| 1 | |
| 2 | * Public API and common code for kernel->userspace relay file support.
|
| 3 | *
|
| 4 | * See Documentation/filesystems/relay.rst for an overview.
|
| 5 | *
|
| 6 | * Copyright (C) 2002-2005 - Tom Zanussi ([email protected]), IBM Corp
|
| 7 | * Copyright (C) 1999-2005 - Karim Yaghmour ([email protected])
|
| 8 | *
|
| 9 | * Moved to kernel/relay.c by Paul Mundt, 2006.
|
| 10 | * November 2006 - CPU hotplug support by Mathieu Desnoyers
|
| 11 | * ([email protected])
|
| 12 | *
|
| 13 | * This file is released under the GPL.
|
| 14 |
|
| 15 | #include <linux/errno.h>
|
| 16 | #include <linux/stddef.h>
|
| 17 | #include <linux/slab.h>
|
| 18 | #include <linux/export.h>
|
| 19 | #include <linux/string.h>
|
| 20 | #include <linux/relay.h>
|
| 21 | #include <linux/vmalloc.h>
|
| 22 | #include <linux/mm.h>
|
| 23 | #include <linux/cpu.h>
|
| 24 | #include <linux/splice.h>
|
| 25 |
|
| 26 |
|
| 27 | static DEFINE_MUTEX(relay_channels_mutex);
|
| 28 | static LIST_HEAD(relay_channels);
|
| 29 |
|
| 30 | |
| 31 | * fault() vm_op implementation for relay file mapping.
|
| 32 |
|
| 33 | static vm_fault_t relay_buf_fault(struct vm_fault *vmf)
|
| 34 | {
|
| 35 | struct page *page;
|
| 36 | struct rchan_buf *buf = vmf->vma->vm_private_data;
|
| 37 | pgoff_t pgoff = vmf->pgoff;
|
| 38 |
|
| 39 | if (!buf)
|
| 40 | return VM_FAULT_OOM;
|
| 41 |
|
| 42 | page = vmalloc_to_page(buf->start + (pgoff << PAGE_SHIFT));
|
| 43 | if (!page)
|
| 44 | return VM_FAULT_SIGBUS;
|
| 45 | get_page(page);
|
| 46 | vmf->page = page;
|
| 47 |
|
| 48 | return 0;
|
| 49 | }
|
| 50 |
|
| 51 | |
| 52 | * vm_ops for relay file mappings.
|
| 53 |
|
| 54 | static const struct vm_operations_struct relay_file_mmap_ops = {
|
| 55 | .fault = relay_buf_fault,
|
| 56 | };
|
| 57 |
|
| 58 | |
| 59 | * allocate an array of pointers of struct page
|
| 60 |
|
| 61 | static struct page **relay_alloc_page_array(unsigned int n_pages)
|
| 62 | {
|
| 63 | const size_t pa_size = n_pages * sizeof(struct page *);
|
| 64 | if (pa_size > PAGE_SIZE)
|
| 65 | return vzalloc(pa_size);
|
| 66 | return kzalloc(pa_size, GFP_KERNEL);
|
| 67 | }
|
| 68 |
|
| 69 | |
| 70 | * free an array of pointers of struct page
|
| 71 |
|
| 72 | static void relay_free_page_array(struct page **array)
|
| 73 | {
|
| 74 | kvfree(array);
|
| 75 | }
|
| 76 |
|
| 77 | |
| 78 | * relay_mmap_buf: - mmap channel buffer to process address space
|
| 79 | * @buf: relay channel buffer
|
| 80 | * @vma: vm_area_struct describing memory to be mapped
|
| 81 | *
|
| 82 | * Returns 0 if ok, negative on error
|
| 83 | *
|
| 84 | * Caller should already have grabbed mmap_lock.
|
| 85 |
|
| 86 | static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
|
| 87 | {
|
| 88 | unsigned long length = vma->vm_end - vma->vm_start;
|
| 89 |
|
| 90 | if (!buf)
|
| 91 | return -EBADF;
|
| 92 |
|
| 93 | if (length != (unsigned long)buf->chan->alloc_size)
|
| 94 | return -EINVAL;
|
| 95 |
|
| 96 | vma->vm_ops = &relay_file_mmap_ops;
|
| 97 | vma->vm_flags |= VM_DONTEXPAND;
|
| 98 | vma->vm_private_data = buf;
|
| 99 |
|
| 100 | return 0;
|
| 101 | }
|
| 102 |
|
| 103 | |
| 104 | * relay_alloc_buf - allocate a channel buffer
|
| 105 | * @buf: the buffer struct
|
| 106 | * @size: total size of the buffer
|
| 107 | *
|
| 108 | * Returns a pointer to the resulting buffer, %NULL if unsuccessful. The
|
| 109 | * passed in size will get page aligned, if it isn't already.
|
| 110 |
|
| 111 | static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
|
| 112 | {
|
| 113 | void *mem;
|
| 114 | unsigned int i, j, n_pages;
|
| 115 |
|
| 116 | *size = PAGE_ALIGN(*size);
|
| 117 | n_pages = *size >> PAGE_SHIFT;
|
| 118 |
|
| 119 | buf->page_array = relay_alloc_page_array(n_pages);
|
| 120 | if (!buf->page_array)
|
| 121 | return NULL;
|
| 122 |
|
| 123 | for (i = 0; i < n_pages; i++) {
|
| 124 | buf->page_array[i] = alloc_page(GFP_KERNEL);
|
| 125 | if (unlikely(!buf->page_array[i]))
|
| 126 | goto depopulate;
|
| 127 | set_page_private(buf->page_array[i], (unsigned long)buf);
|
| 128 | }
|
| 129 | mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL);
|
| 130 | if (!mem)
|
| 131 | goto depopulate;
|
| 132 |
|
| 133 | memset(mem, 0, *size);
|
| 134 | buf->page_count = n_pages;
|
| 135 | return mem;
|
| 136 |
|
| 137 | depopulate:
|
| 138 | for (j = 0; j < i; j++)
|
| 139 | __free_page(buf->page_array[j]);
|
| 140 | relay_free_page_array(buf->page_array);
|
| 141 | return NULL;
|
| 142 | }
|
| 143 |
|
| 144 | |
| 145 | * relay_create_buf - allocate and initialize a channel buffer
|
| 146 | * @chan: the relay channel
|
| 147 | *
|
| 148 | * Returns channel buffer if successful, %NULL otherwise.
