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
sync_file_alloc(void)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
fence_check_cb_func(struct dma_fence * f,struct dma_fence_cb * cb)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 */
sync_file_create(struct dma_fence * fence)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
sync_file_fdget(int fd)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 */
sync_file_get_fence(int fd)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 */
sync_file_get_name(struct sync_file * sync_file,char * buf,int len)132 char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
133 {
134 if (sync_file->user_name[0]) {
135 strlcpy(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
sync_file_set_fence(struct sync_file * sync_file,struct dma_fence ** fences,int num_fences)149 static int sync_file_set_fence(struct sync_file *sync_file,
150 struct dma_fence **fences, int num_fences)
151 {
152 struct dma_fence_array *array;
153
154 /*
155 * The reference for the fences in the new sync_file and held
156 * in add_fence() during the merge procedure, so for num_fences == 1
157 * we already own a new reference to the fence. For num_fence > 1
158 * we own the reference of the dma_fence_array creation.
159 */
160
161 if (num_fences == 0) {
162 sync_file->fence = dma_fence_get_stub();
163 kfree(fences);
164
165 } else if (num_fences == 1) {
166 sync_file->fence = fences[0];
167 kfree(fences);
168
169 } else {
170 array = dma_fence_array_create(num_fences, fences,
171 dma_fence_context_alloc(1),
172 1, false);
173 if (!array)
174 return -ENOMEM;
175
176 sync_file->fence = &array->base;
177 }
178
179 return 0;
180 }
181
add_fence(struct dma_fence ** fences,int * i,struct dma_fence * fence)182 static void add_fence(struct dma_fence **fences,
183 int *i, struct dma_fence *fence)
184 {
185 fences[*i] = fence;
186
187 if (!dma_fence_is_signaled(fence)) {
188 dma_fence_get(fence);
189 (*i)++;
190 }
191 }
192
193 /**
194 * sync_file_merge() - merge two sync_files
195 * @name: name of new fence
196 * @a: sync_file a
197 * @b: sync_file b
198 *
199 * Creates a new sync_file which contains copies of all the fences in both
200 * @a and @b. @a and @b remain valid, independent sync_file. Returns the
201 * new merged sync_file or NULL in case of error.
202 */
sync_file_merge(const char * name,struct sync_file * a,struct sync_file * b)203 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
204 struct sync_file *b)
205 {
206 struct dma_fence *a_fence, *b_fence, **fences;
207 struct dma_fence_unwrap a_iter, b_iter;
208 unsigned int index, num_fences;
209 struct sync_file *sync_file;
210
211 sync_file = sync_file_alloc();
212 if (!sync_file)
213 return NULL;
214
215 num_fences = 0;
216 dma_fence_unwrap_for_each(a_fence, &a_iter, a->fence)
217 ++num_fences;
218 dma_fence_unwrap_for_each(b_fence, &b_iter, b->fence)
219 ++num_fences;
220
221 if (num_fences > INT_MAX)
222 goto err_free_sync_file;
223
224 fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
225 if (!fences)
226 goto err_free_sync_file;
227
228 /*
229 * We can't guarantee that fences in both a and b are ordered, but it is
230 * still quite likely.
231 *
232 * So attempt to order the fences as we pass over them and merge fences
233 * with the same context.
234 */
235
236 index = 0;
237 for (a_fence = dma_fence_unwrap_first(a->fence, &a_iter),
238 b_fence = dma_fence_unwrap_first(b->fence, &b_iter);
239 a_fence || b_fence; ) {
240
241 if (!b_fence) {
242 add_fence(fences, &index, a_fence);
243 a_fence = dma_fence_unwrap_next(&a_iter);
244
245 } else if (!a_fence) {
246 add_fence(fences, &index, b_fence);
247 b_fence = dma_fence_unwrap_next(&b_iter);
248
249 } else if (a_fence->context < b_fence->context) {
250 add_fence(fences, &index, a_fence);
251 a_fence = dma_fence_unwrap_next(&a_iter);
252
253 } else if (b_fence->context < a_fence->context) {
254 add_fence(fences, &index, b_fence);
255 b_fence = dma_fence_unwrap_next(&b_iter);
256
257 } else if (__dma_fence_is_later(a_fence->seqno, b_fence->seqno,
258 a_fence->ops)) {
259 add_fence(fences, &index, a_fence);
260 a_fence = dma_fence_unwrap_next(&a_iter);
261 b_fence = dma_fence_unwrap_next(&b_iter);
262
263 } else {
264 add_fence(fences, &index, b_fence);
265 a_fence = dma_fence_unwrap_next(&a_iter);
266 b_fence = dma_fence_unwrap_next(&b_iter);
267 }
268 }
269
270 if (sync_file_set_fence(sync_file, fences, index) < 0)
271 goto err_put_fences;
272
273 strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
274 return sync_file;
275
276 err_put_fences:
277 while (index)
278 dma_fence_put(fences[--index]);
279 kfree(fences);
280
281 err_free_sync_file:
282 fput(sync_file->file);
283 return NULL;
284 }
285
sync_file_release(struct inode * inode,struct file * file)286 static int sync_file_release(struct inode *inode, struct file *file)
287 {
288 struct sync_file *sync_file = file->private_data;
289
290 if (test_bit(POLL_ENABLED, &sync_file->flags))
291 dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
