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
 21static const struct file_operations sync_file_fops;
 22
 23static 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
 42err:
 43	kfree(sync_file);
 44	return NULL;
 45}
 46
 47static 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 */
 65struct 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}
 77EXPORT_SYMBOL(sync_file_create);
 78
 79static 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
 91err:
 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 */
103struct 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}
117EXPORT_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 */
132char *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		const char __rcu *timeline;
139		const char __rcu *driver;
140
141		rcu_read_lock();
142		driver = dma_fence_driver_name(fence);
143		timeline = dma_fence_timeline_name(fence);
144		snprintf(buf, len, "%s-%s%llu-%lld",
145			 rcu_dereference(driver),
146			 rcu_dereference(timeline),
147			 fence->context,
148			 fence->seqno);
149		rcu_read_unlock();
150	}
151
152	return buf;
153}
154
155/**
156 * sync_file_merge() - merge two sync_files
157 * @name:	name of new fence
158 * @a:		sync_file a
159 * @b:		sync_file b
160 *
161 * Creates a new sync_file which contains copies of all the fences in both
162 * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
163 * new merged sync_file or NULL in case of error.
164 */
165static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
166					 struct sync_file *b)
167{
168	struct sync_file *sync_file;
169	struct dma_fence *fence;
170
171	sync_file = sync_file_alloc();
172	if (!sync_file)
173		return NULL;
174
175	fence = dma_fence_unwrap_merge(a->fence, b->fence);
176	if (!fence) {
177		fput(sync_file->file);
178		return NULL;
179	}
180	sync_file->fence = fence;
181	strscpy(sync_file->user_name, name, sizeof(sync_file->user_name));
182	return sync_file;
183}
184
185static int sync_file_release(struct inode *inode, struct file *file)
186{
187	struct sync_file *sync_file = file->private_data;
188
189	if (test_bit(POLL_ENABLED, &sync_file->flags))
190		dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
191	dma_fence_put(sync_file->fence);
192	kfree(sync_file);
193
194	return 0;
195}
196
197static __poll_t sync_file_poll(struct file *file, poll_table *wait)
198{
199	struct sync_file *sync_file = file->private_data;
200
201	poll_wait(file, &sync_file->wq, wait);
202
203	if (list_empty(&sync_file->cb.node) &&
204	    !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
205		if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
206					   fence_check_cb_func) < 0)
207			wake_up_all(&sync_file->wq);
208	}
209
210	return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
211}
212
213static long sync_file_ioctl_merge(struct sync_file *sync_file,
214				  unsigned long arg)
215{
216	int fd = get_unused_fd_flags(O_CLOEXEC);
217	int err;
218	struct sync_file *fence2, *fence3;
219	struct sync_merge_data data;
220
221	if (fd < 0)
222		return fd;
223
224	if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
225		err = -EFAULT;
226		goto err_put_fd;
227	}
228
229	if (data.flags || data.pad) {
230		err = -EINVAL;
231		goto err_put_fd;
232	}
233
234	fence2 = sync_file_fdget(data.fd2);
235	if (!fence2) {
236		err = -ENOENT;
237		goto err_put_fd;
238	}
239
240	data.name[sizeof(data.name) - 1] = '\0';
241	fence3 = sync_file_merge(data.name, sync_file, fence2);
242	if (!fence3) {
243		err = -ENOMEM;
244		goto err_put_fence2;
245	}
246
247	data.fence = fd;
248	if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
249		err = -EFAULT;
250		goto err_put_fence3;
251	}
252
253	fd_install(fd, fence3->file);
254	fput(fence2->file);
255	return 0;
256
257err_put_fence3:
258	fput(fence3->file);
259
260err_put_fence2:
261	fput(fence2->file);
262
263err_put_fd:
264	put_unused_fd(fd);
265	return err;
266}
267
268static int sync_fill_fence_info(struct dma_fence *fence,
269				 struct sync_fence_info *info)
270{
271	const char __rcu *timeline;
272	const char __rcu *driver;
273
274	rcu_read_lock();
275
276	driver = dma_fence_driver_name(fence);
277	timeline = dma_fence_timeline_name(fence);
278
279	strscpy(info->obj_name, rcu_dereference(timeline),
280		sizeof(info->obj_name));
281	strscpy(info->driver_name, rcu_dereference(driver),
282		sizeof(info->driver_name));
283
284	info->status = dma_fence_get_status(fence);
285	info->timestamp_ns =
286		dma_fence_is_signaled(fence) ?
