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. 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 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 = 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 fence *sync_file_get_fence(int fd)
 125 {
 126         struct sync_file *sync_file;
 127         struct fence *fence;
 128
 129         sync_file = sync_file_fdget(fd);
 130         if (!sync_file)
 131                 return NULL;
 132
 133         fence = 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 fence **fences, int num_fences)
 142 {
 143         struct 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 fence_array creation.
 150          */
 151         if (num_fences == 1) {
 152                 sync_file->fence = fences[0];
 153         } else {
 154                 array = fence_array_create(num_fences, fences,
 155                                            fence_context_alloc(1), 1, false);
 156                 if (!array)
 157                         return -ENOMEM;
 158
 159                 sync_file->fence = &array->base;
 160         }
 161
 162         return 0;
 163 }
 164
 165 static struct fence **get_fences(struct sync_file *sync_file, int *num_fences)
 166 {
 167         if (fence_is_array(sync_file->fence)) {
 168                 struct fence_array *array = to_fence_array(sync_file->fence);
 169
 170                 *num_fences = array->num_fences;
 171                 return array->fences;
 172         }
 173
 174         *num_fences = 1;
 175         return &sync_file->fence;
 176 }
 177
 178 static void add_fence(struct fence **fences, int *i, struct fence *fence)
 179 {
 180         fences[*i] = fence;
 181
 182         if (!fence_is_signaled(fence)) {
 183                 fence_get(fence);
 184                 (*i)++;
 185         }
 186 }
 187
 188 /**
 189  * sync_file_merge() - merge two sync_files
 190  * @name:       name of new fence
 191  * @a:          sync_file a
 192  * @b:          sync_file b
 193  *
 194  * Creates a new sync_file which contains copies of all the fences in both
 195  * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
 196  * new merged sync_file or NULL in case of error.
 197  */
 198 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 199                                          struct sync_file *b)
 200 {
 201         struct sync_file *sync_file;
 202         struct fence **fences, **nfences, **a_fences, **b_fences;
 203         int i, i_a, i_b, num_fences, a_num_fences, b_num_fences;
 204
 205         sync_file = sync_file_alloc();
 206         if (!sync_file)
 207                 return NULL;
 208
 209         a_fences = get_fences(a, &a_num_fences);
 210         b_fences = get_fences(b, &b_num_fences);
 211         if (a_num_fences > INT_MAX - b_num_fences)
 212                 return NULL;
 213
 214         num_fences = a_num_fences + b_num_fences;
 215
 216         fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
 217         if (!fences)
 218                 goto err;
 219
 220         /*
 221          * Assume sync_file a and b are both ordered and have no
 222          * duplicates with the same context.
 223          *
 224          * If a sync_file can only be created with sync_file_merge
 225          * and sync_file_create, this is a reasonable assumption.
 226          */
 227         for (i = i_a = i_b = 0; i_a < a_num_fences && i_b < b_num_fences; ) {
 228                 struct fence *pt_a = a_fences[i_a];
 229                 struct fence *pt_b = b_fences[i_b];
 230
 231                 if (pt_a->context < pt_b->context) {
 232                         add_fence(fences, &i, pt_a);
 233
 234                         i_a++;
 235                 } else if (pt_a->context > pt_b->context) {
 236                         add_fence(fences, &i, pt_b);
 237
 238                         i_b++;
 239                 } else {
 240                         if (pt_a->seqno - pt_b->seqno <= INT_MAX)
 241                                 add_fence(fences, &i, pt_a);
 242                         else
 243                                 add_fence(fences, &i, pt_b);
 244
 245                         i_a++;
 246                         i_b++;
 247                 }
 248         }
 249
 250         for (; i_a < a_num_fences; i_a++)
 251                 add_fence(fences, &i, a_fences[i_a]);
 252
 253         for (; i_b < b_num_fences; i_b++)
 254                 add_fence(fences, &i, b_fences[i_b]);
 255
 256         if (i == 0) {
 257                 add_fence(fences, &i, a_fences[0]);
 258                 i++;
 259         }
 260
 261         if (num_fences > i) {
 262                 nfences = krealloc(fences, i * sizeof(*fences),
 263                                   GFP_KERNEL);
 264                 if (!nfences)
 265                         goto err;
 266
 267                 fences = nfences;
 268         }
 269
 270         if (sync_file_set_fence(sync_file, fences, i) < 0) {
 271                 kfree(fences);
 272                 goto err;
 273         }
 274
 275         strlcpy(sync_file->name, name, sizeof(sync_file->name));
 276         return sync_file;
 277
 278 err:
 279         fput(sync_file->file);
 280         return NULL;
 281
 282 }
 283
 284 static void sync_file_free(struct kref *kref)
 285 {
 286         struct sync_file *sync_file = container_of(kref, struct sync_file,
 287                                                      kref);
 288
 289         if (test_bit(POLL_ENABLED, &sync_file->fence->flags))
 290                 fence_remove_callback(sync_file->fence, &sync_file->cb);
 291         fence_put(sync_file->fence);
 292         kfree(sync_file);