292 dma_fence_put(sync_file->fence);
293 kfree(sync_file);
294
295 return 0;
296 }
297
sync_file_poll(struct file * file,poll_table * wait)298 static __poll_t sync_file_poll(struct file *file, poll_table *wait)
299 {
300 struct sync_file *sync_file = file->private_data;
301
302 poll_wait(file, &sync_file->wq, wait);
303
304 if (list_empty(&sync_file->cb.node) &&
305 !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
306 if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
307 fence_check_cb_func) < 0)
308 wake_up_all(&sync_file->wq);
309 }
310
311 return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
312 }
313
sync_file_ioctl_merge(struct sync_file * sync_file,unsigned long arg)314 static long sync_file_ioctl_merge(struct sync_file *sync_file,
315 unsigned long arg)
316 {
317 int fd = get_unused_fd_flags(O_CLOEXEC);
318 int err;
319 struct sync_file *fence2, *fence3;
320 struct sync_merge_data data;
321
322 if (fd < 0)
323 return fd;
324
325 if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
326 err = -EFAULT;
327 goto err_put_fd;
328 }
329
330 if (data.flags || data.pad) {
331 err = -EINVAL;
332 goto err_put_fd;
333 }
334
335 fence2 = sync_file_fdget(data.fd2);
336 if (!fence2) {
337 err = -ENOENT;
338 goto err_put_fd;
339 }
340
341 data.name[sizeof(data.name) - 1] = '\0';
342 fence3 = sync_file_merge(data.name, sync_file, fence2);
343 if (!fence3) {
344 err = -ENOMEM;
345 goto err_put_fence2;
346 }
347
348 data.fence = fd;
349 if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
350 err = -EFAULT;
351 goto err_put_fence3;
352 }
353
354 fd_install(fd, fence3->file);
355 fput(fence2->file);
356 return 0;
357
358 err_put_fence3:
359 fput(fence3->file);
360
361 err_put_fence2:
362 fput(fence2->file);
363
364 err_put_fd:
365 put_unused_fd(fd);
366 return err;
367 }
368
sync_fill_fence_info(struct dma_fence * fence,struct sync_fence_info * info)369 static int sync_fill_fence_info(struct dma_fence *fence,
370 struct sync_fence_info *info)
371 {
372 strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
373 sizeof(info->obj_name));
374 strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
375 sizeof(info->driver_name));
376
377 info->status = dma_fence_get_status(fence);
378 while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
379 !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
380 cpu_relax();
381 info->timestamp_ns =
382 test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?
383 ktime_to_ns(fence->timestamp) :
384 ktime_set(0, 0);
385
386 return info->status;
387 }
388
sync_file_ioctl_fence_info(struct sync_file * sync_file,unsigned long arg)389 static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
390 unsigned long arg)
391 {
392 struct sync_fence_info *fence_info = NULL;
393 struct dma_fence_unwrap iter;
394 struct sync_file_info info;
395 unsigned int num_fences;
396 struct dma_fence *fence;
397 int ret;
398 __u32 size;
399
400 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
401 return -EFAULT;
402
403 if (info.flags || info.pad)
404 return -EINVAL;
405
406 num_fences = 0;
407 dma_fence_unwrap_for_each(fence, &iter, sync_file->fence)
408 ++num_fences;
409
410 /*
411 * Passing num_fences = 0 means that userspace doesn't want to
412 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
413 * sync_fence_info and return the actual number of fences on
414 * info->num_fences.
415 */
416 if (!info.num_fences) {
417 info.status = dma_fence_get_status(sync_file->fence);
418 goto no_fences;
419 } else {
420 info.status = 1;
421 }
422
423 if (info.num_fences < num_fences)
424 return -EINVAL;
425
426 size = num_fences * sizeof(*fence_info);
427 fence_info = kzalloc(size, GFP_KERNEL);
428 if (!fence_info)
429 return -ENOMEM;
430
431 num_fences = 0;
432 dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) {
433 int status;
434
435 status = sync_fill_fence_info(fence, &fence_info[num_fences++]);
436 info.status = info.status <= 0 ? info.status : status;
437 }
438
439 if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
440 size)) {
441 ret = -EFAULT;
442 goto out;
443 }
444
445 no_fences:
446 sync_file_get_name(sync_file, info.name, sizeof(info.name));
447 info.num_fences = num_fences;
448
449 if (copy_to_user((void __user *)arg, &info, sizeof(info)))
450 ret = -EFAULT;
451 else
452 ret = 0;
453
454 out:
455 kfree(fence_info);
456
457 return ret;
458 }
459
sync_file_ioctl(struct file * file,unsigned int cmd,unsigned long arg)460 static long sync_file_ioctl(struct file *file, unsigned int cmd,
461 unsigned long arg)
462 {
463 struct sync_file *sync_file = file->private_data;
464
465 switch (cmd) {
466 case SYNC_IOC_MERGE:
467 return sync_file_ioctl_merge(sync_file, arg);
468
469 case SYNC_IOC_FILE_INFO:
470 return sync_file_ioctl_fence_info(sync_file, arg);
471
472 default:
473 return -ENOTTY;
474 }
475 }
476
477 static const struct file_operations sync_file_fops = {
478 .release = sync_file_release,
479 .poll = sync_file_poll,
480 .unlocked_ioctl = sync_file_ioctl,
481 .compat_ioctl = compat_ptr_ioctl,
482 };
483