1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * drivers/dma-buf/sync_file.c 4 * 5 * Copyright (C) 2012 Google, Inc. 6 */ 7 8 #include <linux/dma-fence-unwrap.h> 9 #include <linux/export.h> 10 #include <linux/file.h> 11 #include <linux/fs.h> 12 #include <linux/kernel.h> 13 #include <linux/poll.h> 14 #include <linux/sched.h> 15 #include <linux/slab.h> 16 #include <linux/uaccess.h> 17 #include <linux/anon_inodes.h> 18 #include <linux/sync_file.h> 19 #include <uapi/linux/sync_file.h> 20 21 static const struct file_operations sync_file_fops; 22 23 static struct sync_file *sync_file_alloc(void) 24 { 25 struct sync_file *sync_file; 26 27 sync_file = kzalloc(sizeof(*sync_file), GFP_KERNEL); 28 if (!sync_file) 29 return NULL; 30 31 sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops, 32 sync_file, 0); 33 if (IS_ERR(sync_file->file)) 34 goto err; 35 36 init_waitqueue_head(&sync_file->wq); 37 38 INIT_LIST_HEAD(&sync_file->cb.node); 39 40 return sync_file; 41 42 err: 43 kfree(sync_file); 44 return NULL; 45 } 46 47 static void fence_check_cb_func(struct dma_fence *f, struct dma_fence_cb *cb) 48 { 49 struct sync_file *sync_file; 50 51 sync_file = container_of(cb, struct sync_file, cb); 52 53 wake_up_all(&sync_file->wq); 54 } 55 56 /** 57 * sync_file_create() - creates a sync file 58 * @fence: fence to add to the sync_fence 59 * 60 * Creates a sync_file containg @fence. This function acquires and additional 61 * reference of @fence for the newly-created &sync_file, if it succeeds. The 62 * sync_file can be released with fput(sync_file->file). Returns the 63 * sync_file or NULL in case of error. 64 */ 65 struct sync_file *sync_file_create(struct dma_fence *fence) 66 { 67 struct sync_file *sync_file; 68 69 sync_file = sync_file_alloc(); 70 if (!sync_file) 71 return NULL; 72 73 sync_file->fence = dma_fence_get(fence); 74 75 return sync_file; 76 } 77 EXPORT_SYMBOL(sync_file_create); 78 79 static struct sync_file *sync_file_fdget(int fd) 80 { 81 struct file *file = fget(fd); 82 83 if (!file) 84 return NULL; 85 86 if (file->f_op != &sync_file_fops) 87 goto err; 88 89 return file->private_data; 90 91 err: 92 fput(file); 93 return NULL; 94 } 95 96 /** 97 * sync_file_get_fence - get the fence related to the sync_file fd 98 * @fd: sync_file fd to get the fence from 99 * 100 * Ensures @fd references a valid sync_file and returns a fence that 101 * represents all fence in the sync_file. On error NULL is returned. 102 */ 103 struct dma_fence *sync_file_get_fence(int fd) 104 { 105 struct sync_file *sync_file; 106 struct dma_fence *fence; 107 108 sync_file = sync_file_fdget(fd); 109 if (!sync_file) 110 return NULL; 111 112 fence = dma_fence_get(sync_file->fence); 113 fput(sync_file->file); 114 115 return fence; 116 } 117 EXPORT_SYMBOL(sync_file_get_fence); 118 119 /** 120 * sync_file_get_name - get the name of the sync_file 121 * @sync_file: sync_file to get the fence from 122 * @buf: destination buffer to copy sync_file name into 123 * @len: available size of destination buffer. 124 * 125 * Each sync_file may have a name assigned either by the user (when merging 126 * sync_files together) or created from the fence it contains. In the latter 127 * case construction of the name is deferred until use, and so requires 128 * sync_file_get_name(). 129 * 130 * Returns: a string representing the name. 131 */ 132 char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len) 133 { 134 if (sync_file->user_name[0]) { 135 strlcpy(buf, sync_file->user_name, len); 136 } else { 137 struct dma_fence *fence = sync_file->fence; 138 139 snprintf(buf, len, "%s-%s%llu-%lld", 140 fence->ops->get_driver_name(fence), 141 fence->ops->get_timeline_name(fence), 142 fence->context, 143 fence->seqno); 144 } 145 146 return buf; 147 } 148 149 static int sync_file_set_fence(struct sync_file *sync_file, 150 struct dma_fence **fences, int num_fences) 151 { 152 struct dma_fence_array *array; 153 154 /* 155 * The reference for the fences in the new sync_file and held 156 * in add_fence() during the merge procedure, so for num_fences == 1 157 * we already own a new reference to the fence. For num_fence > 1 158 * we own the reference of the dma_fence_array creation. 