| 1 | /* |
| 2 | * Copyright (c) 1996 John S. Dyson |
| 3 | * All rights reserved. |
| 4 | * Copyright (c) 2003-2017 The DragonFly Project. All rights reserved. |
| 5 | * |
| 6 | * This code is derived from software contributed to The DragonFly Project |
| 7 | * by Matthew Dillon <dillon@backplane.com> |
| 8 | * |
| 9 | * Redistribution and use in source and binary forms, with or without |
| 10 | * modification, are permitted provided that the following conditions |
| 11 | * are met: |
| 12 | * 1. Redistributions of source code must retain the above copyright |
| 13 | * notice immediately at the beginning of the file, without modification, |
| 14 | * this list of conditions, and the following disclaimer. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * 3. Absolutely no warranty of function or purpose is made by the author |
| 19 | * John S. Dyson. |
| 20 | * 4. Modifications may be freely made to this file if the above conditions |
| 21 | * are met. |
| 22 | */ |
| 23 | |
| 24 | /* |
| 25 | * This file contains a high-performance replacement for the socket-based |
| 26 | * pipes scheme originally used in FreeBSD/4.4Lite. It does not support |
| 27 | * all features of sockets, but does do everything that pipes normally |
| 28 | * do. |
| 29 | */ |
| 30 | #include <sys/param.h> |
| 31 | #include <sys/systm.h> |
| 32 | #include <sys/kernel.h> |
| 33 | #include <sys/proc.h> |
| 34 | #include <sys/fcntl.h> |
| 35 | #include <sys/file.h> |
| 36 | #include <sys/filedesc.h> |
| 37 | #include <sys/filio.h> |
| 38 | #include <sys/ttycom.h> |
| 39 | #include <sys/stat.h> |
| 40 | #include <sys/signalvar.h> |
| 41 | #include <sys/sysproto.h> |
| 42 | #include <sys/pipe.h> |
| 43 | #include <sys/vnode.h> |
| 44 | #include <sys/uio.h> |
| 45 | #include <sys/event.h> |
| 46 | #include <sys/globaldata.h> |
| 47 | #include <sys/module.h> |
| 48 | #include <sys/malloc.h> |
| 49 | #include <sys/sysctl.h> |
| 50 | #include <sys/socket.h> |
| 51 | #include <sys/kern_syscall.h> |
| 52 | #include <sys/lock.h> |
| 53 | #include <sys/mutex.h> |
| 54 | |
| 55 | #include <vm/vm.h> |
| 56 | #include <vm/vm_param.h> |
| 57 | #include <vm/vm_object.h> |
| 58 | #include <vm/vm_kern.h> |
| 59 | #include <vm/vm_extern.h> |
| 60 | #include <vm/pmap.h> |
| 61 | #include <vm/vm_map.h> |
| 62 | #include <vm/vm_page.h> |
| 63 | #include <vm/vm_zone.h> |
| 64 | |
| 65 | #include <sys/file2.h> |
| 66 | #include <sys/signal2.h> |
| 67 | #include <sys/mutex2.h> |
| 68 | |
| 69 | #include <machine/cpufunc.h> |
| 70 | |
| 71 | struct pipegdlock { |
| 72 | struct mtx mtx; |
| 73 | } __cachealign; |
| 74 | |
| 75 | /* |
| 76 | * interfaces to the outside world |
| 77 | */ |
| 78 | static int pipe_read (struct file *fp, struct uio *uio, |
| 79 | struct ucred *cred, int flags); |
| 80 | static int pipe_write (struct file *fp, struct uio *uio, |
| 81 | struct ucred *cred, int flags); |
| 82 | static int pipe_close (struct file *fp); |
| 83 | static int pipe_shutdown (struct file *fp, int how); |
| 84 | static int pipe_kqfilter (struct file *fp, struct knote *kn); |
| 85 | static int pipe_stat (struct file *fp, struct stat *sb, struct ucred *cred); |
| 86 | static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, |
| 87 | struct ucred *cred, struct sysmsg *msg); |
| 88 | |
| 89 | static struct fileops pipeops = { |
| 90 | .fo_read = pipe_read, |
| 91 | .fo_write = pipe_write, |
| 92 | .fo_ioctl = pipe_ioctl, |
| 93 | .fo_kqfilter = pipe_kqfilter, |
| 94 | .fo_stat = pipe_stat, |
| 95 | .fo_close = pipe_close, |
| 96 | .fo_shutdown = pipe_shutdown |
| 97 | }; |
| 98 | |
| 99 | static void filt_pipedetach(struct knote *kn); |
| 100 | static int filt_piperead(struct knote *kn, long hint); |
| 101 | static int filt_pipewrite(struct knote *kn, long hint); |
| 102 | |
| 103 | static struct filterops pipe_rfiltops = |
| 104 | { FILTEROP_ISFD|FILTEROP_MPSAFE, NULL, filt_pipedetach, filt_piperead }; |
| 105 | static struct filterops pipe_wfiltops = |
| 106 | { FILTEROP_ISFD|FILTEROP_MPSAFE, NULL, filt_pipedetach, filt_pipewrite }; |
| 107 | |
| 108 | MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures"); |
| 109 | |
| 110 | #define PIPEQ_MAX_CACHE 16 /* per-cpu pipe structure cache */ |
| 111 | |
| 112 | static int pipe_maxcache = PIPEQ_MAX_CACHE; |
| 113 | static struct pipegdlock *pipe_gdlocks; |
| 114 | |
| 115 | SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation"); |
| 116 | SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache, |
| 117 | CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu"); |
| 118 | static int pipe_size = 32768; |
| 119 | SYSCTL_INT(_kern_pipe, OID_AUTO, size, |
| 120 | CTLFLAG_RW, &pipe_size, 0, "Pipe buffer size (16384 minimum)"); |
| 121 | static int pipe_delay = 5000; /* 5uS default */ |
| 122 | SYSCTL_INT(_kern_pipe, OID_AUTO, delay, |
| 123 | CTLFLAG_RW, &pipe_delay, 0, "SMP delay optimization in ns"); |
| 124 | |
| 125 | /* |
| 126 | * Auto-size pipe cache to reduce kmem allocations and frees. |
| 127 | */ |
| 128 | static |
| 129 | void |
| 130 | pipeinit(void *dummy) |
| 131 | { |
| 132 | size_t mbytes = kmem_lim_size(); |
| 133 | int n; |
| 134 | |
| 135 | if (pipe_maxcache == PIPEQ_MAX_CACHE) { |
| 136 | if (mbytes >= 7 * 1024) |
| 137 | pipe_maxcache *= 2; |
| 138 | if (mbytes >= 15 * 1024) |
| 139 | pipe_maxcache *= 2; |
| 140 | } |
| 141 | pipe_gdlocks = kmalloc(sizeof(*pipe_gdlocks) * ncpus, |
| 142 | M_PIPE, M_WAITOK | M_ZERO); |
| 143 | for (n = 0; n < ncpus; ++n) |
| 144 | mtx_init(&pipe_gdlocks[n].mtx, "pipekm"); |
