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