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 1.27 2005/03/09 02:22:31 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
  30 /*
  31  * This code has two modes of operation, a small write mode and a large
  32  * write mode.  The small write mode acts like conventional pipes with
  33  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
  34  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
  35  * and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and
  36  * the receiving process can copy it directly from the pages in the sending
  37  * process.
  38  *
  39  * If the sending process receives a signal, it is possible that it will
  40  * go away, and certainly its address space can change, because control
  41  * is returned back to the user-mode side.  In that case, the pipe code
  42  * arranges to copy the buffer supplied by the user process, to a pageable
  43  * kernel buffer, and the receiving process will grab the data from the
  44  * pageable kernel buffer.  Since signals don't happen all that often,
  45  * the copy operation is normally eliminated.
  46  *
  47  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
  48  * happen for small transfers so that the system will not spend all of
  49  * its time context switching.  PIPE_SIZE is constrained by the
  50  * amount of kernel virtual memory.
  51  */
  52
  53 #include <sys/param.h>
  54 #include <sys/systm.h>
  55 #include <sys/kernel.h>
  56 #include <sys/proc.h>
  57 #include <sys/fcntl.h>
  58 #include <sys/file.h>
  59 #include <sys/filedesc.h>
  60 #include <sys/filio.h>
  61 #include <sys/ttycom.h>
  62 #include <sys/stat.h>
  63 #include <sys/poll.h>
  64 #include <sys/select.h>
  65 #include <sys/signalvar.h>
  66 #include <sys/sysproto.h>
  67 #include <sys/pipe.h>
  68 #include <sys/vnode.h>
  69 #include <sys/uio.h>
  70 #include <sys/event.h>
  71 #include <sys/globaldata.h>
  72 #include <sys/module.h>
  73 #include <sys/malloc.h>
  74 #include <sys/sysctl.h>
  75
  76 #include <vm/vm.h>
  77 #include <vm/vm_param.h>
  78 #include <sys/lock.h>
  79 #include <vm/vm_object.h>
  80 #include <vm/vm_kern.h>
  81 #include <vm/vm_extern.h>
  82 #include <vm/pmap.h>
  83 #include <vm/vm_map.h>
  84 #include <vm/vm_page.h>
  85 #include <vm/vm_zone.h>
  86
  87 #include <sys/file2.h>
  88
  89 #include <machine/cpufunc.h>
  90
  91 /*
  92  * interfaces to the outside world
  93  */
  94 static int pipe_read (struct file *fp, struct uio *uio,
  95                 struct ucred *cred, int flags, struct thread *td);
  96 static int pipe_write (struct file *fp, struct uio *uio,
  97                 struct ucred *cred, int flags, struct thread *td);
  98 static int pipe_close (struct file *fp, struct thread *td);
  99 static int pipe_poll (struct file *fp, int events, struct ucred *cred,
 100                 struct thread *td);
 101 static int pipe_kqfilter (struct file *fp, struct knote *kn);
 102 static int pipe_stat (struct file *fp, struct stat *sb, struct thread *td);
 103 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, struct thread *td);
 104
 105 static struct fileops pipeops = {
 106         NULL,   /* port */
 107         NULL,   /* clone */
 108         pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter,
 109         pipe_stat, pipe_close
 110 };
 111
 112 static void     filt_pipedetach(struct knote *kn);
 113 static int      filt_piperead(struct knote *kn, long hint);
 114 static int      filt_pipewrite(struct knote *kn, long hint);
 115
 116 static struct filterops pipe_rfiltops =
 117         { 1, NULL, filt_pipedetach, filt_piperead };
 118 static struct filterops pipe_wfiltops =
 119         { 1, NULL, filt_pipedetach, filt_pipewrite };
 120
 121 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures");
 122
 123 /*
 124  * Default pipe buffer size(s), this can be kind-of large now because pipe
 125  * space is pageable.  The pipe code will try to maintain locality of
 126  * reference for performance reasons, so small amounts of outstanding I/O
 127  * will not wipe the cache.
 128  */
 129 #define MINPIPESIZE (PIPE_SIZE/3)
 130 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 131
 132 /*
 133  * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
 134  * is there so that on large systems, we don't exhaust it.
 135  */
 136 #define MAXPIPEKVA (8*1024*1024)
 137
 138 /*
 139  * Limit for direct transfers, we cannot, of course limit
 140  * the amount of kva for pipes in general though.
 141  */
 142 #define LIMITPIPEKVA (16*1024*1024)
 143
 144 /*
 145  * Limit the number of "big" pipes
 146  */
 147 #define LIMITBIGPIPES   32
 148 #define PIPEQ_MAX_CACHE 16      /* per-cpu pipe structure cache */
 149
 150 static int pipe_maxbig = LIMITBIGPIPES;
 151 static int pipe_maxcache = PIPEQ_MAX_CACHE;
 152 static int pipe_nbig;
 153 static int pipe_bcache_alloc;
 154 static int pipe_bkmem_alloc;
 155 static int pipe_dwrite_enable = 1;      /* 0:copy, 1:kmem/sfbuf 2:force */
 156 static int pipe_dwrite_sfbuf = 1;       /* 0:kmem_map 1:sfbufs 2:sfbufs_dmap */
 157                                         /* 3:sfbuf_dmap w/ forced invlpg */
 158
 159 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation");
 160 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig,
 161         CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated");
 162 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache,
 163         CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu");
 164 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig,
 165         CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes");
 166 SYSCTL_INT(_kern_pipe, OID_AUTO, dwrite_enable,
 167         CTLFLAG_RW, &pipe_dwrite_enable, 0, "1:enable/2:force direct writes");
 168 SYSCTL_INT(_kern_pipe, OID_AUTO, dwrite_sfbuf,
 169         CTLFLAG_RW, &pipe_dwrite_sfbuf, 0,
 170         "(if dwrite_enable) 0:kmem 1:sfbuf 2:sfbuf_dmap 3:sfbuf_dmap_forceinvlpg");
 171 #if !defined(NO_PIPE_SYSCTL_STATS)
 172 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc,
 173         CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache");
 174 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc,
 175         CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem");
 176 #endif
 177
 178 static void pipeclose (struct pipe *cpipe);
 179 static void pipe_free_kmem (struct pipe *cpipe);
 180 static int pipe_create (struct pipe **cpipep);
 181 static __inline int pipelock (struct pipe *cpipe, int catch);
 182 static __inline void pipeunlock (struct pipe *cpipe);
 183 static __inline void pipeselwakeup (struct pipe *cpipe);
 184 #ifndef PIPE_NODIRECT
 185 static int pipe_build_write_buffer (struct pipe *wpipe, struct uio *uio);
 186 static int pipe_direct_write (struct pipe *wpipe, struct uio *uio);
 187 static void pipe_clone_write_buffer (struct pipe *wpipe);
 188 #endif
 189 static int pipespace (struct pipe *cpipe, int size);
 190
 191 /*
 192  * The pipe system call for the DTYPE_PIPE type of pipes
 193  *
 194  * pipe_ARgs(int dummy)
 195  */
 196
 197 /* ARGSUSED */
 198 int
 199 pipe(struct pipe_args *uap)
 200 {
 201         struct thread *td = curthread;
 202         struct proc *p = td->td_proc;
 203         struct filedesc *fdp;
 204         struct file *rf, *wf;
 205         struct pipe *rpipe, *wpipe;
 206         int fd1, fd2, error;
 207
 208         KKASSERT(p);
 209         fdp = p->p_fd;
 210
 211         rpipe = wpipe = NULL;
 212         if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
 213                 pipeclose(rpipe);
 214                 pipeclose(wpipe);
 215                 return (ENFILE);
 216         }
 217
 218         rpipe->pipe_state |= PIPE_DIRECTOK;
 219         wpipe->pipe_state |= PIPE_DIRECTOK;
 220
 221         /*
 222          * Select the direct-map features to use for this pipe.  Since the
 223          * sysctl's can change on the fly we record the settings when the
 224          * pipe is created.
