drivers/dma-buf/dma-fence.c

   1 /*
   2  * Fence mechanism for dma-buf and to allow for asynchronous dma access
   3  *
   4  * Copyright (C) 2012 Canonical Ltd
   5  * Copyright (C) 2012 Texas Instruments
   6  *
   7  * Authors:
   8  * Rob Clark <robdclark@gmail.com>
   9  * Maarten Lankhorst <maarten.lankhorst@canonical.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify it
  12  * under the terms of the GNU General Public License version 2 as published by
  13  * the Free Software Foundation.
  14  *
  15  * This program is distributed in the hope that it will be useful, but WITHOUT
  16  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  18  * more details.
  19  */
  20
  21 #include <linux/slab.h>
  22 #include <linux/export.h>
  23 #include <linux/atomic.h>
  24 #include <linux/dma-fence.h>
  25
  26 #define CREATE_TRACE_POINTS
  27 #include <trace/events/dma_fence.h>
  28
  29 EXPORT_TRACEPOINT_SYMBOL(dma_fence_annotate_wait_on);
  30 EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit);
  31
  32 /*
  33  * fence context counter: each execution context should have its own
  34  * fence context, this allows checking if fences belong to the same
  35  * context or not. One device can have multiple separate contexts,
  36  * and they're used if some engine can run independently of another.
  37  */
  38 static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(0);
  39
  40 /**
  41  * dma_fence_context_alloc - allocate an array of fence contexts
  42  * @num:        [in]    amount of contexts to allocate
  43  *
  44  * This function will return the first index of the number of fences allocated.
  45  * The fence context is used for setting fence->context to a unique number.
  46  */
  47 u64 dma_fence_context_alloc(unsigned num)
  48 {
  49         BUG_ON(!num);
  50         return atomic64_add_return(num, &dma_fence_context_counter) - num;
  51 }
  52 EXPORT_SYMBOL(dma_fence_context_alloc);
  53
  54 /**
  55  * dma_fence_signal_locked - signal completion of a fence
  56  * @fence: the fence to signal
  57  *
  58  * Signal completion for software callbacks on a fence, this will unblock
  59  * dma_fence_wait() calls and run all the callbacks added with
  60  * dma_fence_add_callback(). Can be called multiple times, but since a fence
  61  * can only go from unsignaled to signaled state, it will only be effective
  62  * the first time.
  63  *
  64  * Unlike dma_fence_signal, this function must be called with fence->lock held.
  65  */
  66 int dma_fence_signal_locked(struct dma_fence *fence)
  67 {
  68         struct dma_fence_cb *cur, *tmp;
  69         int ret = 0;
  70
  71         lockdep_assert_held(fence->lock);
  72
  73         if (WARN_ON(!fence))
  74                 return -EINVAL;
  75
  76         if (!ktime_to_ns(fence->timestamp)) {
  77                 fence->timestamp = ktime_get();
  78                 smp_mb__before_atomic();
  79         }
  80
  81         if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
  82                 ret = -EINVAL;
  83
  84                 /*
  85                  * we might have raced with the unlocked dma_fence_signal,
  86                  * still run through all callbacks
  87                  */
  88         } else
  89                 trace_dma_fence_signaled(fence);
  90
  91         list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
  92                 list_del_init(&cur->node);
  93                 cur->func(fence, cur);
  94         }
  95         return ret;
  96 }
  97 EXPORT_SYMBOL(dma_fence_signal_locked);
  98
  99 /**
 100  * dma_fence_signal - signal completion of a fence
 101  * @fence: the fence to signal
 102  *
 103  * Signal completion for software callbacks on a fence, this will unblock
 104  * dma_fence_wait() calls and run all the callbacks added with
 105  * dma_fence_add_callback(). Can be called multiple times, but since a fence
 106  * can only go from unsignaled to signaled state, it will only be effective
 107  * the first time.
 108  */
 109 int dma_fence_signal(struct dma_fence *fence)
 110 {
 111         unsigned long flags;
 112
 113         if (!fence)
 114                 return -EINVAL;
 115
 116         if (!ktime_to_ns(fence->timestamp)) {
 117                 fence->timestamp = ktime_get();
 118                 smp_mb__before_atomic();
 119         }
 120
 121         if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 122                 return -EINVAL;
 123
 124         trace_dma_fence_signaled(fence);
 125
 126         if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
 127                 struct dma_fence_cb *cur, *tmp;
 128
 129                 spin_lock_irqsave(fence->lock, flags);
 130                 list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
 131                         list_del_init(&cur->node);
 132                         cur->func(fence, cur);
 133                 }
 134                 spin_unlock_irqrestore(fence->lock, flags);
 135         }
 136         return 0;
 137 }
 138 EXPORT_SYMBOL(dma_fence_signal);
 139
 140 /**
 141  * dma_fence_wait_timeout - sleep until the fence gets signaled
 142  * or until timeout elapses
 143  * @fence:      [in]    the fence to wait on
 144  * @intr:       [in]    if true, do an interruptible wait
 145  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 146  *
 147  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 148  * remaining timeout in jiffies on success. Other error values may be
 149  * returned on custom implementations.