| 145 | } |
| 146 | SYSINIT(kmem, SI_BOOT2_MACHDEP, SI_ORDER_ANY, pipeinit, NULL); |
| 147 | |
| 148 | static void pipeclose (struct pipe *pipe, |
| 149 | struct pipebuf *pbr, struct pipebuf *pbw); |
| 150 | static void pipe_free_kmem (struct pipebuf *buf); |
| 151 | static int pipe_create (struct pipe **pipep); |
| 152 | |
| 153 | static __inline void |
| 154 | pipewakeup(struct pipebuf *pb, int dosigio) |
| 155 | { |
| 156 | if (dosigio && (pb->state & PIPE_ASYNC) && pb->sigio) { |
| 157 | lwkt_gettoken(&sigio_token); |
| 158 | pgsigio(pb->sigio, SIGIO, 0); |
| 159 | lwkt_reltoken(&sigio_token); |
| 160 | } |
| 161 | KNOTE(&pb->kq.ki_note, 0); |
| 162 | } |
| 163 | |
| 164 | /* |
| 165 | * These routines are called before and after a UIO. The UIO |
| 166 | * may block, causing our held tokens to be lost temporarily. |
| 167 | * |
| 168 | * We use these routines to serialize reads against other reads |
| 169 | * and writes against other writes. |
| 170 | * |
| 171 | * The read token is held on entry so *ipp does not race. |
| 172 | */ |
| 173 | static __inline int |
| 174 | pipe_start_uio(int *ipp) |
| 175 | { |
| 176 | int error; |
| 177 | |
| 178 | while (*ipp) { |
| 179 | *ipp = -1; |
| 180 | error = tsleep(ipp, PCATCH, "pipexx", 0); |
| 181 | if (error) |
| 182 | return (error); |
| 183 | } |
| 184 | *ipp = 1; |
| 185 | return (0); |
| 186 | } |
| 187 | |
| 188 | static __inline void |
| 189 | pipe_end_uio(int *ipp) |
| 190 | { |
| 191 | if (*ipp < 0) { |
| 192 | *ipp = 0; |
| 193 | wakeup(ipp); |
| 194 | } else { |
| 195 | KKASSERT(*ipp > 0); |
| 196 | *ipp = 0; |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | /* |
| 201 | * The pipe system call for the DTYPE_PIPE type of pipes |
| 202 | * |
| 203 | * pipe_args(int dummy) |
| 204 | * |
| 205 | * MPSAFE |
| 206 | */ |
| 207 | int |
| 208 | sys_pipe(struct pipe_args *uap) |
| 209 | { |
| 210 | return kern_pipe(uap->sysmsg_fds, 0); |
| 211 | } |
| 212 | |
| 213 | int |
| 214 | sys_pipe2(struct pipe2_args *uap) |
| 215 | { |
| 216 | return kern_pipe(uap->sysmsg_fds, uap->flags); |
| 217 | } |
| 218 | |
| 219 | int |
| 220 | kern_pipe(long *fds, int flags) |
| 221 | { |
| 222 | struct thread *td = curthread; |
| 223 | struct filedesc *fdp = td->td_proc->p_fd; |
| 224 | struct file *rf, *wf; |
| 225 | struct pipe *pipe; |
| 226 | int fd1, fd2, error; |
| 227 | |
| 228 | pipe = NULL; |
| 229 | if (pipe_create(&pipe)) { |
| 230 | pipeclose(pipe, &pipe->bufferA, &pipe->bufferB); |
| 231 | pipeclose(pipe, &pipe->bufferB, &pipe->bufferA); |
| 232 | return (ENFILE); |
| 233 | } |
| 234 | |
| 235 | error = falloc(td->td_lwp, &rf, &fd1); |
| 236 | if (error) { |
| 237 | pipeclose(pipe, &pipe->bufferA, &pipe->bufferB); |
| 238 | pipeclose(pipe, &pipe->bufferB, &pipe->bufferA); |
| 239 | return (error); |
| 240 | } |
| 241 | fds[0] = fd1; |
| 242 | |
| 243 | /* |
| 244 | * Warning: once we've gotten past allocation of the fd for the |
| 245 | * read-side, we can only drop the read side via fdrop() in order |
| 246 | * to avoid races against processes which manage to dup() the read |
| 247 | * side while we are blocked trying to allocate the write side. |
| 248 | */ |
| 249 | rf->f_type = DTYPE_PIPE; |
| 250 | rf->f_flag = FREAD | FWRITE; |
| 251 | rf->f_ops = &pipeops; |
| 252 | rf->f_data = (void *)((intptr_t)pipe | 0); |
| 253 | if (flags & O_NONBLOCK) |
| 254 | rf->f_flag |= O_NONBLOCK; |
| 255 | if (flags & O_CLOEXEC) |
| 256 | fdp->fd_files[fd1].fileflags |= UF_EXCLOSE; |
| 257 | |
| 258 | error = falloc(td->td_lwp, &wf, &fd2); |
| 259 | if (error) { |
| 260 | fsetfd(fdp, NULL, fd1); |
| 261 | fdrop(rf); |
| 262 | /* pipeA has been closed by fdrop() */ |
| 263 | /* close pipeB here */ |
| 264 | pipeclose(pipe, &pipe->bufferB, &pipe->bufferA); |
| 265 | return (error); |
| 266 | } |
| 267 | wf->f_type = DTYPE_PIPE; |
| 268 | wf->f_flag = FREAD | FWRITE; |
| 269 | wf->f_ops = &pipeops; |
| 270 | wf->f_data = (void *)((intptr_t)pipe | 1); |
| 271 | if (flags & O_NONBLOCK) |
| 272 | wf->f_flag |= O_NONBLOCK; |
| 273 | if (flags & O_CLOEXEC) |
| 274 | fdp->fd_files[fd2].fileflags |= UF_EXCLOSE; |
| 275 | |
| 276 | fds[1] = fd2; |
| 277 | |
| 278 | /* |
| 279 | * Once activated the peer relationship remains valid until |
| 280 | * both sides are closed. |
| 281 | */ |
| 282 | fsetfd(fdp, rf, fd1); |
| 283 | fsetfd(fdp, wf, fd2); |
| 284 | fdrop(rf); |
| 285 | fdrop(wf); |
| 286 | |
| 287 | return (0); |
| 288 | } |
| 289 | |
| 290 | /* |
| 291 | * [re]allocates KVA for the pipe's circular buffer. The space is |
| 292 | * pageable. Called twice to setup full-duplex communications. |
| 293 | * |
| 294 | * NOTE: Independent vm_object's are used to improve performance. |
| 295 | * |
| 296 | * Returns 0 on success, ENOMEM on failure. |
| 297 | */ |
| 298 | static int |
| 299 | pipespace(struct pipe *pipe, struct pipebuf *pb, size_t size) |
| 300 | { |
| 301 | struct vm_object *object; |
| 302 | caddr_t buffer; |
| 303 | vm_pindex_t npages; |
| 304 | int error; |
| 305 | |
| 306 | size = (size + PAGE_MASK) & ~(size_t)PAGE_MASK; |
| 307 | if (size < 16384) |
| 308 | size = 16384; |
| 309 | if (size > 1024*1024) |
| 310 | size = 1024*1024; |
| 311 | |
| 312 | npages = round_page(size) / PAGE_SIZE; |
| 313 | object = pb->object; |
| 314 | |
| 315 | /* |
| 316 | * [re]create the object if necessary and reserve space for it |
| 317 | * in the kernel_map. The object and memory are pageable. On |
| 318 | * success, free the old resources before assigning the new |
| 319 | * ones. |
