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