summaryrefslogtreecommitdiff
path: root/drivers/dma-buf/sw_sync.c
blob: 3d78ca89a605396af847367d8f6aafc4a3b36456 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
/*
 * Sync File validation framework
 *
 * Copyright (C) 2012 Google, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/file.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/sync_file.h>

#include "sync_debug.h"

#define CREATE_TRACE_POINTS
#include "sync_trace.h"

/*
 * SW SYNC validation framework
 *
 * A sync object driver that uses a 32bit counter to coordinate
 * synchronization.  Useful when there is no hardware primitive backing
 * the synchronization.
 *
 * To start the framework just open:
 *
 * <debugfs>/sync/sw_sync
 *
 * That will create a sync timeline, all fences created under this timeline
 * file descriptor will belong to the this timeline.
 *
 * The 'sw_sync' file can be opened many times as to create different
 * timelines.
 *
 * Fences can be created with SW_SYNC_IOC_CREATE_FENCE ioctl with struct
 * sw_sync_create_fence_data as parameter.
 *
 * To increment the timeline counter, SW_SYNC_IOC_INC ioctl should be used
 * with the increment as u32. This will update the last signaled value
 * from the timeline and signal any fence that has a seqno smaller or equal
 * to it.
 *
 * struct sw_sync_create_fence_data
 * @value:	the seqno to initialise the fence with
 * @name:	the name of the new sync point
 * @fence:	return the fd of the new sync_file with the created fence
 */
struct sw_sync_create_fence_data {
	__u32	value;
	char	name[32];
	__s32	fence; /* fd of new fence */
};

#define SW_SYNC_IOC_MAGIC	'W'

#define SW_SYNC_IOC_CREATE_FENCE	_IOWR(SW_SYNC_IOC_MAGIC, 0,\
		struct sw_sync_create_fence_data)

#define SW_SYNC_IOC_INC			_IOW(SW_SYNC_IOC_MAGIC, 1, __u32)

static const struct dma_fence_ops timeline_fence_ops;

static inline struct sync_pt *dma_fence_to_sync_pt(struct dma_fence *fence)
{
	if (fence->ops != &timeline_fence_ops)
		return NULL;
	return container_of(fence, struct sync_pt, base);
}

/**
 * sync_timeline_create() - creates a sync object
 * @name:	sync_timeline name
 *
 * Creates a new sync_timeline. Returns the sync_timeline object or NULL in
 * case of error.
 */
static struct sync_timeline *sync_timeline_create(const char *name)
{
	struct sync_timeline *obj;

	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
	if (!obj)
		return NULL;

	kref_init(&obj->kref);
	obj->context = dma_fence_context_alloc(1);
	strlcpy(obj->name, name, sizeof(obj->name));

	obj->pt_tree = RB_ROOT;
	INIT_LIST_HEAD(&obj->pt_list);
	spin_lock_init(&obj->lock);

	sync_timeline_debug_add(obj);

	return obj;
}

static void sync_timeline_free(struct kref *kref)
{
	struct sync_timeline *obj =
		container_of(kref, struct sync_timeline, kref);

	sync_timeline_debug_remove(obj);

	kfree(obj);
}

static void sync_timeline_get(struct sync_timeline *obj)
{
	kref_get(&obj->kref);
}

static void sync_timeline_put(struct sync_timeline *obj)
{
	kref_put(&obj->kref, sync_timeline_free);
}

static const char *timeline_fence_get_driver_name(struct dma_fence *fence)
{
	return "sw_sync";
}

static const char *timeline_fence_get_timeline_name(struct dma_fence *fence)
{
	struct sync_timeline *parent = dma_fence_parent(fence);

	return parent->name;
}

static void timeline_fence_release(struct dma_fence *fence)
{
	struct sync_pt *pt = dma_fence_to_sync_pt(fence);
	struct sync_timeline *parent = dma_fence_parent(fence);

	if (!list_empty(&pt->link)) {
		unsigned long flags;

		spin_lock_irqsave(fence->lock, flags);
		if (!list_empty(&pt->link)) {
			list_del(&pt->link);
			rb_erase(&pt->node, &parent->pt_tree);
		}
		spin_unlock_irqrestore(fence->lock, flags);
	}

	sync_timeline_put(parent);
	dma_fence_free(fence);
}

static bool timeline_fence_signaled(struct dma_fence *fence)
{
	struct sync_timeline *parent = dma_fence_parent(fence);

	return !__dma_fence_is_later(fence->seqno, parent->value);
}

static bool timeline_fence_enable_signaling(struct dma_fence *fence)
{
	return true;
}

static void timeline_fence_value_str(struct dma_fence *fence,
				    char *str, int size)
{
	snprintf(str, size, "%d", fence->seqno);
}

static void timeline_fence_timeline_value_str(struct dma_fence *fence,
					     char *str, int size)
{
	struct sync_timeline *parent = dma_fence_parent(fence);

	snprintf(str, size, "%d", parent->value);
}

static const struct dma_fence_ops timeline_fence_ops = {
	.get_driver_name = timeline_fence_get_driver_name,
	.get_timeline_name = timeline_fence_get_timeline_name,
	.enable_signaling = timeline_fence_enable_signaling,
	.signaled = timeline_fence_signaled,
	.wait = dma_fence_default_wait,
	.release = timeline_fence_release,
	.fence_value_str = timeline_fence_value_str,
	.timeline_value_str = timeline_fence_timeline_value_str,
};

