drivers/dma-buf/sync_file.c

   1 /*
   2  * drivers/dma-buf/sync_file.c
   3  *
   4  * Copyright (C) 2012 Google, Inc.
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  */
  16
  17 #include <linux/export.h>
  18 #include <linux/file.h>
  19 #include <linux/fs.h>
  20 #include <linux/kernel.h>
  21 #include <linux/poll.h>
  22 #include <linux/sched.h>
  23 #include <linux/slab.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/anon_inodes.h>
  26 #include <linux/sync_file.h>
  27 #include <uapi/linux/sync_file.h>
  28
  29 static const struct file_operations sync_file_fops;
  30
  31 static struct sync_file *sync_file_alloc(void)
  32 {
  33         struct sync_file *sync_file;
  34
  35         sync_file = kzalloc(sizeof(*sync_file), GFP_KERNEL);
  36         if (!sync_file)
  37                 return NULL;
  38
  39         sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
  40                                              sync_file, 0);
  41         if (IS_ERR(sync_file->file))
  42                 goto err;
  43
  44         init_waitqueue_head(&sync_file->wq);
  45
  46         INIT_LIST_HEAD(&sync_file->cb.node);
  47
  48         return sync_file;
  49
  50 err:
  51         kfree(sync_file);
  52         return NULL;
  53 }
  54
  55 static void fence_check_cb_func(struct dma_fence *f, struct dma_fence_cb *cb)
  56 {
  57         struct sync_file *sync_file;
  58
  59         sync_file = container_of(cb, struct sync_file, cb);
  60
  61         wake_up_all(&sync_file->wq);
  62 }
  63
  64 /**
  65  * sync_file_create() - creates a sync file
  66  * @fence:      fence to add to the sync_fence
  67  *
  68  * Creates a sync_file containg @fence. This function acquires and additional
  69  * reference of @fence for the newly-created &sync_file, if it succeeds. The
  70  * sync_file can be released with fput(sync_file->file). Returns the
  71  * sync_file or NULL in case of error.
  72  */
  73 struct sync_file *sync_file_create(struct dma_fence *fence)
  74 {
  75         struct sync_file *sync_file;
  76
  77         sync_file = sync_file_alloc();
  78         if (!sync_file)
  79                 return NULL;
  80
  81         sync_file->fence = dma_fence_get(fence);
  82
  83         return sync_file;
  84 }
  85 EXPORT_SYMBOL(sync_file_create);
  86
  87 static struct sync_file *sync_file_fdget(int fd)
  88 {
  89         struct file *file = fget(fd);
  90
  91         if (!file)
  92                 return NULL;
  93
  94         if (file->f_op != &sync_file_fops)
  95                 goto err;
  96
  97         return file->private_data;
  98
  99 err:
 100         fput(file);
 101         return NULL;
 102 }
 103
 104 /**
 105  * sync_file_get_fence - get the fence related to the sync_file fd
 106  * @fd:         sync_file fd to get the fence from
 107  *
 108  * Ensures @fd references a valid sync_file and returns a fence that
 109  * represents all fence in the sync_file. On error NULL is returned.
 110  */
 111 struct dma_fence *sync_file_get_fence(int fd)
 112 {
 113         struct sync_file *sync_file;
 114         struct dma_fence *fence;
 115
 116         sync_file = sync_file_fdget(fd);
 117         if (!sync_file)
 118                 return NULL;
 119
 120         fence = dma_fence_get(sync_file->fence);
 121         fput(sync_file->file);
 122
 123         return fence;
 124 }
 125 EXPORT_SYMBOL(sync_file_get_fence);
 126
 127 /**
 128  * sync_file_get_name - get the name of the sync_file
 129  * @sync_file:          sync_file to get the fence from
 130  * @buf:                destination buffer to copy sync_file name into
 131  * @len:                available size of destination buffer.
 132  *
 133  * Each sync_file may have a name assigned either by the user (when merging
 134  * sync_files together) or created from the fence it contains. In the latter
 135  * case construction of the name is deferred until use, and so requires
 136  * sync_file_get_name().
 137  *
 138  * Returns: a string representing the name.
 139  */
 140 char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
 141 {
 142         if (sync_file->user_name[0]) {
 143                 strlcpy(buf, sync_file->user_name, len);
 144         } else {
 145                 struct dma_fence *fence = sync_file->fence;
 146
 147                 snprintf(buf, len, "%s-%s%llu-%lld",
 148                          fence->ops->get_driver_name(fence),
 149                          fence->ops->get_timeline_name(fence),
 150                          fence->context,
 151                          fence->seqno);
 152         }
 153
 154         return buf;
 155 }
 156
 157 static int sync_file_set_fence(struct sync_file *sync_file,
 158                                struct dma_fence **fences, int num_fences)
 159 {
 160         struct dma_fence_array *array;
 161
 162         /*
 163          * The reference for the fences in the new sync_file and held
 164          * in add_fence() during the merge procedure, so for num_fences == 1
 165          * we already own a new reference to the fence. For num_fence > 1
 166          * we own the reference of the dma_fence_array creation.
