1 // SPDX-License-Identifier: GPL-2.0-only
3 * Sync File validation framework
5 * Copyright (C) 2012 Google, Inc.
8 #include <linux/file.h>
10 #include <linux/uaccess.h>
11 #include <linux/slab.h>
12 #include <linux/sync_file.h>
14 #include "sync_debug.h"
16 #define CREATE_TRACE_POINTS
17 #include "sync_trace.h"
20 * SW SYNC validation framework
22 * A sync object driver that uses a 32bit counter to coordinate
23 * synchronization. Useful when there is no hardware primitive backing
24 * the synchronization.
26 * To start the framework just open:
28 * <debugfs>/sync/sw_sync
30 * That will create a sync timeline, all fences created under this timeline
31 * file descriptor will belong to the this timeline.
33 * The 'sw_sync' file can be opened many times as to create different
36 * Fences can be created with SW_SYNC_IOC_CREATE_FENCE ioctl with struct
37 * sw_sync_create_fence_data as parameter.
39 * To increment the timeline counter, SW_SYNC_IOC_INC ioctl should be used
40 * with the increment as u32. This will update the last signaled value
41 * from the timeline and signal any fence that has a seqno smaller or equal
44 * struct sw_sync_create_fence_data
45 * @value: the seqno to initialise the fence with
46 * @name: the name of the new sync point
47 * @fence: return the fd of the new sync_file with the created fence
49 struct sw_sync_create_fence_data {
52 __s32 fence; /* fd of new fence */
56 * struct sw_sync_get_deadline - get the deadline hint of a sw_sync fence
57 * @deadline_ns: absolute time of the deadline
59 * @fence_fd: the sw_sync fence fd (in)
61 * Return the earliest deadline set on the fence. The timebase for the
62 * deadline is CLOCK_MONOTONIC (same as vblank). If there is no deadline
63 * set on the fence, this ioctl will return -ENOENT.
65 struct sw_sync_get_deadline {
71 #define SW_SYNC_IOC_MAGIC 'W'
73 #define SW_SYNC_IOC_CREATE_FENCE _IOWR(SW_SYNC_IOC_MAGIC, 0,\
74 struct sw_sync_create_fence_data)
76 #define SW_SYNC_IOC_INC _IOW(SW_SYNC_IOC_MAGIC, 1, __u32)
77 #define SW_SYNC_GET_DEADLINE _IOWR(SW_SYNC_IOC_MAGIC, 2, \
78 struct sw_sync_get_deadline)
81 #define SW_SYNC_HAS_DEADLINE_BIT DMA_FENCE_FLAG_USER_BITS
83 static const struct dma_fence_ops timeline_fence_ops;
85 static inline struct sync_pt *dma_fence_to_sync_pt(struct dma_fence *fence)
87 if (fence->ops != &timeline_fence_ops)
89 return container_of(fence, struct sync_pt, base);
93 * sync_timeline_create() - creates a sync object
94 * @name: sync_timeline name
96 * Creates a new sync_timeline. Returns the sync_timeline object or NULL in
99 static struct sync_timeline *sync_timeline_create(const char *name)
101 struct sync_timeline *obj;
103 obj = kzalloc(sizeof(*obj), GFP_KERNEL);
107 kref_init(&obj->kref);
108 obj->context = dma_fence_context_alloc(1);
109 strscpy(obj->name, name, sizeof(obj->name));
111 obj->pt_tree = RB_ROOT;
112 INIT_LIST_HEAD(&obj->pt_list);
113 spin_lock_init(&obj->lock);
115 sync_timeline_debug_add(obj);
120 static void sync_timeline_free(struct kref *kref)
122 struct sync_timeline *obj =
123 container_of(kref, struct sync_timeline, kref);
125 sync_timeline_debug_remove(obj);
130 static void sync_timeline_get(struct sync_timeline *obj)
132 kref_get(&obj->kref);
135 static void sync_timeline_put(struct sync_timeline *obj)
137 kref_put(&obj->kref, sync_timeline_free);