 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         kref_put(&sync_file->kref, sync_file_free);
 300         return 0;
 301 }
 302
 303 static unsigned int sync_file_poll(struct file *file, poll_table *wait)
 304 {
 305         struct sync_file *sync_file = file->private_data;
 306
 307         poll_wait(file, &sync_file->wq, wait);
 308
 309         if (!poll_does_not_wait(wait) &&
 310             !test_and_set_bit(POLL_ENABLED, &sync_file->fence->flags)) {
 311                 if (fence_add_callback(sync_file->fence, &sync_file->cb,
 312                                        fence_check_cb_func) < 0)
 313                         wake_up_all(&sync_file->wq);
 314         }
 315
 316         return fence_is_signaled(sync_file->fence) ? POLLIN : 0;
 317 }
 318
 319 static long sync_file_ioctl_merge(struct sync_file *sync_file,
 320                                   unsigned long arg)
 321 {
 322         int fd = get_unused_fd_flags(O_CLOEXEC);
 323         int err;
 324         struct sync_file *fence2, *fence3;
 325         struct sync_merge_data data;
 326
 327         if (fd < 0)
 328                 return fd;
 329
 330         if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
 331                 err = -EFAULT;
 332                 goto err_put_fd;
 333         }
 334
 335         if (data.flags || data.pad) {
 336                 err = -EINVAL;
 337                 goto err_put_fd;
 338         }
 339
 340         fence2 = sync_file_fdget(data.fd2);
 341         if (!fence2) {
 342                 err = -ENOENT;
 343                 goto err_put_fd;
 344         }
 345
 346         data.name[sizeof(data.name) - 1] = '\0';
 347         fence3 = sync_file_merge(data.name, sync_file, fence2);
 348         if (!fence3) {
 349                 err = -ENOMEM;
 350                 goto err_put_fence2;
 351         }
 352
 353         data.fence = fd;
 354         if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
 355                 err = -EFAULT;
 356                 goto err_put_fence3;
 357         }
 358
 359         fd_install(fd, fence3->file);
 360         fput(fence2->file);
 361         return 0;
 362
 363 err_put_fence3:
 364         fput(fence3->file);
 365
 366 err_put_fence2:
 367         fput(fence2->file);
 368
 369 err_put_fd:
 370         put_unused_fd(fd);
 371         return err;
 372 }
 373
 374 static void sync_fill_fence_info(struct fence *fence,
 375                                  struct sync_fence_info *info)
 376 {
 377         strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
 378                 sizeof(info->obj_name));
 379         strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
 380                 sizeof(info->driver_name));
 381         if (fence_is_signaled(fence))
 382                 info->status = fence->status >= 0 ? 1 : fence->status;
 383         else
 384                 info->status = 0;
 385         info->timestamp_ns = ktime_to_ns(fence->timestamp);
 386 }
 387
 388 static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 389                                        unsigned long arg)
 390 {
 391         struct sync_file_info info;
 392         struct sync_fence_info *fence_info = NULL;
 393         struct fence **fences;
 394         __u32 size;
 395         int num_fences, ret, i;
 396
 397         if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
 398                 return -EFAULT;
 399
 400         if (info.flags || info.pad)
 401                 return -EINVAL;
 402
 403         fences = get_fences(sync_file, &num_fences);
 404
 405         /*
 406          * Passing num_fences = 0 means that userspace doesn't want to
 407          * retrieve any sync_fence_info. If num_fences = 0 we skip filling
 408          * sync_fence_info and return the actual number of fences on
 409          * info->num_fences.
 410          */
 411         if (!info.num_fences)
 412                 goto no_fences;
 413
 414         if (info.num_fences < num_fences)
 415                 return -EINVAL;
 416
 417         size = num_fences * sizeof(*fence_info);
 418         fence_info = kzalloc(size, GFP_KERNEL);
 419         if (!fence_info)
 420                 return -ENOMEM;
 421
 422         for (i = 0; i < num_fences; i++)
 423                 sync_fill_fence_info(fences[i], &fence_info[i]);
 424
 425         if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
 426                          size)) {
 427                 ret = -EFAULT;
 428                 goto out;
 429         }
 430
 431 no_fences:
 432         strlcpy(info.name, sync_file->name, sizeof(info.name));
 433         info.status = fence_is_signaled(sync_file->fence);
 434         info.num_fences = num_fences;
 435
 436         if (copy_to_user((void __user *)arg, &info, sizeof(info)))
 437                 ret = -EFAULT;
 438         else
 439                 ret = 0;
 440
 441 out:
 442         kfree(fence_info);
 443
 444         return ret;
 445 }
 446
 447 static long sync_file_ioctl(struct file *file, unsigned int cmd,
 448                             unsigned long arg)
 449 {
 450         struct sync_file *sync_file = file->private_data;
 451
 452         switch (cmd) {
 453         case SYNC_IOC_MERGE:
 454                 return sync_file_ioctl_merge(sync_file, arg);
 455
 456         case SYNC_IOC_FILE_INFO:
 457                 return sync_file_ioctl_fence_info(sync_file, arg);
 458
 459         default:
 460                 return -ENOTTY;
 461         }
 462 }
 463
 464 static const struct file_operations sync_file_fops = {
 465         .release = sync_file_release,
 466         .poll = sync_file_poll,
 467         .unlocked_ioctl = sync_file_ioctl,
 468         .compat_ioctl = sync_file_ioctl,
 469 };
 470