xref: /linux/drivers/dma-buf/sync_file.c (revision 2bc46b3ad3c15165f91459b07ff8682478683194)
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 
29 static const struct file_operations sync_file_fops;
30 
31 static struct sync_file *sync_file_alloc(int size)
32 {
33 	struct sync_file *sync_file;
34 
35 	sync_file = kzalloc(size, 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 	kref_init(&sync_file->kref);
45 
46 	init_waitqueue_head(&sync_file->wq);
47 
48 	return sync_file;
49 
50 err:
51 	kfree(sync_file);
52 	return NULL;
53 }
54 
55 static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
56 {
57 	struct sync_file_cb *check;
58 	struct sync_file *sync_file;
59 
60 	check = container_of(cb, struct sync_file_cb, cb);
61 	sync_file = check->sync_file;
62 
63 	if (atomic_dec_and_test(&sync_file->status))
64 		wake_up_all(&sync_file->wq);
65 }
66 
67 /**
68  * sync_file_create() - creates a sync file
69  * @fence:	fence to add to the sync_fence
70  *
71  * Creates a sync_file containg @fence. Once this is called, the sync_file
72  * takes ownership of @fence. The sync_file can be released with
73  * fput(sync_file->file). Returns the sync_file or NULL in case of error.
74  */
75 struct sync_file *sync_file_create(struct fence *fence)
76 {
77 	struct sync_file *sync_file;
78 
79 	sync_file = sync_file_alloc(offsetof(struct sync_file, cbs[1]));
80 	if (!sync_file)
81 		return NULL;
82 
83 	sync_file->num_fences = 1;
84 	atomic_set(&sync_file->status, 1);
85 	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%d-%d",
86 		 fence->ops->get_driver_name(fence),
87 		 fence->ops->get_timeline_name(fence), fence->context,
88 		 fence->seqno);
89 
90 	sync_file->cbs[0].fence = fence;
91 	sync_file->cbs[0].sync_file = sync_file;
92 	if (fence_add_callback(fence, &sync_file->cbs[0].cb,
93 			       fence_check_cb_func))
94 		atomic_dec(&sync_file->status);
95 
96 	return sync_file;
97 }
98 EXPORT_SYMBOL(sync_file_create);
99 
100 /**
101  * sync_file_fdget() - get a sync_file from an fd
102  * @fd:		fd referencing a fence
103  *
104  * Ensures @fd references a valid sync_file, increments the refcount of the
105  * backing file. Returns the sync_file or NULL in case of error.
106  */
107 static struct sync_file *sync_file_fdget(int fd)
108 {
109 	struct file *file = fget(fd);
110 
111 	if (!file)
112 		return NULL;
113 
114 	if (file->f_op != &sync_file_fops)
115 		goto err;
116 
117 	return file->private_data;
118 
119 err:
120 	fput(file);
121 	return NULL;
122 }
123 
124 static void sync_file_add_pt(struct sync_file *sync_file, int *i,
125 			     struct fence *fence)
126 {
127 	sync_file->cbs[*i].fence = fence;
128 	sync_file->cbs[*i].sync_file = sync_file;
129 
130 	if (!fence_add_callback(fence, &sync_file->cbs[*i].cb,
131 				fence_check_cb_func)) {
132 		fence_get(fence);
133 		(*i)++;
134 	}
135 }
136 
137 /**
138  * sync_file_merge() - merge two sync_files
139  * @name:	name of new fence
140  * @a:		sync_file a
141  * @b:		sync_file b
142  *
143  * Creates a new sync_file which contains copies of all the fences in both
144  * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
145  * new merged sync_file or NULL in case of error.
146  */
147 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
148 					 struct sync_file *b)
149 {
150 	int num_fences = a->num_fences + b->num_fences;
151 	struct sync_file *sync_file;
152 	int i, i_a, i_b;
153 	unsigned long size = offsetof(struct sync_file, cbs[num_fences]);
154 
155 	sync_file = sync_file_alloc(size);
156 	if (!sync_file)
157 		return NULL;
158 
159 	atomic_set(&sync_file->status, num_fences);
160 
161 	/*
162 	 * Assume sync_file a and b are both ordered and have no
163 	 * duplicates with the same context.
164 	 *
165 	 * If a sync_file can only be created with sync_file_merge
166 	 * and sync_file_create, this is a reasonable assumption.