| 320 | */ |
| 321 | if (object == NULL || object->size != npages) { |
| 322 | object = vm_object_allocate(OBJT_DEFAULT, npages); |
| 323 | buffer = (caddr_t)vm_map_min(&kernel_map); |
| 324 | |
| 325 | error = vm_map_find(&kernel_map, object, NULL, |
| 326 | 0, (vm_offset_t *)&buffer, size, |
| 327 | PAGE_SIZE, TRUE, |
| 328 | VM_MAPTYPE_NORMAL, VM_SUBSYS_PIPE, |
| 329 | VM_PROT_ALL, VM_PROT_ALL, 0); |
| 330 | |
| 331 | if (error != KERN_SUCCESS) { |
| 332 | vm_object_deallocate(object); |
| 333 | return (ENOMEM); |
| 334 | } |
| 335 | pipe_free_kmem(pb); |
| 336 | pb->object = object; |
| 337 | pb->buffer = buffer; |
| 338 | pb->size = size; |
| 339 | } |
| 340 | pb->rindex = 0; |
| 341 | pb->windex = 0; |
| 342 | |
| 343 | return (0); |
| 344 | } |
| 345 | |
| 346 | /* |
| 347 | * Initialize and allocate VM and memory for pipe, pulling the pipe from |
| 348 | * our per-cpu cache if possible. |
| 349 | * |
| 350 | * Returns 0 on success, else an error code (typically ENOMEM). Caller |
| 351 | * must still deallocate the pipe on failure. |
| 352 | */ |
| 353 | static int |
| 354 | pipe_create(struct pipe **pipep) |
| 355 | { |
| 356 | globaldata_t gd = mycpu; |
| 357 | struct pipe *pipe; |
| 358 | int error; |
| 359 | |
| 360 | if ((pipe = gd->gd_pipeq) != NULL) { |
| 361 | gd->gd_pipeq = pipe->next; |
| 362 | --gd->gd_pipeqcount; |
| 363 | pipe->next = NULL; |
| 364 | } else { |
| 365 | pipe = kmalloc(sizeof(*pipe), M_PIPE, M_WAITOK | M_ZERO); |
| 366 | lwkt_token_init(&pipe->bufferA.rlock, "piper"); |
| 367 | lwkt_token_init(&pipe->bufferA.wlock, "pipew"); |
| 368 | lwkt_token_init(&pipe->bufferB.rlock, "piper"); |
| 369 | lwkt_token_init(&pipe->bufferB.wlock, "pipew"); |
| 370 | } |
| 371 | *pipep = pipe; |
| 372 | if ((error = pipespace(pipe, &pipe->bufferA, pipe_size)) != 0) { |
| 373 | return (error); |
| 374 | } |
| 375 | if ((error = pipespace(pipe, &pipe->bufferB, pipe_size)) != 0) { |
| 376 | return (error); |
| 377 | } |
| 378 | vfs_timestamp(&pipe->ctime); |
| 379 | pipe->bufferA.atime = pipe->ctime; |
| 380 | pipe->bufferA.mtime = pipe->ctime; |
| 381 | pipe->bufferB.atime = pipe->ctime; |
| 382 | pipe->bufferB.mtime = pipe->ctime; |
| 383 | pipe->open_count = 2; |
| 384 | |
| 385 | return (0); |
| 386 | } |
| 387 | |
| 388 | /* |
| 389 | * Read data from a pipe |
| 390 | */ |
| 391 | static int |
| 392 | pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags) |
| 393 | { |
| 394 | struct pipebuf *rpb; |
| 395 | struct pipebuf *wpb; |
| 396 | struct pipe *pipe; |
| 397 | size_t nread = 0; |
| 398 | size_t size; /* total bytes available */ |
| 399 | size_t nsize; /* total bytes to read */ |
| 400 | size_t rindex; /* contiguous bytes available */ |
| 401 | int notify_writer; |
| 402 | int bigread; |
| 403 | int bigcount; |
| 404 | int error; |
| 405 | int nbio; |
| 406 | |
| 407 | pipe = (struct pipe *)((intptr_t)fp->f_data & ~(intptr_t)1); |
| 408 | if ((intptr_t)fp->f_data & 1) { |
| 409 | rpb = &pipe->bufferB; |
| 410 | wpb = &pipe->bufferA; |
| 411 | } else { |
| 412 | rpb = &pipe->bufferA; |
| 413 | wpb = &pipe->bufferB; |
| 414 | } |
| 415 | atomic_set_int(&curthread->td_mpflags, TDF_MP_BATCH_DEMARC); |
| 416 | |
| 417 | if (uio->uio_resid == 0) |
| 418 | return(0); |
| 419 | |
| 420 | /* |
| 421 | * Calculate nbio |
| 422 | */ |
| 423 | if (fflags & O_FBLOCKING) |
| 424 | nbio = 0; |
| 425 | else if (fflags & O_FNONBLOCKING) |
| 426 | nbio = 1; |
| 427 | else if (fp->f_flag & O_NONBLOCK) |
| 428 | nbio = 1; |
| 429 | else |
| 430 | nbio = 0; |
| 431 | |
| 432 | /* |
| 433 | * 'quick' NBIO test before things get expensive. |
| 434 | */ |
| 435 | if (nbio && rpb->rindex == rpb->windex) |
| 436 | return EAGAIN; |
| 437 | |
| 438 | /* |
| 439 | * Reads are serialized. Note however that buffer.buffer and |
| 440 | * buffer.size can change out from under us when the number |
| 441 | * of bytes in the buffer are zero due to the write-side doing a |
| 442 | * pipespace(). |
| 443 | */ |
| 444 | lwkt_gettoken(&rpb->rlock); |
| 445 | error = pipe_start_uio(&rpb->rip); |
| 446 | if (error) { |
| 447 | lwkt_reltoken(&rpb->rlock); |
| 448 | return (error); |
| 449 | } |
| 450 | notify_writer = 0; |
| 451 | |
| 452 | bigread = (uio->uio_resid > 10 * 1024 * 1024); |
| 453 | bigcount = 10; |
| 454 | |
| 455 | while (uio->uio_resid) { |
| 456 | /* |
| 457 | * Don't hog the cpu. |
| 458 | */ |
| 459 | if (bigread && --bigcount == 0) { |
| 460 | lwkt_user_yield(); |
| 461 | bigcount = 10; |
| 462 | if (CURSIG(curthread->td_lwp)) { |
| 463 | error = EINTR; |
| 464 | break; |
| 465 | } |
| 466 | } |
| 467 | |
| 468 | size = rpb->windex - rpb->rindex; |
| 469 | cpu_lfence(); |
| 470 | if (size) { |
| 471 | rindex = rpb->rindex & (rpb->size - 1); |
| 472 | nsize = size; |
| 473 | if (nsize > rpb->size - rindex) |
| 474 | nsize = rpb->size - rindex; |
| 475 | nsize = szmin(nsize, uio->uio_resid); |
| 476 | |
| 477 | error = uiomove(&rpb->buffer[rindex], nsize, uio); |
| 478 | if (error) |
| 479 | break; |
| 480 | cpu_mfence(); |
| 481 | rpb->rindex += nsize; |
| 482 | nread += nsize; |
| 483 | |
| 484 | /* |
| 485 | * If the FIFO is still over half full just continue |
| 486 | * and do not try to notify the writer yet. |
| 487 | */ |
| 488 | if (size - nsize >= (rpb->size >> 1)) { |
| 489 | notify_writer = 0; |
| 490 | continue; |
| 491 | } |
| 492 | |
| 493 | /* |
| 494 | * When the FIFO is less then half full notify any |
| 495 | * waiting writer. WANTW can be checked while |
| 496 | * holding just the rlock. |
