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 */ 160 161 if (num_fences == 0) { 162 sync_file->fence = dma_fence_get_stub(); 163 kfree(fences); 164 165 } else if (num_fences == 1) { 166 sync_file->fence = fences[0]; 167 kfree(fences); 168 169 } else { 170 array = dma_fence_array_create(num_fences, fences, 171 dma_fence_context_alloc(1), 172 1, false); 173 if (!array) 174 return -ENOMEM; 175 176 sync_file->fence = &array->base; 177 } 178 179 return 0; 180 } 181 182 static void add_fence(struct dma_fence **fences, 183 int *i, struct dma_fence *fence) 184 { 185 fences[*i] = fence; 186 187 if (!dma_fence_is_signaled(fence)) { 188 dma_fence_get(fence); 189 (*i)++; 190 } 191 } 192 193 /** 194 * sync_file_merge() - merge two sync_files 195 * @name: name of new fence 196 * @a: sync_file a 197 * @b: sync_file b 198 * 199 * Creates a new sync_file which contains copies of all the fences in both 200 * @a and @b. @a and @b remain valid, independent sync_file. Returns the 201 * new merged sync_file or NULL in case of error. 202 */ 203 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a, 204 struct sync_file *b) 205 { 206 struct dma_fence *a_fence, *b_fence, **fences; 207 struct dma_fence_unwrap a_iter, b_iter; 208 unsigned int index, num_fences; 209 struct sync_file *sync_file; 210 211 sync_file = sync_file_alloc(); 212 if (!sync_file) 213 return NULL; 214 215 num_fences = 0; 216 dma_fence_unwrap_for_each(a_fence, &a_iter, a->fence) 217 ++num_fences; 218 dma_fence_unwrap_for_each(b_fence, &b_iter, b->fence) 219 ++num_fences; 220 221 if (num_fences > INT_MAX) 222 goto err_free_sync_file; 223 224 fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL); 225 if (!fences) 226 goto err_free_sync_file; 227 228 /* 229 * We can't guarantee that fences in both a and b are ordered, but it is 230 * still quite likely. 231 * 232 * So attempt to order the fences as we pass over them and merge fences 233 * with the same context. 234 */ 235 236 index = 0; 237 for (a_fence = dma_fence_unwrap_first(a->fence, &a_iter), 238 b_fence = dma_fence_unwrap_first(b->fence, &b_iter); 239 a_fence || b_fence; ) { 240 241 if (!b_fence) { 242 add_fence(fences, &index, a_fence); 243 a_fence = dma_fence_unwrap_next(&a_iter); 244 245 } else if (!a_fence) { 246 add_fence(fences, &index, b_fence); 247 b_fence = dma_fence_unwrap_next(&b_iter); 248 249 } else if (a_fence->context < b_fence->context) { 250 add_fence(fences, &index, a_fence); 251 a_fence = dma_fence_unwrap_next(&a_iter); 252 253 } else if (b_fence->context < a_fence->context) { 254 add_fence(fences, &index, b_fence); 255 b_fence = dma_fence_unwrap_next(&b_iter); 256 257 } else if (__dma_fence_is_later(a_fence->seqno, b_fence->seqno, 258 a_fence->ops)) { 259 add_fence(fences, &index, a_fence); 260 a_fence = dma_fence_unwrap_next(&a_iter); 261 b_fence = dma_fence_unwrap_next(&b_iter); 262 263 } else { 264 add_fence(fences, &index, b_fence); 265 a_fence = dma_fence_unwrap_next(&a_iter); 266 b_fence = dma_fence_unwrap_next(&b_iter); 267 } 268 } 269 270 if (sync_file_set_fence(sync_file, fences, index) < 0) 271 goto err_put_fences; 272 273 strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name)); 274 return sync_file; 275 276 err_put_fences: 277 while (index) 278 dma_fence_put(fences[--index]); 279 kfree(fences); 280 281 err_free_sync_file: 282 fput(sync_file->file); 283 return NULL; 284 } 285 286 static int sync_file_release(struct inode *inode, struct file *file) 287 { 288 struct sync_file *sync_file = file->private_data; 289 290 if (test_bit(POLL_ENABLED, &sync_file->flags)) 291 dma_fence_remove_callback(sync_file->fence, &sync_file->cb); 292 dma_fence_put(sync_file->fence); 293 kfree(sync_file); 294 295 return 0; 296 } 297 298 static __poll_t sync_file_poll(struct file *file, poll_table *wait) 299 { 300 struct sync_file *sync_file = file->private_data; 301 302 poll_wait(file, &sync_file->wq, wait); 303 304 if (list_empty(&sync_file->cb.node) && 305 !