|
| 149 |
|
| 150 | static struct rchan_buf *relay_create_buf(struct rchan *chan)
|
| 151 | {
|
| 152 | struct rchan_buf *buf;
|
| 153 |
|
| 154 | if (chan->n_subbufs > KMALLOC_MAX_SIZE / sizeof(size_t *))
|
| 155 | return NULL;
|
| 156 |
|
| 157 | buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL);
|
| 158 | if (!buf)
|
| 159 | return NULL;
|
| 160 | buf->padding = kmalloc_array(chan->n_subbufs, sizeof(size_t *),
|
| 161 | GFP_KERNEL);
|
| 162 | if (!buf->padding)
|
| 163 | goto free_buf;
|
| 164 |
|
| 165 | buf->start = relay_alloc_buf(buf, &chan->alloc_size);
|
| 166 | if (!buf->start)
|
| 167 | goto free_buf;
|
| 168 |
|
| 169 | buf->chan = chan;
|
| 170 | kref_get(&buf->chan->kref);
|
| 171 | return buf;
|
| 172 |
|
| 173 | free_buf:
|
| 174 | kfree(buf->padding);
|
| 175 | kfree(buf);
|
| 176 | return NULL;
|
| 177 | }
|
| 178 |
|
| 179 | |
| 180 | * relay_destroy_channel - free the channel struct
|
| 181 | * @kref: target kernel reference that contains the relay channel
|
| 182 | *
|
| 183 | * Should only be called from kref_put().
|
| 184 |
|
| 185 | static void relay_destroy_channel(struct kref *kref)
|
| 186 | {
|
| 187 | struct rchan *chan = container_of(kref, struct rchan, kref);
|
| 188 | free_percpu(chan->buf);
|
| 189 | kfree(chan);
|
| 190 | }
|
| 191 |
|
| 192 | |
| 193 | * relay_destroy_buf - destroy an rchan_buf struct and associated buffer
|
| 194 | * @buf: the buffer struct
|
| 195 |
|
| 196 | static void relay_destroy_buf(struct rchan_buf *buf)
|
| 197 | {
|
| 198 | struct rchan *chan = buf->chan;
|
| 199 | unsigned int i;
|
| 200 |
|
| 201 | if (likely(buf->start)) {
|
| 202 | vunmap(buf->start);
|
| 203 | for (i = 0; i < buf->page_count; i++)
|
| 204 | __free_page(buf->page_array[i]);
|
| 205 | relay_free_page_array(buf->page_array);
|
| 206 | }
|
| 207 | *per_cpu_ptr(chan->buf, buf->cpu) = NULL;
|
| 208 | kfree(buf->padding);
|
| 209 | kfree(buf);
|
| 210 | kref_put(&chan->kref, relay_destroy_channel);
|
| 211 | }
|
| 212 |
|
| 213 | |
| 214 | * relay_remove_buf - remove a channel buffer
|
| 215 | * @kref: target kernel reference that contains the relay buffer
|
| 216 | *
|
| 217 | * Removes the file from the filesystem, which also frees the
|
| 218 | * rchan_buf_struct and the channel buffer. Should only be called from
|
| 219 | * kref_put().
|
| 220 |
|
| 221 | static void relay_remove_buf(struct kref *kref)
|
| 222 | {
|
| 223 | struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
|
| 224 | relay_destroy_buf(buf);
|
| 225 | }
|
| 226 |
|
| 227 | |
| 228 | * relay_buf_empty - boolean, is the channel buffer empty?
|
| 229 | * @buf: channel buffer
|
| 230 | *
|
| 231 | * Returns 1 if the buffer is empty, 0 otherwise.
|
| 232 |
|
| 233 | static int relay_buf_empty(struct rchan_buf *buf)
|
| 234 | {
|
| 235 | return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1;
|
| 236 | }
|
| 237 |
|
| 238 | |
| 239 | * relay_buf_full - boolean, is the channel buffer full?
|
| 240 | * @buf: channel buffer
|
| 241 | *
|
| 242 | * Returns 1 if the buffer is full, 0 otherwise.
|
| 243 |
|
| 244 | int relay_buf_full(struct rchan_buf *buf)
|
| 245 | {
|
| 246 | size_t ready = buf->subbufs_produced - buf->subbufs_consumed;
|
| 247 | return (ready >= buf->chan->n_subbufs) ? 1 : 0;
|
| 248 | }
|
| 249 | EXPORT_SYMBOL_GPL(relay_buf_full);
|
| 250 |
|
| 251 | |
| 252 | * High-level relay kernel API and associated functions.
|
| 253 |
|
| 254 |
|
| 255 | static int relay_subbuf_start(struct rchan_buf *buf, void *subbuf,
|
| 256 | void *prev_subbuf, size_t prev_padding)
|
| 257 | {
|
| 258 | if (!buf->chan->cb->subbuf_start)
|
| 259 | return !relay_buf_full(buf);
|
| 260 |
|
| 261 | return buf->chan->cb->subbuf_start(buf, subbuf,
|
| 262 | prev_subbuf, prev_padding);
|
| 263 | }
|
| 264 |
|
| 265 | |
| 266 | * wakeup_readers - wake up readers waiting on a channel
|
| 267 | * @work: contains the channel buffer
|
| 268 | *
|
| 269 | * This is the function used to defer reader waking
|
| 270 |
|
| 271 | static void wakeup_readers(struct irq_work *work)
|
| 272 | {
|
| 273 | struct rchan_buf *buf;
|
| 274 |
|
| 275 | buf = container_of(work, struct rchan_buf, wakeup_work);
|
| 276 | wake_up_interruptible(&buf->read_wait);
|
| 277 | }
|
| 278 |
|
| 279 | |
| 280 | * __relay_reset - reset a channel buffer
|
| 281 | * @buf: the channel buffer
|
| 282 | * @init: 1 if this is a first-time initialization
|
| 283 | *
|
| 284 | * See relay_reset() for description of effect.
|
| 285 |
|
| 286 | static void __relay_reset(struct rchan_buf *buf, unsigned int init)
|
| 287 | {
|
| 288 | size_t i;
|
| 289 |
|
| 290 | if (init) {
|
| 291 | init_waitqueue_head(&buf->read_wait);
|
| 292 | kref_init(&buf->kref);
|
| 293 | init_irq_work(&buf->wakeup_work, wakeup_readers);
|
| 294 | } else {
|
| 295 | irq_work_sync(&buf->wakeup_work);
|
| 296 | }
|
| 297 |
|
| 298 | buf->subbufs_produced = 0;
|
| 299 | buf->subbufs_consumed = 0;
|
| 300 | buf->bytes_consumed = 0;
|
| 301 | buf->finalized = 0;
|
| 302 | buf->data = buf->start;
|
| 303 | buf->offset = 0;
|
| 304 |
|
| 305 | for (i = 0; i < buf->chan->n_subbufs; i++)
|
| 306 | buf->padding[i] = 0;
|
| 307 |
|
| 308 | relay_subbuf_start(buf, buf->data, NULL, 0);
|
| 309 | }
|
| 310 |
|
| 311 | |
| 312 | * relay_reset - reset the channel
|
| 313 | * @chan: the channel
|
| 314 | *
|
| 315 | * This has the effect of erasing all data from all channel buffers
|
| 316 | * and restarting the channel in its initial state. The buffers
|
| 317 | * are not freed, so any mappings are still in effect.
