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
29static const struct file_operations sync_file_fops;
30
31static struct sync_file *sync_file_alloc(void)
32{
33 struct sync_file *sync_file;
34
35 sync_file = kzalloc(sizeof(*sync_file), 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 init_waitqueue_head(&sync_file->wq);
45
46 INIT_LIST_HEAD(&sync_file->cb.node);
47
48 return sync_file;
49
50err:
51 kfree(sync_file);
52 return NULL;
53}
54
55static void fence_check_cb_func(struct dma_fence *f, struct dma_fence_cb *cb)
56{
57 struct sync_file *sync_file;
58
59 sync_file = container_of(cb, struct sync_file, cb);
60
61 wake_up_all(&sync_file->wq);
62}
63
64/**
65 * sync_file_create() - creates a sync file
66 * @fence: fence to add to the sync_fence
67 *
68 * Creates a sync_file containg @fence. This function acquires and additional
69 * reference of @fence for the newly-created &sync_file, if it succeeds. The
70 * sync_file can be released with fput(sync_file->file). Returns the
71 * sync_file or NULL in case of error.
72 */
73struct sync_file *sync_file_create(struct dma_fence *fence)
74{
75 struct sync_file *sync_file;
76
77 sync_file = sync_file_alloc();
78 if (!sync_file)
79 return NULL;
80
81 sync_file->fence = dma_fence_get(fence);
82
83 return sync_file;
84}
85EXPORT_SYMBOL(sync_file_create);
86
87static struct sync_file *sync_file_fdget(int fd)
88{
89 struct file *file = fget(fd);
90
91 if (!file)
92 return NULL;
93
94 if (file->f_op != &sync_file_fops)
95 goto err;
96
97 return file->private_data;
98
99err:
100 fput(file);
101 return NULL;
102}
103
104/**
105 * sync_file_get_fence - get the fence related to the sync_file fd
106 * @fd: sync_file fd to get the fence from
107 *
108 * Ensures @fd references a valid sync_file and returns a fence that
109 * represents all fence in the sync_file. On error NULL is returned.
110 */
111struct dma_fence *sync_file_get_fence(int fd)
112{
113 struct sync_file *sync_file;
114 struct dma_fence *fence;
115
116 sync_file = sync_file_fdget(fd);
117 if (!sync_file)
118 return NULL;
119
120 fence = dma_fence_get(sync_file->fence);
121 fput(sync_file->file);
122
123 return fence;
124}
125EXPORT_SYMBOL(sync_file_get_fence);
126
127/**
128 * sync_file_get_name - get the name of the sync_file
129 * @sync_file: sync_file to get the fence from
130 * @buf: destination buffer to copy sync_file name into
131 * @len: available size of destination buffer.
132 *
133 * Each sync_file may have a name assigned either by the user (when merging
134 * sync_files together) or created from the fence it contains. In the latter
135 * case construction of the name is deferred until use, and so requires
136 * sync_file_get_name().
137 *
138 * Returns: a string representing the name.
139 */
140char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
141{
142 if (sync_file->user_name[0]) {
143 strlcpy(buf, sync_file->user_name, len);
144 } else {
145 struct dma_fence *fence = sync_file->fence;
146
147 snprintf(buf, len, "%s-%s%llu-%lld",
148 fence->ops->get_driver_name(fence),
149 fence->ops->get_timeline_name(fence),
150 fence->context,
151 fence->seqno);
152 }
153
154 return buf;
155}
156
157static int sync_file_set_fence(struct sync_file *sync_file,
158 struct dma_fence **fences, int num_fences)
159{
160 struct dma_fence_array *array;
161
162 /*
163 * The reference for the fences in the new sync_file and held
164 * in add_fence() during the merge procedure, so for num_fences == 1
165 * we already own a new reference to the fence. For num_fence > 1
166 * we own the reference of the dma_fence_array creation.