140 static const char *timeline_fence_get_driver_name(struct dma_fence *fence)
145 static const char *timeline_fence_get_timeline_name(struct dma_fence *fence)
147 struct sync_timeline *parent = dma_fence_parent(fence);
152 static void timeline_fence_release(struct dma_fence *fence)
154 struct sync_pt *pt = dma_fence_to_sync_pt(fence);
155 struct sync_timeline *parent = dma_fence_parent(fence);
158 spin_lock_irqsave(fence->lock, flags);
159 if (!list_empty(&pt->link)) {
161 rb_erase(&pt->node, &parent->pt_tree);
163 spin_unlock_irqrestore(fence->lock, flags);
165 sync_timeline_put(parent);
166 dma_fence_free(fence);
169 static bool timeline_fence_signaled(struct dma_fence *fence)
171 struct sync_timeline *parent = dma_fence_parent(fence);
173 return !__dma_fence_is_later(fence->seqno, parent->value, fence->ops);
176 static bool timeline_fence_enable_signaling(struct dma_fence *fence)
181 static void timeline_fence_value_str(struct dma_fence *fence,
184 snprintf(str, size, "%lld", fence->seqno);
187 static void timeline_fence_timeline_value_str(struct dma_fence *fence,
190 struct sync_timeline *parent = dma_fence_parent(fence);
192 snprintf(str, size, "%d", parent->value);
195 static void timeline_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
197 struct sync_pt *pt = dma_fence_to_sync_pt(fence);
200 spin_lock_irqsave(fence->lock, flags);
201 if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
202 if (ktime_before(deadline, pt->deadline))
203 pt->deadline = deadline;
205 pt->deadline = deadline;
206 __set_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags);
208 spin_unlock_irqrestore(fence->lock, flags);
211 static const struct dma_fence_ops timeline_fence_ops = {
212 .get_driver_name = timeline_fence_get_driver_name,
213 .get_timeline_name = timeline_fence_get_timeline_name,
214 .enable_signaling = timeline_fence_enable_signaling,
215 .signaled = timeline_fence_signaled,
216 .release = timeline_fence_release,
217 .fence_value_str = timeline_fence_value_str,
218 .timeline_value_str = timeline_fence_timeline_value_str,
219 .set_deadline = timeline_fence_set_deadline,
223 * sync_timeline_signal() - signal a status change on a sync_timeline
224 * @obj: sync_timeline to signal
225 * @inc: num to increment on timeline->value
227 * A sync implementation should call this any time one of it's fences
228 * has signaled or has an error condition.
230 static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc)
232 LIST_HEAD(signalled);
233 struct sync_pt *pt, *next;
235 trace_sync_timeline(obj);
237 spin_lock_irq(&obj->lock);
241 list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
242 if (!timeline_fence_signaled(&pt->base))
245 dma_fence_get(&pt->base);
247 list_move_tail(&pt->link, &signalled);
248 rb_erase(&pt->node, &obj->pt_tree);
250 dma_fence_signal_locked(&pt->base);
253 spin_unlock_irq(&obj->lock);
255 list_for_each_entry_safe(pt, next, &signalled, link) {
256 list_del_init(&pt->link);
257 dma_fence_put(&pt->base);
262 * sync_pt_create() - creates a sync pt
263 * @obj: parent sync_timeline
264 * @value: value of the fence
266 * Creates a new sync_pt (fence) as a child of @parent. @size bytes will be
267 * allocated allowing for implementation specific data to be kept after
268 * the generic sync_timeline struct. Returns the sync_pt object or
269 * NULL in case of error.
