root/drivers/dma-buf/sync_file.c

DEFINITIONS

1. sync_file_alloc
2. fence_check_cb_func
3. sync_file_create
4. sync_file_fdget
5. sync_file_get_fence
6. sync_file_get_name
7. sync_file_set_fence
8. get_fences
9. add_fence
10. sync_file_merge
11. sync_file_release
12. sync_file_poll
13. sync_file_ioctl_merge
14. sync_fill_fence_info
15. sync_file_ioctl_fence_info
16. sync_file_ioctl

   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, **nfences, **a_fences, **b_fences;
 215         int i, 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 = 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                 kfree(fences);
 283                 goto err;
 284         }
 285 
 286         strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
 287         return sync_file;
 288 
 289 err:
 290         fput(sync_file->file);
 291         return NULL;
 292 
 293 }
 294 
 295 static int sync_file_release(struct inode *inode, struct file *file)
 296 {
 297         struct sync_file *sync_file = file->private_data;
 298 
 299         if (test_bit(POLL_ENABLED, &sync_file->flags))
 300                 dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
 301         dma_fence_put(sync_file->fence);
 302         kfree(sync_file);
 303 
 304         return 0;
 305 }
 306 
 307 static __poll_t sync_file_poll(struct file *file, poll_table *wait)
 308 {
 309         struct sync_file *sync_file = file->private_data;
 310 
 311         poll_wait(file, &sync_file->wq, wait);
 312 
 313         if (list_empty(&sync_file->cb.node) &&
 314             !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
 315                 if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
 316                                            fence_check_cb_func) < 0)
 317                         wake_up_all(&sync_file->wq);
 318         }
 319 
 320         return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
 321 }
 322 
 323 static long sync_file_ioctl_merge(struct sync_file *sync_file,
 324                                   unsigned long arg)
 325 {
 326         int fd = get_unused_fd_flags(O_CLOEXEC);
 327         int err;
 328         struct sync_file *fence2, *fence3;
 329         struct sync_merge_data data;
 330 
 331         if (fd < 0)
 332                 return fd;
 333 
 334         if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
 335                 err = -EFAULT;
 336                 goto err_put_fd;
 337         }
 338 
 339         if (data.flags || data.pad) {
 340                 err = -EINVAL;
 341                 goto err_put_fd;
 342         }
 343 
 344         fence2 = sync_file_fdget(data.fd2);
 345         if (!fence2) {
 346                 err = -ENOENT;
 347                 goto err_put_fd;
 348         }
 349 
 350         data.name[sizeof(data.name) - 1] = '\0';
 351         fence3 = sync_file_merge(data.name, sync_file, fence2);
 352         if (!fence3) {
 353                 err = -ENOMEM;
 354                 goto err_put_fence2;
 355         }
 356 
 357         data.fence = fd;
 358         if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
 359                 err = -EFAULT;
 360                 goto err_put_fence3;
 361         }
 362 
 363         fd_install(fd, fence3->file);
 364         fput(fence2->file);
 365         return 0;
 366 
 367 err_put_fence3:
 368         fput(fence3->file);
 369 
 370 err_put_fence2:
 371         fput(fence2->file);
 372 
 373 err_put_fd:
 374         put_unused_fd(fd);
 375         return err;
 376 }
 377 
 378 static int sync_fill_fence_info(struct dma_fence *fence,
 379                                  struct sync_fence_info *info)
 380 {
 381         strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
 382                 sizeof(info->obj_name));
 383         strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
 384                 sizeof(info->driver_name));
 385 
 386         info->status = dma_fence_get_status(fence);
 387         while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
 388                !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
 389                 cpu_relax();
 390         info->timestamp_ns =
 391                 test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?
 392                 ktime_to_ns(fence->timestamp) :
 393                 ktime_set(0, 0);
 394 
 395         return info->status;
 396 }
 397 
 398 static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 399                                        unsigned long arg)
 400 {
 401         struct sync_file_info info;
 402         struct sync_fence_info *fence_info = NULL;
 403         struct dma_fence **fences;
 404         __u32 size;
 405         int num_fences, ret, i;
 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         fences = get_fences(sync_file, &num_fences);
 414 
 415         /*
 416          * Passing num_fences = 0 means that userspace doesn't want to
 417          * retrieve any sync_fence_info. If num_fences = 0 we skip filling
 418          * sync_fence_info and return the actual number of fences on
 419          * info->num_fences.
 420          */
 421         if (!info.num_fences) {
 422                 info.status = dma_fence_get_status(sync_file->fence);
 423                 goto no_fences;
 424         } else {
 425                 info.status = 1;
 426         }
 427 
 428         if (info.num_fences < num_fences)
 429                 return -EINVAL;
 430 
 431         size = num_fences * sizeof(*fence_info);
 432         fence_info = kzalloc(size, GFP_KERNEL);
 433         if (!fence_info)
 434                 return -ENOMEM;
 435 
 436         for (i = 0; i < num_fences; i++) {
 437                 int status = sync_fill_fence_info(fences[i], &fence_info[i]);
 438                 info.status = info.status <= 0 ? info.status : status;
 439         }
 440 
 441         if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
 442                          size)) {
 443                 ret = -EFAULT;
 444                 goto out;
 445         }
 446 
 447 no_fences:
 448         sync_file_get_name(sync_file, info.name, sizeof(info.name));
 449         info.num_fences = num_fences;
 450 
 451         if (copy_to_user((void __user *)arg, &info, sizeof(info)))
 452                 ret = -EFAULT;
 453         else
 454                 ret = 0;
 455 
 456 out:
 457         kfree(fence_info);
 458 
 459         return ret;
 460 }
 461 
 462 static long sync_file_ioctl(struct file *file, unsigned int cmd,
 463                             unsigned long arg)
 464 {
 465         struct sync_file *sync_file = file->private_data;
 466 
 467         switch (cmd) {
 468         case SYNC_IOC_MERGE:
 469                 return sync_file_ioctl_merge(sync_file, arg);
 470 
 471         case SYNC_IOC_FILE_INFO:
 472                 return sync_file_ioctl_fence_info(sync_file, arg);
 473 
 474         default:
 475                 return -ENOTTY;
 476         }
 477 }
 478 
 479 static const struct file_operations sync_file_fops = {
 480         .release = sync_file_release,
 481         .poll = sync_file_poll,
 482         .unlocked_ioctl = sync_file_ioctl,
 483         .compat_ioctl = sync_file_ioctl,
 484 };