 225          *
 226          * Generally speaking the system will default to what we consider
 227          * to be the best-balanced and most stable option.  Right now this
 228          * is SFBUF1.  Modes 2 and 3 are considered experiemental at the
 229          * moment.
 230          */
 231         wpipe->pipe_feature = PIPE_COPY;
 232         if (pipe_dwrite_enable) {
 233                 switch(pipe_dwrite_sfbuf) {
 234                 case 0:
 235                         wpipe->pipe_feature = PIPE_KMEM;
 236                         break;
 237                 case 1:
 238                         wpipe->pipe_feature = PIPE_SFBUF1;
 239                         break;
 240                 case 2:
 241                 case 3:
 242                         wpipe->pipe_feature = PIPE_SFBUF2;
 243                         break;
 244                 }
 245         }
 246         rpipe->pipe_feature = wpipe->pipe_feature;
 247
 248         error = falloc(p, &rf, &fd1);
 249         if (error) {
 250                 pipeclose(rpipe);
 251                 pipeclose(wpipe);
 252                 return (error);
 253         }
 254         uap->sysmsg_fds[0] = fd1;
 255
 256         /*
 257          * Warning: once we've gotten past allocation of the fd for the
 258          * read-side, we can only drop the read side via fdrop() in order
 259          * to avoid races against processes which manage to dup() the read
 260          * side while we are blocked trying to allocate the write side.
 261          */
 262         rf->f_flag = FREAD | FWRITE;
 263         rf->f_type = DTYPE_PIPE;
 264         rf->f_data = (caddr_t)rpipe;
 265         rf->f_ops = &pipeops;
 266         error = falloc(p, &wf, &fd2);
 267         if (error) {
 268                 if (fdp->fd_ofiles[fd1] == rf) {
 269                         fdp->fd_ofiles[fd1] = NULL;
 270                         fdrop(rf, td);
 271                 }
 272                 fdrop(rf, td);
 273                 /* rpipe has been closed by fdrop(). */
 274                 pipeclose(wpipe);
 275                 return (error);
 276         }
 277         wf->f_flag = FREAD | FWRITE;
 278         wf->f_type = DTYPE_PIPE;
 279         wf->f_data = (caddr_t)wpipe;
 280         wf->f_ops = &pipeops;
 281         uap->sysmsg_fds[1] = fd2;
 282
 283         rpipe->pipe_peer = wpipe;
 284         wpipe->pipe_peer = rpipe;
 285         fdrop(rf, td);
 286         fdrop(wf, td);
 287
 288         return (0);
 289 }
 290
 291 /*
 292  * Allocate kva for pipe circular buffer, the space is pageable
 293  * This routine will 'realloc' the size of a pipe safely, if it fails
 294  * it will retain the old buffer.
 295  * If it fails it will return ENOMEM.
 296  */
 297 static int
 298 pipespace(struct pipe *cpipe, int size)
 299 {
 300         struct vm_object *object;
 301         caddr_t buffer;
 302         int npages, error;
 303
 304         npages = round_page(size) / PAGE_SIZE;
 305         object = cpipe->pipe_buffer.object;
 306
 307         /*
 308          * [re]create the object if necessary and reserve space for it
 309          * in the kernel_map.  The object and memory are pageable.  On
 310          * success, free the old resources before assigning the new
 311          * ones.
 312          */
 313         if (object == NULL || object->size != npages) {
 314                 object = vm_object_allocate(OBJT_DEFAULT, npages);
 315                 buffer = (caddr_t) vm_map_min(kernel_map);
 316
 317                 error = vm_map_find(kernel_map, object, 0,
 318                         (vm_offset_t *) &buffer, size, 1,
 319                         VM_PROT_ALL, VM_PROT_ALL, 0);
 320
 321                 if (error != KERN_SUCCESS) {
 322                         vm_object_deallocate(object);
 323                         return (ENOMEM);
 324                 }
 325                 pipe_free_kmem(cpipe);
 326                 cpipe->pipe_buffer.object = object;
 327                 cpipe->pipe_buffer.buffer = buffer;
 328                 cpipe->pipe_buffer.size = size;
 329                 ++pipe_bkmem_alloc;
 330         } else {
 331                 ++pipe_bcache_alloc;
 332         }
 333         cpipe->pipe_buffer.in = 0;
 334         cpipe->pipe_buffer.out = 0;
 335         cpipe->pipe_buffer.cnt = 0;
 336         return (0);
 337 }
 338
 339 /*
 340  * Initialize and allocate VM and memory for pipe, pulling the pipe from
 341  * our per-cpu cache if possible.  For now make sure it is sized for the
 342  * smaller PIPE_SIZE default.
