ub->st_mode = S_IFIFO;
1048         ub->st_blksize = pipe->pipe_buffer.size;
1049         ub->st_size = pipe->pipe_buffer.windex - pipe->pipe_buffer.rindex;
1050         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1051         ub->st_atimespec = pipe->pipe_atime;
1052         ub->st_mtimespec = pipe->pipe_mtime;
1053         ub->st_ctimespec = pipe->pipe_ctime;
1054         /*
1055          * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1056          * st_flags, st_gen.
1057          * XXX (st_dev, st_ino) should be unique.
1058          */
1059         pipe_rel_mplock(&mpsave);
1060         return (0);
1061 }
1062
1063 /*
1064  * MPALMOSTSAFE - acquires mplock
1065  */
1066 static int
1067 pipe_close(struct file *fp)
1068 {
1069         struct pipe *cpipe;
1070
1071         get_mplock();
1072         cpipe = (struct pipe *)fp->f_data;
1073         fp->f_ops = &badfileops;
1074         fp->f_data = NULL;
1075         funsetown(cpipe->pipe_sigio);
1076         pipeclose(cpipe);
1077         rel_mplock();
1078         return (0);
1079 }
1080
1081 /*
1082  * Shutdown one or both directions of a full-duplex pipe.
1083  *
1084  * MPALMOSTSAFE - acquires mplock
1085  */
1086 static int
1087 pipe_shutdown(struct file *fp, int how)
1088 {
1089         struct pipe *rpipe;
1090         struct pipe *wpipe;
1091         int error = EPIPE;
1092         int mpsave;
1093
1094         pipe_get_mplock(&mpsave);
1095         rpipe = (struct pipe *)fp->f_data;
1096         wpipe = rpipe->pipe_peer;
1097
1098         /*
1099          * We modify pipe_state on both pipes, which means we need
1100          * all four tokens!
1101          */
1102         lwkt_gettoken(&rpipe->pipe_rlock);
1103         lwkt_gettoken(&rpipe->pipe_wlock);
1104         lwkt_gettoken(&wpipe->pipe_rlock);
1105         lwkt_gettoken(&wpipe->pipe_wlock);
1106
1107         switch(how) {
1108         case SHUT_RDWR:
1109         case SHUT_RD:
1110                 rpipe->pipe_state |= PIPE_REOF;         /* my reads */
1111                 rpipe->pipe_state |= PIPE_WEOF;         /* peer writes */
1112                 if (rpipe->pipe_state & PIPE_WANTR) {
1113                         rpipe->pipe_state &= ~PIPE_WANTR;
1114                         wakeup(rpipe);
1115                 }
1116                 if (rpipe->pipe_state & PIPE_WANTW) {
1117                         rpipe->pipe_state &= ~PIPE_WANTW;
1118                         wakeup(rpipe);
1119                 }
1120                 error = 0;
1121                 if (how == SHUT_RD)
1122                         break;
1123                 /* fall through */
1124         case SHUT_WR:
1125                 wpipe->pipe_state |= PIPE_REOF;         /* peer reads */
1126                 wpipe->pipe_state |= PIPE_WEOF;         /* my writes */
1127                 if (wpipe->pipe_state & PIPE_WANTR) {
1128                         wpipe->pipe_state &= ~PIPE_WANTR;
1129                         wakeup(wpipe);
1130                 }
1131                 if (wpipe->pipe_state & PIPE_WANTW) {
1132                         wpipe->pipe_state &= ~PIPE_WANTW;
1133                         wakeup(wpipe);
1134                 }
1135                 error = 0;
1136                 break;
1137         }
1138         pipewakeup(rpipe);
1139         pipewakeup(wpipe);
1140
1141         lwkt_reltoken(&wpipe->pipe_wlock);
1142         lwkt_reltoken(&wpipe->pipe_rlock);
1143         lwkt_reltoken(&rpipe->pipe_wlock);
1144         lwkt_reltoken(&rpipe->pipe_rlock);
1145
1146         pipe_rel_mplock(&mpsave);
1147         return (error);
1148 }
1149
1150 static void
1151 pipe_free_kmem(struct pipe *cpipe)
1152 {
1153         if (cpipe->pipe_buffer.buffer != NULL) {
1154                 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1155                         atomic_subtract_int(&pipe_nbig, 1);
1156                 kmem_free(&kernel_map,
1157                         (vm_offset_t)cpipe->pipe_buffer.buffer,
1158                         cpipe->pipe_buffer.size);
1159                 cpipe->pipe_buffer.buffer = NULL;
1160                 cpipe->pipe_buffer.object = NULL;
1161         }
1162 }
1163
1164 /*
1165  * Close the pipe.  The slock must be held to interlock against simultanious
1166  * closes.  The rlock and wlock must be held to adjust the pipe_state.
1167  */
1168 static void
1169 pipeclose(struct pipe *cpipe)
1170 {
1171         globaldata_t gd;
1172         struct pipe *ppipe;
1173
1174         if (cpipe == NULL)
1175                 return;
1176
1177         /*
1178          * The slock may not have been allocated yet (close during
1179          * initialization)
1180          *
1181          * We need both the read and write tokens to modify pipe_state.
1182          */
1183         if (cpipe->pipe_slock)
1184                 lockmgr(cpipe->pipe_slock, LK_EXCLUSIVE);
1185         lwkt_gettoken(&cpipe->pipe_rlock);
1186         lwkt_gettoken(&cpipe->pipe_wlock);
1187
1188         /*
1189          * Set our state, wakeup anyone waiting in select/poll/kq, and
1190          * wakeup anyone blocked on our pipe.
