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/export.h>
9#include <linux/file.h>
10#include <linux/fs.h>
11#include <linux/kernel.h>
12#include <linux/poll.h>
13#include <linux/sched.h>
14#include <linux/slab.h>
15#include <linux/uaccess.h>
16#include <linux/anon_inodes.h>
17#include <linux/sync_file.h>
18#include <uapi/linux/sync_file.h>
19
20static const struct file_operations sync_file_fops;
21
22static struct sync_file *sync_file_alloc(void)
23{
24	struct sync_file *sync_file;
25
26	sync_file = kzalloc(sizeof(*sync_file), GFP_KERNEL);
27	if (!sync_file)
28		return NULL;
29
30	sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
31					     sync_file, 0);
32	if (IS_ERR(sync_file->file))
33		goto err;
34
35	init_waitqueue_head(&sync_file->wq);
36
37	INIT_LIST_HEAD(&sync_file->cb.node);
38
39	return sync_file;
40
41err:
42	kfree(sync_file);
43	return NULL;
44}
45
46static void fence_check_cb_func(struct dma_fence *f, struct dma_fence_cb *cb)
47{
48	struct sync_file *sync_file;
49
50	sync_file = container_of(cb, struct sync_file, cb);
51
52	wake_up_all(&sync_file->wq);
53}
54
55/**
56 * sync_file_create() - creates a sync file
57 * @fence:	fence to add to the sync_fence
58 *
59 * Creates a sync_file containg @fence. This function acquires and additional
60 * reference of @fence for the newly-created &sync_file, if it succeeds. The
61 * sync_file can be released with fput(sync_file->file). Returns the
62 * sync_file or NULL in case of error.
63 */
64struct sync_file *sync_file_create(struct dma_fence *fence)
65{
66	struct sync_file *sync_file;
67
68	sync_file = sync_file_alloc();
69	if (!sync_file)
70		return NULL;
71
72	sync_file->fence = dma_fence_get(fence);
73
74	return sync_file;
75}
76EXPORT_SYMBOL(sync_file_create);
77
78static struct sync_file *sync_file_fdget(int fd)
79{
80	struct file *file = fget(fd);
81
82	if (!file)
83		return NULL;
84
85	if (file->f_op != &sync_file_fops)
86		goto err;
87
88	return file->private_data;
89
90err:
91	fput(file);
92	return NULL;
93}
94
95/**
96 * sync_file_get_fence - get the fence related to the sync_file fd
97 * @fd:		sync_file fd to get the fence from
98 *
99 * Ensures @fd references a valid sync_file and returns a fence that
100 * represents all fence in the sync_file. On error NULL is returned.
101 */
102struct dma_fence *sync_file_get_fence(int fd)
103{
104	struct sync_file *sync_file;
105	struct dma_fence *fence;
106
107	sync_file = sync_file_fdget(fd);
108	if (!sync_file)
109		return NULL;
110
111	fence = dma_fence_get(sync_file->fence);
112	fput(sync_file->file);
113
114	return fence;
115}
116EXPORT_SYMBOL(sync_file_get_fence);
117
118/**
119 * sync_file_get_name - get the name of the sync_file
120 * @sync_file:		sync_file to get the fence from
121 * @buf:		destination buffer to copy sync_file name into
122 * @len:		available size of destination buffer.
123 *
124 * Each sync_file may have a name assigned either by the user (when merging
125 * sync_files together) or created from the fence it contains. In the latter
126 * case construction of the name is deferred until use, and so requires
127 * sync_file_get_name().
128 *
129 * Returns: a string representing the name.
130 */
131char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
132{
133	if (sync_file->user_name[0]) {
134		strlcpy(buf, sync_file->user_name, len);
135	} else {
136		struct dma_fence *fence = sync_file->fence;
137
138		snprintf(buf, len, "%s-%s%llu-%lld",
139			 fence->ops->get_driver_name(fence),
140			 fence->ops->get_timeline_name(fence),
141			 fence->context,
142			 fence->seqno);
143	}
144
145	return buf;
146}
147
148static int sync_file_set_fence(struct sync_file *sync_file,
149			       struct dma_fence **fences, int num_fences)
150{
151	struct dma_fence_array *array;
152
153	/*
154	 * The reference for the fences in the new sync_file and held
155	 * in add_fence() during the merge procedure, so for num_fences == 1
156	 * we already own a new reference to the fence. For num_fence > 1
157	 * we own the reference of the dma_fence_array creation.