 343  */
 344 static int
 345 pipe_create(cpipep)
 346         struct pipe **cpipep;
 347 {
 348         globaldata_t gd = mycpu;
 349         struct pipe *cpipe;
 350         int error;
 351
 352         if ((cpipe = gd->gd_pipeq) != NULL) {
 353                 gd->gd_pipeq = cpipe->pipe_peer;
 354                 --gd->gd_pipeqcount;
 355                 cpipe->pipe_peer = NULL;
 356         } else {
 357                 cpipe = malloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
 358         }
 359         *cpipep = cpipe;
 360         if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
 361                 return (error);
 362         vfs_timestamp(&cpipe->pipe_ctime);
 363         cpipe->pipe_atime = cpipe->pipe_ctime;
 364         cpipe->pipe_mtime = cpipe->pipe_ctime;
 365         return (0);
 366 }
 367
 368
 369 /*
 370  * lock a pipe for I/O, blocking other access
 371  */
 372 static __inline int
 373 pipelock(cpipe, catch)
 374         struct pipe *cpipe;
 375         int catch;
 376 {
 377         int error;
 378
 379         while (cpipe->pipe_state & PIPE_LOCK) {
 380                 cpipe->pipe_state |= PIPE_LWANT;
 381                 error = tsleep(cpipe, (catch ? PCATCH : 0), "pipelk", 0);
 382                 if (error != 0)
 383                         return (error);
 384         }
 385         cpipe->pipe_state |= PIPE_LOCK;
 386         return (0);
 387 }
 388
 389 /*
 390  * unlock a pipe I/O lock
 391  */
 392 static __inline void
 393 pipeunlock(cpipe)
 394         struct pipe *cpipe;
 395 {
 396
 397         cpipe->pipe_state &= ~PIPE_LOCK;
 398         if (cpipe->pipe_state & PIPE_LWANT) {
 399                 cpipe->pipe_state &= ~PIPE_LWANT;
 400                 wakeup(cpipe);
 401         }
 402 }
 403
 404 static __inline void
 405 pipeselwakeup(cpipe)
 406         struct pipe *cpipe;
 407 {
 408
 409         if (cpipe->pipe_state & PIPE_SEL) {
 410                 cpipe->pipe_state &= ~PIPE_SEL;
 411                 selwakeup(&cpipe->pipe_sel);
 412         }
 413         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 414                 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
 415         KNOTE(&cpipe->pipe_sel.si_note, 0);
 416 }
 417
 418 /* ARGSUSED */
 419 static int
 420 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred,
 421         int flags, struct thread *td)
 422 {
 423         struct pipe *rpipe = (struct pipe *) fp->f_data;
 424         int error;
 425         int nread = 0;
 426         u_int size;
 427
 428         ++rpipe->pipe_busy;
 429         error = pipelock(rpipe, 1);
 430         if (error)
 431                 goto unlocked_error;
 432
 433         while (uio->uio_resid) {
 434                 caddr_t va;
 435
 436                 if (rpipe->pipe_buffer.cnt > 0) {
 437                         /*
 438                          * normal pipe buffer receive
 439                          */
 440                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 441                         if (size > rpipe->pipe_buffer.cnt)
 442                                 size = rpipe->pipe_buffer.cnt;
 443                         if (size > (u_int) uio->uio_resid)
 444                                 size = (u_int) uio->uio_resid;
 445
 446                         error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 447                                         size, uio);
 448                         if (error)
 449                                 break;
 450
 451                         rpipe->pipe_buffer.out += size;
 452                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 453                                 rpipe->pipe_buffer.out = 0;
 454
 455                         rpipe->pipe_buffer.cnt -= size;
 456
 457                         /*
 458                          * If there is no more to read in the pipe, reset
 459                          * its pointers to the beginning.  This improves
 460                          * cache hit stats.
 461                          */
 462                         if (rpipe->pipe_buffer.cnt == 0) {
 463                                 rpipe->pipe_buffer.in = 0;
 464                                 rpipe->pipe_buffer.out = 0;
 465                         }
 466                         nread += size;
 467 #ifndef PIPE_NODIRECT
 468                 } else if (rpipe->pipe_kva &&
 469                            rpipe->pipe_feature == PIPE_KMEM &&
 470                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
 471                                == PIPE_DIRECTW
 472                 ) {
 473                         /*
 474                          * Direct copy using source-side kva mapping
 475                          */
 476                         size = rpipe->pipe_map.xio_bytes -
 477                                 rpipe->pipe_buffer.out;
 478                         if (size > (u_int)uio->uio_resid)
 479                                 size = (u_int)uio->uio_resid;
 480                         va = (caddr_t)rpipe->pipe_kva +
 481                                 xio_kvaoffset(&rpipe->pipe_map, rpipe->pipe_buffer.out);
 482                         error = uiomove(va, size, uio);
 483                         if (error)
 484                                 break;
 485                         nread += size;
 486                         rpipe->pipe_buffer.out += size;
 487                         if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
 488                                 rpipe->pipe_state |= PIPE_DIRECTIP;
 489                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 490                                 /* reset out index for copy mode */
 491                                 rpipe->pipe_buffer.out = 0;
 492                                 wakeup(rpipe);
 493                         }
 494                 } else if (rpipe->pipe_buffer.out != rpipe->pipe_map.xio_bytes &&
 495                            rpipe->pipe_kva &&
 496                            rpipe->pipe_feature == PIPE_SFBUF2 &&
 497                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
 498                                == PIPE_DIRECTW
 499                 ) {
 500                         /*
 501                          * Direct copy, bypassing a kernel buffer.  We cannot
 502                          * mess with the direct-write buffer until
 503                          * PIPE_DIRECTIP is cleared.  In order to prevent
 504                          * the pipe_write code from racing itself in
 505                          * direct_write, we set DIRECTIP when we clear
 506                          * DIRECTW after we have exhausted the buffer.