|
| 318 | *
|
| 319 | * NOTE. Care should be taken that the channel isn't actually
|
| 320 | * being used by anything when this call is made.
|
| 321 |
|
| 322 | void relay_reset(struct rchan *chan)
|
| 323 | {
|
| 324 | struct rchan_buf *buf;
|
| 325 | unsigned int i;
|
| 326 |
|
| 327 | if (!chan)
|
| 328 | return;
|
| 329 |
|
| 330 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) {
|
| 331 | __relay_reset(buf, 0);
|
| 332 | return;
|
| 333 | }
|
| 334 |
|
| 335 | mutex_lock(&relay_channels_mutex);
|
| 336 | for_each_possible_cpu(i)
|
| 337 | if ((buf = *per_cpu_ptr(chan->buf, i)))
|
| 338 | __relay_reset(buf, 0);
|
| 339 | mutex_unlock(&relay_channels_mutex);
|
| 340 | }
|
| 341 | EXPORT_SYMBOL_GPL(relay_reset);
|
| 342 |
|
| 343 | static inline void relay_set_buf_dentry(struct rchan_buf *buf,
|
| 344 | struct dentry *dentry)
|
| 345 | {
|
| 346 | buf->dentry = dentry;
|
| 347 | d_inode(buf->dentry)->i_size = buf->early_bytes;
|
| 348 | }
|
| 349 |
|
| 350 | static struct dentry *relay_create_buf_file(struct rchan *chan,
|
| 351 | struct rchan_buf *buf,
|
| 352 | unsigned int cpu)
|
| 353 | {
|
| 354 | struct dentry *dentry;
|
| 355 | char *tmpname;
|
| 356 |
|
| 357 | tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL);
|
| 358 | if (!tmpname)
|
| 359 | return NULL;
|
| 360 | snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
|
| 361 |
|
| 362 |
|
| 363 | dentry = chan->cb->create_buf_file(tmpname, chan->parent,
|
| 364 | S_IRUSR, buf,
|
| 365 | &chan->is_global);
|
| 366 | if (IS_ERR(dentry))
|
| 367 | dentry = NULL;
|
| 368 |
|
| 369 | kfree(tmpname);
|
| 370 |
|
| 371 | return dentry;
|
| 372 | }
|
| 373 |
|
| 374 | |
| 375 | * relay_open_buf - create a new relay channel buffer
|
| 376 | *
|
| 377 | * used by relay_open() and CPU hotplug.
|
| 378 |
|
| 379 | static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
|
| 380 | {
|
| 381 | struct rchan_buf *buf = NULL;
|
| 382 | struct dentry *dentry;
|
| 383 |
|
| 384 | if (chan->is_global)
|
| 385 | return *per_cpu_ptr(chan->buf, 0);
|
| 386 |
|
| 387 | buf = relay_create_buf(chan);
|
| 388 | if (!buf)
|
| 389 | return NULL;
|
| 390 |
|
| 391 | if (chan->has_base_filename) {
|
| 392 | dentry = relay_create_buf_file(chan, buf, cpu);
|
| 393 | if (!dentry)
|
| 394 | goto free_buf;
|
| 395 | relay_set_buf_dentry(buf, dentry);
|
| 396 | } else {
|
| 397 |
|
| 398 | dentry = chan->cb->create_buf_file(NULL, NULL,
|
| 399 | S_IRUSR, buf,
|
| 400 | &chan->is_global);
|
| 401 | if (IS_ERR_OR_NULL(dentry))
|
| 402 | goto free_buf;
|
| 403 | }
|
| 404 |
|
| 405 | buf->cpu = cpu;
|
| 406 | __relay_reset(buf, 1);
|
| 407 |
|
| 408 | if(chan->is_global) {
|
| 409 | *per_cpu_ptr(chan->buf, 0) = buf;
|
| 410 | buf->cpu = 0;
|
| 411 | }
|
| 412 |
|
| 413 | return buf;
|
| 414 |
|
| 415 | free_buf:
|
| 416 | relay_destroy_buf(buf);
|
| 417 | return NULL;
|
| 418 | }
|
| 419 |
|
| 420 | |
| 421 | * relay_close_buf - close a channel buffer
|
| 422 | * @buf: channel buffer
|
| 423 | *
|
| 424 | * Marks the buffer finalized and restores the default callbacks.
|
| 425 | * The channel buffer and channel buffer data structure are then freed
|
| 426 | * automatically when the last reference is given up.
|
| 427 |
|
| 428 | static void relay_close_buf(struct rchan_buf *buf)
|
| 429 | {
|
| 430 | buf->finalized = 1;
|
| 431 | irq_work_sync(&buf->wakeup_work);
|
| 432 | buf->chan->cb->remove_buf_file(buf->dentry);
|
| 433 | kref_put(&buf->kref, relay_remove_buf);
|
| 434 | }
|
| 435 |
|
| 436 | int relay_prepare_cpu(unsigned int cpu)
|
| 437 | {
|
| 438 | struct rchan *chan;
|
| 439 | struct rchan_buf *buf;
|
| 440 |
|
| 441 | mutex_lock(&relay_channels_mutex);
|
| 442 | list_for_each_entry(chan, &relay_channels, list) {
|
| 443 | if (*per_cpu_ptr(chan->buf, cpu))
|
| 444 | continue;
|
| 445 | buf = relay_open_buf(chan, cpu);
|
| 446 | if (!buf) {
|
| 447 | pr_err("relay: cpu %d buffer creation failed\n", cpu);
|
| 448 | mutex_unlock(&relay_channels_mutex);
|
| 449 | return -ENOMEM;
|
| 450 | }
|
| 451 | *per_cpu_ptr(chan->buf, cpu) = buf;
|
| 452 | }
|
| 453 | mutex_unlock(&relay_channels_mutex);
|
| 454 | return 0;
|
| 455 | }
|
| 456 |
|
| 457 | |
| 458 | * relay_open - create a new relay channel
|
| 459 | * @base_filename: base name of files to create, %NULL for buffering only
|
| 460 | * @parent: dentry of parent directory, %NULL for root directory or buffer
|
| 461 | * @subbuf_size: size of sub-buffers
|
| 462 | * @n_subbufs: number of sub-buffers
|
| 463 | * @cb: client callback functions
|
| 464 | * @private_data: user-defined data
|
| 465 | *
|
| 466 | * Returns channel pointer if successful, %NULL otherwise.
|
| 467 | *
|
| 468 | * Creates a channel buffer for each cpu using the sizes and
|
| 469 | * attributes specified. The created channel buffer files
|
| 470 | * will be named base_filename0...base_filenameN-1. File
|
| 471 | * permissions will be %S_IRUSR.
|
| 472 | *
|
| 473 | * If opening a buffer (@parent = NULL) that you later wish to register
|
| 474 | * in a filesystem, call relay_late_setup_files() once the @parent dentry
|
| 475 | * is available.
