x86/speculation/mds: Fix documentation typo
[linux/fpc-iii.git] / drivers / dma-buf / sw_sync.c
blob24f83f9eeaedce12904ce8190edd1e5ed0b67e76
1 /*
2 * Sync File validation framework
4 * Copyright (C) 2012 Google, Inc.
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.
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.
17 #include <linux/file.h>
18 #include <linux/fs.h>
19 #include <linux/uaccess.h>
20 #include <linux/slab.h>
21 #include <linux/sync_file.h>
23 #include "sync_debug.h"
25 #define CREATE_TRACE_POINTS
26 #include "sync_trace.h"
29 * SW SYNC validation framework
31 * A sync object driver that uses a 32bit counter to coordinate
32 * synchronization. Useful when there is no hardware primitive backing
33 * the synchronization.
35 * To start the framework just open:
37 * <debugfs>/sync/sw_sync
39 * That will create a sync timeline, all fences created under this timeline
40 * file descriptor will belong to the this timeline.
42 * The 'sw_sync' file can be opened many times as to create different
43 * timelines.
45 * Fences can be created with SW_SYNC_IOC_CREATE_FENCE ioctl with struct
46 * sw_sync_ioctl_create_fence as parameter.
48 * To increment the timeline counter, SW_SYNC_IOC_INC ioctl should be used
49 * with the increment as u32. This will update the last signaled value
50 * from the timeline and signal any fence that has a seqno smaller or equal
51 * to it.
53 * struct sw_sync_ioctl_create_fence
54 * @value: the seqno to initialise the fence with
55 * @name: the name of the new sync point
56 * @fence: return the fd of the new sync_file with the created fence
58 struct sw_sync_create_fence_data {
59 __u32 value;
60 char name[32];
61 __s32 fence; /* fd of new fence */
64 #define SW_SYNC_IOC_MAGIC 'W'
66 #define SW_SYNC_IOC_CREATE_FENCE _IOWR(SW_SYNC_IOC_MAGIC, 0,\
67 struct sw_sync_create_fence_data)
69 #define SW_SYNC_IOC_INC _IOW(SW_SYNC_IOC_MAGIC, 1, __u32)
71 static const struct dma_fence_ops timeline_fence_ops;
73 static inline struct sync_pt *dma_fence_to_sync_pt(struct dma_fence *fence)
75 if (fence->ops != &timeline_fence_ops)
76 return NULL;
77 return container_of(fence, struct sync_pt, base);
80 /**
81 * sync_timeline_create() - creates a sync object
82 * @name: sync_timeline name
84 * Creates a new sync_timeline. Returns the sync_timeline object or NULL in
85 * case of error.
87 static struct sync_timeline *sync_timeline_create(const char *name)
89 struct sync_timeline *obj;
91 obj = kzalloc(sizeof(*obj), GFP_KERNEL);
92 if (!obj)
93 return NULL;
95 kref_init(&obj->kref);
96 obj->context = dma_fence_context_alloc(1);
97 strlcpy(obj->name, name, sizeof(obj->name));
99 obj->pt_tree = RB_ROOT;
100 INIT_LIST_HEAD(&obj->pt_list);
101 spin_lock_init(&obj->lock);
103 sync_timeline_debug_add(obj);
105 return obj;
108 static void sync_timeline_free(struct kref *kref)
110 struct sync_timeline *obj =
111 container_of(kref, struct sync_timeline, kref);
113 sync_timeline_debug_remove(obj);
115 kfree(obj);
118 static void sync_timeline_get(struct sync_timeline *obj)
120 kref_get(&obj->kref);
123 static void sync_timeline_put(struct sync_timeline *obj)
125 kref_put(&obj->kref, sync_timeline_free);
128 static const char *timeline_fence_get_driver_name(struct dma_fence *fence)