 167          */
 168         if (num_fences == 1) {
 169                 sync_file->fence = fences[0];
 170                 kfree(fences);
 171         } else {
 172                 array = dma_fence_array_create(num_fences, fences,
 173                                                dma_fence_context_alloc(1),
 174                                                1, false);
 175                 if (!array)
 176                         return -ENOMEM;
 177
 178                 sync_file->fence = &array->base;
 179         }
 180
 181         return 0;
 182 }
 183
 184 static struct dma_fence **get_fences(struct sync_file *sync_file,
 185                                      int *num_fences)
 186 {
 187         if (dma_fence_is_array(sync_file->fence)) {
 188                 struct dma_fence_array *array = to_dma_fence_array(sync_file->fence);
 189
 190                 *num_fences = array->num_fences;
 191                 return array->fences;
 192         }
 193
 194         *num_fences = 1;
 195         return &sync_file->fence;
 196 }
 197
 198 static void add_fence(struct dma_fence **fences,
 199                       int *i, struct dma_fence *fence)
 200 {
 201         fences[*i] = fence;
 202
 203         if (!dma_fence_is_signaled(fence)) {
 204                 dma_fence_get(fence);
 205                 (*i)++;
 206         }
 207 }
 208
 209 /**
 210  * sync_file_merge() - merge two sync_files
 211  * @name:       name of new fence
 212  * @a:          sync_file a
 213  * @b:          sync_file b
 214  *
 215  * Creates a new sync_file which contains copies of all the fences in both
 216  * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
 217  * new merged sync_file or NULL in case of error.
 218  */
 219 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 220                                          struct sync_file *b)
 221 {
 222         struct sync_file *sync_file;
 223         struct dma_fence **fences, **nfences, **a_fences, **b_fences;
 224         int i, i_a, i_b, num_fences, a_num_fences, b_num_fences;
 225
 226         sync_file = sync_file_alloc();
 227         if (!sync_file)
 228                 return NULL;
 229
 230         a_fences = get_fences(a, &a_num_fences);
 231         b_fences = get_fences(b, &b_num_fences);
 232         if (a_num_fences > INT_MAX - b_num_fences)
 233                 return NULL;
 234
 235         num_fences = a_num_fences + b_num_fences;
 236
 237         fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
 238         if (!fences)
 239                 goto err;
 240
 241         /*
 242          * Assume sync_file a and b are both ordered and have no
 243          * duplicates with the same context.
 244          *
 245          * If a sync_file can only be created with sync_file_merge
 246          * and sync_file_create, this is a reasonable assumption.
 247          */
 248         for (i = i_a = i_b = 0; i_a < a_num_fences && i_b < b_num_fences; ) {
 249                 struct dma_fence *pt_a = a_fences[i_a];
 250                 struct dma_fence *pt_b = b_fences[i_b];
 251
 252                 if (pt_a->context < pt_b->context) {
 253                         add_fence(fences, &i, pt_a);
 254
 255                         i_a++;
 256                 } else if (pt_a->context > pt_b->context) {
 257                         add_fence(fences, &i, pt_b);
 258
 259                         i_b++;
 260                 } else {
 261                         if (__dma_fence_is_later(pt_a->seqno, pt_b->seqno))
 262                                 add_fence(fences, &i, pt_a);
 263                         else
 264                                 add_fence(fences, &i, pt_b);
 265
 266                         i_a++;
 267                         i_b++;
 268                 }
 269         }
 270
 271         for (; i_a < a_num_fences; i_a++)
 272                 add_fence(fences, &i, a_fences[i_a]);
 273
 274         for (; i_b < b_num_fences; i_b++)
 275                 add_fence(fences, &i, b_fences[i_b]);
 276
 277         if (i == 0)
 278                 fences[i++] = dma_fence_get(a_fences[0]);
 279
 280         if (num_fences > i) {
 281                 nfences = krealloc(fences, i * sizeof(*fences),
 282                                   GFP_KERNEL);
 283                 if (!nfences)
 284                         goto err;
 285
 286                 fences = nfences;
 287         }
 288
 289         if (sync_file_set_fence(sync_file, fences, i) < 0) {
 290                 kfree(fences);
 291                 goto err;
 292         }
 293
 294         strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
 295         return sync_file;
 296
 297 err:
 298         fput(sync_file->file);
 299         return NULL;
 300
 301 }
 302
 303 static int sync_file_release(struct inode *inode, struct file *file)
 304 {
 305         struct sync_file *sync_file = file->private_data;
 306
 307         if (test_bit(POLL_ENABLED, &sync_file->flags))
 308                 dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
 309         dma_fence_put(sync_file->fence);
 310         kfree(sync_file);
 311
 312         return 0;
 313 }
 314
 315 static __poll_t sync_file_poll(struct file *file, poll_table *wait)
 316 {
 317         struct sync_file *sync_file = file->private_data;
 318
 319         poll_wait(file, &sync_file->wq, wait);
 320
 321         if (list_empty(&sync_file->cb.node) &&
 322             !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
 323                 if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
 324                                            fence_check_cb_func) < 0)