|
| 476 |
|
| 477 | struct rchan *relay_open(const char *base_filename,
|
| 478 | struct dentry *parent,
|
| 479 | size_t subbuf_size,
|
| 480 | size_t n_subbufs,
|
| 481 | const struct rchan_callbacks *cb,
|
| 482 | void *private_data)
|
| 483 | {
|
| 484 | unsigned int i;
|
| 485 | struct rchan *chan;
|
| 486 | struct rchan_buf *buf;
|
| 487 |
|
| 488 | if (!(subbuf_size && n_subbufs))
|
| 489 | return NULL;
|
| 490 | if (subbuf_size > UINT_MAX / n_subbufs)
|
| 491 | return NULL;
|
| 492 | if (!cb || !cb->create_buf_file || !cb->remove_buf_file)
|
| 493 | return NULL;
|
| 494 |
|
| 495 | chan = kzalloc(sizeof(struct rchan), GFP_KERNEL);
|
| 496 | if (!chan)
|
| 497 | return NULL;
|
| 498 |
|
| 499 | chan->buf = alloc_percpu(struct rchan_buf *);
|
| 500 | if (!chan->buf) {
|
| 501 | kfree(chan);
|
| 502 | return NULL;
|
| 503 | }
|
| 504 |
|
| 505 | chan->version = RELAYFS_CHANNEL_VERSION;
|
| 506 | chan->n_subbufs = n_subbufs;
|
| 507 | chan->subbuf_size = subbuf_size;
|
| 508 | chan->alloc_size = PAGE_ALIGN(subbuf_size * n_subbufs);
|
| 509 | chan->parent = parent;
|
| 510 | chan->private_data = private_data;
|
| 511 | if (base_filename) {
|
| 512 | chan->has_base_filename = 1;
|
| 513 | strlcpy(chan->base_filename, base_filename, NAME_MAX);
|
| 514 | }
|
| 515 | chan->cb = cb;
|
| 516 | kref_init(&chan->kref);
|
| 517 |
|
| 518 | mutex_lock(&relay_channels_mutex);
|
| 519 | for_each_online_cpu(i) {
|
| 520 | buf = relay_open_buf(chan, i);
|
| 521 | if (!buf)
|
| 522 | goto free_bufs;
|
| 523 | *per_cpu_ptr(chan->buf, i) = buf;
|
| 524 | }
|
| 525 | list_add(&chan->list, &relay_channels);
|
| 526 | mutex_unlock(&relay_channels_mutex);
|
| 527 |
|
| 528 | return chan;
|
| 529 |
|
| 530 | free_bufs:
|
| 531 | for_each_possible_cpu(i) {
|
| 532 | if ((buf = *per_cpu_ptr(chan->buf, i)))
|
| 533 | relay_close_buf(buf);
|
| 534 | }
|
| 535 |
|
| 536 | kref_put(&chan->kref, relay_destroy_channel);
|
| 537 | mutex_unlock(&relay_channels_mutex);
|
| 538 | return NULL;
|
| 539 | }
|
| 540 | EXPORT_SYMBOL_GPL(relay_open);
|
| 541 |
|
| 542 | struct rchan_percpu_buf_dispatcher {
|
| 543 | struct rchan_buf *buf;
|
| 544 | struct dentry *dentry;
|
| 545 | };
|
| 546 |
|
| 547 |
|
| 548 | static void __relay_set_buf_dentry(void *info)
|
| 549 | {
|
| 550 | struct rchan_percpu_buf_dispatcher *p = info;
|
| 551 |
|
| 552 | relay_set_buf_dentry(p->buf, p->dentry);
|
| 553 | }
|
| 554 |
|
| 555 | |
| 556 | * relay_late_setup_files - triggers file creation
|
| 557 | * @chan: channel to operate on
|
| 558 | * @base_filename: base name of files to create
|
| 559 | * @parent: dentry of parent directory, %NULL for root directory
|
| 560 | *
|
| 561 | * Returns 0 if successful, non-zero otherwise.
|
| 562 | *
|
| 563 | * Use to setup files for a previously buffer-only channel created
|
| 564 | * by relay_open() with a NULL parent dentry.
|
| 565 | *
|
| 566 | * For example, this is useful for perfomring early tracing in kernel,
|
| 567 | * before VFS is up and then exposing the early results once the dentry
|
| 568 | * is available.
|
| 569 |
|
| 570 | int relay_late_setup_files(struct rchan *chan,
|
| 571 | const char *base_filename,
|
| 572 | struct dentry *parent)
|
| 573 | {
|
| 574 | int err = 0;
|
| 575 | unsigned int i, curr_cpu;
|
| 576 | unsigned long flags;
|
| 577 | struct dentry *dentry;
|
| 578 | struct rchan_buf *buf;
|
| 579 | struct rchan_percpu_buf_dispatcher disp;
|
| 580 |
|
| 581 | if (!chan || !base_filename)
|
| 582 | return -EINVAL;
|
| 583 |
|
| 584 | strlcpy(chan->base_filename, base_filename, NAME_MAX);
|
| 585 |
|
| 586 | mutex_lock(&relay_channels_mutex);
|
| 587 |
|
| 588 | if (unlikely(chan->has_base_filename)) {
|
| 589 | mutex_unlock(&relay_channels_mutex);
|
| 590 | return -EEXIST;
|
| 591 | }
|
| 592 | chan->has_base_filename = 1;
|
| 593 | chan->parent = parent;
|
| 594 |
|
| 595 | if (chan->is_global) {
|
| 596 | err = -EINVAL;
|
| 597 | buf = *per_cpu_ptr(chan->buf, 0);
|
| 598 | if (!WARN_ON_ONCE(!buf)) {
|
| 599 | dentry = relay_create_buf_file(chan, buf, 0);
|
| 600 | if (dentry && !WARN_ON_ONCE(!chan->is_global)) {
|
| 601 | relay_set_buf_dentry(buf, dentry);
|
| 602 | err = 0;
|
| 603 | }
|
| 604 | }
|
| 605 | mutex_unlock(&relay_channels_mutex);
|
| 606 | return err;
|
| 607 | }
|
| 608 |
|
| 609 | curr_cpu = get_cpu();
|
| 610 | |
| 611 | * The CPU hotplug notifier ran before us and created buffers with
|
| 612 | * no files associated. So it's safe to call relay_setup_buf_file()
|
| 613 | * on all currently online CPUs.
