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
20 static const struct file_operations sync_file_fops;
21
sync_file_alloc(void)22 static 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
41 err:
42 kfree(sync_file);
43 return NULL;
44 }
45
fence_check_cb_func(struct dma_fence * f,struct dma_fence_cb * cb)46 static 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 */
sync_file_create(struct dma_fence * fence)64 struct 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 }
76 EXPORT_SYMBOL(sync_file_create);
77
sync_file_fdget(int fd)78 static 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
90 err:
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 */
sync_file_get_fence(int fd)102 struct 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 }
116 EXPORT_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 */
sync_file_get_name(struct sync_file * sync_file,char * buf,int len)131 char *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
sync_file_set_fence(struct sync_file * sync_file,struct dma_fence ** fences,int num_fences)148 static 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
get_fences(struct sync_file * sync_file,int * num_fences)175 static 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
add_fence(struct dma_fence ** fences,int * i,struct dma_fence * fence)189 static 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 */
sync_file_merge(const char * name,struct sync_file * a,struct sync_file * b)210 static 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, **nfences, **a_fences, **b_fences;
215 int i, 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 = 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 kfree(fences);
283 goto err;
284 }
285
286 strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
287 return sync_file;
288
289 err:
290 fput(sync_file->file);
291 return NULL;
292
293 }
294
sync_file_release(struct inode * inode,struct file * file)295 static int sync_file_release(struct inode *inode, struct file *file)
296 {
297 struct sync_file *sync_file = file->private_data;
298
299 if (test_bit(POLL_ENABLED, &sync_file->flags))
300 dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
301 dma_fence_put(sync_file->fence);
302 kfree(sync_file);
303
304 return 0;
305 }
306
sync_file_poll(struct file * file,poll_table * wait)307 static __poll_t sync_file_poll(struct file *file, poll_table *wait)
308 {
309 struct sync_file *sync_file = file->private_data;
310
311 poll_wait(file, &sync_file->wq, wait);
312
313 if (list_empty(&sync_file->cb.node) &&
314 !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
315 if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
316 fence_check_cb_func) < 0)
317 wake_up_all(&sync_file->wq);
318 }
319
320 return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
321 }
322
sync_file_ioctl_merge(struct sync_file * sync_file,unsigned long arg)323 static long sync_file_ioctl_merge(struct sync_file *sync_file,
324 unsigned long arg)
325 {
326 int fd = get_unused_fd_flags(O_CLOEXEC);
327 int err;
328 struct sync_file *fence2, *fence3;
329 struct sync_merge_data data;
330
331 if (fd < 0)
332 return fd;
333
334 if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
335 err = -EFAULT;
336 goto err_put_fd;
337 }
338
339 if (data.flags || data.pad) {
340 err = -EINVAL;
341 goto err_put_fd;
342 }
343
344 fence2 = sync_file_fdget(data.fd2);
345 if (!fence2) {
346 err = -ENOENT;
347 goto err_put_fd;
348 }
349
350 data.name[sizeof(data.name) - 1] = '\0';
351 fence3 = sync_file_merge(data.name, sync_file, fence2);
352 if (!fence3) {
353 err = -ENOMEM;
354 goto err_put_fence2;
355 }
356
357 data.fence = fd;
358 if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
359 err = -EFAULT;
360 goto err_put_fence3;
361 }
362
363 fd_install(fd, fence3->file);
364 fput(fence2->file);
365 return 0;
366
367 err_put_fence3:
368 fput(fence3->file);
369
370 err_put_fence2:
371 fput(fence2->file);
372
373 err_put_fd:
374 put_unused_fd(fd);
375 return err;
376 }
377
sync_fill_fence_info(struct dma_fence * fence,struct sync_fence_info * info)378 static int sync_fill_fence_info(struct dma_fence *fence,
379 struct sync_fence_info *info)
380 {
381 strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
382 sizeof(info->obj_name));
383 strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
384 sizeof(info->driver_name));
385
386 info->status = dma_fence_get_status(fence);
387 while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
388 !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
389 cpu_relax();
390 info->timestamp_ns =
391 test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?
392 ktime_to_ns(fence->timestamp) :
393 ktime_set(0, 0);
394
395 return info->status;
396 }
397
sync_file_ioctl_fence_info(struct sync_file * sync_file,unsigned long arg)398 static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
399 unsigned long arg)
400 {
401 struct sync_file_info info;
402 struct sync_fence_info *fence_info = NULL;
403 struct dma_fence **fences;
404 __u32 size;
405 int num_fences, ret, i;
406
407 if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
408 return -EFAULT;
409
410 if (info.flags || info.pad)
411 return -EINVAL;
412
413 fences = get_fences(sync_file, &num_fences);
414
415 /*
416 * Passing num_fences = 0 means that userspace doesn't want to
417 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
418 * sync_fence_info and return the actual number of fences on
419 * info->num_fences.
420 */
421 if (!info.num_fences) {
422 info.status = dma_fence_get_status(sync_file->fence);
423 goto no_fences;
424 } else {
425 info.status = 1;
426 }
427
428 if (info.num_fences < num_fences)
429 return -EINVAL;
430
431 size = num_fences * sizeof(*fence_info);
432 fence_info = kzalloc(size, GFP_KERNEL);
433 if (!fence_info)
434 return -ENOMEM;
435
436 for (i = 0; i < num_fences; i++) {
437 int status = sync_fill_fence_info(fences[i], &fence_info[i]);
438 info.status = info.status <= 0 ? info.status : status;
439 }
440
441 if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
442 size)) {
443 ret = -EFAULT;
444 goto out;
445 }
446
447 no_fences:
448 sync_file_get_name(sync_file, info.name, sizeof(info.name));
449 info.num_fences = num_fences;
450
451 if (copy_to_user((void __user *)arg, &info, sizeof(info)))
452 ret = -EFAULT;
453 else
454 ret = 0;
455
456 out:
457 kfree(fence_info);
458
459 return ret;
460 }
461
sync_file_ioctl(struct file * file,unsigned int cmd,unsigned long arg)462 static long sync_file_ioctl(struct file *file, unsigned int cmd,
463 unsigned long arg)
464 {
465 struct sync_file *sync_file = file->private_data;
466
467 switch (cmd) {
468 case SYNC_IOC_MERGE:
469 return sync_file_ioctl_merge(sync_file, arg);
470
471 case SYNC_IOC_FILE_INFO:
472 return sync_file_ioctl_fence_info(sync_file, arg);
473
474 default:
475 return -ENOTTY;
476 }
477 }
478
479 static const struct file_operations sync_file_fops = {
480 .release = sync_file_release,
481 .poll = sync_file_poll,
482 .unlocked_ioctl = sync_file_ioctl,
483 .compat_ioctl = sync_file_ioctl,
484 };
485