167 */
168 if (num_fences == 1) {
169 sync_file->fence = fences[0];
170 kfree(fences);
171 } else {
172 array = dma_fence_array_create(num_fences, fences,
173 dma_fence_context_alloc(1),
174 1, false);
175 if (!array)
176 return -ENOMEM;
177
178 sync_file->fence = &array->base;
179 }
180
181 return 0;
182}
183
184static struct dma_fence **get_fences(struct sync_file *sync_file,
185 int *num_fences)
186{
187 if (dma_fence_is_array(sync_file->fence)) {
188 struct dma_fence_array *array = to_dma_fence_array(sync_file->fence);
189
190 *num_fences = array->num_fences;
191 return array->fences;
192 }
193
194 *num_fences = 1;
195 return &sync_file->fence;
196}
197
198static void add_fence(struct dma_fence **fences,
199 int *i, struct dma_fence *fence)
200{
201 fences[*i] = fence;
202
203 if (!dma_fence_is_signaled(fence)) {
204 dma_fence_get(fence);
205 (*i)++;
206 }
207}
208
209/**
210 * sync_file_merge() - merge two sync_files
211 * @name: name of new fence
212 * @a: sync_file a
213 * @b: sync_file b
214 *
215 * Creates a new sync_file which contains copies of all the fences in both
216 * @a and @b. @a and @b remain valid, independent sync_file. Returns the
217 * new merged sync_file or NULL in case of error.
218 */
219static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
220 struct sync_file *b)
221{
222 struct sync_file *sync_file;
223 struct dma_fence **fences, **nfences, **a_fences, **b_fences;
224 int i, i_a, i_b, num_fences, a_num_fences, b_num_fences;
225
226 sync_file = sync_file_alloc();
227 if (!sync_file)
228 return NULL;
229
230 a_fences = get_fences(a, &a_num_fences);
231 b_fences = get_fences(b, &b_num_fences);
232 if (a_num_fences > INT_MAX - b_num_fences)
233 return NULL;
234
235 num_fences = a_num_fences + b_num_fences;
236
237 fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
238 if (!fences)
239 goto err;
240
241 /*
242 * Assume sync_file a and b are both ordered and have no
243 * duplicates with the same context.
244 *
245 * If a sync_file can only be created with sync_file_merge
246 * and sync_file_create, this is a reasonable assumption.
247 */
248 for (i = i_a = i_b = 0; i_a < a_num_fences && i_b < b_num_fences; ) {
249 struct dma_fence *pt_a = a_fences[i_a];
250 struct dma_fence *pt_b = b_fences[i_b];
251
252 if (pt_a->context < pt_b->context) {
253 add_fence(fences, &i, pt_a);
254
255 i_a++;
256 } else if (pt_a->context > pt_b->context) {
257 add_fence(fences, &i, pt_b);
258
259 i_b++;
260 } else {
261 if (__dma_fence_is_later(pt_a->seqno, pt_b->seqno))
262 add_fence(fences, &i, pt_a);
263 else
264 add_fence(fences, &i, pt_b);
265
266 i_a++;
267 i_b++;
268 }
269 }
270
271 for (; i_a < a_num_fences; i_a++)
272 add_fence(fences, &i, a_fences[i_a]);
273
274 for (; i_b < b_num_fences; i_b++)
275 add_fence(fences, &i, b_fences[i_b]);
276
277 if (i == 0)
278 fences[i++] = dma_fence_get(a_fences[0]);
279
280 if (num_fences > i) {
281 nfences = krealloc(fences, i * sizeof(*fences),
282 GFP_KERNEL);
283 if (!nfences)
284 goto err;
285
286 fences = nfences;
287 }
288
289 if (sync_file_set_fence(sync_file, fences, i) < 0) {
290 kfree(fences);
291 goto err;
292 }
293
294 strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
295 return sync_file;
296
297err:
298 fput(sync_file->file);
299 return NULL;
300
301}
302
303static int sync_file_release(struct inode *inode, struct file *file)
304{
305 struct sync_file *sync_file = file->private_data;
306
307 if (test_bit(POLL_ENABLED, &sync_file->flags))
308 dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
309 dma_fence_put(sync_file->fence);
310 kfree(sync_file);
311
312 return 0;
313}
314
315static __poll_t sync_file_poll(struct file *file, poll_table *wait)
316{
317 struct sync_file *sync_file = file->private_data;
318
319 poll_wait(file, &sync_file->wq, wait);
320
321 if (list_empty(&sync_file->cb.node) &&
322 !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
323 if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
324 fence_check_cb_func) < 0)
325 wake_up_all(&sync_file->wq);