| 497 | */ |
| 498 | notify_writer = 1; |
| 499 | if ((rpb->state & PIPE_WANTW) == 0) |
| 500 | continue; |
| 501 | } |
| 502 | |
| 503 | /* |
| 504 | * If the "write-side" was blocked we wake it up. This code |
| 505 | * is reached either when the buffer is completely emptied |
| 506 | * or if it becomes more then half-empty. |
| 507 | * |
| 508 | * Pipe_state can only be modified if both the rlock and |
| 509 | * wlock are held. |
| 510 | */ |
| 511 | if (rpb->state & PIPE_WANTW) { |
| 512 | lwkt_gettoken(&rpb->wlock); |
| 513 | if (rpb->state & PIPE_WANTW) { |
| 514 | rpb->state &= ~PIPE_WANTW; |
| 515 | lwkt_reltoken(&rpb->wlock); |
| 516 | wakeup(rpb); |
| 517 | } else { |
| 518 | lwkt_reltoken(&rpb->wlock); |
| 519 | } |
| 520 | } |
| 521 | |
| 522 | /* |
| 523 | * Pick up our copy loop again if the writer sent data to |
| 524 | * us while we were messing around. |
| 525 | * |
| 526 | * On a SMP box poll up to pipe_delay nanoseconds for new |
| 527 | * data. Typically a value of 2000 to 4000 is sufficient |
| 528 | * to eradicate most IPIs/tsleeps/wakeups when a pipe |
| 529 | * is used for synchronous communications with small packets, |
| 530 | * and 8000 or so (8uS) will pipeline large buffer xfers |
| 531 | * between cpus over a pipe. |
| 532 | * |
| 533 | * For synchronous communications a hit means doing a |
| 534 | * full Awrite-Bread-Bwrite-Aread cycle in less then 2uS, |
| 535 | * where as miss requiring a tsleep/wakeup sequence |
| 536 | * will take 7uS or more. |
| 537 | */ |
| 538 | if (rpb->windex != rpb->rindex) |
| 539 | continue; |
| 540 | |
| 541 | #ifdef _RDTSC_SUPPORTED_ |
| 542 | if (pipe_delay) { |
| 543 | int64_t tsc_target; |
| 544 | int good = 0; |
| 545 | |
| 546 | tsc_target = tsc_get_target(pipe_delay); |
| 547 | while (tsc_test_target(tsc_target) == 0) { |
| 548 | if (rpb->windex != rpb->rindex) { |
| 549 | good = 1; |
| 550 | break; |
| 551 | } |
| 552 | } |
| 553 | if (good) |
| 554 | continue; |
| 555 | } |
| 556 | #endif |
| 557 | |
| 558 | /* |
| 559 | * Detect EOF condition, do not set error. |
| 560 | */ |
| 561 | if (rpb->state & PIPE_REOF) |
| 562 | break; |
| 563 | |
| 564 | /* |
| 565 | * Break if some data was read, or if this was a non-blocking |
| 566 | * read. |
| 567 | */ |
| 568 | if (nread > 0) |
| 569 | break; |
| 570 | |
| 571 | if (nbio) { |
| 572 | error = EAGAIN; |
| 573 | break; |
| 574 | } |
| 575 | |
| 576 | /* |
| 577 | * Last chance, interlock with WANTR. |
| 578 | */ |
| 579 | lwkt_gettoken(&rpb->wlock); |
| 580 | size = rpb->windex - rpb->rindex; |
| 581 | if (size) { |
| 582 | lwkt_reltoken(&rpb->wlock); |
| 583 | continue; |
| 584 | } |
| 585 | |
| 586 | /* |
| 587 | * Retest EOF - acquiring a new token can temporarily release |
| 588 | * tokens already held. |
| 589 | */ |
| 590 | if (rpb->state & PIPE_REOF) { |
| 591 | lwkt_reltoken(&rpb->wlock); |
| 592 | break; |
| 593 | } |
| 594 | |
| 595 | /* |
| 596 | * If there is no more to read in the pipe, reset its |
| 597 | * pointers to the beginning. This improves cache hit |
| 598 | * stats. |
| 599 | * |
| 600 | * We need both locks to modify both pointers, and there |
| 601 | * must also not be a write in progress or the uiomove() |
| 602 | * in the write might block and temporarily release |
| 603 | * its wlock, then reacquire and update windex. We are |
| 604 | * only serialized against reads, not writes. |
| 605 | * |
| 606 | * XXX should we even bother resetting the indices? It |
| 607 | * might actually be more cache efficient not to. |
| 608 | */ |
| 609 | if (rpb->rindex == rpb->windex && rpb->wip == 0) { |
| 610 | rpb->rindex = 0; |
| 611 | rpb->windex = 0; |
| 612 | } |
| 613 | |
| 614 | /* |
| 615 | * Wait for more data. |
| 616 | * |
| 617 | * Pipe_state can only be set if both the rlock and wlock |
| 618 | * are held. |
| 619 | */ |
| 620 | rpb->state |= PIPE_WANTR; |
| 621 | tsleep_interlock(rpb, PCATCH); |
| 622 | lwkt_reltoken(&rpb->wlock); |
| 623 | error = tsleep(rpb, PCATCH | PINTERLOCKED, "piperd", 0); |
| 624 | if (error) |
| 625 | break; |
| 626 | } |
| 627 | pipe_end_uio(&rpb->rip); |
| 628 | |
| 629 | /* |
| 630 | * Uptime last access time |
| 631 | */ |
| 632 | if (error == 0 && nread) |
| 633 | vfs_timestamp(&rpb->atime); |
| 634 | |
| 635 | /* |
| 636 | * If we drained the FIFO more then half way then handle |
| 637 | * write blocking hysteresis. |
| 638 | * |
| 639 | * Note that PIPE_WANTW cannot be set by the writer without |
| 640 | * it holding both rlock and wlock, so we can test it |
| 641 | * while holding just rlock. |
| 642 | */ |
| 643 | if (notify_writer) { |
| 644 | /* |
| 645 | * Synchronous blocking is done on the pipe involved |
| 646 | */ |
| 647 | if (rpb->state & PIPE_WANTW) { |
| 648 | lwkt_gettoken(&rpb->wlock); |
| 649 | if (rpb->state & PIPE_WANTW) { |
| 650 | rpb->state &= ~PIPE_WANTW; |
| 651 | lwkt_reltoken(&rpb->wlock); |
| 652 | wakeup(rpb); |
| 653 | } else { |
| 654 | lwkt_reltoken(&rpb->wlock); |
| 655 | } |
| 656 | } |
| 657 | |
| 658 | /* |
| 659 | * But we may also have to deal with a kqueue which is |
| 660 | * stored on the same pipe as its descriptor, so a |
| 661 | * EVFILT_WRITE event waiting for our side to drain will |
| 662 | * be on the other side. |
| 663 | */ |
| 664 | lwkt_gettoken(&wpb->wlock); |
| 665 | pipewakeup(wpb, 0); |
| 666 | lwkt_reltoken(&wpb->wlock); |
| 667 | } |
| 668 | /*size = rpb->windex - rpb->rindex;*/ |
| 669 | lwkt_reltoken(&rpb->rlock); |
| 670 | |
| 671 | return (error); |
| 672 | } |
| 673 | |
| 674 | static int |