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) { 306 if (dma_fence_add_callback(sync_file->fence, &sync_file->cb, 307 fence_check_cb_func) < 0) 308 wake_up_all(&sync_file->wq); 309 } 310 311 return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0; 312 } 313 314 static long sync_file_ioctl_merge(struct sync_file *sync_file, 315 unsigned long arg) 316 { 317 int fd = get_unused_fd_flags(O_CLOEXEC); 318 int err; 319 struct sync_file *fence2, *fence3; 320 struct sync_merge_data data; 321 322 if (fd < 0) 323 return fd; 324 325 if (copy_from_user(&data, (void __user *)arg, sizeof(data))) { 326 err = -EFAULT; 327 goto err_put_fd; 328 } 329 330 if (data.flags || data.pad) { 331 err = -EINVAL; 332 goto err_put_fd; 333 } 334 335 fence2 = sync_file_fdget(data.fd2); 336 if (!fence2) { 337 err = -ENOENT; 338 goto err_put_fd; 339 } 340 341 data.name[sizeof(data.name) - 1] = '\0'; 342 fence3 = sync_file_merge(data.name, sync_file, fence2); 343 if (!fence3) { 344 err = -ENOMEM; 345 goto err_put_fence2; 346 } 347 348 data.fence = fd; 349 if (copy_to_user((void __user *)arg, &data, sizeof(data))) { 350 err = -EFAULT; 351 goto err_put_fence3; 352 } 353 354 fd_install(fd, fence3->file); 355 fput(fence2->file); 356 return 0; 357 358 err_put_fence3: 359 fput(fence3->file); 360 361 err_put_fence2: 362 fput(fence2->file); 363 364 err_put_fd: 365 put_unused_fd(fd); 366 return err; 367 } 368 369 static int sync_fill_fence_info(struct dma_fence *fence, 370 struct sync_fence_info *info) 371 { 372 strlcpy(info->obj_name, fence->ops->get_timeline_name(fence), 373 sizeof(info->obj_name)); 374 strlcpy(info->driver_name, fence->ops->get_driver_name(fence), 375 sizeof(info->driver_name)); 376 377 info->status = dma_fence_get_status(fence); 378 while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && 379 !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags)) 380 cpu_relax(); 381 info->timestamp_ns = 382 test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ? 383 ktime_to_ns(fence->timestamp) : 384 ktime_set(0, 0); 385 386 return info->status; 387 } 388 389 static long sync_file_ioctl_fence_info(struct sync_file *sync_file, 390 unsigned long arg) 391 { 392 struct sync_fence_info *fence_info = NULL; 393 struct dma_fence_unwrap iter; 394 struct sync_file_info info; 395 unsigned int num_fences; 396 struct dma_fence *fence; 397 int ret; 398 __u32 size; 399 400 if (copy_from_user(&info, (void __user *)arg, sizeof(info))) 401 return -EFAULT; 402 403 if (info.flags || info.pad) 404 return -EINVAL; 405 406 num_fences = 0; 407 dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) 408 ++num_fences; 409 410 /* 411 * Passing num_fences = 0 means that userspace doesn't want to 412 * retrieve any sync_fence_info. If num_fences = 0 we skip filling 413 * sync_fence_info and return the actual number of fences on 414 * info->num_fences. 415 */ 416 if (!info.num_fences) { 417 info.status = dma_fence_get_status(sync_file->fence); 418 goto no_fences; 419 } else { 420 info.status = 1; 421 } 422 423 if (info.num_fences < num_fences) 424 return -EINVAL; 425 426 size = num_fences * sizeof(*fence_info); 427 fence_info = kzalloc(size, GFP_KERNEL); 428 if (!fence_info) 429 return -ENOMEM; 430 431 num_fences = 0; 432 dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) { 433 int status; 434 435 status = sync_fill_fence_info(fence, &fence_info[num_fences++]); 436 info.status = info.status <= 0 ? info.status : status; 437 } 438 439 if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info, 440 size)) { 441 ret = -EFAULT; 442 goto out; 443 } 444 445 no_fences: 446 sync_file_get_name(sync_file, info.name, sizeof(info.name)); 447 info.num_fences = num_fences; 448 449 if (copy_to_user((void __user *)arg, &info, sizeof(info))) 450 ret = -EFAULT; 451 else 452 ret = 0; 453 454 out: 455 kfree(fence_info); 456 457 return ret; 458 } 459 460 static long sync_file_ioctl(struct file *file, unsigned int cmd, 461 unsigned long arg) 462 { 463 struct sync_file *sync_file = file->private_data; 464 465 switch (cmd) { 466 case SYNC_IOC_MERGE: 467 return sync_file_ioctl_merge(sync_file, arg); 468 469 case SYNC_IOC_FILE_INFO: 470 return sync_file_ioctl_fence_info(sync_file, arg); 471 472 default: 473 return -ENOTTY; 474 } 475 } 476 477 static const struct file_operations sync_file_fops = { 478 .release = sync_file_release, 479 .poll = sync_file_poll, 480 .unlocked_ioctl = sync_file_ioctl, 481 .compat_ioctl = compat_ptr_ioctl, 482 }; 483