|
| 614 |
|
| 615 | for_each_online_cpu(i) {
|
| 616 | buf = *per_cpu_ptr(chan->buf, i);
|
| 617 | if (unlikely(!buf)) {
|
| 618 | WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n");
|
| 619 | err = -EINVAL;
|
| 620 | break;
|
| 621 | }
|
| 622 |
|
| 623 | dentry = relay_create_buf_file(chan, buf, i);
|
| 624 | if (unlikely(!dentry)) {
|
| 625 | err = -EINVAL;
|
| 626 | break;
|
| 627 | }
|
| 628 |
|
| 629 | if (curr_cpu == i) {
|
| 630 | local_irq_save(flags);
|
| 631 | relay_set_buf_dentry(buf, dentry);
|
| 632 | local_irq_restore(flags);
|
| 633 | } else {
|
| 634 | disp.buf = buf;
|
| 635 | disp.dentry = dentry;
|
| 636 | smp_mb();
|
| 637 |
|
| 638 | err = smp_call_function_single(i,
|
| 639 | __relay_set_buf_dentry,
|
| 640 | &disp, 1);
|
| 641 | }
|
| 642 | if (unlikely(err))
|
| 643 | break;
|
| 644 | }
|
| 645 | put_cpu();
|
| 646 | mutex_unlock(&relay_channels_mutex);
|
| 647 |
|
| 648 | return err;
|
| 649 | }
|
| 650 | EXPORT_SYMBOL_GPL(relay_late_setup_files);
|
| 651 |
|
| 652 | |
| 653 | * relay_switch_subbuf - switch to a new sub-buffer
|
| 654 | * @buf: channel buffer
|
| 655 | * @length: size of current event
|
| 656 | *
|
| 657 | * Returns either the length passed in or 0 if full.
|
| 658 | *
|
| 659 | * Performs sub-buffer-switch tasks such as invoking callbacks,
|
| 660 | * updating padding counts, waking up readers, etc.
|
| 661 |
|
| 662 | size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
|
| 663 | {
|
| 664 | void *old, *new;
|
| 665 | size_t old_subbuf, new_subbuf;
|
| 666 |
|
| 667 | if (unlikely(length > buf->chan->subbuf_size))
|
| 668 | goto toobig;
|
| 669 |
|
| 670 | if (buf->offset != buf->chan->subbuf_size + 1) {
|
| 671 | buf->prev_padding = buf->chan->subbuf_size - buf->offset;
|
| 672 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
|
| 673 | buf->padding[old_subbuf] = buf->prev_padding;
|
| 674 | buf->subbufs_produced++;
|
| 675 | if (buf->dentry)
|
| 676 | d_inode(buf->dentry)->i_size +=
|
| 677 | buf->chan->subbuf_size -
|
| 678 | buf->padding[old_subbuf];
|
| 679 | else
|
| 680 | buf->early_bytes += buf->chan->subbuf_size -
|
| 681 | buf->padding[old_subbuf];
|
| 682 | smp_mb();
|
| 683 | if (waitqueue_active(&buf->read_wait)) {
|
| 684 | |
| 685 | * Calling wake_up_interruptible() from here
|
| 686 | * will deadlock if we happen to be logging
|
| 687 | * from the scheduler (trying to re-grab
|
| 688 | * rq->lock), so defer it.
|
| 689 |
|
| 690 | irq_work_queue(&buf->wakeup_work);
|
| 691 | }
|
| 692 | }
|
| 693 |
|
| 694 | old = buf->data;
|
| 695 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
|
| 696 | new = buf->start + new_subbuf * buf->chan->subbuf_size;
|
| 697 | buf->offset = 0;
|
| 698 | if (!relay_subbuf_start(buf, new, old, buf->prev_padding)) {
|
| 699 | buf->offset = buf->chan->subbuf_size + 1;
|
| 700 | return 0;
|
| 701 | }
|
| 702 | buf->data = new;
|
| 703 | buf->padding[new_subbuf] = 0;
|
| 704 |
|
| 705 | if (unlikely(length + buf->offset > buf->chan->subbuf_size))
|
| 706 | goto toobig;
|
| 707 |
|
| 708 | return length;
|
| 709 |
|
| 710 | toobig:
|
| 711 | buf->chan->last_toobig = length;
|
| 712 | return 0;
|
| 713 | }
|
| 714 | EXPORT_SYMBOL_GPL(relay_switch_subbuf);
|
| 715 |
|
| 716 | |
| 717 | * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count
|
| 718 | * @chan: the channel
|
| 719 | * @cpu: the cpu associated with the channel buffer to update
|
| 720 | * @subbufs_consumed: number of sub-buffers to add to current buf's count
|
| 721 | *
|
| 722 | * Adds to the channel buffer's consumed sub-buffer count.
|
| 723 | * subbufs_consumed should be the number of sub-buffers newly consumed,
|
| 724 | * not the total consumed.
|
| 725 | *
|
| 726 | * NOTE. Kernel clients don't need to call this function if the channel
|
| 727 | * mode is 'overwrite'.
|
| 728 |
|
| 729 | void relay_subbufs_consumed(struct rchan *chan,
|
| 730 | unsigned int cpu,
|
| 731 | size_t subbufs_consumed)
|
| 732 | {
|
| 733 | struct rchan_buf *buf;
|
| 734 |
|
| 735 | if (!chan || cpu >= NR_CPUS)
|
| 736 | return;
|
| 737 |
|
| 738 | buf = *per_cpu_ptr(chan->buf, cpu);
|
| 739 | if (!buf || subbufs_consumed > chan->n_subbufs)
|
| 740 | return;
|
| 741 |
|
| 742 | if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed)
|
| 743 | buf->subbufs_consumed = buf->subbufs_produced;
|
| 744 | else
|
| 745 | buf->subbufs_consumed += subbufs_consumed;
|
| 746 | }
|
| 747 | EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
|
| 748 |
|
| 749 | |
| 750 | * relay_close - close the channel
|
| 751 | * @chan: the channel
|
| 752 | *
|
| 753 | * Closes all channel buffers and frees the channel.
|
| 754 |
|
| 755 | void relay_close(struct rchan *chan)
|
| 756 | {
|
| 757 | struct rchan_buf *buf;
|
| 758 | unsigned int i;
|
| 759 |
|
| 760 | if (!chan)
|
| 761 | return;
|
| 762 |
|
| 763 | mutex_lock(&relay_channels_mutex);
|
| 764 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0)))
|
| 765 | relay_close_buf(buf);
|
| 766 | else
|
| 767 | for_each_possible_cpu(i)
|
| 768 | if ((buf = *per_cpu_ptr(chan->buf, i)))
|
| 769 | relay_close_buf(buf);
|
| 770 |
|
| 771 | if (chan->last_toobig)
|
| 772 | printk(KERN_WARNING "relay: one or more items not logged "
|
| 773 | "[item size (%zd) > sub-buffer size (%zd)]\n",
|
| 774 | chan->last_toobig, chan->subbuf_size);
|
| 775 |
|
| 776 | list_del(&chan->list);
|
| 777 | kref_put(&chan->kref, relay_destroy_channel);
|
| 778 | mutex_unlock(&relay_channels_mutex);
|
| 779 | }
|
| 780 | EXPORT_SYMBOL_GPL(relay_close);
|
| 781 |
|
| 782 | |
| 783 | * relay_flush - close the channel
|
| 784 | * @chan: the channel
|
| 785 | *
|
| 786 | * Flushes all channel buffers, i.e. forces buffer switch.