| 675 | pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags) |
| 676 | { |
| 677 | struct pipebuf *rpb; |
| 678 | struct pipebuf *wpb; |
| 679 | struct pipe *pipe; |
| 680 | size_t windex; |
| 681 | size_t space; |
| 682 | size_t wcount; |
| 683 | size_t orig_resid; |
| 684 | int bigwrite; |
| 685 | int bigcount; |
| 686 | int error; |
| 687 | int nbio; |
| 688 | |
| 689 | pipe = (struct pipe *)((intptr_t)fp->f_data & ~(intptr_t)1); |
| 690 | if ((intptr_t)fp->f_data & 1) { |
| 691 | rpb = &pipe->bufferB; |
| 692 | wpb = &pipe->bufferA; |
| 693 | } else { |
| 694 | rpb = &pipe->bufferA; |
| 695 | wpb = &pipe->bufferB; |
| 696 | } |
| 697 | |
| 698 | /* |
| 699 | * Calculate nbio |
| 700 | */ |
| 701 | if (fflags & O_FBLOCKING) |
| 702 | nbio = 0; |
| 703 | else if (fflags & O_FNONBLOCKING) |
| 704 | nbio = 1; |
| 705 | else if (fp->f_flag & O_NONBLOCK) |
| 706 | nbio = 1; |
| 707 | else |
| 708 | nbio = 0; |
| 709 | |
| 710 | /* |
| 711 | * 'quick' NBIO test before things get expensive. |
| 712 | */ |
| 713 | if (nbio && wpb->size == (wpb->windex - wpb->rindex) && |
| 714 | uio->uio_resid && (wpb->state & PIPE_WEOF) == 0) { |
| 715 | return EAGAIN; |
| 716 | } |
| 717 | |
| 718 | /* |
| 719 | * Writes go to the peer. The peer will always exist. |
| 720 | */ |
| 721 | lwkt_gettoken(&wpb->wlock); |
| 722 | if (wpb->state & PIPE_WEOF) { |
| 723 | lwkt_reltoken(&wpb->wlock); |
| 724 | return (EPIPE); |
| 725 | } |
| 726 | |
| 727 | /* |
| 728 | * Degenerate case (EPIPE takes prec) |
| 729 | */ |
| 730 | if (uio->uio_resid == 0) { |
| 731 | lwkt_reltoken(&wpb->wlock); |
| 732 | return(0); |
| 733 | } |
| 734 | |
| 735 | /* |
| 736 | * Writes are serialized (start_uio must be called with wlock) |
| 737 | */ |
| 738 | error = pipe_start_uio(&wpb->wip); |
| 739 | if (error) { |
| 740 | lwkt_reltoken(&wpb->wlock); |
| 741 | return (error); |
| 742 | } |
| 743 | |
| 744 | orig_resid = uio->uio_resid; |
| 745 | wcount = 0; |
| 746 | |
| 747 | bigwrite = (uio->uio_resid > 10 * 1024 * 1024); |
| 748 | bigcount = 10; |
| 749 | |
| 750 | while (uio->uio_resid) { |
| 751 | if (wpb->state & PIPE_WEOF) { |
| 752 | error = EPIPE; |
| 753 | break; |
| 754 | } |
| 755 | |
| 756 | /* |
| 757 | * Don't hog the cpu. |
| 758 | */ |
| 759 | if (bigwrite && --bigcount == 0) { |
| 760 | lwkt_user_yield(); |
| 761 | bigcount = 10; |
| 762 | if (CURSIG(curthread->td_lwp)) { |
| 763 | error = EINTR; |
| 764 | break; |
| 765 | } |
| 766 | } |
| 767 | |
| 768 | windex = wpb->windex & (wpb->size - 1); |
| 769 | space = wpb->size - (wpb->windex - wpb->rindex); |
| 770 | cpu_lfence(); |
| 771 | |
| 772 | /* Writes of size <= PIPE_BUF must be atomic. */ |
| 773 | if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) |
| 774 | space = 0; |
| 775 | |
| 776 | /* |
| 777 | * Write to fill, read size handles write hysteresis. Also |
| 778 | * additional restrictions can cause select-based non-blocking |
| 779 | * writes to spin. |
| 780 | */ |
| 781 | if (space > 0) { |
| 782 | size_t segsize; |
| 783 | |
| 784 | /* |
| 785 | * Transfer size is minimum of uio transfer |
| 786 | * and free space in pipe buffer. |
| 787 | * |
| 788 | * Limit each uiocopy to no more then wpb->size |
| 789 | * so we can keep the gravy train going on a |
| 790 | * SMP box. This significantly increases write |
| 791 | * performance. Otherwise large writes wind up doing |
| 792 | * an inefficient synchronous ping-pong. |
| 793 | */ |
| 794 | space = szmin(space, uio->uio_resid); |
| 795 | if (space > (wpb->size >> 1)) |
| 796 | space = (wpb->size >> 1); |
| 797 | |
| 798 | /* |
| 799 | * First segment to transfer is minimum of |
| 800 | * transfer size and contiguous space in |
| 801 | * pipe buffer. If first segment to transfer |
| 802 | * is less than the transfer size, we've got |
| 803 | * a wraparound in the buffer. |
| 804 | */ |
| 805 | segsize = wpb->size - windex; |
| 806 | if (segsize > space) |
| 807 | segsize = space; |
| 808 | |
| 809 | /* |
| 810 | * If this is the first loop and the reader is |
| 811 | * blocked, do a preemptive wakeup of the reader. |
| 812 | * |
| 813 | * On SMP the IPI latency plus the wlock interlock |
| 814 | * on the reader side is the fastest way to get the |
| 815 | * reader going. (The scheduler will hard loop on |
| 816 | * lock tokens). |
| 817 | * |
| 818 | * NOTE: We can't clear WANTR here without acquiring |
| 819 | * the rlock, which we don't want to do here! |
| 820 | */ |
| 821 | if ((wpb->state & PIPE_WANTR)) |
| 822 | wakeup(wpb); |
| 823 | |
| 824 | /* |
| 825 | * Transfer segment, which may include a wrap-around. |
| 826 | * Update windex to account for both all in one go |
| 827 | * so the reader can read() the data atomically. |
| 828 | */ |
| 829 | error = uiomove(&wpb->buffer[windex], segsize, uio); |
| 830 | if (error == 0 && segsize < space) { |
| 831 | segsize = space - segsize; |
| 832 | error = uiomove(&wpb->buffer[0], segsize, uio); |
| 833 | } |
| 834 | if (error) |
| 835 | break; |
| 836 | cpu_mfence(); |
| 837 | wpb->windex += space; |
| 838 | wcount += space; |
| 839 | continue; |
| 840 | } |
| 841 | |
| 842 | /* |
| 843 | * We need both the rlock and the wlock to interlock against |
| 844 | * the EOF, WANTW, and size checks, and to modify pipe_state. |
| 845 | * |
| 846 | * These are token locks so we do not have to worry about |
| 847 | * deadlocks. |
| 848 | */ |
| 849 | lwkt_gettoken(&wpb->rlock); |
| 850 | |
| 851 | /* |
| 852 | * If the "read-side" has been blocked, wake it up now |