271 static struct sync_pt *sync_pt_create(struct sync_timeline *obj,
276 pt = kzalloc(sizeof(*pt), GFP_KERNEL);
280 sync_timeline_get(obj);
281 dma_fence_init(&pt->base, &timeline_fence_ops, &obj->lock,
282 obj->context, value);
283 INIT_LIST_HEAD(&pt->link);
285 spin_lock_irq(&obj->lock);
286 if (!dma_fence_is_signaled_locked(&pt->base)) {
287 struct rb_node **p = &obj->pt_tree.rb_node;
288 struct rb_node *parent = NULL;
291 struct sync_pt *other;
295 other = rb_entry(parent, typeof(*pt), node);
296 cmp = value - other->base.seqno;
298 p = &parent->rb_right;
299 } else if (cmp < 0) {
300 p = &parent->rb_left;
302 if (dma_fence_get_rcu(&other->base)) {
303 sync_timeline_put(obj);
308 p = &parent->rb_left;
311 rb_link_node(&pt->node, parent, p);
312 rb_insert_color(&pt->node, &obj->pt_tree);
314 parent = rb_next(&pt->node);
315 list_add_tail(&pt->link,
316 parent ? &rb_entry(parent, typeof(*pt), node)->link : &obj->pt_list);
319 spin_unlock_irq(&obj->lock);
327 * improper use of this can result in deadlocking kernel drivers from userspace.
330 /* opening sw_sync create a new sync obj */
331 static int sw_sync_debugfs_open(struct inode *inode, struct file *file)
333 struct sync_timeline *obj;
334 char task_comm[TASK_COMM_LEN];
336 get_task_comm(task_comm, current);
338 obj = sync_timeline_create(task_comm);
342 file->private_data = obj;
347 static int sw_sync_debugfs_release(struct inode *inode, struct file *file)
349 struct sync_timeline *obj = file->private_data;
350 struct sync_pt *pt, *next;
352 spin_lock_irq(&obj->lock);
354 list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
355 dma_fence_set_error(&pt->base, -ENOENT);
356 dma_fence_signal_locked(&pt->base);
359 spin_unlock_irq(&obj->lock);
361 sync_timeline_put(obj);
365 static long sw_sync_ioctl_create_fence(struct sync_timeline *obj,
368 int fd = get_unused_fd_flags(O_CLOEXEC);
371 struct sync_file *sync_file;
372 struct sw_sync_create_fence_data data;
377 if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
382 pt = sync_pt_create(obj, data.value);
388 sync_file = sync_file_create(&pt->base);
389 dma_fence_put(&pt->base);
396 if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
397 fput(sync_file->file);
402 fd_install(fd, sync_file->file);
411 static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg)
415 if (copy_from_user(&value, (void __user *)arg, sizeof(value)))
418 while (value > INT_MAX) {
419 sync_timeline_signal(obj, INT_MAX);
423 sync_timeline_signal(obj, value);
428 static int sw_sync_ioctl_get_deadline(struct sync_timeline *obj, unsigned long arg)
430 struct sw_sync_get_deadline data;
431 struct dma_fence *fence;
436 if (copy_from_user(&data, (void __user *)arg, sizeof(data)))
439 if (data.deadline_ns || data.pad)
442 fence = sync_file_get_fence(data.fence_fd);
446 pt = dma_fence_to_sync_pt(fence);
450 spin_lock_irqsave(fence->lock, flags);
451 if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
452 data.deadline_ns = ktime_to_ns(pt->deadline);
456 spin_unlock_irqrestore(fence->lock, flags);
458 dma_fence_put(fence);
463 if (copy_to_user((void __user *)arg, &data, sizeof(data)))
469 static long sw_sync_ioctl(struct file *file, unsigned int cmd,
472 struct sync_timeline *obj = file->private_data;
475 case SW_SYNC_IOC_CREATE_FENCE:
476 return sw_sync_ioctl_create_fence(obj, arg);
478 case SW_SYNC_IOC_INC:
479 return sw_sync_ioctl_inc(obj, arg);
481 case SW_SYNC_GET_DEADLINE:
482 return sw_sync_ioctl_get_deadline(obj, arg);
489 const struct file_operations sw_sync_debugfs_fops = {
490 .open = sw_sync_debugfs_open,
491 .release = sw_sync_debugfs_release,
492 .unlocked_ioctl = sw_sync_ioctl,
493 .compat_ioctl = compat_ptr_ioctl,