159 */ 160 if (num_fences == 1) { 161 sync_file->fence = fences[0]; 162 kfree(fences); 163 } else { 164 array = dma_fence_array_create(num_fences, fences, 165 dma_fence_context_alloc(1), 166 1, false); 167 if (!array) 168 return -ENOMEM; 169 170 sync_file->fence = &array->base; 171 } 172 173 return 0; 174 } 175 176 static void add_fence(struct dma_fence **fences, 177 int *i, struct dma_fence *fence) 178 { 179 fences[*i] = fence; 180 181 if (!dma_fence_is_signaled(fence)) { 182 dma_fence_get(fence); 183 (*i)++; 184 } 185 } 186 187 /** 188 * sync_file_merge() - merge two sync_files 189 * @name: name of new fence 190 * @a: sync_file a 191 * @b: sync_file b 192 * 193 * Creates a new sync_file which contains copies of all the fences in both 194 * @a and @b. @a and @b remain valid, independent sync_file. Returns the 195 * new merged sync_file or NULL in case of error. 196 */ 197 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a, 198 struct sync_file *b) 199 { 200 struct dma_fence *a_fence, *b_fence, **fences; 201 struct dma_fence_unwrap a_iter, b_iter; 202 unsigned int index, num_fences; 203 struct sync_file *sync_file; 204 205 sync_file = sync_file_alloc(); 206 if (!sync_file) 207 return NULL; 208 209 num_fences = 0; 210 dma_fence_unwrap_for_each(a_fence, &a_iter, a->fence) 211 ++num_fences; 212 dma_fence_unwrap_for_each(b_fence, &b_iter, b->fence) 213 ++num_fences; 214 215 if (num_fences > INT_MAX) 216 goto err_free_sync_file; 217 218 fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL); 219 if (!fences) 220 goto err_free_sync_file; 221 222 /* 223 * We can't guarantee that fences in both a and b are ordered, but it is 224 * still quite likely. 225 * 226 * So attempt to order the fences as we pass over them and merge fences 227 * with the same context. 228 */ 229 230 index = 0; 231 for (a_fence = dma_fence_unwrap_first(a->fence, &a_iter), 232 b_fence = dma_fence_unwrap_first(b->fence, &b_iter); 233 a_fence || b_fence; ) { 234 235 if (!b_fence) { 236 add_fence(fences, &index, a_fence); 237 a_fence = dma_fence_unwrap_next(&a_iter); 238 239 } else if (!a_fence) { 240 add_fence(fences, &index, b_fence); 241 b_fence = dma_fence_unwrap_next(&b_iter); 242 243 } else if (a_fence->context < b_fence->context) { 244 add_fence(fences, &index, a_fence); 245 a_fence = dma_fence_unwrap_next(&a_iter); 246 247 } else if (b_fence->context < a_fence->context) { 248 add_fence(fences, &index, b_fence); 249 b_fence = dma_fence_unwrap_next(&b_iter); 250 251 } else if (__dma_fence_is_later(a_fence->seqno, b_fence->seqno, 252 a_fence->ops)) { 253 add_fence(fences, &index, a_fence); 254 a_fence = dma_fence_unwrap_next(&a_iter); 255 b_fence = dma_fence_unwrap_next(&b_iter); 256 257 } else { 258 add_fence(fences, &index, b_fence); 259 a_fence = dma_fence_unwrap_next(&a_iter); 260 b_fence = dma_fence_unwrap_next(&b_iter); 261 } 262 } 263 264 if (index == 0) 265 fences[index++] = dma_fence_get_stub(); 266 267 if (num_fences > index) { 268 struct dma_fence **tmp; 269 270 /* Keep going even when reducing the size failed */ 271 tmp = krealloc_array(fences, index, sizeof(*fences), 272 GFP_KERNEL); 273 if (tmp) 274 fences = tmp; 275 } 276 277 if (sync_file_set_fence(sync_file, fences, index) < 0) 278 goto err_put_fences; 279 280 strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name)); 281 return sync_file; 282 283 err_put_fences: 284 while (index) 285 dma_fence_put(fences[--index]); 286 kfree(fences); 287 288 err_free_sync_file: 289 fput(sync_file->file); 290 return NULL; 291 } 292 293 static int sync_file_release(struct inode *inode, struct file *file) 294 { 295 struct sync_file *sync_file = file->private_data; 296 297 if (test_bit(POLL_ENABLED, &sync_file->flags)) 298 dma_fence_remove_callback(sync_file->fence, &sync_file->cb); 299 dma_fence_put(sync_file->fence); 300 kfree(sync_file); 301 302 return 0; 303 } 304 305 static __poll_t sync_file_poll(struct file *file, poll_table *wait) 306 { 307 struct sync_file *sync_file = file->private_data; 308 309 poll_wait(file, &sync_file->wq, wait); 310 311 if (list_empty(&sync_file->cb.node) && 312 !