| 853 | * and yield to let it drain synchronously rather |
| 854 | * then block. |
| 855 | */ |
| 856 | if (wpb->state & PIPE_WANTR) { |
| 857 | wpb->state &= ~PIPE_WANTR; |
| 858 | wakeup(wpb); |
| 859 | } |
| 860 | |
| 861 | /* |
| 862 | * don't block on non-blocking I/O |
| 863 | */ |
| 864 | if (nbio) { |
| 865 | lwkt_reltoken(&wpb->rlock); |
| 866 | error = EAGAIN; |
| 867 | break; |
| 868 | } |
| 869 | |
| 870 | /* |
| 871 | * re-test whether we have to block in the writer after |
| 872 | * acquiring both locks, in case the reader opened up |
| 873 | * some space. |
| 874 | */ |
| 875 | space = wpb->size - (wpb->windex - wpb->rindex); |
| 876 | cpu_lfence(); |
| 877 | if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) |
| 878 | space = 0; |
| 879 | |
| 880 | /* |
| 881 | * Retest EOF - acquiring a new token can temporarily release |
| 882 | * tokens already held. |
| 883 | */ |
| 884 | if (wpb->state & PIPE_WEOF) { |
| 885 | lwkt_reltoken(&wpb->rlock); |
| 886 | error = EPIPE; |
| 887 | break; |
| 888 | } |
| 889 | |
| 890 | /* |
| 891 | * We have no more space and have something to offer, |
| 892 | * wake up select/poll/kq. |
| 893 | */ |
| 894 | if (space == 0) { |
| 895 | wpb->state |= PIPE_WANTW; |
| 896 | pipewakeup(wpb, 1); |
| 897 | if (wpb->state & PIPE_WANTW) |
| 898 | error = tsleep(wpb, PCATCH, "pipewr", 0); |
| 899 | } |
| 900 | lwkt_reltoken(&wpb->rlock); |
| 901 | |
| 902 | /* |
| 903 | * Break out if we errored or the read side wants us to go |
| 904 | * away. |
| 905 | */ |
| 906 | if (error) |
| 907 | break; |
| 908 | if (wpb->state & PIPE_WEOF) { |
| 909 | error = EPIPE; |
| 910 | break; |
| 911 | } |
| 912 | } |
| 913 | pipe_end_uio(&wpb->wip); |
| 914 | |
| 915 | /* |
| 916 | * If we have put any characters in the buffer, we wake up |
| 917 | * the reader. |
| 918 | * |
| 919 | * Both rlock and wlock are required to be able to modify pipe_state. |
| 920 | */ |
| 921 | if (wpb->windex != wpb->rindex) { |
| 922 | if (wpb->state & PIPE_WANTR) { |
| 923 | lwkt_gettoken(&wpb->rlock); |
| 924 | if (wpb->state & PIPE_WANTR) { |
| 925 | wpb->state &= ~PIPE_WANTR; |
| 926 | lwkt_reltoken(&wpb->rlock); |
| 927 | wakeup(wpb); |
| 928 | } else { |
| 929 | lwkt_reltoken(&wpb->rlock); |
| 930 | } |
| 931 | } |
| 932 | lwkt_gettoken(&wpb->rlock); |
| 933 | pipewakeup(wpb, 1); |
| 934 | lwkt_reltoken(&wpb->rlock); |
| 935 | } |
| 936 | |
| 937 | /* |
| 938 | * Don't return EPIPE if I/O was successful |
| 939 | */ |
| 940 | if ((wpb->rindex == wpb->windex) && |
| 941 | (uio->uio_resid == 0) && |
| 942 | (error == EPIPE)) { |
| 943 | error = 0; |
| 944 | } |
| 945 | |
| 946 | if (error == 0) |
| 947 | vfs_timestamp(&wpb->mtime); |
| 948 | |
| 949 | /* |
| 950 | * We have something to offer, |
| 951 | * wake up select/poll/kq. |
| 952 | */ |
| 953 | /*space = wpb->windex - wpb->rindex;*/ |
| 954 | lwkt_reltoken(&wpb->wlock); |
| 955 | |
| 956 | return (error); |
| 957 | } |
| 958 | |
| 959 | /* |
| 960 | * we implement a very minimal set of ioctls for compatibility with sockets. |
| 961 | */ |
| 962 | static int |
| 963 | pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, |
| 964 | struct ucred *cred, struct sysmsg *msg) |
| 965 | { |
| 966 | struct pipebuf *rpb; |
| 967 | struct pipe *pipe; |
| 968 | int error; |
| 969 | |
| 970 | pipe = (struct pipe *)((intptr_t)fp->f_data & ~(intptr_t)1); |
| 971 | if ((intptr_t)fp->f_data & 1) { |
| 972 | rpb = &pipe->bufferB; |
| 973 | } else { |
| 974 | rpb = &pipe->bufferA; |
| 975 | } |
| 976 | |
| 977 | lwkt_gettoken(&rpb->rlock); |
| 978 | lwkt_gettoken(&rpb->wlock); |
| 979 | |
| 980 | switch (cmd) { |
| 981 | case FIOASYNC: |
| 982 | if (*(int *)data) { |
| 983 | rpb->state |= PIPE_ASYNC; |
| 984 | } else { |
| 985 | rpb->state &= ~PIPE_ASYNC; |
| 986 | } |
| 987 | error = 0; |
| 988 | break; |
| 989 | case FIONREAD: |
| 990 | *(int *)data = (int)(rpb->windex - rpb->rindex); |
| 991 | error = 0; |
| 992 | break; |
| 993 | case FIOSETOWN: |
| 994 | error = fsetown(*(int *)data, &rpb->sigio); |
| 995 | break; |
| 996 | case FIOGETOWN: |
| 997 | *(int *)data = fgetown(&rpb->sigio); |
| 998 | error = 0; |
| 999 | break; |
| 1000 | case TIOCSPGRP: |
| 1001 | /* This is deprecated, FIOSETOWN should be used instead. */ |
| 1002 | error = fsetown(-(*(int *)data), &rpb->sigio); |
| 1003 | break; |
| 1004 | |
| 1005 | case TIOCGPGRP: |
| 1006 | /* This is deprecated, FIOGETOWN should be used instead. */ |
| 1007 | *(int *)data = -fgetown(&rpb->sigio); |
| 1008 | error = 0; |
| 1009 | break; |
| 1010 | default: |
| 1011 | error = ENOTTY; |
| 1012 | break; |
| 1013 | } |
| 1014 | lwkt_reltoken(&rpb->wlock); |
| 1015 | lwkt_reltoken(&rpb->rlock); |
| 1016 | |
| 1017 | return (error); |
| 1018 | } |
| 1019 | |
| 1020 | /* |
| 1021 | * MPSAFE |
| 1022 | */ |
| 1023 | static int |
| 1024 | pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred) |
| 1025 | { |
| 1026 | struct pipebuf *rpb; |
| 1027 | struct pipe *pipe; |
| 1028 | |
| 1029 | pipe = (struct pipe *)((intptr_t)fp->f_data & ~(intptr_t)1); |
| 1030 | if ((intptr_t)fp->f_data & 1) { |
| 1031 | rpb = &pipe->bufferB; |
| 1032 | } else { |
| 1033 | rpb = &pipe->bufferA; |
| 1034 | } |
| 1035 | |
| 1036 | bzero((caddr_t)ub, sizeof(*ub)); |
| 1037 | ub->st_mode = S_IFIFO; |
| 1038 | ub->st_blksize = rpb->size; |
| 1039 | ub->st_size = rpb->windex - rpb->rindex; |
| 1040 | ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; |
| 1041 | ub->st_atimespec = rpb->atime; |
| 1042 | ub->st_mtimespec = rpb->mtime; |
| 1043 | ub->st_ctimespec = pipe->ctime; |
