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(int size)
  32 {
  33         struct sync_file *sync_file;
  34
  35         sync_file = kzalloc(size, 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         return sync_file;
  49
  50 err:
  51         kfree(sync_file);
  52         return NULL;
  53 }
  54
  55 static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
  56 {
  57         struct sync_file_cb *check;
  58         struct sync_file *sync_file;
  59
  60         check = container_of(cb, struct sync_file_cb, cb);
  61         sync_file = check->sync_file;
  62
  63         if (atomic_dec_and_test(&sync_file->status))
  64                 wake_up_all(&sync_file->wq);
  65 }
  66
  67 /**
  68  * sync_file_create() - creates a sync file
  69  * @fence:      fence to add to the sync_fence
  70  *
  71  * Creates a sync_file containg @fence. Once this is called, the sync_file
  72  * takes ownership of @fence. The sync_file can be released with
  73  * fput(sync_file->file). Returns the 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(offsetof(struct sync_file, cbs[1]));
  80         if (!sync_file)
  81                 return NULL;
  82
  83         sync_file->num_fences = 1;
  84         atomic_set(&sync_file->status, 1);
  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         sync_file->cbs[0].fence = fence;
  91         sync_file->cbs[0].sync_file = sync_file;
  92         if (fence_add_callback(fence, &sync_file->cbs[0].cb,
  93                                fence_check_cb_func))
  94                 atomic_dec(&sync_file->status);
  95
  96         return sync_file;
  97 }
  98 EXPORT_SYMBOL(sync_file_create);
  99
 100 /**
 101  * sync_file_fdget() - get a sync_file from an fd
 102  * @fd:         fd referencing a fence
 103  *
 104  * Ensures @fd references a valid sync_file, increments the refcount of the
 105  * backing file. Returns the sync_file or NULL in case of error.
 106  */
 107 static struct sync_file *sync_file_fdget(int fd)
 108 {
 109         struct file *file = fget(fd);
 110
 111         if (!file)
 112                 return NULL;
 113
 114         if (file->f_op != &sync_file_fops)
 115                 goto err;
 116
 117         return file->private_data;
 118
 119 err:
 120         fput(file);
 121         return NULL;
 122 }
 123
 124 static void sync_file_add_pt(struct sync_file *sync_file, int *i,
 125                              struct fence *fence)
 126 {
 127         sync_file->cbs[*i].fence = fence;
 128         sync_file->cbs[*i].sync_file = sync_file;
 129
 130         if (!fence_add_callback(fence, &sync_file->cbs[*i].cb,
 131                                 fence_check_cb_func)) {
 132                 fence_get(fence);
 133                 (*i)++;
 134         }
 135 }
 136
 137 /**
 138  * sync_file_merge() - merge two sync_files
 139  * @name:       name of new fence
 140  * @a:          sync_file a
 141  * @b:          sync_file b
 142  *
 143  * Creates a new sync_file which contains copies of all the fences in both
 144  * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
 145  * new merged sync_file or NULL in case of error.
 146  */
 147 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 148                                          struct sync_file *b)
 149 {
 150         int num_fences = a->num_fences + b->num_fences;
 151         struct sync_file *sync_file;
 152         int i, i_a, i_b;
 153         unsigned long size = offsetof(struct sync_file, cbs[num_fences]);
 154
 155         sync_file = sync_file_alloc(size);
 156         if (!sync_file)
 157                 return NULL;
 158
 159         atomic_set(&sync_file->status, num_fences);
 160
 161         /*
 162          * Assume sync_file a and b are both ordered and have no
 163          * duplicates with the same context.
 164          *
 165          * If a sync_file can only be created with sync_file_merge
 166          * and sync_file_create, this is a reasonable assumption.
 167          */
 168         for (i = i_a = i_b = 0; i_a < a->num_fences && i_b < b->num_fences; ) {
 169                 struct fence *pt_a = a->cbs[i_a].fence;
 170                 struct fence *pt_b = b->cbs[i_b].fence;
 171
 172                 if (pt_a->context < pt_b->context) {
 173                         sync_file_add_pt(sync_file, &i, pt_a);
 174
 175                         i_a++;
 176                 } else if (pt_a->context > pt_b->context) {
 177                         sync_file_add_pt(sync_file, &i, pt_b);
 178
 179                         i_b++;
 180                 } else {
 181                         if (pt_a->seqno - pt_b->seqno <= INT_MAX)
 182                                 sync_file_add_pt(sync_file, &i, pt_a);
 183                         else
 184                                 sync_file_add_pt(sync_file, &i, pt_b);
 185
 186                         i_a++;
 187                         i_b++;
 188                 }
 189         }
 190
 191         for (; i_a < a->num_fences; i_a++)
 192                 sync_file_add_pt(sync_file, &i, a->cbs[i_a].fence);
 193
 194         for (; i_b < b->num_fences; i_b++)
 195                 sync_file_add_pt(sync_file, &i, b->cbs[i_b].fence);
 196
 197         if (num_fences > i)
 198                 atomic_sub(num_fences - i, &sync_file->status);
 199         sync_file->num_fences = i;
 200
 201         strlcpy(sync_file->name, name, sizeof(sync_file->name));
 202         return sync_file;
 203 }
 204
 205 static void sync_file_free(struct kref *kref)
 206 {
 207         struct sync_file *sync_file = container_of(kref, struct sync_file,
 208                                                      kref);
 209         int i;
 210
 211         for (i = 0; i < sync_file->num_fences; ++i) {
 212                 fence_remove_callback(sync_file->cbs[i].fence,
