drivers/dma-buf/sync_file.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * drivers/dma-buf/sync_file.c
   4  *
   5  * Copyright (C) 2012 Google, Inc.
   6  */
   7
   8 #include <linux/dma-fence-unwrap.h>
   9 #include <linux/export.h>
  10 #include <linux/file.h>
  11 #include <linux/fs.h>
  12 #include <linux/kernel.h>
  13 #include <linux/poll.h>
  14 #include <linux/sched.h>
  15 #include <linux/slab.h>
  16 #include <linux/uaccess.h>
  17 #include <linux/anon_inodes.h>
  18 #include <linux/sync_file.h>
  19 #include <uapi/linux/sync_file.h>
  20
  21 static const struct file_operations sync_file_fops;
  22
  23 static struct sync_file *sync_file_alloc(void)
  24 {
  25         struct sync_file *sync_file;
  26
  27         sync_file = kzalloc(sizeof(*sync_file), GFP_KERNEL);
  28         if (!sync_file)
  29                 return NULL;
  30
  31         sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
  32                                              sync_file, 0);
  33         if (IS_ERR(sync_file->file))
  34                 goto err;
  35
  36         init_waitqueue_head(&sync_file->wq);
  37
  38         INIT_LIST_HEAD(&sync_file->cb.node);
  39
  40         return sync_file;
  41
  42 err:
  43         kfree(sync_file);
  44         return NULL;
  45 }
  46
  47 static void fence_check_cb_func(struct dma_fence *f, struct dma_fence_cb *cb)
  48 {
  49         struct sync_file *sync_file;
  50
  51         sync_file = container_of(cb, struct sync_file, cb);
  52
  53         wake_up_all(&sync_file->wq);
  54 }
  55
  56 /**
  57  * sync_file_create() - creates a sync file
  58  * @fence:      fence to add to the sync_fence
  59  *
  60  * Creates a sync_file containg @fence. This function acquires and additional
  61  * reference of @fence for the newly-created &sync_file, if it succeeds. The
  62  * sync_file can be released with fput(sync_file->file). Returns the
  63  * sync_file or NULL in case of error.
  64  */
  65 struct sync_file *sync_file_create(struct dma_fence *fence)
  66 {
  67         struct sync_file *sync_file;
  68
  69         sync_file = sync_file_alloc();
  70         if (!sync_file)
  71                 return NULL;
  72
  73         sync_file->fence = dma_fence_get(fence);
  74
  75         return sync_file;
  76 }
  77 EXPORT_SYMBOL(sync_file_create);
  78
  79 static struct sync_file *sync_file_fdget(int fd)
  80 {
  81         struct file *file = fget(fd);
  82
  83         if (!file)
  84                 return NULL;
  85
  86         if (file->f_op != &sync_file_fops)
  87                 goto err;
  88
  89         return file->private_data;
  90
  91 err:
  92         fput(file);
  93         return NULL;
  94 }
  95
  96 /**
  97  * sync_file_get_fence - get the fence related to the sync_file fd
  98  * @fd:         sync_file fd to get the fence from
  99  *
 100  * Ensures @fd references a valid sync_file and returns a fence that
 101  * represents all fence in the sync_file. On error NULL is returned.
 102  */
 103 struct dma_fence *sync_file_get_fence(int fd)
 104 {
 105         struct sync_file *sync_file;
 106         struct dma_fence *fence;
 107
 108         sync_file = sync_file_fdget(fd);
 109         if (!sync_file)
 110                 return NULL;
 111
 112         fence = dma_fence_get(sync_file->fence);
 113         fput(sync_file->file);
 114
 115         return fence;
 116 }
 117 EXPORT_SYMBOL(sync_file_get_fence);
 118
 119 /**
 120  * sync_file_get_name - get the name of the sync_file
 121  * @sync_file:          sync_file to get the fence from
 122  * @buf:                destination buffer to copy sync_file name into
 123  * @len:                available size of destination buffer.
