drivers/dma-buf/sync_file.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * drivers/dma-buf/sync_file.c
0004  *
0005  * Copyright (C) 2012 Google, Inc.
0006  */
0007
0008 #include <linux/dma-fence-unwrap.h>
0009 #include <linux/export.h>
0010 #include <linux/file.h>
0011 #include <linux/fs.h>
0012 #include <linux/kernel.h>
0013 #include <linux/poll.h>
0014 #include <linux/sched.h>
0015 #include <linux/slab.h>
0016 #include <linux/uaccess.h>
0017 #include <linux/anon_inodes.h>
0018 #include <linux/sync_file.h>
0019 #include <uapi/linux/sync_file.h>
0020
0021 static const struct file_operations sync_file_fops;
0022
0023 static struct sync_file *sync_file_alloc(void)
0024 {
0025     struct sync_file *sync_file;
0026
0027     sync_file = kzalloc(sizeof(*sync_file), GFP_KERNEL);
0028     if (!sync_file)
0029         return NULL;
0030
0031     sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
0032                          sync_file, 0);
0033     if (IS_ERR(sync_file->file))
0034         goto err;
0035
0036     init_waitqueue_head(&sync_file->wq);
0037
0038     INIT_LIST_HEAD(&sync_file->cb.node);
0039
0040     return sync_file;
0041
0042 err:
0043     kfree(sync_file);
0044     return NULL;
0045 }
0046
0047 static void fence_check_cb_func(struct dma_fence *f, struct dma_fence_cb *cb)
0048 {
0049     struct sync_file *sync_file;
0050
0051     sync_file = container_of(cb, struct sync_file, cb);
0052
0053     wake_up_all(&sync_file->wq);
0054 }
0055
0056 /**
0057  * sync_file_create() - creates a sync file
0058  * @fence:  fence to add to the sync_fence
0059  *
0060  * Creates a sync_file containg @fence. This function acquires and additional
0061  * reference of @fence for the newly-created &sync_file, if it succeeds. The
0062  * sync_file can be released with fput(sync_file->file). Returns the
0063  * sync_file or NULL in case of error.
0064  */
0065 struct sync_file *sync_file_create(struct dma_fence *fence)
0066 {
0067     struct sync_file *sync_file;
0068
0069     sync_file = sync_file_alloc();
0070     if (!sync_file)
0071         return NULL;
0072
0073     sync_file->fence = dma_fence_get(fence);
0074
0075     return sync_file;
0076 }
0077 EXPORT_SYMBOL(sync_file_create);
0078
0079 static struct sync_file *sync_file_fdget(int fd)
0080 {
0081     struct file *file = fget(fd);
0082
0083     if (!file)
0084         return NULL;
0085
0086     if (file->f_op != &sync_file_fops)
0087         goto err;
0088
0089     return file->private_data;
0090
0091 err:
0092     fput(file);
0093     return NULL;
0094 }
0095
0096 /**
0097  * sync_file_get_fence - get the fence related to the sync_file fd
0098  * @fd:     sync_file fd to get the fence from
0099  *
0100  * Ensures @fd references a valid sync_file and returns a fence that
0101  * represents all fence in the sync_file. On error NULL is returned.
0102  */
0103 struct dma_fence *sync_file_get_fence(int fd)
0104 {
0105     struct sync_file *sync_file;
0106     struct dma_fence *fence;
0107
0108     sync_file = sync_file_fdget(fd);
0109     if (!sync_file)
0110         return NULL;
0111
0112     fence = dma_fence_get(sync_file->fence);
0113     fput(sync_file->file);
0114
0115     return fence;
0116 }
0117 EXPORT_SYMBOL(sync_file_get_fence);
0118
0119 /**
0120  * sync_file_get_name - get the name of the sync_file
0121  * @sync_file:      sync_file to get the fence from
0122  * @buf:        destination buffer to copy sync_file name into
0123  * @len:        available size of destination buffer.
0124  *
0125  * Each sync_file may have a name assigned either by the user (when merging
0126  * sync_files together) or created from the fence it contains. In the latter
0127  * case construction of the name is deferred until use, and so requires
0128  * sync_file_get_name().
0129  *
0130  * Returns: a string representing the name.
0131  */
0132 char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
0133 {
0134     if (sync_file->user_name[0]) {
0135         strlcpy(buf, sync_file->user_name, len);
0136     } else {
0137         struct dma_fence *fence = sync_file->fence;
0138
0139         snprintf(buf, len, "%s-%s%llu-%lld",
0140              fence->ops->get_driver_name(fence),
0141              fence->ops->get_timeline_name(fence),
0142              fence->context,
0143              fence->seqno);
0144     }
0145
0146     return buf;
0147 }
0148
0149 /**
0150  * sync_file_merge() - merge two sync_files
0151  * @name:   name of new fence
0152  * @a:      sync_file a
0153  * @b:      sync_file b
0154  *
0155  * Creates a new sync_file which contains copies of all the fences in both
0156  * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
0157  * new merged sync_file or NULL in case of error.