167 	 */
168 	for (i = i_a = i_b = 0; i_a < a->num_fences && i_b < b->num_fences; ) {
169 		struct fence *pt_a = a->cbs[i_a].fence;
170 		struct fence *pt_b = b->cbs[i_b].fence;
171 
172 		if (pt_a->context < pt_b->context) {
173 			sync_file_add_pt(sync_file, &i, pt_a);
174 
175 			i_a++;
176 		} else if (pt_a->context > pt_b->context) {
177 			sync_file_add_pt(sync_file, &i, pt_b);
178 
179 			i_b++;
180 		} else {
181 			if (pt_a->seqno - pt_b->seqno <= INT_MAX)
182 				sync_file_add_pt(sync_file, &i, pt_a);
183 			else
184 				sync_file_add_pt(sync_file, &i, pt_b);
185 
186 			i_a++;
187 			i_b++;
188 		}
189 	}
190 
191 	for (; i_a < a->num_fences; i_a++)
192 		sync_file_add_pt(sync_file, &i, a->cbs[i_a].fence);
193 
194 	for (; i_b < b->num_fences; i_b++)
195 		sync_file_add_pt(sync_file, &i, b->cbs[i_b].fence);
196 
197 	if (num_fences > i)
198 		atomic_sub(num_fences - i, &sync_file->status);
199 	sync_file->num_fences = i;
200 
201 	strlcpy(sync_file->name, name, sizeof(sync_file->name));
202 	return sync_file;
203 }
204 
205 static void sync_file_free(struct kref *kref)
206 {
207 	struct sync_file *sync_file = container_of(kref, struct sync_file,
208 						     kref);
209 	int i;
210 
211 	for (i = 0; i < sync_file->num_fences; ++i) {
212 		fence_remove_callback(sync_file->cbs[i].fence,
213 				      &sync_file->cbs[i].cb);
214 		fence_put(sync_file->cbs[i].fence);
215 	}
216 
217 	kfree(sync_file);
218 }
219 
220 static int sync_file_release(struct inode *inode, struct file *file)
221 {
222 	struct sync_file *sync_file = file->private_data;
223 
224 	kref_put(&sync_file->kref, sync_file_free);
225 	return 0;
226 }
227 
228 static unsigned int sync_file_poll(struct file *file, poll_table *wait)
229 {
230 	struct sync_file *sync_file = file->private_data;
231 	int status;
232 
233 	poll_wait(file, &sync_file->wq, wait);
234 
235 	status = atomic_read(&sync_file->status);
236 
237 	if (!status)
238 		return POLLIN;
239 	if (status < 0)
240 		return POLLERR;
241 	return 0;
242 }
243 
244 static long sync_file_ioctl_merge(struct sync_file *sync_file,
245 				  unsigned long arg)
246 {
247 	int fd = get_unused_fd_flags(O_CLOEXEC);
248 	int err;
249 	struct sync_file *fence2, *fence3;
250 	struct sync_merge_data data;
251 
252 	if (fd < 0)
253 		return fd;
254 
255 	if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
256 		err = -EFAULT;
257 		goto err_put_fd;
258 	}
259 
260 	if (data.flags || data.pad) {
261 		err = -EINVAL;
262 		goto err_put_fd;
263 	}
264 
265 	fence2 = sync_file_fdget(data.fd2);
266 	if (!fence2) {
267 		err = -ENOENT;
268 		goto err_put_fd;
269 	}
270 
271 	data.name[sizeof(data.name) - 1] = '\0';
272 	fence3 = sync_file_merge(data.name, sync_file, fence2);
273 	if (!fence3) {
274 		err = -ENOMEM;
275 		goto err_put_fence2;
276 	}
277 
278 	data.fence = fd;
279 	if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
280 		err = -EFAULT;
281 		goto err_put_fence3;
282 	}
283 
284 	fd_install(fd, fence3->file);
285 	fput(fence2->file);
286 	return 0;
287 
288 err_put_fence3:
289 	fput(fence3->file);
290 
291 err_put_fence2:
292 	fput(fence2->file);
293 
294 err_put_fd:
295 	put_unused_fd(fd);
296 	return err;
297 }
298 
299 static void sync_fill_fence_info(struct fence *fence,
300 				 struct sync_fence_info *info)
301 {
302 	strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
303 		sizeof(info->obj_name));
304 	strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
305 		sizeof(info->driver_name));
306 	if (fence_is_signaled(fence))
307 		info->status = fence->status >= 0 ? 1 : fence->status;
308 	else
309 		info->status = 0;
310 	info->timestamp_ns = ktime_to_ns(fence->timestamp);
311 }
312 
313 static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
314 				       unsigned long arg)
315 {
316 	struct sync_file_info info;
317 	struct sync_fence_info *fence_info = NULL;
318 	__u32 size;
319 	int ret, i;
320 
321 	if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
322 		return -EFAULT;
323 
324 	if (info.flags || info.pad)
325 		return -EINVAL;
326 
327 	/*
328 	 * Passing num_fences = 0 means that userspace doesn't want to
329 	 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
330 	 * sync_fence_info and return the actual number of fences on
331 	 * info->num_fences.
332 	 */
333 	if (!info.num_fences)
334 		goto no_fences;
335 
336 	if (info.num_fences < sync_file->num_fences)
337 		return -EINVAL;
338 
339 	size = sync_file->num_fences * sizeof(*fence_info);
340 	fence_info = kzalloc(size, GFP_KERNEL);
341 	if (!fence_info)
342 		return -ENOMEM;
343 
344 	for (i = 0; i < sync_file->num_fences; ++i)
345 		sync_fill_fence_info(sync_file->cbs[i].fence, &fence_info[i]);
346 
347 	if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
348 			 size)) {
349 		ret = -EFAULT;
350 		goto out;
351 	}
352 
353 no_fences:
354 	strlcpy(info.name, sync_file->name, sizeof(info.name));
355 	info.status = atomic_read(&sync_file->status);
356 	if (info.status >= 0)
357 		info.status = !info.status;
358 
359 	info.num_fences = sync_file->num_fences;
360 
361 	if (copy_to_user((void __user *)arg, &info, sizeof(info)))
362 		ret = -EFAULT;
363 	else
364 		ret = 0;
365 
366 out:
367 	kfree(fence_info);
368 
369 	return ret;
370 }
371 
372 static long sync_file_ioctl(struct file *file, unsigned int cmd,
373 			    unsigned long arg)
374 {
375 	struct sync_file *sync_file = file->private_data;
376 
377 	switch (cmd) {
378 	case SYNC_IOC_MERGE:
379 		return sync_file_ioctl_merge(sync_file, arg);
380 
381 	case SYNC_IOC_FILE_INFO:
382 		return sync_file_ioctl_fence_info(sync_file, arg);
383 
384 	default:
385 		return -ENOTTY;
386 	}
387 }
388 
389 static const struct file_operations sync_file_fops = {
390 	.release = sync_file_release,
391 	.poll = sync_file_poll,
392 	.unlocked_ioctl = sync_file_ioctl,
393 	.compat_ioctl = sync_file_ioctl,
394 };
395 
396