 507                          */
 508                         if (pipe_dwrite_sfbuf == 3)
 509                                 rpipe->pipe_kvamask = 0;
 510                         pmap_qenter2(rpipe->pipe_kva, rpipe->pipe_map.xio_pages,
 511                                     rpipe->pipe_map.xio_npages,
 512                                     &rpipe->pipe_kvamask);
 513                         size = rpipe->pipe_map.xio_bytes -
 514                                 rpipe->pipe_buffer.out;
 515                         if (size > (u_int)uio->uio_resid)
 516                                 size = (u_int)uio->uio_resid;
 517                         va = (caddr_t)rpipe->pipe_kva + xio_kvaoffset(&rpipe->pipe_map, rpipe->pipe_buffer.out);
 518                         error = uiomove(va, size, uio);
 519                         if (error)
 520                                 break;
 521                         nread += size;
 522                         rpipe->pipe_buffer.out += size;
 523                         if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
 524                                 rpipe->pipe_state |= PIPE_DIRECTIP;
 525                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 526                                 /* reset out index for copy mode */
 527                                 rpipe->pipe_buffer.out = 0;
 528                                 wakeup(rpipe);
 529                         }
 530                 } else if (rpipe->pipe_buffer.out != rpipe->pipe_map.xio_bytes &&
 531                            rpipe->pipe_feature == PIPE_SFBUF1 &&
 532                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
 533                                 == PIPE_DIRECTW
 534                 ) {
 535                         /*
 536                          * Direct copy, bypassing a kernel buffer.  We cannot
 537                          * mess with the direct-write buffer until
 538                          * PIPE_DIRECTIP is cleared.  In order to prevent
 539                          * the pipe_write code from racing itself in
 540                          * direct_write, we set DIRECTIP when we clear
 541                          * DIRECTW after we have exhausted the buffer.
 542                          */
 543                         error = xio_uio_copy(&rpipe->pipe_map, rpipe->pipe_buffer.out, uio, &size);
 544                         if (error)
 545                                 break;
 546                         nread += size;
 547                         rpipe->pipe_buffer.out += size;
 548                         if (rpipe->pipe_buffer.out == rpipe->pipe_map.xio_bytes) {
 549                                 rpipe->pipe_state |= PIPE_DIRECTIP;
 550                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 551                                 /* reset out index for copy mode */
 552                                 rpipe->pipe_buffer.out = 0;
 553                                 wakeup(rpipe);
 554                         }
 555 #endif
 556                 } else {
 557                         /*
 558                          * detect EOF condition
 559                          * read returns 0 on EOF, no need to set error
 560                          */
 561                         if (rpipe->pipe_state & PIPE_EOF)
 562                                 break;
 563
 564                         /*
 565                          * If the "write-side" has been blocked, wake it up now.
 566                          */
 567                         if (rpipe->pipe_state & PIPE_WANTW) {
 568                                 rpipe->pipe_state &= ~PIPE_WANTW;
 569                                 wakeup(rpipe);
 570                         }
 571
 572                         /*
 573                          * Break if some data was read.
 574                          */
 575                         if (nread > 0)
 576                                 break;
 577
 578                         /*
 579                          * Unlock the pipe buffer for our remaining
 580                          * processing.  We will either break out with an
 581                          * error or we will sleep and relock to loop.
 582                          */
 583                         pipeunlock(rpipe);
 584
 585                         /*
 586                          * Handle non-blocking mode operation or
 587                          * wait for more data.
 588                          */
 589                         if (fp->f_flag & FNONBLOCK) {
 590                                 error = EAGAIN;
 591                         } else {
 592                                 rpipe->pipe_state |= PIPE_WANTR;
 593                                 if ((error = tsleep(rpipe, PCATCH|PNORESCHED,
 594                                     "piperd", 0)) == 0) {
 595                                         error = pipelock(rpipe, 1);
 596                                 }
 597                         }
 598                         if (error)
 599                                 goto unlocked_error;
 600                 }
 601         }
 602         pipeunlock(rpipe);
 603
 604         if (error == 0)
 605                 vfs_timestamp(&rpipe->pipe_atime);
 606 unlocked_error:
 607         --rpipe->pipe_busy;
 608
 609         /*
 610          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 611          */
 612         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 613                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 614                 wakeup(rpipe);
 615         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 616                 /*
 617                  * Handle write blocking hysteresis.
 618                  */
 619                 if (rpipe->pipe_state & PIPE_WANTW) {
 620                         rpipe->pipe_state &= ~PIPE_WANTW;
 621                         wakeup(rpipe);
 622                 }
 623         }
 624
 625         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 626                 pipeselwakeup(rpipe);
 627         return (error);
 628 }
 629
 630 #ifndef PIPE_NODIRECT
 631 /*
 632  * Map the sending processes' buffer into kernel space and wire it.
 633  * This is similar to a physical write operation.
 634  */
 635 static int
 636 pipe_build_write_buffer(wpipe, uio)
 637         struct pipe *wpipe;
 638         struct uio *uio;
 639 {
 640         int error;
 641         u_int size;
 642
 643         size = (u_int) uio->uio_iov->iov_len;
 644         if (size > wpipe->pipe_buffer.size)
 645                 size = wpipe->pipe_buffer.size;
 646
 647         error = xio_init_ubuf(&wpipe->pipe_map, uio->uio_iov->iov_base,
 648                                 size, XIOF_READ);
 649         wpipe->pipe_buffer.out = 0;
 650         if (error)
 651                 return(error);
 652
 653         /*
 654          * Create a kernel map for KMEM and SFBUF2 copy modes.  SFBUF2 will
 655          * map the pages on the target while KMEM maps the pages now.
 656          */
 657         switch(wpipe->pipe_feature) {
 658         case PIPE_KMEM:
 659         case PIPE_SFBUF2:
 660                 if (wpipe->pipe_kva == NULL) {
 661                         wpipe->pipe_kva =
 662                             kmem_alloc_nofault(kernel_map, XIO_INTERNAL_SIZE);
 663                         wpipe->pipe_kvamask = 0;
 664                 }
 665                 if (wpipe->pipe_feature == PIPE_KMEM) {
 666                         pmap_qenter(wpipe->pipe_kva, wpipe->pipe_map.xio_pages,
 667                                     wpipe->pipe_map.xio_npages);
 668                 }
 669                 break;
 670         default:
 671                 break;
 672         }
 673
 674         /*
 675          * And update the uio data.  The XIO might have loaded fewer bytes
 676          * then requested so reload 'size'.