 213                                       &sync_file->cbs[i].cb);
 214                 fence_put(sync_file->cbs[i].fence);
 215         }
 216
 217         kfree(sync_file);
 218 }
 219
 220 static int sync_file_release(struct inode *inode, struct file *file)
 221 {
 222         struct sync_file *sync_file = file->private_data;
 223
 224         kref_put(&sync_file->kref, sync_file_free);
 225         return 0;
 226 }
 227
 228 static unsigned int sync_file_poll(struct file *file, poll_table *wait)
 229 {
 230         struct sync_file *sync_file = file->private_data;
 231         int status;
 232
 233         poll_wait(file, &sync_file->wq, wait);
 234
 235         status = atomic_read(&sync_file->status);
 236
 237         if (!status)
 238                 return POLLIN;
 239         if (status < 0)
 240                 return POLLERR;
 241         return 0;
 242 }
 243
 244 static long sync_file_ioctl_merge(struct sync_file *sync_file,
 245                                   unsigned long arg)
 246 {
 247         int fd = get_unused_fd_flags(O_CLOEXEC);
 248         int err;
 249         struct sync_file *fence2, *fence3;
 250         struct sync_merge_data data;
 251
 252         if (fd < 0)
 253                 return fd;
 254
 255         if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
 256                 err = -EFAULT;
 257                 goto err_put_fd;
 258         }
 259
 260         if (data.flags || data.pad) {
 261                 err = -EINVAL;
 262                 goto err_put_fd;
 263         }
 264
 265         fence2 = sync_file_fdget(data.fd2);
 266         if (!fence2) {
 267                 err = -ENOENT;
 268                 goto err_put_fd;
 269         }
 270
 271         data.name[sizeof(data.name) - 1] = '\0';
 272         fence3 = sync_file_merge(data.name, sync_file, fence2);
 273         if (!fence3) {
 274                 err = -ENOMEM;
 275                 goto err_put_fence2;
 276         }
 277
 278         data.fence = fd;
 279         if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
 280                 err = -EFAULT;
 281                 goto err_put_fence3;
 282         }
 283
 284         fd_install(fd, fence3->file);
 285         fput(fence2->file);
 286         return 0;
 287
 288 err_put_fence3:
 289         fput(fence3->file);
 290
 291 err_put_fence2:
 292         fput(fence2->file);
 293
 294 err_put_fd:
 295         put_unused_fd(fd);
 296         return err;
 297 }
 298
 299 static void sync_fill_fence_info(struct fence *fence,
 300                                  struct sync_fence_info *info)
 301 {
 302         strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
 303                 sizeof(info->obj_name));
 304         strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
 305                 sizeof(info->driver_name));
 306         if (fence_is_signaled(fence))
 307                 info->status = fence->status >= 0 ? 1 : fence->status;
 308         else
 309                 info->status = 0;
 310         info->timestamp_ns = ktime_to_ns(fence->timestamp);
 311 }
 312
 313 static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 314                                        unsigned long arg)
 315 {
 316         struct sync_file_info info;
 317         struct sync_fence_info *fence_info = NULL;
 318         __u32 size;
 319         int ret, i;
 320
 321         if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
 322                 return -EFAULT;
 323
 324         if (info.flags || info.pad)
 325                 return -EINVAL;
 326
 327         /*
 328          * Passing num_fences = 0 means that userspace doesn't want to
 329          * retrieve any sync_fence_info. If num_fences = 0 we skip filling
 330          * sync_fence_info and return the actual number of fences on
 331          * info->num_fences.
 332          */
 333         if (!info.num_fences)
 334                 goto no_fences;
 335
 336         if (info.num_fences < sync_file->num_fences)
 337                 return -EINVAL;
 338
 339         size = sync_file->num_fences * sizeof(*fence_info);
 340         fence_info = kzalloc(size, GFP_KERNEL);
 341         if (!fence_info)
 342                 return -ENOMEM;
 343
 344         for (i = 0; i < sync_file->num_fences; ++i)
 345                 sync_fill_fence_info(sync_file->cbs[i].fence, &fence_info[i]);
 346
 347         if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
 348                          size)) {
 349                 ret = -EFAULT;
 350                 goto out;
 351         }
 352
 353 no_fences:
 354         strlcpy(info.name, sync_file->name, sizeof(info.name));
 355         info.status = atomic_read(&sync_file->status);
 356         if (info.status >= 0)
 357                 info.status = !info.status;
 358
 359         info.num_fences = sync_file->num_fences;
 360
 361         if (copy_to_user((void __user *)arg, &info, sizeof(info)))
 362                 ret = -EFAULT;
 363         else
 364                 ret = 0;
 365
 366 out:
 367         kfree(fence_info);
 368
 369         return ret;
 370 }
 371
 372 static long sync_file_ioctl(struct file *file, unsigned int cmd,
 373                             unsigned long arg)
 374 {
 375         struct sync_file *sync_file = file->private_data;
 376
 377         switch (cmd) {
 378         case SYNC_IOC_MERGE:
 379                 return sync_file_ioctl_merge(sync_file, arg);
 380
 381         case SYNC_IOC_FILE_INFO:
 382                 return sync_file_ioctl_fence_info(sync_file, arg);
 383
 384         default:
 385                 return -ENOTTY;
 386         }
 387 }
 388
 389 static const struct file_operations sync_file_fops = {
 390         .release = sync_file_release,
 391         .poll = sync_file_poll,
 392         .unlocked_ioctl = sync_file_ioctl,
 393         .compat_ioctl = sync_file_ioctl,
 394 };
 395