 124  *
 125  * Each sync_file may have a name assigned either by the user (when merging
 126  * sync_files together) or created from the fence it contains. In the latter
 127  * case construction of the name is deferred until use, and so requires
 128  * sync_file_get_name().
 129  *
 130  * Returns: a string representing the name.
 131  */
 132 char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
 133 {
 134         if (sync_file->user_name[0]) {
 135                 strscpy(buf, sync_file->user_name, len);
 136         } else {
 137                 struct dma_fence *fence = sync_file->fence;
 138
 139                 snprintf(buf, len, "%s-%s%llu-%lld",
 140                          fence->ops->get_driver_name(fence),
 141                          fence->ops->get_timeline_name(fence),
 142                          fence->context,
 143                          fence->seqno);
 144         }
 145
 146         return buf;
 147 }
 148
 149 /**
 150  * sync_file_merge() - merge two sync_files
 151  * @name:       name of new fence
 152  * @a:          sync_file a
 153  * @b:          sync_file b
 154  *
 155  * Creates a new sync_file which contains copies of all the fences in both
 156  * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
 157  * new merged sync_file or NULL in case of error.
 158  */
 159 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 160                                          struct sync_file *b)
 161 {
 162         struct sync_file *sync_file;
 163         struct dma_fence *fence;
 164
 165         sync_file = sync_file_alloc();
 166         if (!sync_file)
 167                 return NULL;
 168
 169         fence = dma_fence_unwrap_merge(a->fence, b->fence);
 170         if (!fence) {
 171                 fput(sync_file->file);
 172                 return NULL;
 173         }
 174         sync_file->fence = fence;
 175         strscpy(sync_file->user_name, name, sizeof(sync_file->user_name));
 176         return sync_file;
 177 }
 178
 179 static int sync_file_release(struct inode *inode, struct file *file)
 180 {
 181         struct sync_file *sync_file = file->private_data;
 182
 183         if (test_bit(POLL_ENABLED, &sync_file->flags))
 184                 dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
 185         dma_fence_put(sync_file->fence);
 186         kfree(sync_file);
 187
 188         return 0;
 189 }
 190
 191 static __poll_t sync_file_poll(struct file *file, poll_table *wait)
 192 {
 193         struct sync_file *sync_file = file->private_data;
 194
 195         poll_wait(file, &sync_file->wq, wait);
 196
 197         if (list_empty(&sync_file->cb.node) &&
 198             !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
 199                 if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
 200                                            fence_check_cb_func) < 0)
 201                         wake_up_all(&sync_file->wq);
 202         }
 203
 204         return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
 205 }
 206
 207 static long sync_file_ioctl_merge(struct sync_file *sync_file,
 208                                   unsigned long arg)
 209 {
 210         int fd = get_unused_fd_flags(O_CLOEXEC);
 211         int err;
 212         struct sync_file *fence2, *fence3;
 213         struct sync_merge_data data;
 214
 215         if (fd < 0)
 216                 return fd;
 217
 218         if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
 219                 err = -EFAULT;
 220                 goto err_put_fd;
 221         }
 222
 223         if (data.flags || data.pad) {
 224                 err = -EINVAL;
 225                 goto err_put_fd;
 226         }
 227
 228         fence2 = sync_file_fdget(data.fd2);
 229         if (!fence2) {
 230                 err = -ENOENT;
 231                 goto err_put_fd;
 232         }
 233
 234         data.name[sizeof(data.name) - 1] = '\0';
 235         fence3 = sync_file_merge(data.name, sync_file, fence2);
 236         if (!fence3) {
 237                 err = -ENOMEM;
 238                 goto err_put_fence2;
 239         }
 240
 241         data.fence = fd;
 242         if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
 243                 err = -EFAULT;
 244                 goto err_put_fence3;
 245         }
 246
 247         fd_install(fd, fence3->file);
 248         fput(fence2->file);
 249         return 0;
 250
 251 err_put_fence3:
 252         fput(fence3->file);
 253
 254 err_put_fence2:
 255         fput(fence2->file);
 256
 257 err_put_fd:
 258         put_unused_fd(fd);
 259         return err;
 260 }
 261
 262 static int sync_fill_fence_info(struct dma_fence *fence,
 263                                  struct sync_fence_info *info)
 264 {
 265         strscpy(info->obj_name, fence->ops->get_timeline_name(fence),
 266                 sizeof(info->obj_name));
 267         strscpy(info->driver_name, fence->ops->get_driver_name(fence),
 268                 sizeof(info->driver_name));
 269
 270         info->status = dma_fence_get_status(fence);
 271         while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
 272                !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
 273                 cpu_relax();
 274         info->timestamp_ns =
 275                 test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?