 677          */
 678         size = wpipe->pipe_map.xio_bytes;
 679         uio->uio_iov->iov_len -= size;
 680         uio->uio_iov->iov_base += size;
 681         if (uio->uio_iov->iov_len == 0)
 682                 uio->uio_iov++;
 683         uio->uio_resid -= size;
 684         uio->uio_offset += size;
 685         return (0);
 686 }
 687
 688 /*
 689  * In the case of a signal, the writing process might go away.  This
 690  * code copies the data into the circular buffer so that the source
 691  * pages can be freed without loss of data.
 692  *
 693  * Note that in direct mode pipe_buffer.out is used to track the
 694  * XIO offset.  We are converting the direct mode into buffered mode
 695  * which changes the meaning of pipe_buffer.out.
 696  */
 697 static void
 698 pipe_clone_write_buffer(wpipe)
 699         struct pipe *wpipe;
 700 {
 701         int size;
 702         int offset;
 703
 704         offset = wpipe->pipe_buffer.out;
 705         size = wpipe->pipe_map.xio_bytes - offset;
 706
 707         KKASSERT(size <= wpipe->pipe_buffer.size);
 708
 709         wpipe->pipe_buffer.in = size;
 710         wpipe->pipe_buffer.out = 0;
 711         wpipe->pipe_buffer.cnt = size;
 712         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
 713
 714         xio_copy_xtok(&wpipe->pipe_map, offset, wpipe->pipe_buffer.buffer, size);
 715         xio_release(&wpipe->pipe_map);
 716         if (wpipe->pipe_kva) {
 717                 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
 718                 kmem_free(kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
 719                 wpipe->pipe_kva = NULL;
 720         }
 721 }
 722
 723 /*
 724  * This implements the pipe buffer write mechanism.  Note that only
 725  * a direct write OR a normal pipe write can be pending at any given time.
 726  * If there are any characters in the pipe buffer, the direct write will
 727  * be deferred until the receiving process grabs all of the bytes from
 728  * the pipe buffer.  Then the direct mapping write is set-up.
 729  */
 730 static int
 731 pipe_direct_write(wpipe, uio)
 732         struct pipe *wpipe;
 733         struct uio *uio;
 734 {
 735         int error;
 736
 737 retry:
 738         while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
 739                 if (wpipe->pipe_state & PIPE_WANTR) {
 740                         wpipe->pipe_state &= ~PIPE_WANTR;
 741                         wakeup(wpipe);
 742                 }
 743                 wpipe->pipe_state |= PIPE_WANTW;
 744                 error = tsleep(wpipe, PCATCH, "pipdww", 0);
 745                 if (error)
 746                         goto error2;
 747                 if (wpipe->pipe_state & PIPE_EOF) {
 748                         error = EPIPE;
 749                         goto error2;
 750                 }
 751         }
 752         KKASSERT(wpipe->pipe_map.xio_bytes == 0);
 753         if (wpipe->pipe_buffer.cnt > 0) {
 754                 if (wpipe->pipe_state & PIPE_WANTR) {
 755                         wpipe->pipe_state &= ~PIPE_WANTR;
 756                         wakeup(wpipe);
 757                 }
 758
 759                 wpipe->pipe_state |= PIPE_WANTW;
 760                 error = tsleep(wpipe, PCATCH, "pipdwc", 0);
 761                 if (error)
 762                         goto error2;
 763                 if (wpipe->pipe_state & PIPE_EOF) {
 764                         error = EPIPE;
 765                         goto error2;
 766                 }
 767                 goto retry;
 768         }
 769
 770         /*
 771          * Build our direct-write buffer
 772          */
 773         wpipe->pipe_state |= PIPE_DIRECTW | PIPE_DIRECTIP;
 774         error = pipe_build_write_buffer(wpipe, uio);
 775         if (error)
 776                 goto error1;
 777         wpipe->pipe_state &= ~PIPE_DIRECTIP;
 778
 779         /*
 780          * Wait until the receiver has snarfed the data.  Since we are likely
 781          * going to sleep we optimize the case and yield synchronously,
 782          * possibly avoiding the tsleep().
 783          */
 784         error = 0;
 785         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
 786                 if (wpipe->pipe_state & PIPE_EOF) {
 787                         pipelock(wpipe, 0);
 788                         xio_release(&wpipe->pipe_map);
 789                         if (wpipe->pipe_kva) {
 790                                 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
 791                                 kmem_free(kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
 792                                 wpipe->pipe_kva = NULL;
 793                         }
 794                         pipeunlock(wpipe);
 795                         pipeselwakeup(wpipe);
 796                         error = EPIPE;
 797                         goto error1;
 798                 }
 799                 if (wpipe->pipe_state & PIPE_WANTR) {
 800                         wpipe->pipe_state &= ~PIPE_WANTR;
 801                         wakeup(wpipe);
 802                 }
 803                 pipeselwakeup(wpipe);
 804                 error = tsleep(wpipe, PCATCH|PNORESCHED, "pipdwt", 0);
 805         }
 806         pipelock(wpipe,0);
 807         if (wpipe->pipe_state & PIPE_DIRECTW) {
 808                 /*
 809                  * this bit of trickery substitutes a kernel buffer for
 810                  * the process that might be going away.
 811                  */
 812                 pipe_clone_write_buffer(wpipe);
 813                 KKASSERT((wpipe->pipe_state & PIPE_DIRECTIP) == 0);
 814         } else {
 815                 /*
 816                  * note: The pipe_kva mapping is not qremove'd here.  For
 817                  * legacy PIPE_KMEM mode this constitutes an improvement
 818                  * over the original FreeBSD-4 algorithm.  For PIPE_SFBUF2
 819                  * mode the kva mapping must not be removed to get the
 820                  * caching benefit.
 821                  *
 822                  * For testing purposes we will give the original algorithm
 823                  * the benefit of the doubt 'what it could have been', and
 824                  * keep the optimization.
 825                  */
 826                 KKASSERT(wpipe->pipe_state & PIPE_DIRECTIP);
 827                 xio_release(&wpipe->pipe_map);
 828                 wpipe->pipe_state &= ~PIPE_DIRECTIP;
 829         }
 830         pipeunlock(wpipe);
 831         return (error);
 832
 833         /*
 834          * Direct-write error, clear the direct write flags.
 835          */
 836 error1:
 837         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
 838         /* fallthrough */
 839
 840         /*
 841          * General error, wakeup the other side if it happens to be sleeping.