287			ktime_to_ns(dma_fence_timestamp(fence)) :
288			ktime_set(0, 0);
289
290	rcu_read_unlock();
291
292	return info->status;
293}
294
295static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
296				       unsigned long arg)
297{
298	struct sync_fence_info *fence_info = NULL;
299	struct dma_fence_unwrap iter;
300	struct sync_file_info info;
301	unsigned int num_fences;
302	struct dma_fence *fence;
303	int ret;
304	__u32 size;
305
306	if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
307		return -EFAULT;
308
309	if (info.flags || info.pad)
310		return -EINVAL;
311
312	num_fences = 0;
313	dma_fence_unwrap_for_each(fence, &iter, sync_file->fence)
314		++num_fences;
315
316	/*
317	 * Passing num_fences = 0 means that userspace doesn't want to
318	 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
319	 * sync_fence_info and return the actual number of fences on
320	 * info->num_fences.
321	 */
322	if (!info.num_fences) {
323		info.status = dma_fence_get_status(sync_file->fence);
324		goto no_fences;
325	} else {
326		info.status = 1;
327	}
328
329	if (info.num_fences < num_fences)
330		return -EINVAL;
331
332	size = num_fences * sizeof(*fence_info);
333	fence_info = kzalloc(size, GFP_KERNEL);
334	if (!fence_info)
335		return -ENOMEM;
336
337	num_fences = 0;
338	dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) {
339		int status;
340
341		status = sync_fill_fence_info(fence, &fence_info[num_fences++]);
342		info.status = info.status <= 0 ? info.status : status;
343	}
344
345	if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
346			 size)) {
347		ret = -EFAULT;
348		goto out;
349	}
350
351no_fences:
352	sync_file_get_name(sync_file, info.name, sizeof(info.name));
353	info.num_fences = num_fences;
354
355	if (copy_to_user((void __user *)arg, &info, sizeof(info)))
356		ret = -EFAULT;
357	else
358		ret = 0;
359
360out:
361	kfree(fence_info);
362
363	return ret;
364}
365
366static int sync_file_ioctl_set_deadline(struct sync_file *sync_file,
367					unsigned long arg)
368{
369	struct sync_set_deadline ts;
370
371	if (copy_from_user(&ts, (void __user *)arg, sizeof(ts)))
372		return -EFAULT;
373
374	if (ts.pad)
375		return -EINVAL;
376
377	dma_fence_set_deadline(sync_file->fence, ns_to_ktime(ts.deadline_ns));
378
379	return 0;
380}
381
382static long sync_file_ioctl(struct file *file, unsigned int cmd,
383			    unsigned long arg)
384{
385	struct sync_file *sync_file = file->private_data;
386
387	switch (cmd) {
388	case SYNC_IOC_MERGE:
389		return sync_file_ioctl_merge(sync_file, arg);
390
391	case SYNC_IOC_FILE_INFO:
392		return sync_file_ioctl_fence_info(sync_file, arg);
393
394	case SYNC_IOC_SET_DEADLINE:
395		return sync_file_ioctl_set_deadline(sync_file, arg);
396
397	default:
398		return -ENOTTY;
399	}
400}
401
402static const struct file_operations sync_file_fops = {
403	.release = sync_file_release,
404	.poll = sync_file_poll,
405	.unlocked_ioctl = sync_file_ioctl,
406	.compat_ioctl = compat_ptr_ioctl,
407};