drivers/dma-buf/sync_file.c

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