 150  *
 151  * Performs a synchronous wait on this fence. It is assumed the caller
 152  * directly or indirectly (buf-mgr between reservation and committing)
 153  * holds a reference to the fence, otherwise the fence might be
 154  * freed before return, resulting in undefined behavior.
 155  */
 156 signed long
 157 dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
 158 {
 159         signed long ret;
 160
 161         if (WARN_ON(timeout < 0))
 162                 return -EINVAL;
 163
 164         trace_dma_fence_wait_start(fence);
 165         ret = fence->ops->wait(fence, intr, timeout);
 166         trace_dma_fence_wait_end(fence);
 167         return ret;
 168 }
 169 EXPORT_SYMBOL(dma_fence_wait_timeout);
 170
 171 void dma_fence_release(struct kref *kref)
 172 {
 173         struct dma_fence *fence =
 174                 container_of(kref, struct dma_fence, refcount);
 175
 176         trace_dma_fence_destroy(fence);
 177
 178         BUG_ON(!list_empty(&fence->cb_list));
 179
 180         if (fence->ops->release)
 181                 fence->ops->release(fence);
 182         else
 183                 dma_fence_free(fence);
 184 }
 185 EXPORT_SYMBOL(dma_fence_release);
 186
 187 void dma_fence_free(struct dma_fence *fence)
 188 {
 189         kfree_rcu(fence, rcu);
 190 }
 191 EXPORT_SYMBOL(dma_fence_free);
 192
 193 /**
 194  * dma_fence_enable_sw_signaling - enable signaling on fence
 195  * @fence:      [in]    the fence to enable
 196  *
 197  * this will request for sw signaling to be enabled, to make the fence
 198  * complete as soon as possible
 199  */
 200 void dma_fence_enable_sw_signaling(struct dma_fence *fence)
 201 {
 202         unsigned long flags;
 203
 204         if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 205                               &fence->flags) &&
 206             !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 207                 trace_dma_fence_enable_signal(fence);
 208
 209                 spin_lock_irqsave(fence->lock, flags);
 210
 211                 if (!fence->ops->enable_signaling(fence))
 212                         dma_fence_signal_locked(fence);
 213
 214                 spin_unlock_irqrestore(fence->lock, flags);
 215         }
 216 }
 217 EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
 218
 219 /**
 220  * dma_fence_add_callback - add a callback to be called when the fence
 221  * is signaled
 222  * @fence:      [in]    the fence to wait on
 223  * @cb:         [in]    the callback to register
 224  * @func:       [in]    the function to call
 225  *
 226  * cb will be initialized by dma_fence_add_callback, no initialization
 227  * by the caller is required. Any number of callbacks can be registered
 228  * to a fence, but a callback can only be registered to one fence at a time.
 229  *
 230  * Note that the callback can be called from an atomic context.  If
 231  * fence is already signaled, this function will return -ENOENT (and
 232  * *not* call the callback)
 233  *
 234  * Add a software callback to the fence. Same restrictions apply to
 235  * refcount as it does to dma_fence_wait, however the caller doesn't need to
 236  * keep a refcount to fence afterwards: when software access is enabled,
 237  * the creator of the fence is required to keep the fence alive until
 238  * after it signals with dma_fence_signal. The callback itself can be called
 239  * from irq context.
 240  *
 241  */
 242 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
 243                            dma_fence_func_t func)
 244 {
 245         unsigned long flags;
 246         int ret = 0;
 247         bool was_set;
 248
 249         if (WARN_ON(!fence || !func))
 250                 return -EINVAL;
 251
 252         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 253                 INIT_LIST_HEAD(&cb->node);
 254                 return -ENOENT;
 255         }
 256
 257         spin_lock_irqsave(fence->lock, flags);
 258
 259         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 260                                    &fence->flags);
 261
 262         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 263                 ret = -ENOENT;
 264         else if (!was_set) {
 265                 trace_dma_fence_enable_signal(fence);
 266
 267                 if (!fence->ops->enable_signaling(fence)) {
 268                         dma_fence_signal_locked(fence);
 269                         ret = -ENOENT;
 270                 }
 271         }
 272
 273         if (!ret) {
 274                 cb->func = func;
 275                 list_add_tail(&cb->node, &fence->cb_list);
 276         } else
 277                 INIT_LIST_HEAD(&cb->node);
 278         spin_unlock_irqrestore(fence->lock, flags);
 279
 280         return ret;
 281 }
 282 EXPORT_SYMBOL(dma_fence_add_callback);
 283
 284 /**
 285  * dma_fence_remove_callback - remove a callback from the signaling list
 286  * @fence:      [in]    the fence to wait on
 287  * @cb:         [in]    the callback to remove
 288  *
 289  * Remove a previously queued callback from the fence. This function returns
 290  * true if the callback is successfully removed, or false if the fence has
 291  * already been signaled.
 292  *
 293  * *WARNING*:
 294  * Cancelling a callback should only be done if you really know what you're
 295  * doing, since deadlocks and race conditions could occur all too easily. For
 296  * this reason, it should only ever be done on hardware lockup recovery,
 297  * with a reference held to the fence.