|
| 787 |
|
| 788 | void relay_flush(struct rchan *chan)
|
| 789 | {
|
| 790 | struct rchan_buf *buf;
|
| 791 | unsigned int i;
|
| 792 |
|
| 793 | if (!chan)
|
| 794 | return;
|
| 795 |
|
| 796 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) {
|
| 797 | relay_switch_subbuf(buf, 0);
|
| 798 | return;
|
| 799 | }
|
| 800 |
|
| 801 | mutex_lock(&relay_channels_mutex);
|
| 802 | for_each_possible_cpu(i)
|
| 803 | if ((buf = *per_cpu_ptr(chan->buf, i)))
|
| 804 | relay_switch_subbuf(buf, 0);
|
| 805 | mutex_unlock(&relay_channels_mutex);
|
| 806 | }
|
| 807 | EXPORT_SYMBOL_GPL(relay_flush);
|
| 808 |
|
| 809 | |
| 810 | * relay_file_open - open file op for relay files
|
| 811 | * @inode: the inode
|
| 812 | * @filp: the file
|
| 813 | *
|
| 814 | * Increments the channel buffer refcount.
|
| 815 |
|
| 816 | static int relay_file_open(struct inode *inode, struct file *filp)
|
| 817 | {
|
| 818 | struct rchan_buf *buf = inode->i_private;
|
| 819 | kref_get(&buf->kref);
|
| 820 | filp->private_data = buf;
|
| 821 |
|
| 822 | return nonseekable_open(inode, filp);
|
| 823 | }
|
| 824 |
|
| 825 | |
| 826 | * relay_file_mmap - mmap file op for relay files
|
| 827 | * @filp: the file
|
| 828 | * @vma: the vma describing what to map
|
| 829 | *
|
| 830 | * Calls upon relay_mmap_buf() to map the file into user space.
|
| 831 |
|
| 832 | static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma)
|
| 833 | {
|
| 834 | struct rchan_buf *buf = filp->private_data;
|
| 835 | return relay_mmap_buf(buf, vma);
|
| 836 | }
|
| 837 |
|
| 838 | |
| 839 | * relay_file_poll - poll file op for relay files
|
| 840 | * @filp: the file
|
| 841 | * @wait: poll table
|
| 842 | *
|
| 843 | * Poll implemention.
|
| 844 |
|
| 845 | static __poll_t relay_file_poll(struct file *filp, poll_table *wait)
|
| 846 | {
|
| 847 | __poll_t mask = 0;
|
| 848 | struct rchan_buf *buf = filp->private_data;
|
| 849 |
|
| 850 | if (buf->finalized)
|
| 851 | return EPOLLERR;
|
| 852 |
|
| 853 | if (filp->f_mode & FMODE_READ) {
|
| 854 | poll_wait(filp, &buf->read_wait, wait);
|
| 855 | if (!relay_buf_empty(buf))
|
| 856 | mask |= EPOLLIN | EPOLLRDNORM;
|
| 857 | }
|
| 858 |
|
| 859 | return mask;
|
| 860 | }
|
| 861 |
|
| 862 | |
| 863 | * relay_file_release - release file op for relay files
|
| 864 | * @inode: the inode
|
| 865 | * @filp: the file
|
| 866 | *
|
| 867 | * Decrements the channel refcount, as the filesystem is
|
| 868 | * no longer using it.
|
| 869 |
|
| 870 | static int relay_file_release(struct inode *inode, struct file *filp)
|
| 871 | {
|
| 872 | struct rchan_buf *buf = filp->private_data;
|
| 873 | kref_put(&buf->kref, relay_remove_buf);
|
| 874 |
|
| 875 | return 0;
|
| 876 | }
|
| 877 |
|
| 878 | |
| 879 | * relay_file_read_consume - update the consumed count for the buffer
|
| 880 |
|
| 881 | static void relay_file_read_consume(struct rchan_buf *buf,
|
| 882 | size_t read_pos,
|
| 883 | size_t bytes_consumed)
|
| 884 | {
|
| 885 | size_t subbuf_size = buf->chan->subbuf_size;
|
| 886 | size_t n_subbufs = buf->chan->n_subbufs;
|
| 887 | size_t read_subbuf;
|
| 888 |
|
| 889 | if (buf->subbufs_produced == buf->subbufs_consumed &&
|
| 890 | buf->offset == buf->bytes_consumed)
|
| 891 | return;
|
| 892 |
|
| 893 | if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
|
| 894 | relay_subbufs_consumed(buf->chan, buf->cpu, 1);
|
| 895 | buf->bytes_consumed = 0;
|
| 896 | }
|
| 897 |
|
| 898 | buf->bytes_consumed += bytes_consumed;
|
| 899 | if (!read_pos)
|
| 900 | read_subbuf = buf->subbufs_consumed % n_subbufs;
|
| 901 | else
|
| 902 | read_subbuf = read_pos / buf->chan->subbuf_size;
|
| 903 | if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
|
| 904 | if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
|
| 905 | (buf->offset == subbuf_size))
|
| 906 | return;
|
| 907 | relay_subbufs_consumed(buf->chan, buf->cpu, 1);
|
| 908 | buf->bytes_consumed = 0;
|
| 909 | }
|
| 910 | }
|
| 911 |
|
| 912 | |
| 913 | * relay_file_read_avail - boolean, are there unconsumed bytes available?