 842          */
 843 error2:
 844         wakeup(wpipe);
 845         return (error);
 846 }
 847 #endif
 848
 849 static int
 850 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred,
 851         int flags, struct thread *td)
 852 {
 853         int error = 0;
 854         int orig_resid;
 855         struct pipe *wpipe, *rpipe;
 856
 857         rpipe = (struct pipe *) fp->f_data;
 858         wpipe = rpipe->pipe_peer;
 859
 860         /*
 861          * detect loss of pipe read side, issue SIGPIPE if lost.
 862          */
 863         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 864                 return (EPIPE);
 865         }
 866         ++wpipe->pipe_busy;
 867
 868         /*
 869          * If it is advantageous to resize the pipe buffer, do
 870          * so.
 871          */
 872         if ((uio->uio_resid > PIPE_SIZE) &&
 873                 (pipe_nbig < pipe_maxbig) &&
 874                 (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) == 0 &&
 875                 (wpipe->pipe_buffer.size <= PIPE_SIZE) &&
 876                 (wpipe->pipe_buffer.cnt == 0)) {
 877
 878                 if ((error = pipelock(wpipe,1)) == 0) {
 879                         if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
 880                                 pipe_nbig++;
 881                         pipeunlock(wpipe);
 882                 }
 883         }
 884
 885         /*
 886          * If an early error occured unbusy and return, waking up any pending
 887          * readers.
 888          */
 889         if (error) {
 890                 --wpipe->pipe_busy;
 891                 if ((wpipe->pipe_busy == 0) &&
 892                     (wpipe->pipe_state & PIPE_WANT)) {
 893                         wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
 894                         wakeup(wpipe);
 895                 }
 896                 return(error);
 897         }
 898
 899         KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone"));
 900
 901         orig_resid = uio->uio_resid;
 902
 903         while (uio->uio_resid) {
 904                 int space;
 905
 906 #ifndef PIPE_NODIRECT
 907                 /*
 908                  * If the transfer is large, we can gain performance if
 909                  * we do process-to-process copies directly.
 910                  * If the write is non-blocking, we don't use the
 911                  * direct write mechanism.
 912                  *
 913                  * The direct write mechanism will detect the reader going
 914                  * away on us.
 915                  */
 916                 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT ||
 917                     pipe_dwrite_enable > 1) &&
 918                     (fp->f_flag & FNONBLOCK) == 0 &&
 919                     pipe_dwrite_enable) {
 920                         error = pipe_direct_write( wpipe, uio);
 921                         if (error)
 922                                 break;
 923                         continue;
 924                 }
 925 #endif
 926
 927                 /*
 928                  * Pipe buffered writes cannot be coincidental with
 929                  * direct writes.  We wait until the currently executing
 930                  * direct write is completed before we start filling the
 931                  * pipe buffer.  We break out if a signal occurs or the
 932                  * reader goes away.
 933                  */
 934         retrywrite:
 935                 while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
 936                         if (wpipe->pipe_state & PIPE_WANTR) {
 937                                 wpipe->pipe_state &= ~PIPE_WANTR;
 938                                 wakeup(wpipe);
 939                         }
 940                         error = tsleep(wpipe, PCATCH, "pipbww", 0);
 941                         if (wpipe->pipe_state & PIPE_EOF)
 942                                 break;
 943                         if (error)
 944                                 break;
 945                 }
 946                 if (wpipe->pipe_state & PIPE_EOF) {
 947                         error = EPIPE;
 948                         break;
 949                 }
 950
 951                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
 952
 953                 /* Writes of size <= PIPE_BUF must be atomic. */
 954                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
 955                         space = 0;
 956
 957                 /*
 958                  * Write to fill, read size handles write hysteresis.  Also
 959                  * additional restrictions can cause select-based non-blocking
 960                  * writes to spin.
 961                  */
 962                 if (space > 0) {
 963                         if ((error = pipelock(wpipe,1)) == 0) {
 964                                 int size;       /* Transfer size */
 965                                 int segsize;    /* first segment to transfer */
 966
 967                                 /*
 968                                  * It is possible for a direct write to
 969                                  * slip in on us... handle it here...
 970                                  */
 971                                 if (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
 972                                         pipeunlock(wpipe);
 973                                         goto retrywrite;
 974                                 }
 975                                 /*
 976                                  * If a process blocked in uiomove, our
 977                                  * value for space might be bad.
 978                                  *
 979                                  * XXX will we be ok if the reader has gone
 980                                  * away here?
 981                                  */
 982                                 if (space > wpipe->pipe_buffer.size -
 983                                     wpipe->pipe_buffer.cnt) {
 984                                         pipeunlock(wpipe);
 985                                         goto retrywrite;
 986                                 }
 987
 988                                 /*
 989                                  * Transfer size is minimum of uio transfer
 990                                  * and free space in pipe buffer.
 991                                  */
 992                                 if (space > uio->uio_resid)
 993                                         size = uio->uio_resid;
 994                                 else
 995                                         size = space;
 996                                 /*
 997                                  * First segment to transfer is minimum of
 998                                  * transfer size and contiguous space in
 999                                  * pipe buffer.  If first segment to transfer
1000                                  * is less than the transfer size, we've got
1001                                  * a wraparound in the buffer.
1002                                  */
1003                                 segsize = wpipe->pipe_buffer.size -
1004                                         wpipe->pipe_buffer.in;
1005                                 if (segsize > size)
1006                                         segsize = size;
1007
1008                                 /* Transfer first segment */
1009
1010                                 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1011                                                 segsize, uio);
1012
1013                                 if (error == 0 && segsize < size) {
1014                                         /*
1015                                          * Transfer remaining part now, to
1016                                          * support atomic writes.  Wraparound
1017                                          * happened.
1018                                          */
1019                                         if (wpipe->pipe_buffer.in + segsize !=
1020                                             wpipe->pipe_buffer.size)
1021                                                 panic("Expected pipe buffer wraparound disappeared");
1022
1023                                         error = uiomove(&wpipe->pipe_buffer.buffer[0],
1024                                                         size - segsize, uio);
1025                                 }
1026                                 if (error == 0) {
1027                                         wpipe->pipe_buffer.in += size;
1028                                         if (wpipe->pipe_buffer.in >=
1029                                             wpipe->pipe_buffer.size) {
1030                                                 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
1031                                                         panic("Expected wraparound bad");
1032                                                 wpipe->pipe_buffer.in = size - segsize;
1033                                         }
1034
1035                                         wpipe->pipe_buffer.cnt += size;
1036                                         if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
1037                                                 panic("Pipe buffer overflow");
1038
1039                                 }
1040                                 pipeunlock(wpipe);
1041                         }
1042                         if (error)
1043                                 break;
1044
1045                 } else {
1046                         /*
1047                          * If the "read-side" has been blocked, wake it up now
1048                          * and yield to let it drain synchronously rather
1049                          * then block.