158	 */
159	if (num_fences == 1) {
160		sync_file->fence = fences[0];
161		kfree(fences);
162	} else {
163		array = dma_fence_array_create(num_fences, fences,
164					       dma_fence_context_alloc(1),
165					       1, false);
166		if (!array)
167			return -ENOMEM;
168
169		sync_file->fence = &array->base;
170	}
171
172	return 0;
173}
174
175static struct dma_fence **get_fences(struct sync_file *sync_file,
176				     int *num_fences)
177{
178	if (dma_fence_is_array(sync_file->fence)) {
179		struct dma_fence_array *array = to_dma_fence_array(sync_file->fence);
180
181		*num_fences = array->num_fences;
182		return array->fences;
183	}
184
185	*num_fences = 1;
186	return &sync_file->fence;
187}
188
189static void add_fence(struct dma_fence **fences,
190		      int *i, struct dma_fence *fence)
191{
192	fences[*i] = fence;
193
194	if (!dma_fence_is_signaled(fence)) {
195		dma_fence_get(fence);
196		(*i)++;
197	}
198}
199
200/**
201 * sync_file_merge() - merge two sync_files
202 * @name:	name of new fence
203 * @a:		sync_file a
204 * @b:		sync_file b
205 *
206 * Creates a new sync_file which contains copies of all the fences in both
207 * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
208 * new merged sync_file or NULL in case of error.
209 */
210static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
211					 struct sync_file *b)
212{
213	struct sync_file *sync_file;
214	struct dma_fence **fences = NULL, **nfences, **a_fences, **b_fences;
215	int i = 0, i_a, i_b, num_fences, a_num_fences, b_num_fences;
216
217	sync_file = sync_file_alloc();
218	if (!sync_file)
219		return NULL;
220
221	a_fences = get_fences(a, &a_num_fences);
222	b_fences = get_fences(b, &b_num_fences);
223	if (a_num_fences > INT_MAX - b_num_fences)
224		goto err;
225
226	num_fences = a_num_fences + b_num_fences;
227
228	fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
229	if (!fences)
230		goto err;
231
232	/*
233	 * Assume sync_file a and b are both ordered and have no
234	 * duplicates with the same context.
235	 *
236	 * If a sync_file can only be created with sync_file_merge
237	 * and sync_file_create, this is a reasonable assumption.
238	 */
239	for (i_a = i_b = 0; i_a < a_num_fences && i_b < b_num_fences; ) {
240		struct dma_fence *pt_a = a_fences[i_a];
241		struct dma_fence *pt_b = b_fences[i_b];
242
243		if (pt_a->context < pt_b->context) {
244			add_fence(fences, &i, pt_a);
245
246			i_a++;
247		} else if (pt_a->context > pt_b->context) {
248			add_fence(fences, &i, pt_b);
249
250			i_b++;
251		} else {
252			if (__dma_fence_is_later(pt_a->seqno, pt_b->seqno,
253						 pt_a->ops))
254				add_fence(fences, &i, pt_a);
255			else
256				add_fence(fences, &i, pt_b);
257
258			i_a++;
259			i_b++;
260		}
261	}
262
263	for (; i_a < a_num_fences; i_a++)
264		add_fence(fences, &i, a_fences[i_a]);
265
266	for (; i_b < b_num_fences; i_b++)
267		add_fence(fences, &i, b_fences[i_b]);
268
269	if (i == 0)
270		fences[i++] = dma_fence_get(a_fences[0]);
271
272	if (num_fences > i) {
273		nfences = krealloc(fences, i * sizeof(*fences),
274				  GFP_KERNEL);
275		if (!nfences)
276			goto err;
277
278		fences = nfences;
279	}
280
281	if (sync_file_set_fence(sync_file, fences, i) < 0)
282		goto err;
283
284	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
285	return sync_file;
286
287err:
288	while (i)
289		dma_fence_put(fences[--i]);
290	kfree(fences);
291	fput(sync_file->file);
292	return NULL;
293
294}
295
296static int sync_file_release(struct inode *inode, struct file *file)
297{
298	struct sync_file *sync_file = file->private_data;
299
300	if (test_bit(POLL_ENABLED, &sync_file->flags))
301		dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
302	dma_fence_put(sync_file->fence);
303	kfree(sync_file);
304
305	return 0;
306}
307
308static __poll_t sync_file_poll(struct file *file, poll_table *wait)
309{
310	struct sync_file *sync_file = file->private_data;
311
312	poll_wait(file, &sync_file->wq, wait);
313
314	if (list_empty(&sync_file->cb.node) &&
315	    !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
316		if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
317					   fence_check_cb_func) < 0)
