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