| 1044 | /* |
| 1045 | * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev, |
| 1046 | * st_flags, st_gen. |
| 1047 | * XXX (st_dev, st_ino) should be unique. |
| 1048 | */ |
| 1049 | |
| 1050 | return (0); |
| 1051 | } |
| 1052 | |
| 1053 | static int |
| 1054 | pipe_close(struct file *fp) |
| 1055 | { |
| 1056 | struct pipebuf *rpb; |
| 1057 | struct pipebuf *wpb; |
| 1058 | struct pipe *pipe; |
| 1059 | |
| 1060 | pipe = (struct pipe *)((intptr_t)fp->f_data & ~(intptr_t)1); |
| 1061 | if ((intptr_t)fp->f_data & 1) { |
| 1062 | rpb = &pipe->bufferB; |
| 1063 | wpb = &pipe->bufferA; |
| 1064 | } else { |
| 1065 | rpb = &pipe->bufferA; |
| 1066 | wpb = &pipe->bufferB; |
| 1067 | } |
| 1068 | |
| 1069 | fp->f_ops = &badfileops; |
| 1070 | fp->f_data = NULL; |
| 1071 | funsetown(&rpb->sigio); |
| 1072 | pipeclose(pipe, rpb, wpb); |
| 1073 | |
| 1074 | return (0); |
| 1075 | } |
| 1076 | |
| 1077 | /* |
| 1078 | * Shutdown one or both directions of a full-duplex pipe. |
| 1079 | */ |
| 1080 | static int |
| 1081 | pipe_shutdown(struct file *fp, int how) |
| 1082 | { |
| 1083 | struct pipebuf *rpb; |
| 1084 | struct pipebuf *wpb; |
| 1085 | struct pipe *pipe; |
| 1086 | int error = EPIPE; |
| 1087 | |
| 1088 | pipe = (struct pipe *)((intptr_t)fp->f_data & ~(intptr_t)1); |
| 1089 | if ((intptr_t)fp->f_data & 1) { |
| 1090 | rpb = &pipe->bufferB; |
| 1091 | wpb = &pipe->bufferA; |
| 1092 | } else { |
| 1093 | rpb = &pipe->bufferA; |
| 1094 | wpb = &pipe->bufferB; |
| 1095 | } |
| 1096 | |
| 1097 | /* |
| 1098 | * We modify pipe_state on both pipes, which means we need |
| 1099 | * all four tokens! |
| 1100 | */ |
| 1101 | lwkt_gettoken(&rpb->rlock); |
| 1102 | lwkt_gettoken(&rpb->wlock); |
| 1103 | lwkt_gettoken(&wpb->rlock); |
| 1104 | lwkt_gettoken(&wpb->wlock); |
| 1105 | |
| 1106 | switch(how) { |
| 1107 | case SHUT_RDWR: |
| 1108 | case SHUT_RD: |
| 1109 | rpb->state |= PIPE_REOF; /* my reads */ |
| 1110 | rpb->state |= PIPE_WEOF; /* peer writes */ |
| 1111 | if (rpb->state & PIPE_WANTR) { |
| 1112 | rpb->state &= ~PIPE_WANTR; |
| 1113 | wakeup(rpb); |
| 1114 | } |
| 1115 | if (rpb->state & PIPE_WANTW) { |
| 1116 | rpb->state &= ~PIPE_WANTW; |
| 1117 | wakeup(rpb); |
| 1118 | } |
| 1119 | error = 0; |
| 1120 | if (how == SHUT_RD) |
| 1121 | break; |
| 1122 | /* fall through */ |
| 1123 | case SHUT_WR: |
| 1124 | wpb->state |= PIPE_REOF; /* peer reads */ |
| 1125 | wpb->state |= PIPE_WEOF; /* my writes */ |
| 1126 | if (wpb->state & PIPE_WANTR) { |
| 1127 | wpb->state &= ~PIPE_WANTR; |
| 1128 | wakeup(wpb); |
| 1129 | } |
| 1130 | if (wpb->state & PIPE_WANTW) { |
| 1131 | wpb->state &= ~PIPE_WANTW; |
| 1132 | wakeup(wpb); |
| 1133 | } |
| 1134 | error = 0; |
| 1135 | break; |
| 1136 | } |
| 1137 | pipewakeup(rpb, 1); |
| 1138 | pipewakeup(wpb, 1); |
| 1139 | |
| 1140 | lwkt_reltoken(&wpb->wlock); |
| 1141 | lwkt_reltoken(&wpb->rlock); |
| 1142 | lwkt_reltoken(&rpb->wlock); |
| 1143 | lwkt_reltoken(&rpb->rlock); |
| 1144 | |
| 1145 | return (error); |
| 1146 | } |
| 1147 | |
| 1148 | /* |
| 1149 | * Destroy the pipe buffer. |
| 1150 | */ |
| 1151 | static void |
| 1152 | pipe_free_kmem(struct pipebuf *pb) |
| 1153 | { |
| 1154 | if (pb->buffer != NULL) { |
| 1155 | kmem_free(&kernel_map, (vm_offset_t)pb->buffer, pb->size); |
| 1156 | pb->buffer = NULL; |
| 1157 | pb->object = NULL; |
| 1158 | } |
| 1159 | } |
| 1160 | |
| 1161 | /* |
| 1162 | * Close one half of the pipe. We are closing the pipe for reading on rpb |
| 1163 | * and writing on wpb. This routine must be called twice with the pipebufs |
| 1164 | * reversed to close both directions. |
| 1165 | */ |
| 1166 | static void |
| 1167 | pipeclose(struct pipe *pipe, struct pipebuf *rpb, struct pipebuf *wpb) |
| 1168 | { |
| 1169 | globaldata_t gd; |
| 1170 | |
| 1171 | if (pipe == NULL) |
| 1172 | return; |
| 1173 | |
| 1174 | /* |
| 1175 | * We need both the read and write tokens to modify pipe_state. |
| 1176 | */ |
| 1177 | lwkt_gettoken(&rpb->rlock); |
| 1178 | lwkt_gettoken(&rpb->wlock); |
| 1179 | |
| 1180 | /* |
| 1181 | * Set our state, wakeup anyone waiting in select/poll/kq, and |
| 1182 | * wakeup anyone blocked on our pipe. No action if our side |
| 1183 | * is already closed. |
| 1184 | */ |
| 1185 | if (rpb->state & PIPE_CLOSED) { |
| 1186 | lwkt_reltoken(&rpb->wlock); |
| 1187 | lwkt_reltoken(&rpb->rlock); |
| 1188 | return; |
| 1189 | } |
| 1190 | |
| 1191 | rpb->state |= PIPE_CLOSED | PIPE_REOF | PIPE_WEOF; |
| 1192 | pipewakeup(rpb, 1); |
| 1193 | if (rpb->state & (PIPE_WANTR | PIPE_WANTW)) { |
| 1194 | rpb->state &= ~(PIPE_WANTR | PIPE_WANTW); |
| 1195 | wakeup(rpb); |
| 1196 | } |
| 1197 | lwkt_reltoken(&rpb->wlock); |
| 1198 | lwkt_reltoken(&rpb->rlock); |
| 1199 | |
| 1200 | /* |
| 1201 | * Disconnect from peer. |
| 1202 | */ |
| 1203 | lwkt_gettoken(&wpb->rlock); |
| 1204 | lwkt_gettoken(&wpb->wlock); |
| 1205 | |
| 1206 | wpb->state |= PIPE_REOF | PIPE_WEOF; |
| 1207 | pipewakeup(wpb, 1); |
| 1208 | if (wpb->state & (PIPE_WANTR | PIPE_WANTW)) { |
| 1209 | wpb->state &= ~(PIPE_WANTR | PIPE_WANTW); |
| 1210 | wakeup(wpb); |
| 1211 | } |
| 1212 | if (SLIST_FIRST(&wpb->kq.ki_note)) |
| 1213 | KNOTE(&wpb->kq.ki_note, 0); |
| 1214 | lwkt_reltoken(&wpb->wlock); |
| 1215 | lwkt_reltoken(&wpb->rlock); |
| 1216 | |
| 1217 | /* |
| 1218 | * Free resources once both sides are closed. We maintain a pcpu |
| 1219 | * cache to improve performance, so the actual tear-down case is |
| 1220 | * limited to bulk situations. |
| 1221 | * |