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) { 313 if (dma_fence_add_callback(sync_file->fence, &sync_file->cb, 314 fence_check_cb_func) < 0) 315 wake_up_all(&sync_file->wq); 316 } 317 318 return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0; 319 } 320 321 static long sync_file_ioctl_merge(struct sync_file *sync_file, 322 unsigned long arg) 323 { 324 int fd = get_unused_fd_flags(O_CLOEXEC); 325 int err; 326 struct sync_file *fence2, *fence3; 327 struct sync_merge_data data; 328 329 if (fd < 0) 330 return fd; 331 332 if (copy_from_user(&data, (void __user *)arg, sizeof(data))) { 333 err = -EFAULT; 334 goto err_put_fd; 335 } 336 337 if (data.flags || data.pad) { 338 err = -EINVAL; 339 goto err_put_fd; 340 } 341 342 fence2 = sync_file_fdget(data.fd2); 343 if (!fence2) { 344 err = -ENOENT; 345 goto err_put_fd; 346 } 347 348 data.name[sizeof(data.name) - 1] = '\0'; 349 fence3 = sync_file_merge(data.name, sync_file, fence2); 350 if (!fence3) { 351 err = -ENOMEM; 352 goto err_put_fence2; 353 } 354 355 data.fence = fd; 356 if (copy_to_user((void __user *)arg, &data, sizeof(data))) { 357 err = -EFAULT; 358 goto err_put_fence3; 359 } 360 361 fd_install(fd, fence3->file); 362 fput(fence2->file); 363 return 0; 364 365 err_put_fence3: 366 fput(fence3->file); 367 368 err_put_fence2: 369 fput(fence2->file); 370 371 err_put_fd: 372 put_unused_fd(fd); 373 return err; 374 } 375 376 static int sync_fill_fence_info(struct dma_fence *fence, 377 struct sync_fence_info *info) 378 { 379 strlcpy(info->obj_name, fence->ops->get_timeline_name(fence), 380 sizeof(info->obj_name)); 381 strlcpy(info->driver_name, fence->ops->get_driver_name(fence), 382 sizeof(info->driver_name)); 383 384 info->status = dma_fence_get_status(fence); 385 while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && 386 !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags)) 387 cpu_relax(); 388 info->timestamp_ns = 389 test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ? 390 ktime_to_ns(fence->timestamp) : 391 ktime_set(0, 0); 392 393 return info->status; 394 } 395 396 static long sync_file_ioctl_fence_info(struct sync_file *sync_file, 397 unsigned long arg) 398 { 399 struct sync_fence_info *fence_info = NULL; 400 struct dma_fence_unwrap iter; 401 struct sync_file_info info; 402 unsigned int num_fences; 403 struct dma_fence *fence; 404 int ret; 405 __u32 size; 406 407 if (copy_from_user(&info, (void __user *)arg, sizeof(info))) 408 return -EFAULT; 409 410 if (info.flags || info.pad) 411 return -EINVAL; 412 413 num_fences = 0; 414 dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) 415 ++num_fences; 416 417 /* 418 * Passing num_fences = 0 means that userspace doesn't want to 419 * retrieve any sync_fence_info. If num_fences = 0 we skip filling 420 * sync_fence_info and return the actual number of fences on 421 * info->num_fences. 422 */ 423 if (!info.num_fences) { 424 info.status = dma_fence_get_status(sync_file->fence); 425 goto no_fences; 426 } else { 427 info.status = 1; 428 } 429 430 if (info.num_fences < num_fences) 431 return -EINVAL; 432 433 size = num_fences * sizeof(*fence_info); 434 fence_info = kzalloc(size, GFP_KERNEL); 435 if (!fence_info) 436 return -ENOMEM; 437 438 num_fences = 0; 439 dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) { 440 int status; 441 442 status = sync_fill_fence_info(fence, &fence_info[num_fences++]); 443 info.status = info.status <= 0 ? info.status : status; 444 } 445 446 if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info, 447 size)) { 448 ret = -EFAULT; 449 goto out; 450 } 451 452 no_fences: 453 sync_file_get_name(sync_file, info.name, sizeof(info.name)); 454 info.num_fences = num_fences; 455 456 if (copy_to_user((void __user *)arg, &info, sizeof(info))) 457 ret = -EFAULT; 458 else 459 ret = 0; 460 461 out: 462 kfree(fence_info); 463 464 return ret; 465 } 466 467 static long sync_file_ioctl(struct file *file, unsigned int cmd, 468 unsigned long arg) 469 { 470 struct sync_file *sync_file = file->private_data; 471 472 switch (cmd) { 473 case SYNC_IOC_MERGE: 474 return sync_file_ioctl_merge(sync_file, arg); 475 476 case SYNC_IOC_FILE_INFO: 477 return sync_file_ioctl_fence_info(sync_file, arg); 478 479 default: 480 return -ENOTTY; 481 } 482 } 483 484 static const struct file_operations sync_file_fops = { 485 .release = sync_file_release, 486 .poll = sync_file_poll, 487 .unlocked_ioctl = sync_file_ioctl, 488 .compat_ioctl = compat_ptr_ioctl, 489 }; 490