 325                         wake_up_all(&sync_file->wq);
 326         }
 327
 328         return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
 329 }
 330
 331 static long sync_file_ioctl_merge(struct sync_file *sync_file,
 332                                   unsigned long arg)
 333 {
 334         int fd = get_unused_fd_flags(O_CLOEXEC);
 335         int err;
 336         struct sync_file *fence2, *fence3;
 337         struct sync_merge_data data;
 338
 339         if (fd < 0)
 340                 return fd;
 341
 342         if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
 343                 err = -EFAULT;
 344                 goto err_put_fd;
 345         }
 346
 347         if (data.flags || data.pad) {
 348                 err = -EINVAL;
 349                 goto err_put_fd;
 350         }
 351
 352         fence2 = sync_file_fdget(data.fd2);
 353         if (!fence2) {
 354                 err = -ENOENT;
 355                 goto err_put_fd;
 356         }
 357
 358         data.name[sizeof(data.name) - 1] = '\0';
 359         fence3 = sync_file_merge(data.name, sync_file, fence2);
 360         if (!fence3) {
 361                 err = -ENOMEM;
 362                 goto err_put_fence2;
 363         }
 364
 365         data.fence = fd;
 366         if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
 367                 err = -EFAULT;
 368                 goto err_put_fence3;
 369         }
 370
 371         fd_install(fd, fence3->file);
 372         fput(fence2->file);
 373         return 0;
 374
 375 err_put_fence3:
 376         fput(fence3->file);
 377
 378 err_put_fence2:
 379         fput(fence2->file);
 380
 381 err_put_fd:
 382         put_unused_fd(fd);
 383         return err;
 384 }
 385
 386 static int sync_fill_fence_info(struct dma_fence *fence,
 387                                  struct sync_fence_info *info)
 388 {
 389         strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
 390                 sizeof(info->obj_name));
 391         strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
 392                 sizeof(info->driver_name));
 393
 394         info->status = dma_fence_get_status(fence);
 395         while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
 396                !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
 397                 cpu_relax();
 398         info->timestamp_ns =
 399                 test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?
 400                 ktime_to_ns(fence->timestamp) :
 401                 ktime_set(0, 0);
 402
 403         return info->status;
 404 }
 405
 406 static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 407                                        unsigned long arg)
 408 {
 409         struct sync_file_info info;
 410         struct sync_fence_info *fence_info = NULL;
 411         struct dma_fence **fences;
 412         __u32 size;
 413         int num_fences, ret, i;
 414
 415         if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
 416                 return -EFAULT;
 417
 418         if (info.flags || info.pad)
 419                 return -EINVAL;
 420
 421         fences = get_fences(sync_file, &num_fences);
 422
 423         /*
 424          * Passing num_fences = 0 means that userspace doesn't want to
 425          * retrieve any sync_fence_info. If num_fences = 0 we skip filling
 426          * sync_fence_info and return the actual number of fences on
 427          * info->num_fences.
 428          */
 429         if (!info.num_fences) {
 430                 info.status = dma_fence_is_signaled(sync_file->fence);
 431                 goto no_fences;
 432         } else {
 433                 info.status = 1;
 434         }
 435
 436         if (info.num_fences < num_fences)
 437                 return -EINVAL;
 438
 439         size = num_fences * sizeof(*fence_info);
 440         fence_info = kzalloc(size, GFP_KERNEL);
 441         if (!fence_info)
 442                 return -ENOMEM;
 443
 444         for (i = 0; i < num_fences; i++) {
 445                 int status = sync_fill_fence_info(fences[i], &fence_info[i]);
 446                 info.status = info.status <= 0 ? info.status : status;
 447         }
 448
 449         if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
 450                          size)) {
 451                 ret = -EFAULT;
 452                 goto out;
 453         }
 454
 455 no_fences:
 456         sync_file_get_name(sync_file, info.name, sizeof(info.name));
 457         info.num_fences = num_fences;
 458
 459         if (copy_to_user((void __user *)arg, &info, sizeof(info)))
 460                 ret = -EFAULT;
 461         else
 462                 ret = 0;
 463
 464 out:
 465         kfree(fence_info);
 466
 467         return ret;
 468 }
 469
 470 static long sync_file_ioctl(struct file *file, unsigned int cmd,
 471                             unsigned long arg)
 472 {
 473         struct sync_file *sync_file = file->private_data;
 474
 475         switch (cmd) {
 476         case SYNC_IOC_MERGE:
 477                 return sync_file_ioctl_merge(sync_file, arg);
 478
 479         case SYNC_IOC_FILE_INFO:
 480                 return sync_file_ioctl_fence_info(sync_file, arg);
 481
 482         default:
 483                 return -ENOTTY;
 484         }
 485 }
 486
 487 static const struct file_operations sync_file_fops = {
 488         .release = sync_file_release,
 489         .poll = sync_file_poll,
 490         .unlocked_ioctl = sync_file_ioctl,
 491         .compat_ioctl = sync_file_ioctl,
 492 };