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