/**
 * sync_timeline_signal() - signal a status change on a sync_timeline
 * @obj:	sync_timeline to signal
 * @inc:	num to increment on timeline->value
 *
 * A sync implementation should call this any time one of it's fences
 * has signaled or has an error condition.
 */
static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc)
{
	struct sync_pt *pt, *next;

	trace_sync_timeline(obj);

	spin_lock_irq(&obj->lock);

	obj->value += inc;

	list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
		if (!timeline_fence_signaled(&pt->base))
			break;

		list_del_init(&pt->link);
		rb_erase(&pt->node, &obj->pt_tree);

		/*
		 * A signal callback may release the last reference to this
		 * fence, causing it to be freed. That operation has to be
		 * last to avoid a use after free inside this loop, and must
		 * be after we remove the fence from the timeline in order to
		 * prevent deadlocking on timeline->lock inside
		 * timeline_fence_release().
		 */
		dma_fence_signal_locked(&pt->base);
	}

	spin_unlock_irq(&obj->lock);
}

/**
 * sync_pt_create() - creates a sync pt
 * @obj:	parent sync_timeline
 * @value:	value of the fence
 *
 * Creates a new sync_pt (fence) as a child of @parent.  @size bytes will be
 * allocated allowing for implementation specific data to be kept after
 * the generic sync_timeline struct. Returns the sync_pt object or
 * NULL in case of error.
 */
static struct sync_pt *sync_pt_create(struct sync_timeline *obj,
				      unsigned int value)
{
	struct sync_pt *pt;

	pt = kzalloc(sizeof(*pt), GFP_KERNEL);
	if (!pt)
		return NULL;

	sync_timeline_get(obj);
	dma_fence_init(&pt->base, &timeline_fence_ops, &obj->lock,
		       obj->context, value);
	INIT_LIST_HEAD(&pt->link);

	spin_lock_irq(&obj->lock);
	if (!dma_fence_is_signaled_locked(&pt->base)) {
		struct rb_node **p = &obj->pt_tree.rb_node;
		struct rb_node *parent = NULL;

		while (*p) {
			struct sync_pt *other;
			int cmp;

			parent = *p;
			other = rb_entry(parent, typeof(*pt), node);
			cmp = value - other->base.seqno;
			if (cmp > 0) {
				p = &parent->rb_right;
			} else if (cmp < 0) {
				p = &parent->rb_left;
			} else {
				if (dma_fence_get_rcu(&other->base)) {
					dma_fence_put(&pt->base);
					pt = other;
					goto unlock;
				}
				p = &parent->rb_left;
			}
		}
		rb_link_node(&pt->node, parent, p);
		rb_insert_color(&pt->node, &obj->pt_tree);

		parent = rb_next(&pt->node);
		list_add_tail(&pt->link,
			      parent ? &rb_entry(parent, typeof(*pt), node)->link : &obj->pt_list);
	}
unlock:
	spin_unlock_irq(&obj->lock);

	return pt;
}

/*
 * *WARNING*
 *
 * improper use of this can result in deadlocking kernel drivers from userspace.
 */

/* opening sw_sync create a new sync obj */
static int sw_sync_debugfs_open(struct inode *inode, struct file *file)
{
	struct sync_timeline *obj;
	char task_comm[TASK_COMM_LEN];

	get_task_comm(task_comm, current);

	obj = sync_timeline_create(task_comm);
	if (!obj)
		return -ENOMEM;

	file->private_data = obj;

	return 0;
}

static int sw_sync_debugfs_release(struct inode *inode, struct file *file)
{
	struct sync_timeline *obj = file->private_data;
	struct sync_pt *pt, *next;

	spin_lock_irq(&obj->lock);

	list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
		dma_fence_set_error(&pt->base, -ENOENT);
		dma_fence_signal_locked(&pt->base);
	}

	spin_unlock_irq(&obj->lock);

	sync_timeline_put(obj);
	return 0;
}

static long sw_sync_ioctl_create_fence(struct sync_timeline *obj,
				       unsigned long arg)
{
	int fd = get_unused_fd_flags(O_CLOEXEC);
	int err;
	struct sync_pt *pt;
	struct sync_file *sync_file;
	struct sw_sync_create_fence_data data;

	if (fd < 0)
		return fd;

	if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
		err = -EFAULT;
		goto err;
	}

	pt = sync_pt_create(obj, data.value);
	if (!pt) {
		err = -ENOMEM;
		goto err;
	}

	sync_file = sync_file_create(&pt->base);
	dma_fence_put(&pt->base);
	if (!sync_file) {
		err = -ENOMEM;
		goto err;
	}

	data.fence = fd;
	if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
		fput(sync_file->file);
		err = -EFAULT;
		goto err;
	}

	fd_install(fd, sync_file->file);

	return 0;

err:
	put_unused_fd(fd);
	return err;
}

static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg)
{
	u32 value;

	if (copy_from_user(&value, (void __user *)arg, sizeof(value)))
		return -EFAULT;

	while (value > INT_MAX)  {
		sync_timeline_signal(obj, INT_MAX);
		value -= INT_MAX;
	}

	sync_timeline_signal(obj, value);

	return 0;
}

static long sw_sync_ioctl(struct file *file, unsigned int cmd,
			  unsigned long arg)
{
	struct sync_timeline *obj = file->private_data;

	switch (cmd) {
	case SW_SYNC_IOC_CREATE_FENCE:
		return sw_sync_ioctl_create_fence(obj, arg);

	case SW_SYNC_IOC_INC:
		return sw_sync_ioctl_inc(obj, arg);

	default:
		return -ENOTTY;
	}
}

const struct file_operations sw_sync_debugfs_fops = {
	.open           = sw_sync_debugfs_open,
	.release        = sw_sync_debugfs_release,
	.unlocked_ioctl = sw_sync_ioctl,
	.compat_ioctl	= sw_sync_ioctl,
};