318			wake_up_all(&sync_file->wq);
319	}
320
321	return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
322}
323
324static long sync_file_ioctl_merge(struct sync_file *sync_file,
325				  unsigned long arg)
326{
327	int fd = get_unused_fd_flags(O_CLOEXEC);
328	int err;
329	struct sync_file *fence2, *fence3;
330	struct sync_merge_data data;
331
332	if (fd < 0)
333		return fd;
334
335	if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
336		err = -EFAULT;
337		goto err_put_fd;
338	}
339
340	if (data.flags || data.pad) {
341		err = -EINVAL;
342		goto err_put_fd;
343	}
344
345	fence2 = sync_file_fdget(data.fd2);
346	if (!fence2) {
347		err = -ENOENT;
348		goto err_put_fd;
349	}
350
351	data.name[sizeof(data.name) - 1] = '\0';
352	fence3 = sync_file_merge(data.name, sync_file, fence2);
353	if (!fence3) {
354		err = -ENOMEM;
355		goto err_put_fence2;
356	}
357
358	data.fence = fd;
359	if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
360		err = -EFAULT;
361		goto err_put_fence3;
362	}
363
364	fd_install(fd, fence3->file);
365	fput(fence2->file);
366	return 0;
367
368err_put_fence3:
369	fput(fence3->file);
370
371err_put_fence2:
372	fput(fence2->file);
373
374err_put_fd:
375	put_unused_fd(fd);
376	return err;
377}
378
379static int sync_fill_fence_info(struct dma_fence *fence,
380				 struct sync_fence_info *info)
381{
382	strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
383		sizeof(info->obj_name));
384	strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
385		sizeof(info->driver_name));
386
387	info->status = dma_fence_get_status(fence);
388	while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
389	       !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
390		cpu_relax();
391	info->timestamp_ns =
392		test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?
393		ktime_to_ns(fence->timestamp) :
394		ktime_set(0, 0);
395
396	return info->status;
397}
398
399static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
400				       unsigned long arg)
401{
402	struct sync_file_info info;
403	struct sync_fence_info *fence_info = NULL;
404	struct dma_fence **fences;
405	__u32 size;
406	int num_fences, ret, i;
407
408	if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
409		return -EFAULT;
410
411	if (info.flags || info.pad)
412		return -EINVAL;
413
414	fences = get_fences(sync_file, &num_fences);
415
416	/*
417	 * Passing num_fences = 0 means that userspace doesn't want to
418	 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
419	 * sync_fence_info and return the actual number of fences on
420	 * info->num_fences.
421	 */
422	if (!info.num_fences) {
423		info.status = dma_fence_get_status(sync_file->fence);
424		goto no_fences;
425	} else {
426		info.status = 1;
427	}
428
429	if (info.num_fences < num_fences)
430		return -EINVAL;
431
432	size = num_fences * sizeof(*fence_info);
433	fence_info = kzalloc(size, GFP_KERNEL);
434	if (!fence_info)
435		return -ENOMEM;
436
437	for (i = 0; i < num_fences; i++) {
438		int status = sync_fill_fence_info(fences[i], &fence_info[i]);
439		info.status = info.status <= 0 ? info.status : status;
440	}
441
442	if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
443			 size)) {
444		ret = -EFAULT;
445		goto out;
446	}
447
448no_fences:
449	sync_file_get_name(sync_file, info.name, sizeof(info.name));
450	info.num_fences = num_fences;
451
452	if (copy_to_user((void __user *)arg, &info, sizeof(info)))
453		ret = -EFAULT;
454	else
455		ret = 0;
456
457out:
458	kfree(fence_info);
459
460	return ret;
461}
462
463static long sync_file_ioctl(struct file *file, unsigned int cmd,
464			    unsigned long arg)
465{
466	struct sync_file *sync_file = file->private_data;
467
468	switch (cmd) {
469	case SYNC_IOC_MERGE:
470		return sync_file_ioctl_merge(sync_file, arg);
471
472	case SYNC_IOC_FILE_INFO:
473		return sync_file_ioctl_fence_info(sync_file, arg);
474
475	default:
476		return -ENOTTY;
477	}
478}
479
480static const struct file_operations sync_file_fops = {
481	.release = sync_file_release,
482	.poll = sync_file_poll,
483	.unlocked_ioctl = sync_file_ioctl,
484	.compat_ioctl = compat_ptr_ioctl,
485};
486