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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * dma-fence-array: aggregate fences to be waited together
4 *
5 * Copyright (C) 2016 Collabora Ltd
6 * Copyright (C) 2016 Advanced Micro Devices, Inc.
7 * Authors:
8 * Gustavo Padovan <[email protected]>
9 * Christian König <[email protected]>
10 */
11
12#include <linux/export.h>
13#include <linux/slab.h>
14#include <linux/dma-fence-array.h>
15
16#define PENDING_ERROR 1
17
18static const char *dma_fence_array_get_driver_name(struct dma_fence *fence)
19{
20 return "dma_fence_array";
21}
22
23static const char *dma_fence_array_get_timeline_name(struct dma_fence *fence)
24{
25 return "unbound";
26}
27
28static void dma_fence_array_set_pending_error(struct dma_fence_array *array,
29 int error)
30{
31 /*
32 * Propagate the first error reported by any of our fences, but only
33 * before we ourselves are signaled.
34 */
35 if (error)
36 cmpxchg(&array->base.error, PENDING_ERROR, error);
37}
38
39static void dma_fence_array_clear_pending_error(struct dma_fence_array *array)
40{
41 /* Clear the error flag if not actually set. */
42 cmpxchg(&array->base.error, PENDING_ERROR, 0);
43}
44
45static void irq_dma_fence_array_work(struct irq_work *wrk)
46{
47 struct dma_fence_array *array = container_of(wrk, typeof(*array), work);
48
49 dma_fence_array_clear_pending_error(array);
50
51 dma_fence_signal(&array->base);
52 dma_fence_put(&array->base);
53}
54
55static void dma_fence_array_cb_func(struct dma_fence *f,
56 struct dma_fence_cb *cb)
57{
58 struct dma_fence_array_cb *array_cb =
59 container_of(cb, struct dma_fence_array_cb, cb);
60 struct dma_fence_array *array = array_cb->array;
61
62 dma_fence_array_set_pending_error(array, f->error);
63
64 if (atomic_dec_and_test(&array->num_pending))
65 irq_work_queue(&array->work);
66 else
67 dma_fence_put(&array->base);
68}
69
70static bool dma_fence_array_enable_signaling(struct dma_fence *fence)
71{
72 struct dma_fence_array *array = to_dma_fence_array(fence);
73 struct dma_fence_array_cb *cb = array->callbacks;
74 unsigned i;
75
76 for (i = 0; i < array->num_fences; ++i) {
77 cb[i].array = array;
78 /*
79 * As we may report that the fence is signaled before all
80 * callbacks are complete, we need to take an additional
81 * reference count on the array so that we do not free it too
82 * early. The core fence handling will only hold the reference
83 * until we signal the array as complete (but that is now
84 * insufficient).
85 */
86 dma_fence_get(&array->base);
87 if (dma_fence_add_callback(array->fences[i], &cb[i].cb,
88 dma_fence_array_cb_func)) {
89 int error = array->fences[i]->error;
90
91 dma_fence_array_set_pending_error(array, error);
92 dma_fence_put(&array->base);
93 if (atomic_dec_and_test(&array->num_pending)) {
94 dma_fence_array_clear_pending_error(array);
95 return false;
96 }
97 }
98 }
99
100 return true;
101}
102
103static bool dma_fence_array_signaled(struct dma_fence *fence)
104{
105 struct dma_fence_array *array = to_dma_fence_array(fence);
106 int num_pending;
107 unsigned int i;
108
109 /*
110 * We need to read num_pending before checking the enable_signal bit
111 * to avoid racing with the enable_signaling() implementation, which
112 * might decrement the counter, and cause a partial check.
113 * atomic_read_acquire() pairs with atomic_dec_and_test() in
114 * dma_fence_array_enable_signaling()
115 *
116 * The !--num_pending check is here to account for the any_signaled case
117 * if we race with enable_signaling(), that means the !num_pending check
118 * in the is_signalling_enabled branch might be outdated (num_pending
119 * might have been decremented), but that's fine. The user will get the
120 * right value when testing again later.
121 */
122 num_pending = atomic_read_acquire(&array->num_pending);
123 if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &array->base.flags)) {
124 if (num_pending <= 0)
125 goto signal;
126 return false;
127 }
128
129 for (i = 0; i < array->num_fences; ++i) {
130 if (dma_fence_is_signaled(array->fences[i]) && !--num_pending)
131 goto signal;
132 }
133 return false;
134
135signal:
136 dma_fence_array_clear_pending_error(array);
137 return true;
138}
139
140static void dma_fence_array_release(struct dma_fence *fence)
141{
142 struct dma_fence_array *array = to_dma_fence_array(fence);
143 unsigned i;
144
145 for (i = 0; i < array->num_fences; ++i)
146 dma_fence_put(array->fences[i]);
147
148 kfree(array->fences);
149 dma_fence_free(fence);
150}
151
152static void dma_fence_array_set_deadline(struct dma_fence *fence,
153 ktime_t deadline)
154{
155 struct dma_fence_array *array = to_dma_fence_array(fence);
156 unsigned i;
157
158 for (i = 0; i < array->num_fences; ++i)
159 dma_fence_set_deadline(array->fences[i], deadline);
160}
161
162const struct dma_fence_ops dma_fence_array_ops = {
163 .get_driver_name = dma_fence_array_get_driver_name,
164 .get_timeline_name = dma_fence_array_get_timeline_name,
165 .enable_signaling = dma_fence_array_enable_signaling,
166 .signaled = dma_fence_array_signaled,
167 .release = dma_fence_array_release,
168 .set_deadline = dma_fence_array_set_deadline,
169};
170EXPORT_SYMBOL(dma_fence_array_ops);
171
172/**
173 * dma_fence_array_alloc - Allocate a custom fence array
174 * @num_fences: [in] number of fences to add in the array
175 *
176 * Return dma fence array on success, NULL on failure
177 */
178struct dma_fence_array *dma_fence_array_alloc(int num_fences)
179{
180 struct dma_fence_array *array;
181
182 return kzalloc_flex(*array, callbacks, num_fences);
183}
184EXPORT_SYMBOL(dma_fence_array_alloc);
185
186/**
187 * dma_fence_array_init - Init a custom fence array
188 * @array: [in] dma fence array to arm
189 * @num_fences: [in] number of fences to add in the array
190 * @fences: [in] array containing the fences
191 * @context: [in] fence context to use
192 * @seqno: [in] sequence number to use
193 *
194 * Implementation of @dma_fence_array_create without allocation. Useful to init
195 * a preallocated dma fence array in the path of reclaim or dma fence signaling.