1050                          */
1051                         if (wpipe->pipe_state & PIPE_WANTR) {
1052                                 wpipe->pipe_state &= ~PIPE_WANTR;
1053                                 wakeup(wpipe);
1054                         }
1055
1056                         /*
1057                          * don't block on non-blocking I/O
1058                          */
1059                         if (fp->f_flag & FNONBLOCK) {
1060                                 error = EAGAIN;
1061                                 break;
1062                         }
1063
1064                         /*
1065                          * We have no more space and have something to offer,
1066                          * wake up select/poll.
1067                          */
1068                         pipeselwakeup(wpipe);
1069
1070                         wpipe->pipe_state |= PIPE_WANTW;
1071                         error = tsleep(wpipe, PCATCH|PNORESCHED, "pipewr", 0);
1072                         if (error != 0)
1073                                 break;
1074                         /*
1075                          * If read side wants to go away, we just issue a signal
1076                          * to ourselves.
1077                          */
1078                         if (wpipe->pipe_state & PIPE_EOF) {
1079                                 error = EPIPE;
1080                                 break;
1081                         }
1082                 }
1083         }
1084
1085         --wpipe->pipe_busy;
1086
1087         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1088                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1089                 wakeup(wpipe);
1090         } else if (wpipe->pipe_buffer.cnt > 0) {
1091                 /*
1092                  * If we have put any characters in the buffer, we wake up
1093                  * the reader.
1094                  */
1095                 if (wpipe->pipe_state & PIPE_WANTR) {
1096                         wpipe->pipe_state &= ~PIPE_WANTR;
1097                         wakeup(wpipe);
1098                 }
1099         }
1100
1101         /*
1102          * Don't return EPIPE if I/O was successful
1103          */
1104         if ((wpipe->pipe_buffer.cnt == 0) &&
1105             (uio->uio_resid == 0) &&
1106             (error == EPIPE)) {
1107                 error = 0;
1108         }
1109
1110         if (error == 0)
1111                 vfs_timestamp(&wpipe->pipe_mtime);
1112
1113         /*
1114          * We have something to offer,
1115          * wake up select/poll.
1116          */
1117         if (wpipe->pipe_buffer.cnt)
1118                 pipeselwakeup(wpipe);
1119
1120         return (error);
1121 }
1122
1123 /*
1124  * we implement a very minimal set of ioctls for compatibility with sockets.
1125  */
1126 int
1127 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct thread *td)
1128 {
1129         struct pipe *mpipe = (struct pipe *)fp->f_data;
1130
1131         switch (cmd) {
1132
1133         case FIONBIO:
1134                 return (0);
1135
1136         case FIOASYNC:
1137                 if (*(int *)data) {
1138                         mpipe->pipe_state |= PIPE_ASYNC;
1139                 } else {
1140                         mpipe->pipe_state &= ~PIPE_ASYNC;
1141                 }
1142                 return (0);
1143
1144         case FIONREAD:
1145                 if (mpipe->pipe_state & PIPE_DIRECTW) {
1146                         *(int *)data = mpipe->pipe_map.xio_bytes -
1147                                         mpipe->pipe_buffer.out;
1148                 } else {
1149                         *(int *)data = mpipe->pipe_buffer.cnt;
1150                 }
1151                 return (0);
1152
1153         case FIOSETOWN:
1154                 return (fsetown(*(int *)data, &mpipe->pipe_sigio));
1155
1156         case FIOGETOWN:
1157                 *(int *)data = fgetown(mpipe->pipe_sigio);
1158                 return (0);
1159
1160         /* This is deprecated, FIOSETOWN should be used instead. */
1161         case TIOCSPGRP:
1162                 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
1163
1164         /* This is deprecated, FIOGETOWN should be used instead. */
1165         case TIOCGPGRP:
1166                 *(int *)data = -fgetown(mpipe->pipe_sigio);
1167                 return (0);
1168
1169         }
1170         return (ENOTTY);
1171 }
1172
1173 int
1174 pipe_poll(struct file *fp, int events, struct ucred *cred, struct thread *td)
1175 {
1176         struct pipe *rpipe = (struct pipe *)fp->f_data;
1177         struct pipe *wpipe;
1178         int revents = 0;
1179
1180         wpipe = rpipe->pipe_peer;
1181         if (events & (POLLIN | POLLRDNORM))
1182                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1183                     (rpipe->pipe_buffer.cnt > 0) ||
1184                     (rpipe->pipe_state & PIPE_EOF))
1185                         revents |= events & (POLLIN | POLLRDNORM);
1186
1187         if (events & (POLLOUT | POLLWRNORM))
1188                 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) ||
1189                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1190                      (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1191                         revents |= events & (POLLOUT | POLLWRNORM);
1192
1193         if ((rpipe->pipe_state & PIPE_EOF) ||
1194             (wpipe == NULL) ||
1195             (wpipe->pipe_state & PIPE_EOF))
1196                 revents |= POLLHUP;
1197
1198         if (revents == 0) {
1199                 if (events & (POLLIN | POLLRDNORM)) {
1200                         selrecord(td, &rpipe->pipe_sel);
1201                         rpipe->pipe_state |= PIPE_SEL;
1202                 }
1203
1204                 if (events & (POLLOUT | POLLWRNORM)) {
1205                         selrecord(td, &wpipe->pipe_sel);
1206                         wpipe->pipe_state |= PIPE_SEL;
1207                 }
1208         }
1209
1210         return (revents);
1211 }
1212
1213 static int
1214 pipe_stat(struct file *fp, struct stat *ub, struct thread *td)
1215 {
1216         struct pipe *pipe = (struct pipe *)fp->f_data;
1217
1218         bzero((caddr_t)ub, sizeof(*ub));
1219         ub->st_mode = S_IFIFO;
1220         ub->st_blksize = pipe->pipe_buffer.size;
1221         ub->st_size = pipe->pipe_buffer.cnt;
1222         if (ub->st_size == 0 && (pipe->pipe_state & PIPE_DIRECTW)) {
1223                 ub->st_size = pipe->pipe_map.xio_bytes -
1224                                 pipe->pipe_buffer.out;
1225         }
1226         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1227         ub->st_atimespec = pipe->pipe_atime;
1228         ub->st_mtimespec = pipe->pipe_mtime;
1229         ub->st_ctimespec = pipe->pipe_ctime;
1230         /*
1231          * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1232          * st_flags, st_gen.