|
| 914 |
|
| 915 | static int relay_file_read_avail(struct rchan_buf *buf)
|
| 916 | {
|
| 917 | size_t subbuf_size = buf->chan->subbuf_size;
|
| 918 | size_t n_subbufs = buf->chan->n_subbufs;
|
| 919 | size_t produced = buf->subbufs_produced;
|
| 920 | size_t consumed;
|
| 921 |
|
| 922 | relay_file_read_consume(buf, 0, 0);
|
| 923 |
|
| 924 | consumed = buf->subbufs_consumed;
|
| 925 |
|
| 926 | if (unlikely(buf->offset > subbuf_size)) {
|
| 927 | if (produced == consumed)
|
| 928 | return 0;
|
| 929 | return 1;
|
| 930 | }
|
| 931 |
|
| 932 | if (unlikely(produced - consumed >= n_subbufs)) {
|
| 933 | consumed = produced - n_subbufs + 1;
|
| 934 | buf->subbufs_consumed = consumed;
|
| 935 | buf->bytes_consumed = 0;
|
| 936 | }
|
| 937 |
|
| 938 | produced = (produced % n_subbufs) * subbuf_size + buf->offset;
|
| 939 | consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed;
|
| 940 |
|
| 941 | if (consumed > produced)
|
| 942 | produced += n_subbufs * subbuf_size;
|
| 943 |
|
| 944 | if (consumed == produced) {
|
| 945 | if (buf->offset == subbuf_size &&
|
| 946 | buf->subbufs_produced > buf->subbufs_consumed)
|
| 947 | return 1;
|
| 948 | return 0;
|
| 949 | }
|
| 950 |
|
| 951 | return 1;
|
| 952 | }
|
| 953 |
|
| 954 | |
| 955 | * relay_file_read_subbuf_avail - return bytes available in sub-buffer
|
| 956 | * @read_pos: file read position
|
| 957 | * @buf: relay channel buffer
|
| 958 |
|
| 959 | static size_t relay_file_read_subbuf_avail(size_t read_pos,
|
| 960 | struct rchan_buf *buf)
|
| 961 | {
|
| 962 | size_t padding, avail = 0;
|
| 963 | size_t read_subbuf, read_offset, write_subbuf, write_offset;
|
| 964 | size_t subbuf_size = buf->chan->subbuf_size;
|
| 965 |
|
| 966 | write_subbuf = (buf->data - buf->start) / subbuf_size;
|
| 967 | write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
|
| 968 | read_subbuf = read_pos / subbuf_size;
|
| 969 | read_offset = read_pos % subbuf_size;
|
| 970 | padding = buf->padding[read_subbuf];
|
| 971 |
|
| 972 | if (read_subbuf == write_subbuf) {
|
| 973 | if (read_offset + padding < write_offset)
|
| 974 | avail = write_offset - (read_offset + padding);
|
| 975 | } else
|
| 976 | avail = (subbuf_size - padding) - read_offset;
|
| 977 |
|
| 978 | return avail;
|
| 979 | }
|
| 980 |
|
| 981 | |
| 982 | * relay_file_read_start_pos - find the first available byte to read
|
| 983 | * @buf: relay channel buffer
|
| 984 | *
|
| 985 | * If the read_pos is in the middle of padding, return the
|
| 986 | * position of the first actually available byte, otherwise
|
| 987 | * return the original value.
|
| 988 |
|
| 989 | static size_t relay_file_read_start_pos(struct rchan_buf *buf)
|
| 990 | {
|
| 991 | size_t read_subbuf, padding, padding_start, padding_end;
|
| 992 | size_t subbuf_size = buf->chan->subbuf_size;
|
| 993 | size_t n_subbufs = buf->chan->n_subbufs;
|
| 994 | size_t consumed = buf->subbufs_consumed % n_subbufs;
|
| 995 | size_t read_pos = consumed * subbuf_size + buf->bytes_consumed;
|
| 996 |
|
| 997 | read_subbuf = read_pos / subbuf_size;
|
| 998 | padding = buf->padding[read_subbuf];
|
| 999 | padding_start = (read_subbuf + 1) * subbuf_size - padding;
|
| 1000 | padding_end = (read_subbuf + 1) * subbuf_size;
|
| 1001 | if (read_pos >= padding_start && read_pos < padding_end) {
|
| 1002 | read_subbuf = (read_subbuf + 1) % n_subbufs;
|
| 1003 | read_pos = read_subbuf * subbuf_size;
|
| 1004 | }
|
| 1005 |
|
| 1006 | return read_pos;
|
| 1007 | }
|
| 1008 |
|
| 1009 | |
| 1010 | * relay_file_read_end_pos - return the new read position
|
| 1011 | * @read_pos: file read position
|
| 1012 | * @buf: relay channel buffer
|
| 1013 | * @count: number of bytes to be read
|
| 1014 |
|
| 1015 | static size_t relay_file_read_end_pos(struct rchan_buf *buf,
|
| 1016 | size_t read_pos,
|
| 1017 | size_t count)
|
| 1018 | {
|
| 1019 | size_t read_subbuf, padding, end_pos;
|
| 1020 | size_t subbuf_size = buf->chan->subbuf_size;
|
| 1021 | size_t n_subbufs = buf->chan->n_subbufs;
|
| 1022 |
|
| 1023 | read_subbuf = read_pos / subbuf_size;
|
| 1024 | padding = buf->padding[read_subbuf];
|
| 1025 | if (read_pos % subbuf_size + count + padding == subbuf_size)
|
| 1026 | end_pos = (read_subbuf + 1) * subbuf_size;
|
| 1027 | else
|
| 1028 | end_pos = read_pos + count;
|
| 1029 | if (end_pos >= subbuf_size * n_subbufs)
|
| 1030 | end_pos = 0;
|
| 1031 |
|
| 1032 | return end_pos;
|
| 1033 | }
|
| 1034 |
|
| 1035 | static ssize_t relay_file_read(struct file *filp,
|
| 1036 | char __user *buffer,
|
| 1037 | size_t count,
|
| 1038 | loff_t *ppos)
|
| 1039 | {
|
| 1040 | struct rchan_buf *buf = filp->private_data;
|
| 1041 | size_t read_start, avail;
|
| 1042 | size_t written = 0;
|
| 1043 | int ret;
|
| 1044 |
|
| 1045 | if (!count)
|
| 1046 | return 0;
|
| 1047 |
|
| 1048 | inode_lock(file_inode(filp));
|
| 1049 | do {
|
| 1050 | void *from;
|
| 1051 |
|
| 1052 | if (!relay_file_read_avail(buf))
|
| 1053 | break;
|
| 1054 |
|
| 1055 | read_start = relay_file_read_start_pos(buf);
|
| 1056 | avail = relay_file_read_subbuf_avail(read_start, buf);
|
| 1057 | if (!avail)
|
| 1058 | break;
|
| 1059 |
|
| 1060 | avail = min(count, avail);
|
| 1061 | from = buf->start + read_start;
|
| 1062 | ret = avail;
|
| 1063 | if (copy_to_user(buffer, from, avail))
|
| 1064 | break;
|
| 1065 |
|
| 1066 | buffer += ret;
|
| 1067 | written += ret;
|
| 1068 | count -= ret;
|
| 1069 |
|
| 1070 | relay_file_read_consume(buf, read_start, ret);
|
| 1071 | *ppos = relay_file_read_end_pos(buf, read_start, ret);
|
| 1072 | } while (count);
|
| 1073 | inode_unlock(file_inode(filp));
|
| 1074 |
|
| 1075 | return written;
|
| 1076 | }
|
| 1077 |
|