0158  */
0159 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
0160                      struct sync_file *b)
0161 {
0162     struct sync_file *sync_file;
0163     struct dma_fence *fence;
0164
0165     sync_file = sync_file_alloc();
0166     if (!sync_file)
0167         return NULL;
0168
0169     fence = dma_fence_unwrap_merge(a->fence, b->fence);
0170     if (!fence) {
0171         fput(sync_file->file);
0172         return NULL;
0173     }
0174     sync_file->fence = fence;
0175     strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
0176     return sync_file;
0177 }
0178
0179 static int sync_file_release(struct inode *inode, struct file *file)
0180 {
0181     struct sync_file *sync_file = file->private_data;
0182
0183     if (test_bit(POLL_ENABLED, &sync_file->flags))
0184         dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
0185     dma_fence_put(sync_file->fence);
0186     kfree(sync_file);
0187
0188     return 0;
0189 }
0190
0191 static __poll_t sync_file_poll(struct file *file, poll_table *wait)
0192 {
0193     struct sync_file *sync_file = file->private_data;
0194
0195     poll_wait(file, &sync_file->wq, wait);
0196
0197     if (list_empty(&sync_file->cb.node) &&
0198         !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
0199         if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
0200                        fence_check_cb_func) < 0)
0201             wake_up_all(&sync_file->wq);
0202     }
0203
0204     return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
0205 }
0206
0207 static long sync_file_ioctl_merge(struct sync_file *sync_file,
0208                   unsigned long arg)
0209 {
0210     int fd = get_unused_fd_flags(O_CLOEXEC);
0211     int err;
0212     struct sync_file *fence2, *fence3;
0213     struct sync_merge_data data;
0214
0215     if (fd < 0)
0216         return fd;
0217
0218     if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
0219         err = -EFAULT;
0220         goto err_put_fd;
0221     }
0222
0223     if (data.flags || data.pad) {
0224         err = -EINVAL;
0225         goto err_put_fd;
0226     }
0227
0228     fence2 = sync_file_fdget(data.fd2);
0229     if (!fence2) {
0230         err = -ENOENT;
0231         goto err_put_fd;
0232     }
0233
0234     data.name[sizeof(data.name) - 1] = '\0';
0235     fence3 = sync_file_merge(data.name, sync_file, fence2);
0236     if (!fence3) {
0237         err = -ENOMEM;
0238         goto err_put_fence2;
0239     }
0240
0241     data.fence = fd;
0242     if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
0243         err = -EFAULT;
0244         goto err_put_fence3;
0245     }
0246
0247     fd_install(fd, fence3->file);
0248     fput(fence2->file);
0249     return 0;
0250
0251 err_put_fence3:
0252     fput(fence3->file);
0253
0254 err_put_fence2:
0255     fput(fence2->file);
0256
0257 err_put_fd:
0258     put_unused_fd(fd);
0259     return err;
0260 }
0261
0262 static int sync_fill_fence_info(struct dma_fence *fence,
0263                  struct sync_fence_info *info)
0264 {
0265     strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
0266         sizeof(info->obj_name));
0267     strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
0268         sizeof(info->driver_name));
0269
0270     info->status = dma_fence_get_status(fence);
0271     while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
0272            !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
0273         cpu_relax();
0274     info->timestamp_ns =
0275         test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?
0276         ktime_to_ns(fence->timestamp) :
0277         ktime_set(0, 0);
0278
0279     return info->status;
0280 }
0281
0282 static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
0283                        unsigned long arg)
0284 {
0285     struct sync_fence_info *fence_info = NULL;
0286     struct dma_fence_unwrap iter;
0287     struct sync_file_info info;
0288     unsigned int num_fences;
0289     struct dma_fence *fence;
0290     int ret;
0291     __u32 size;
0292
0293     if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
0294         return -EFAULT;
0295
0296     if (info.flags || info.pad)
0297         return -EINVAL;
0298
0299     num_fences = 0;
0300     dma_fence_unwrap_for_each(fence, &iter, sync_file->fence)
0301         ++num_fences;
0302
0303     /*
0304      * Passing num_fences = 0 means that userspace doesn't want to
0305      * retrieve any sync_fence_info. If num_fences = 0 we skip filling
0306      * sync_fence_info and return the actual number of fences on
0307      * info->num_fences.
0308      */
0309     if (!info.num_fences) {
0310         info.status = dma_fence_get_status(sync_file->fence);
0311         goto no_fences;
0312     } else {
0313         info.status = 1;
0314     }
0315
0316     if (info.num_fences < num_fences)
0317         return -EINVAL;
0318
0319     size = num_fences * sizeof(*fence_info);
0320     fence_info = kzalloc(size, GFP_KERNEL);
0321     if (!fence_info)
0322         return -ENOMEM;
0323
0324     num_fences = 0;
0325     dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) {
0326         int status;
0327
0328         status = sync_fill_fence_info(fence, &fence_info[num_fences++]);
0329         info.status = info.status <= 0 ? info.status : status;
0330     }
0331
0332     if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
0333              size)) {
0334         ret = -EFAULT;
0335         goto out;
0336     }
0337
0338 no_fences:
0339     sync_file_get_name(sync_file, info.name, sizeof(info.name));
0340     info.num_fences = num_fences;
0341
0342     if (copy_to_user((void __user *)arg, &info, sizeof(info)))
0343         ret = -EFAULT;
0344     else
0345         ret = 0;
0346
0347 out:
0348     kfree(fence_info);
0349
0350     return ret;
0351 }
0352
0353 static long sync_file_ioctl(struct file *file, unsigned int cmd,
0354                 unsigned long arg)
0355 {
0356     struct sync_file *sync_file = file->private_data;
0357
0358     switch (cmd) {
0359     case SYNC_IOC_MERGE:
0360         return sync_file_ioctl_merge(sync_file, arg);
0361
0362     case SYNC_IOC_FILE_INFO:
0363         return sync_file_ioctl_fence_info(sync_file, arg);
0364
0365     default:
0366         return -ENOTTY;
0367     }
0368 }
0369
0370 static const struct file_operations sync_file_fops = {
0371     .release = sync_file_release,
0372     .poll = sync_file_poll,
0373     .unlocked_ioctl = sync_file_ioctl,
0374     .compat_ioctl = compat_ptr_ioctl,
0375 };