 276                 ktime_to_ns(fence->timestamp) :
 277                 ktime_set(0, 0);
 278
 279         return info->status;
 280 }
 281
 282 static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 283                                        unsigned long arg)
 284 {
 285         struct sync_fence_info *fence_info = NULL;
 286         struct dma_fence_unwrap iter;
 287         struct sync_file_info info;
 288         unsigned int num_fences;
 289         struct dma_fence *fence;
 290         int ret;
 291         __u32 size;
 292
 293         if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
 294                 return -EFAULT;
 295
 296         if (info.flags || info.pad)
 297                 return -EINVAL;
 298
 299         num_fences = 0;
 300         dma_fence_unwrap_for_each(fence, &iter, sync_file->fence)
 301                 ++num_fences;
 302
 303         /*
 304          * Passing num_fences = 0 means that userspace doesn't want to
 305          * retrieve any sync_fence_info. If num_fences = 0 we skip filling
 306          * sync_fence_info and return the actual number of fences on
 307          * info->num_fences.
 308          */
 309         if (!info.num_fences) {
 310                 info.status = dma_fence_get_status(sync_file->fence);
 311                 goto no_fences;
 312         } else {
 313                 info.status = 1;
 314         }
 315
 316         if (info.num_fences < num_fences)
 317                 return -EINVAL;
 318
 319         size = num_fences * sizeof(*fence_info);
 320         fence_info = kzalloc(size, GFP_KERNEL);
 321         if (!fence_info)
 322                 return -ENOMEM;
 323
 324         num_fences = 0;
 325         dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) {
 326                 int status;
 327
 328                 status = sync_fill_fence_info(fence, &fence_info[num_fences++]);
 329                 info.status = info.status <= 0 ? info.status : status;
 330         }
 331
 332         if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
 333                          size)) {
 334                 ret = -EFAULT;
 335                 goto out;
 336         }
 337
 338 no_fences:
 339         sync_file_get_name(sync_file, info.name, sizeof(info.name));
 340         info.num_fences = num_fences;
 341
 342         if (copy_to_user((void __user *)arg, &info, sizeof(info)))
 343                 ret = -EFAULT;
 344         else
 345                 ret = 0;
 346
 347 out:
 348         kfree(fence_info);
 349
 350         return ret;
 351 }
 352
 353 static long sync_file_ioctl(struct file *file, unsigned int cmd,
 354                             unsigned long arg)
 355 {
 356         struct sync_file *sync_file = file->private_data;
 357
 358         switch (cmd) {
 359         case SYNC_IOC_MERGE:
 360                 return sync_file_ioctl_merge(sync_file, arg);
 361
 362         case SYNC_IOC_FILE_INFO:
 363                 return sync_file_ioctl_fence_info(sync_file, arg);
 364
 365         default:
 366                 return -ENOTTY;
 367         }
 368 }
 369
 370 static const struct file_operations sync_file_fops = {
 371         .release = sync_file_release,
 372         .poll = sync_file_poll,
 373         .unlocked_ioctl = sync_file_ioctl,
 374         .compat_ioctl = compat_ptr_ioctl,
 375 };