| 1078 | static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
|
| 1079 | {
|
| 1080 | rbuf->bytes_consumed += bytes_consumed;
|
| 1081 |
|
| 1082 | if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) {
|
| 1083 | relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
|
| 1084 | rbuf->bytes_consumed %= rbuf->chan->subbuf_size;
|
| 1085 | }
|
| 1086 | }
|
| 1087 |
|
| 1088 | static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
|
| 1089 | struct pipe_buffer *buf)
|
| 1090 | {
|
| 1091 | struct rchan_buf *rbuf;
|
| 1092 |
|
| 1093 | rbuf = (struct rchan_buf *)page_private(buf->page);
|
| 1094 | relay_consume_bytes(rbuf, buf->private);
|
| 1095 | }
|
| 1096 |
|
| 1097 | static const struct pipe_buf_operations relay_pipe_buf_ops = {
|
| 1098 | .release = relay_pipe_buf_release,
|
| 1099 | .try_steal = generic_pipe_buf_try_steal,
|
| 1100 | .get = generic_pipe_buf_get,
|
| 1101 | };
|
| 1102 |
|
| 1103 | static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
|
| 1104 | {
|
| 1105 | }
|
| 1106 |
|
| 1107 | |
| 1108 | * subbuf_splice_actor - splice up to one subbuf's worth of data
|
| 1109 |
|
| 1110 | static ssize_t subbuf_splice_actor(struct file *in,
|
| 1111 | loff_t *ppos,
|
| 1112 | struct pipe_inode_info *pipe,
|
| 1113 | size_t len,
|
| 1114 | unsigned int flags,
|
| 1115 | int *nonpad_ret)
|
| 1116 | {
|
| 1117 | unsigned int pidx, poff, total_len, subbuf_pages, nr_pages;
|
| 1118 | struct rchan_buf *rbuf = in->private_data;
|
| 1119 | unsigned int subbuf_size = rbuf->chan->subbuf_size;
|
| 1120 | uint64_t pos = (uint64_t) *ppos;
|
| 1121 | uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size;
|
| 1122 | size_t read_start = (size_t) do_div(pos, alloc_size);
|
| 1123 | size_t read_subbuf = read_start / subbuf_size;
|
| 1124 | size_t padding = rbuf->padding[read_subbuf];
|
| 1125 | size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
|
| 1126 | struct page *pages[PIPE_DEF_BUFFERS];
|
| 1127 | struct partial_page partial[PIPE_DEF_BUFFERS];
|
| 1128 | struct splice_pipe_desc spd = {
|
| 1129 | .pages = pages,
|
| 1130 | .nr_pages = 0,
|
| 1131 | .nr_pages_max = PIPE_DEF_BUFFERS,
|
| 1132 | .partial = partial,
|
| 1133 | .ops = &relay_pipe_buf_ops,
|
| 1134 | .spd_release = relay_page_release,
|
| 1135 | };
|
| 1136 | ssize_t ret;
|
| 1137 |
|
| 1138 | if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
|
| 1139 | return 0;
|
| 1140 | if (splice_grow_spd(pipe, &spd))
|
| 1141 | return -ENOMEM;
|
| 1142 |
|
| 1143 | |
| 1144 | * Adjust read len, if longer than what is available
|
| 1145 |
|
| 1146 | if (len > (subbuf_size - read_start % subbuf_size))
|
| 1147 | len = subbuf_size - read_start % subbuf_size;
|
| 1148 |
|
| 1149 | subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
|
| 1150 | pidx = (read_start / PAGE_SIZE) % subbuf_pages;
|
| 1151 | poff = read_start & ~PAGE_MASK;
|
| 1152 | nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max);
|
| 1153 |
|
| 1154 | for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) {
|
| 1155 | unsigned int this_len, this_end, private;
|
| 1156 | unsigned int cur_pos = read_start + total_len;
|
| 1157 |
|
| 1158 | if (!len)
|
| 1159 | break;
|
| 1160 |
|
| 1161 | this_len = min_t(unsigned long, len, PAGE_SIZE - poff);
|
| 1162 | private = this_len;
|
| 1163 |
|
| 1164 | spd.pages[spd.nr_pages] = rbuf->page_array[pidx];
|
| 1165 | spd.partial[spd.nr_pages].offset = poff;
|
| 1166 |
|
| 1167 | this_end = cur_pos + this_len;
|
| 1168 | if (this_end >= nonpad_end) {
|
| 1169 | this_len = nonpad_end - cur_pos;
|
| 1170 | private = this_len + padding;
|
| 1171 | }
|
| 1172 | spd.partial[spd.nr_pages].len = this_len;
|
| 1173 | spd.partial[spd.nr_pages].private = private;
|
| 1174 |
|
| 1175 | len -= this_len;
|
| 1176 | total_len += this_len;
|
| 1177 | poff = 0;
|
| 1178 | pidx = (pidx + 1) % subbuf_pages;
|
| 1179 |
|
| 1180 | if (this_end >= nonpad_end) {
|
| 1181 | spd.nr_pages++;
|
| 1182 | break;
|
| 1183 | }
|
| 1184 | }
|
| 1185 |
|
| 1186 | ret = 0;
|
| 1187 | if (!spd.nr_pages)
|
| 1188 | goto out;
|
| 1189 |
|
| 1190 | ret = *nonpad_ret = splice_to_pipe(pipe, &spd);
|
| 1191 | if (ret < 0 || ret < total_len)
|
| 1192 | goto out;
|
| 1193 |
|
| 1194 | if (read_start + ret == nonpad_end)
|
| 1195 | ret += padding;
|
| 1196 |
|
| 1197 | out:
|
| 1198 | splice_shrink_spd(&spd);
|
| 1199 | return ret;
|
| 1200 | }
|
| 1201 |
|
| 1202 | static ssize_t relay_file_splice_read(struct file *in,
|
| 1203 | loff_t *ppos,
|
| 1204 | struct pipe_inode_info *pipe,
|
| 1205 | size_t len,
|
| 1206 | unsigned int flags)
|
| 1207 | {
|
| 1208 | ssize_t spliced;
|
| 1209 | int ret;
|
| 1210 | int nonpad_ret = 0;
|
| 1211 |
|
| 1212 | ret = 0;
|
| 1213 | spliced = 0;
|
| 1214 |
|
| 1215 | while (len && !spliced) {
|
| 1216 | ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret);
|
| 1217 | if (ret < 0)
|
| 1218 | break;
|
| 1219 | else if (!ret) {
|
| 1220 | if (flags & SPLICE_F_NONBLOCK)
|
| 1221 | ret = -EAGAIN;
|
| 1222 | break;
|
| 1223 | }
|
| 1224 |
|
| 1225 | *ppos += ret;
|
| 1226 | if (ret > len)
|
| 1227 | len = 0;
|
| 1228 | else
|
| 1229 | len -= ret;
|
| 1230 | spliced += nonpad_ret;
|
| 1231 | nonpad_ret = 0;
|
| 1232 | }
|
| 1233 |
|
| 1234 | if (spliced)
|
| 1235 | return spliced;
|
| 1236 |
|
| 1237 | return ret;
|
| 1238 | }
|
| 1239 |
|
| 1240 | const struct file_operations relay_file_operations = {
|
| 1241 | .open = relay_file_open,
|
| 1242 | .poll = relay_file_poll,
|
| 1243 | .mmap = relay_file_mmap,
|
| 1244 | .read = relay_file_read,
|
| 1245 | .llseek = no_llseek,
|
| 1246 | .release = relay_file_release,
|
| 1247 | .splice_read = relay_file_splice_read,
|
| 1248 | };
|
| 1249 | EXPORT_SYMBOL_GPL(relay_file_operations);
|