1233          * XXX (st_dev, st_ino) should be unique.
1234          */
1235         return (0);
1236 }
1237
1238 /* ARGSUSED */
1239 static int
1240 pipe_close(struct file *fp, struct thread *td)
1241 {
1242         struct pipe *cpipe = (struct pipe *)fp->f_data;
1243
1244         fp->f_ops = &badfileops;
1245         fp->f_data = NULL;
1246         funsetown(cpipe->pipe_sigio);
1247         pipeclose(cpipe);
1248         return (0);
1249 }
1250
1251 static void
1252 pipe_free_kmem(struct pipe *cpipe)
1253 {
1254         if (cpipe->pipe_buffer.buffer != NULL) {
1255                 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1256                         --pipe_nbig;
1257                 kmem_free(kernel_map,
1258                         (vm_offset_t)cpipe->pipe_buffer.buffer,
1259                         cpipe->pipe_buffer.size);
1260                 cpipe->pipe_buffer.buffer = NULL;
1261                 cpipe->pipe_buffer.object = NULL;
1262         }
1263 #ifndef PIPE_NODIRECT
1264         KKASSERT(cpipe->pipe_map.xio_bytes == 0 &&
1265                 cpipe->pipe_map.xio_offset == 0 &&
1266                 cpipe->pipe_map.xio_npages == 0);
1267 #endif
1268 }
1269
1270 /*
1271  * shutdown the pipe
1272  */
1273 static void
1274 pipeclose(struct pipe *cpipe)
1275 {
1276         globaldata_t gd;
1277         struct pipe *ppipe;
1278
1279         if (cpipe == NULL)
1280                 return;
1281
1282         pipeselwakeup(cpipe);
1283
1284         /*
1285          * If the other side is blocked, wake it up saying that
1286          * we want to close it down.
1287          */
1288         while (cpipe->pipe_busy) {
1289                 wakeup(cpipe);
1290                 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
1291                 tsleep(cpipe, 0, "pipecl", 0);
1292         }
1293
1294         /*
1295          * Disconnect from peer
1296          */
1297         if ((ppipe = cpipe->pipe_peer) != NULL) {
1298                 pipeselwakeup(ppipe);
1299
1300                 ppipe->pipe_state |= PIPE_EOF;
1301                 wakeup(ppipe);
1302                 KNOTE(&ppipe->pipe_sel.si_note, 0);
1303                 ppipe->pipe_peer = NULL;
1304         }
1305
1306         if (cpipe->pipe_kva) {
1307                 pmap_qremove(cpipe->pipe_kva, XIO_INTERNAL_PAGES);
1308                 kmem_free(kernel_map, cpipe->pipe_kva, XIO_INTERNAL_SIZE);
1309                 cpipe->pipe_kva = NULL;
1310         }
1311
1312         /*
1313          * free or cache resources
1314          */
1315         gd = mycpu;
1316         if (gd->gd_pipeqcount >= pipe_maxcache ||
1317             cpipe->pipe_buffer.size != PIPE_SIZE
1318         ) {
1319                 pipe_free_kmem(cpipe);
1320                 free(cpipe, M_PIPE);
1321         } else {
1322                 KKASSERT(cpipe->pipe_map.xio_npages == 0 &&
1323                         cpipe->pipe_map.xio_bytes == 0 &&
1324                         cpipe->pipe_map.xio_offset == 0);
1325                 cpipe->pipe_state = 0;
1326                 cpipe->pipe_busy = 0;
1327                 cpipe->pipe_peer = gd->gd_pipeq;
1328                 gd->gd_pipeq = cpipe;
1329                 ++gd->gd_pipeqcount;
1330         }
1331 }
1332
1333 /*ARGSUSED*/
1334 static int
1335 pipe_kqfilter(struct file *fp, struct knote *kn)
1336 {
1337         struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
1338
1339         switch (kn->kn_filter) {
1340         case EVFILT_READ:
1341                 kn->kn_fop = &pipe_rfiltops;
1342                 break;
1343         case EVFILT_WRITE:
1344                 kn->kn_fop = &pipe_wfiltops;
1345                 cpipe = cpipe->pipe_peer;
1346                 if (cpipe == NULL)
1347                         /* other end of pipe has been closed */
1348                         return (EPIPE);
1349                 break;
1350         default:
1351                 return (1);
1352         }
1353         kn->kn_hook = (caddr_t)cpipe;
1354
1355         SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1356         return (0);
1357 }
1358
1359 static void
1360 filt_pipedetach(struct knote *kn)
1361 {
1362         struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1363
1364         SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1365 }
1366
1367 /*ARGSUSED*/
1368 static int
1369 filt_piperead(struct knote *kn, long hint)
1370 {
1371         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1372         struct pipe *wpipe = rpipe->pipe_peer;
1373
1374         kn->kn_data = rpipe->pipe_buffer.cnt;
1375         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) {
1376                 kn->kn_data = rpipe->pipe_map.xio_bytes -
1377                                 rpipe->pipe_buffer.out;
1378         }
1379
1380         if ((rpipe->pipe_state & PIPE_EOF) ||
1381             (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1382                 kn->kn_flags |= EV_EOF;
1383                 return (1);
1384         }
1385         return (kn->kn_data > 0);
1386 }
1387
1388 /*ARGSUSED*/
1389 static int
1390 filt_pipewrite(struct knote *kn, long hint)
1391 {
1392         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1393         struct pipe *wpipe = rpipe->pipe_peer;
1394
1395         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1396                 kn->kn_data = 0;
1397                 kn->kn_flags |= EV_EOF;
1398                 return (1);
1399         }
1400         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1401         if (wpipe->pipe_state & PIPE_DIRECTW)
1402                 kn->kn_data = 0;
1403
1404         return (kn->kn_data >= PIPE_BUF);
1405 }