130 return "sw_sync";
133 static const char *timeline_fence_get_timeline_name(struct dma_fence *fence)
135 struct sync_timeline *parent = dma_fence_parent(fence);
137 return parent->name;
140 static void timeline_fence_release(struct dma_fence *fence)
142 struct sync_pt *pt = dma_fence_to_sync_pt(fence);
143 struct sync_timeline *parent = dma_fence_parent(fence);
145 if (!list_empty(&pt->link)) {
146 unsigned long flags;
148 spin_lock_irqsave(fence->lock, flags);
149 if (!list_empty(&pt->link)) {
150 list_del(&pt->link);
151 rb_erase(&pt->node, &parent->pt_tree);
153 spin_unlock_irqrestore(fence->lock, flags);
156 sync_timeline_put(parent);
157 dma_fence_free(fence);
160 static bool timeline_fence_signaled(struct dma_fence *fence)
162 struct sync_timeline *parent = dma_fence_parent(fence);
164 return !__dma_fence_is_later(fence->seqno, parent->value);
167 static bool timeline_fence_enable_signaling(struct dma_fence *fence)
169 return true;
172 static void timeline_fence_value_str(struct dma_fence *fence,
173 char *str, int size)
175 snprintf(str, size, "%d", fence->seqno);
178 static void timeline_fence_timeline_value_str(struct dma_fence *fence,
179 char *str, int size)
181 struct sync_timeline *parent = dma_fence_parent(fence);
183 snprintf(str, size, "%d", parent->value);
186 static const struct dma_fence_ops timeline_fence_ops = {
187 .get_driver_name = timeline_fence_get_driver_name,
188 .get_timeline_name = timeline_fence_get_timeline_name,
189 .enable_signaling = timeline_fence_enable_signaling,
190 .signaled = timeline_fence_signaled,
191 .wait = dma_fence_default_wait,
192 .release = timeline_fence_release,
193 .fence_value_str = timeline_fence_value_str,
194 .timeline_value_str = timeline_fence_timeline_value_str,
198 * sync_timeline_signal() - signal a status change on a sync_timeline
199 * @obj: sync_timeline to signal
200 * @inc: num to increment on timeline->value
202 * A sync implementation should call this any time one of it's fences
203 * has signaled or has an error condition.
205 static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc)
207 struct sync_pt *pt, *next;
209 trace_sync_timeline(obj);
211 spin_lock_irq(&obj->lock);
213 obj->value += inc;
215 list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
216 if (!timeline_fence_signaled(&pt->base))
217 break;
219 list_del_init(&pt->link);
220 rb_erase(&pt->node, &obj->pt_tree);
223 * A signal callback may release the last reference to this
224 * fence, causing it to be freed. That operation has to be
225 * last to avoid a use after free inside this loop, and must
226 * be after we remove the fence from the timeline in order to
227 * prevent deadlocking on timeline->lock inside
228 * timeline_fence_release().
230 dma_fence_signal_locked(&pt->base);
233 spin_unlock_irq(&obj->lock);
237 * sync_pt_create() - creates a sync pt
238 * @parent: fence's parent sync_timeline
239 * @inc: value of the fence
241 * Creates a new sync_pt as a child of @parent. @size bytes will be
242 * allocated allowing for implementation specific data to be kept after
243 * the generic sync_timeline struct. Returns the sync_pt object or
244 * NULL in case of error.