| 1222 | * However, the bulk tear-down case can cause intense contention |
| 1223 | * on the kernel_map when, e.g. hundreds to hundreds of thousands |
| 1224 | * of processes are killed at the same time. To deal with this we |
| 1225 | * use a pcpu mutex to maintain concurrency but also limit the |
| 1226 | * number of threads banging on the map and pmap. |
| 1227 | * |
| 1228 | * We use the mtx mechanism instead of the lockmgr mechanism because |
| 1229 | * the mtx mechanism utilizes a queued design which will not break |
| 1230 | * down in the face of thousands to hundreds of thousands of |
| 1231 | * processes trying to free pipes simultaneously. The lockmgr |
| 1232 | * mechanism will wind up waking them all up each time a lock |
| 1233 | * cycles. |
| 1234 | */ |
| 1235 | if (atomic_fetchadd_int(&pipe->open_count, -1) == 1) { |
| 1236 | gd = mycpu; |
| 1237 | if (gd->gd_pipeqcount >= pipe_maxcache) { |
| 1238 | mtx_lock(&pipe_gdlocks[gd->gd_cpuid].mtx); |
| 1239 | pipe_free_kmem(rpb); |
| 1240 | pipe_free_kmem(wpb); |
| 1241 | mtx_unlock(&pipe_gdlocks[gd->gd_cpuid].mtx); |
| 1242 | kfree(pipe, M_PIPE); |
| 1243 | } else { |
| 1244 | rpb->state = 0; |
| 1245 | wpb->state = 0; |
| 1246 | pipe->next = gd->gd_pipeq; |
| 1247 | gd->gd_pipeq = pipe; |
| 1248 | ++gd->gd_pipeqcount; |
| 1249 | } |
| 1250 | } |
| 1251 | } |
| 1252 | |
| 1253 | static int |
| 1254 | pipe_kqfilter(struct file *fp, struct knote *kn) |
| 1255 | { |
| 1256 | struct pipebuf *rpb; |
| 1257 | struct pipebuf *wpb; |
| 1258 | struct pipe *pipe; |
| 1259 | |
| 1260 | pipe = (struct pipe *)((intptr_t)fp->f_data & ~(intptr_t)1); |
| 1261 | if ((intptr_t)fp->f_data & 1) { |
| 1262 | rpb = &pipe->bufferB; |
| 1263 | wpb = &pipe->bufferA; |
| 1264 | } else { |
| 1265 | rpb = &pipe->bufferA; |
| 1266 | wpb = &pipe->bufferB; |
| 1267 | } |
| 1268 | |
| 1269 | switch (kn->kn_filter) { |
| 1270 | case EVFILT_READ: |
| 1271 | kn->kn_fop = &pipe_rfiltops; |
| 1272 | break; |
| 1273 | case EVFILT_WRITE: |
| 1274 | kn->kn_fop = &pipe_wfiltops; |
| 1275 | if (wpb->state & PIPE_CLOSED) { |
| 1276 | /* other end of pipe has been closed */ |
| 1277 | return (EPIPE); |
| 1278 | } |
| 1279 | break; |
| 1280 | default: |
| 1281 | return (EOPNOTSUPP); |
| 1282 | } |
| 1283 | |
| 1284 | if (rpb == &pipe->bufferA) |
| 1285 | kn->kn_hook = (caddr_t)(void *)((intptr_t)pipe | 0); |
| 1286 | else |
| 1287 | kn->kn_hook = (caddr_t)(void *)((intptr_t)pipe | 1); |
| 1288 | |
| 1289 | knote_insert(&rpb->kq.ki_note, kn); |
| 1290 | |
| 1291 | return (0); |
| 1292 | } |
| 1293 | |
| 1294 | static void |
| 1295 | filt_pipedetach(struct knote *kn) |
| 1296 | { |
| 1297 | struct pipebuf *rpb; |
| 1298 | struct pipebuf *wpb; |
| 1299 | struct pipe *pipe; |
| 1300 | |
| 1301 | pipe = (struct pipe *)((intptr_t)kn->kn_hook & ~(intptr_t)1); |
| 1302 | if ((intptr_t)kn->kn_hook & 1) { |
| 1303 | rpb = &pipe->bufferB; |
| 1304 | wpb = &pipe->bufferA; |
| 1305 | } else { |
| 1306 | rpb = &pipe->bufferA; |
| 1307 | wpb = &pipe->bufferB; |
| 1308 | } |
| 1309 | knote_remove(&rpb->kq.ki_note, kn); |
| 1310 | } |
| 1311 | |
| 1312 | /*ARGSUSED*/ |
| 1313 | static int |
| 1314 | filt_piperead(struct knote *kn, long hint) |
| 1315 | { |
| 1316 | struct pipebuf *rpb; |
| 1317 | struct pipebuf *wpb; |
| 1318 | struct pipe *pipe; |
| 1319 | int ready = 0; |
| 1320 | |
| 1321 | pipe = (struct pipe *)((intptr_t)kn->kn_fp->f_data & ~(intptr_t)1); |
| 1322 | if ((intptr_t)kn->kn_fp->f_data & 1) { |
| 1323 | rpb = &pipe->bufferB; |
| 1324 | wpb = &pipe->bufferA; |
| 1325 | } else { |
| 1326 | rpb = &pipe->bufferA; |
| 1327 | wpb = &pipe->bufferB; |
| 1328 | } |
| 1329 | |
| 1330 | lwkt_gettoken(&rpb->rlock); |
| 1331 | lwkt_gettoken(&rpb->wlock); |
| 1332 | |
| 1333 | kn->kn_data = rpb->windex - rpb->rindex; |
| 1334 | |
| 1335 | if (rpb->state & PIPE_REOF) { |
| 1336 | /* |
| 1337 | * Only set NODATA if all data has been exhausted |
| 1338 | */ |
| 1339 | if (kn->kn_data == 0) |
| 1340 | kn->kn_flags |= EV_NODATA; |
| 1341 | kn->kn_flags |= EV_EOF; |
| 1342 | ready = 1; |
| 1343 | } |
| 1344 | |
| 1345 | lwkt_reltoken(&rpb->wlock); |
| 1346 | lwkt_reltoken(&rpb->rlock); |
| 1347 | |
| 1348 | if (!ready) |
| 1349 | ready = kn->kn_data > 0; |
| 1350 | |
| 1351 | return (ready); |
| 1352 | } |
| 1353 | |
| 1354 | /*ARGSUSED*/ |
| 1355 | static int |
| 1356 | filt_pipewrite(struct knote *kn, long hint) |
| 1357 | { |
| 1358 | struct pipebuf *rpb; |
| 1359 | struct pipebuf *wpb; |
| 1360 | struct pipe *pipe; |
| 1361 | int ready = 0; |
| 1362 | |
| 1363 | pipe = (struct pipe *)((intptr_t)kn->kn_fp->f_data & ~(intptr_t)1); |
| 1364 | if ((intptr_t)kn->kn_fp->f_data & 1) { |
| 1365 | rpb = &pipe->bufferB; |
| 1366 | wpb = &pipe->bufferA; |
| 1367 | } else { |
| 1368 | rpb = &pipe->bufferA; |
| 1369 | wpb = &pipe->bufferB; |
| 1370 | } |
| 1371 | |
| 1372 | kn->kn_data = 0; |
| 1373 | if (wpb->state & PIPE_CLOSED) { |
| 1374 | kn->kn_flags |= (EV_EOF | EV_NODATA); |
| 1375 | return (1); |
| 1376 | } |
| 1377 | |
| 1378 | lwkt_gettoken(&wpb->rlock); |
| 1379 | lwkt_gettoken(&wpb->wlock); |
| 1380 | |
| 1381 | if (wpb->state & PIPE_WEOF) { |
| 1382 | kn->kn_flags |= (EV_EOF | EV_NODATA); |
| 1383 | ready = 1; |
| 1384 | } |
| 1385 | |
| 1386 | if (!ready) |
| 1387 | kn->kn_data = wpb->size - (wpb->windex - wpb->rindex); |
| 1388 | |
| 1389 | lwkt_reltoken(&wpb->wlock); |
| 1390 | lwkt_reltoken(&wpb->rlock); |
| 1391 | |
| 1392 | if (!ready) |
| 1393 | ready = kn->kn_data >= PIPE_BUF; |
| 1394 | |
| 1395 | return (ready); |
| 1396 | } |