1191          */
1192         cpipe->pipe_state |= PIPE_CLOSED | PIPE_REOF | PIPE_WEOF;
1193         pipewakeup(cpipe);
1194         if (cpipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) {
1195                 cpipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW);
1196                 wakeup(cpipe);
1197         }
1198
1199         /*
1200          * Disconnect from peer.
1201          */
1202         if ((ppipe = cpipe->pipe_peer) != NULL) {
1203                 lwkt_gettoken(&ppipe->pipe_rlock);
1204                 lwkt_gettoken(&ppipe->pipe_wlock);
1205                 ppipe->pipe_state |= PIPE_REOF | PIPE_WEOF;
1206                 pipewakeup(ppipe);
1207                 if (ppipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) {
1208                         ppipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW);
1209                         wakeup(ppipe);
1210                 }
1211                 if (SLIST_FIRST(&ppipe->pipe_kq.ki_note))
1212                         KNOTE(&ppipe->pipe_kq.ki_note, 0);
1213                 lwkt_reltoken(&ppipe->pipe_wlock);
1214                 lwkt_reltoken(&ppipe->pipe_rlock);
1215         }
1216
1217         /*
1218          * If the peer is also closed we can free resources for both
1219          * sides, otherwise we leave our side intact to deal with any
1220          * races (since we only have the slock).
1221          */
1222         if (ppipe && (ppipe->pipe_state & PIPE_CLOSED)) {
1223                 cpipe->pipe_peer = NULL;
1224                 ppipe->pipe_peer = NULL;
1225                 ppipe->pipe_slock = NULL;       /* we will free the slock */
1226                 pipeclose(ppipe);
1227                 ppipe = NULL;
1228         }
1229
1230         lwkt_reltoken(&cpipe->pipe_wlock);
1231         lwkt_reltoken(&cpipe->pipe_rlock);
1232         if (cpipe->pipe_slock)
1233                 lockmgr(cpipe->pipe_slock, LK_RELEASE);
1234
1235         /*
1236          * If we disassociated from our peer we can free resources
1237          */
1238         if (ppipe == NULL) {
1239                 gd = mycpu;
1240                 if (cpipe->pipe_slock) {
1241                         kfree(cpipe->pipe_slock, M_PIPE);
1242                         cpipe->pipe_slock = NULL;
1243                 }
1244                 if (gd->gd_pipeqcount >= pipe_maxcache ||
1245                     cpipe->pipe_buffer.size != PIPE_SIZE
1246                 ) {
1247                         pipe_free_kmem(cpipe);
1248                         kfree(cpipe, M_PIPE);
1249                 } else {
1250                         cpipe->pipe_state = 0;
1251                         cpipe->pipe_peer = gd->gd_pipeq;
1252                         gd->gd_pipeq = cpipe;
1253                         ++gd->gd_pipeqcount;
1254                 }
1255         }
1256 }
1257
1258 /*
1259  * MPALMOSTSAFE - acquires mplock
1260  */
1261 static int
1262 pipe_kqfilter(struct file *fp, struct knote *kn)
1263 {
1264         struct pipe *cpipe;
1265
1266         cpipe = (struct pipe *)kn->kn_fp->f_data;
1267
1268         switch (kn->kn_filter) {
1269         case EVFILT_READ:
1270                 kn->kn_fop = &pipe_rfiltops;
1271                 break;
1272         case EVFILT_WRITE:
1273                 kn->kn_fop = &pipe_wfiltops;
1274                 if (cpipe->pipe_peer == NULL) {
1275                         /* other end of pipe has been closed */
1276                         rel_mplock();
1277                         return (EPIPE);
1278                 }
1279                 break;
1280         default:
1281                 return (EOPNOTSUPP);
1282         }
1283         kn->kn_hook = (caddr_t)cpipe;
1284
1285         knote_insert(&cpipe->pipe_kq.ki_note, kn);
1286
1287         return (0);
1288 }
1289
1290 static void
1291 filt_pipedetach(struct knote *kn)
1292 {
1293         struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1294
1295         knote_remove(&cpipe->pipe_kq.ki_note, kn);
1296 }
1297
1298 /*ARGSUSED*/
1299 static int
1300 filt_piperead(struct knote *kn, long hint)
1301 {
1302         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1303
1304         /* XXX RACE */
1305         kn->kn_data = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
1306         if (rpipe->pipe_state & PIPE_REOF) {
1307                 kn->kn_flags |= EV_EOF;
1308                 return (1);
1309         }
1310
1311         return (kn->kn_data > 0);
1312 }
1313
1314 /*ARGSUSED*/
1315 static int
1316 filt_pipewrite(struct knote *kn, long hint)
1317 {
1318         struct pipe *wpipe = (struct pipe *)kn->kn_fp->f_data;
1319         u_int32_t space;
1320
1321         /* XXX RACE */
1322         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_WEOF)) {
1323                 kn->kn_data = 0;
1324                 kn->kn_flags |= EV_EOF;
1325                 return (1);
1326         }
1327         space = wpipe->pipe_buffer.windex -
1328                 wpipe->pipe_buffer.rindex;
1329         space = wpipe->pipe_buffer.size - space;
1330
1331         kn->kn_data = space;
1332         return (kn->kn_data >= PIPE_BUF);
1333 }