196 */
197void dma_fence_array_init(struct dma_fence_array *array,
198 int num_fences, struct dma_fence **fences,
199 u64 context, unsigned seqno)
200{
201 static struct lock_class_key dma_fence_array_lock_key;
202
203 WARN_ON(!num_fences || !fences);
204
205 array->num_fences = num_fences;
206
207 dma_fence_init(&array->base, &dma_fence_array_ops, NULL, context,
208 seqno);
209 init_irq_work(&array->work, irq_dma_fence_array_work);
210
211 /*
212 * dma_fence_array_enable_signaling() is invoked while holding
213 * array->base.inline_lock and may call dma_fence_add_callback()
214 * on the underlying fences, which takes their inline_lock.
215 *
216 * Since both locks share the same lockdep class, this legitimate
217 * nesting confuses lockdep and triggers a recursive locking
218 * warning. Assign a separate lockdep class to the array lock
219 * to model this hierarchy correctly.
220 */
221 lockdep_set_class(&array->base.inline_lock, &dma_fence_array_lock_key);
222
223 atomic_set(&array->num_pending, num_fences);
224 array->fences = fences;
225
226 array->base.error = PENDING_ERROR;
227
228 /*
229 * dma_fence_array objects should never contain any other fence
230 * containers or otherwise we run into recursion and potential kernel
231 * stack overflow on operations on the dma_fence_array.
232 *
233 * The correct way of handling this is to flatten out the array by the
234 * caller instead.
235 *
236 * Enforce this here by checking that we don't create a dma_fence_array
237 * with any container inside.
238 */
239 while (num_fences--)
240 WARN_ON(dma_fence_is_container(fences[num_fences]));
241}
242EXPORT_SYMBOL(dma_fence_array_init);
243
244/**
245 * dma_fence_array_create - Create a custom fence array
246 * @num_fences: [in] number of fences to add in the array
247 * @fences: [in] array containing the fences
248 * @context: [in] fence context to use
249 * @seqno: [in] sequence number to use
250 *
251 * Allocate a dma_fence_array object and initialize the base fence with
252 * dma_fence_init().
253 * In case of error it returns NULL.
254 *
255 * The caller should allocate the fences array with num_fences size
256 * and fill it with the fences it wants to add to the object. Ownership of this
257 * array is taken and dma_fence_put() is used on each fence on release.
258 *
259 * If @signal_on_any is true the fence array signals if any fence in the array
260 * signals, otherwise it signals when all fences in the array signal.
261 */
262struct dma_fence_array *dma_fence_array_create(int num_fences,
263 struct dma_fence **fences,
264 u64 context, unsigned seqno)
265{
266 struct dma_fence_array *array;
267
268 array = dma_fence_array_alloc(num_fences);
269 if (!array)
270 return NULL;
271
272 dma_fence_array_init(array, num_fences, fences, context, seqno);
273
274 return array;
275}
276EXPORT_SYMBOL(dma_fence_array_create);
277
278/**
279 * dma_fence_match_context - Check if all fences are from the given context
280 * @fence: [in] fence or fence array
281 * @context: [in] fence context to check all fences against
282 *
283 * Checks the provided fence or, for a fence array, all fences in the array
284 * against the given context. Returns false if any fence is from a different
285 * context.
286 */
287bool dma_fence_match_context(struct dma_fence *fence, u64 context)
288{
289 struct dma_fence_array *array = to_dma_fence_array(fence);
290 unsigned i;
291
292 if (!dma_fence_is_array(fence))
293 return fence->context == context;
294
295 for (i = 0; i < array->num_fences; i++) {
296 if (array->fences[i]->context != context)
297 return false;
298 }
299
300 return true;
301}
302EXPORT_SYMBOL(dma_fence_match_context);
303
304struct dma_fence *dma_fence_array_first(struct dma_fence *head)
305{
306 struct dma_fence_array *array;
307
308 if (!head)
309 return NULL;
310
311 array = to_dma_fence_array(head);
312 if (!array)
313 return head;
314
315 if (!array->num_fences)
316 return NULL;
317
318 return array->fences[0];
319}
320EXPORT_SYMBOL(dma_fence_array_first);
321
322struct dma_fence *dma_fence_array_next(struct dma_fence *head,
323 unsigned int index)
324{
325 struct dma_fence_array *array = to_dma_fence_array(head);
326
327 if (!array || index >= array->num_fences)
328 return NULL;
329
330 return array->fences[index];
331}
332EXPORT_SYMBOL(dma_fence_array_next);