246 static struct sync_pt *sync_pt_create(struct sync_timeline *obj,
247 unsigned int value)
249 struct sync_pt *pt;
251 pt = kzalloc(sizeof(*pt), GFP_KERNEL);
252 if (!pt)
253 return NULL;
255 sync_timeline_get(obj);
256 dma_fence_init(&pt->base, &timeline_fence_ops, &obj->lock,
257 obj->context, value);
258 INIT_LIST_HEAD(&pt->link);
260 spin_lock_irq(&obj->lock);
261 if (!dma_fence_is_signaled_locked(&pt->base)) {
262 struct rb_node **p = &obj->pt_tree.rb_node;
263 struct rb_node *parent = NULL;
265 while (*p) {
266 struct sync_pt *other;
267 int cmp;
269 parent = *p;
270 other = rb_entry(parent, typeof(*pt), node);
271 cmp = value - other->base.seqno;
272 if (cmp > 0) {
273 p = &parent->rb_right;
274 } else if (cmp < 0) {
275 p = &parent->rb_left;
276 } else {
277 if (dma_fence_get_rcu(&other->base)) {
278 dma_fence_put(&pt->base);
279 pt = other;
280 goto unlock;
282 p = &parent->rb_left;
285 rb_link_node(&pt->node, parent, p);
286 rb_insert_color(&pt->node, &obj->pt_tree);
288 parent = rb_next(&pt->node);
289 list_add_tail(&pt->link,
290 parent ? &rb_entry(parent, typeof(*pt), node)->link : &obj->pt_list);
292 unlock:
293 spin_unlock_irq(&obj->lock);
295 return pt;
299 * *WARNING*
301 * improper use of this can result in deadlocking kernel drivers from userspace.
304 /* opening sw_sync create a new sync obj */
305 static int sw_sync_debugfs_open(struct inode *inode, struct file *file)
307 struct sync_timeline *obj;
308 char task_comm[TASK_COMM_LEN];
310 get_task_comm(task_comm, current);
312 obj = sync_timeline_create(task_comm);
313 if (!obj)
314 return -ENOMEM;
316 file->private_data = obj;
318 return 0;
321 static int sw_sync_debugfs_release(struct inode *inode, struct file *file)
323 struct sync_timeline *obj = file->private_data;
324 struct sync_pt *pt, *next;
326 spin_lock_irq(&obj->lock);
328 list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
329 dma_fence_set_error(&pt->base, -ENOENT);
330 dma_fence_signal_locked(&pt->base);
333 spin_unlock_irq(&obj->lock);
335 sync_timeline_put(obj);
336 return 0;
339 static long sw_sync_ioctl_create_fence(struct sync_timeline *obj,
340 unsigned long arg)
342 int fd = get_unused_fd_flags(O_CLOEXEC);
343 int err;
344 struct sync_pt *pt;
345 struct sync_file *sync_file;
346 struct sw_sync_create_fence_data data;
348 if (fd < 0)
349 return fd;
351 if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
352 err = -EFAULT;
353 goto err;
356 pt = sync_pt_create(obj, data.value);
357 if (!pt) {
358 err = -ENOMEM;
359 goto err;
362 sync_file = sync_file_create(&pt->base);
363 dma_fence_put(&pt->base);
364 if (!sync_file) {
365 err = -ENOMEM;
366 goto err;
369 data.fence = fd;
370 if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
371 fput(sync_file->file);
372 err = -EFAULT;
373 goto err;
376 fd_install(fd, sync_file->file);
378 return 0;
380 err:
381 put_unused_fd(fd);
382 return err;
385 static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg)
387 u32 value;
389 if (copy_from_user(&value, (void __user *)arg, sizeof(value)))
390 return -EFAULT;
392 while (value > INT_MAX) {
393 sync_timeline_signal(obj, INT_MAX);
394 value -= INT_MAX;
397 sync_timeline_signal(obj, value);
399 return 0;
402 static long sw_sync_ioctl(struct file *file, unsigned int cmd,
403 unsigned long arg)
405 struct sync_timeline *obj = file->private_data;
407 switch (cmd) {
408 case SW_SYNC_IOC_CREATE_FENCE:
409 return sw_sync_ioctl_create_fence(obj, arg);
411 case SW_SYNC_IOC_INC:
412 return sw_sync_ioctl_inc(obj, arg);
414 default:
415 return -ENOTTY;
419 const struct file_operations sw_sync_debugfs_fops = {
420 .open = sw_sync_debugfs_open,
421 .release = sw_sync_debugfs_release,
422 .unlocked_ioctl = sw_sync_ioctl,
423 .compat_ioctl = sw_sync_ioctl,