326 }
327
328 return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
329}
330
331static long sync_file_ioctl_merge(struct sync_file *sync_file,
332 unsigned long arg)
333{
334 int fd = get_unused_fd_flags(O_CLOEXEC);
335 int err;
336 struct sync_file *fence2, *fence3;
337 struct sync_merge_data data;
338
339 if (fd < 0)
340 return fd;
341
342 if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
343 err = -EFAULT;
344 goto err_put_fd;
345 }
346
347 if (data.flags || data.pad) {
348 err = -EINVAL;
349 goto err_put_fd;
350 }
351
352 fence2 = sync_file_fdget(data.fd2);
353 if (!fence2) {
354 err = -ENOENT;
355 goto err_put_fd;
356 }
357
358 data.name[sizeof(data.name) - 1] = '\0';
359 fence3 = sync_file_merge(data.name, sync_file, fence2);
360 if (!fence3) {
361 err = -ENOMEM;
362 goto err_put_fence2;
363 }
364
365 data.fence = fd;
366 if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
367 err = -EFAULT;
368 goto err_put_fence3;
369 }
370
371 fd_install(fd, fence3->file);
372 fput(fence2->file);
373 return 0;
374
375err_put_fence3:
376 fput(fence3->file);
377
378err_put_fence2:
379 fput(fence2->file);
380
381err_put_fd:
382 put_unused_fd(fd);
383 return err;
384}
385
386static int sync_fill_fence_info(struct dma_fence *fence,
387 struct sync_fence_info *info)
388{
389 strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
390 sizeof(info->obj_name));
391 strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
392 sizeof(info->driver_name));
393
394 info->status = dma_fence_get_status(fence);
395 while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
396 !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
397 cpu_relax();
398 info->timestamp_ns =
399 test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?
400 ktime_to_ns(fence->timestamp) :
401 ktime_set(0, 0);
402
403 return info->status;
404}
405
406static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
407 unsigned long arg)
408{
409 struct sync_file_info info;
410 struct sync_fence_info *fence_info = NULL;
411 struct dma_fence **fences;
412 __u32 size;
413 int num_fences, ret, i;
414
415 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
416 return -EFAULT;
417
418 if (info.flags || info.pad)
419 return -EINVAL;
420
421 fences = get_fences(sync_file, &num_fences);
422
423 /*
424 * Passing num_fences = 0 means that userspace doesn't want to
425 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
426 * sync_fence_info and return the actual number of fences on
427 * info->num_fences.
428 */
429 if (!info.num_fences) {
430 info.status = dma_fence_is_signaled(sync_file->fence);
431 goto no_fences;
432 } else {
433 info.status = 1;
434 }
435
436 if (info.num_fences < num_fences)
437 return -EINVAL;
438
439 size = num_fences * sizeof(*fence_info);
440 fence_info = kzalloc(size, GFP_KERNEL);
441 if (!fence_info)
442 return -ENOMEM;
443
444 for (i = 0; i < num_fences; i++) {
445 int status = sync_fill_fence_info(fences[i], &fence_info[i]);
446 info.status = info.status <= 0 ? info.status : status;
447 }
448
449 if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
450 size)) {
451 ret = -EFAULT;
452 goto out;
453 }
454
455no_fences:
456 sync_file_get_name(sync_file, info.name, sizeof(info.name));
457 info.num_fences = num_fences;
458
459 if (copy_to_user((void __user *)arg, &info, sizeof(info)))
460 ret = -EFAULT;
461 else
462 ret = 0;
463
464out:
465 kfree(fence_info);
466
467 return ret;
468}
469
470static long sync_file_ioctl(struct file *file, unsigned int cmd,
471 unsigned long arg)
472{
473 struct sync_file *sync_file = file->private_data;
474
475 switch (cmd) {
476 case SYNC_IOC_MERGE:
477 return sync_file_ioctl_merge(sync_file, arg);
478
479 case SYNC_IOC_FILE_INFO:
480 return sync_file_ioctl_fence_info(sync_file, arg);
481
482 default:
483 return -ENOTTY;
484 }
485}
486
487static const struct file_operations sync_file_fops = {
488 .release = sync_file_release,
489 .poll = sync_file_poll,
490 .unlocked_ioctl = sync_file_ioctl,
491 .compat_ioctl = sync_file_ioctl,
492};
493