 298  */
 299 bool
 300 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
 301 {
 302         unsigned long flags;
 303         bool ret;
 304
 305         spin_lock_irqsave(fence->lock, flags);
 306
 307         ret = !list_empty(&cb->node);
 308         if (ret)
 309                 list_del_init(&cb->node);
 310
 311         spin_unlock_irqrestore(fence->lock, flags);
 312
 313         return ret;
 314 }
 315 EXPORT_SYMBOL(dma_fence_remove_callback);
 316
 317 struct default_wait_cb {
 318         struct dma_fence_cb base;
 319         struct task_struct *task;
 320 };
 321
 322 static void
 323 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 324 {
 325         struct default_wait_cb *wait =
 326                 container_of(cb, struct default_wait_cb, base);
 327
 328         wake_up_state(wait->task, TASK_NORMAL);
 329 }
 330
 331 /**
 332  * dma_fence_default_wait - default sleep until the fence gets signaled
 333  * or until timeout elapses
 334  * @fence:      [in]    the fence to wait on
 335  * @intr:       [in]    if true, do an interruptible wait
 336  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 337  *
 338  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 339  * remaining timeout in jiffies on success. If timeout is zero the value one is
 340  * returned if the fence is already signaled for consistency with other
 341  * functions taking a jiffies timeout.
 342  */
 343 signed long
 344 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
 345 {
 346         struct default_wait_cb cb;
 347         unsigned long flags;
 348         signed long ret = timeout ? timeout : 1;
 349         bool was_set;
 350
 351         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 352                 return ret;
 353
 354         spin_lock_irqsave(fence->lock, flags);
 355
 356         if (intr && signal_pending(current)) {
 357                 ret = -ERESTARTSYS;
 358                 goto out;
 359         }
 360
 361         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 362                                    &fence->flags);
 363
 364         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 365                 goto out;
 366
 367         if (!was_set) {
 368                 trace_dma_fence_enable_signal(fence);
 369
 370                 if (!fence->ops->enable_signaling(fence)) {
 371                         dma_fence_signal_locked(fence);
 372                         goto out;
 373                 }
 374         }
 375
 376         cb.base.func = dma_fence_default_wait_cb;
 377         cb.task = current;
 378         list_add(&cb.base.node, &fence->cb_list);
 379
 380         while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
 381                 if (intr)
 382                         __set_current_state(TASK_INTERRUPTIBLE);
 383                 else
 384                         __set_current_state(TASK_UNINTERRUPTIBLE);
 385                 spin_unlock_irqrestore(fence->lock, flags);
 386
 387                 ret = schedule_timeout(ret);
 388
 389                 spin_lock_irqsave(fence->lock, flags);
 390                 if (ret > 0 && intr && signal_pending(current))
 391                         ret = -ERESTARTSYS;
 392         }
 393
 394         if (!list_empty(&cb.base.node))
 395                 list_del(&cb.base.node);
 396         __set_current_state(TASK_RUNNING);
 397
 398 out:
 399         spin_unlock_irqrestore(fence->lock, flags);
 400         return ret;
 401 }
 402 EXPORT_SYMBOL(dma_fence_default_wait);
 403
 404 static bool
 405 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
 406                             uint32_t *idx)
 407 {
 408         int i;
 409
 410         for (i = 0; i < count; ++i) {
 411                 struct dma_fence *fence = fences[i];
 412                 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 413                         if (idx)
 414                                 *idx = i;
 415                         return true;
 416                 }
 417         }
 418         return false;
 419 }
 420
 421 /**
 422  * dma_fence_wait_any_timeout - sleep until any fence gets signaled
 423  * or until timeout elapses
 424  * @fences:     [in]    array of fences to wait on
 425  * @count:      [in]    number of fences to wait on
 426  * @intr:       [in]    if true, do an interruptible wait
 427  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 428  * @idx:       [out]    the first signaled fence index, meaningful only on
 429  *                      positive return
 430  *
 431  * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
 432  * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
 433  * on success.
 434  *
 435  * Synchronous waits for the first fence in the array to be signaled. The
 436  * caller needs to hold a reference to all fences in the array, otherwise a
 437  * fence might be freed before return, resulting in undefined behavior.
 438  */
 439 signed long
 440 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 441                            bool intr, signed long timeout, uint32_t *idx)
 442 {
 443         struct default_wait_cb *cb;
 444         signed long ret = timeout;
 445         unsigned i;
 446
 447         if (WARN_ON(!fences || !count || timeout < 0))
 448                 return -EINVAL;
 449
 450         if (timeout == 0) {
 451                 for (i = 0; i < count; ++i)
 452                         if (dma_fence_is_signaled(fences[i])) {
 453                                 if (idx)
 454                                         *idx = i;
 455                                 return 1;
 456                         }
 457
 458                 return 0;
 459         }
 460
 461         cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
 462         if (cb == NULL) {
 463                 ret = -ENOMEM;
 464                 goto err_free_cb;
 465         }
 466
 467         for (i = 0; i < count; ++i) {
 468                 struct dma_fence *fence = fences[i];
 469
 470                 if (fence->ops->wait != dma_fence_default_wait) {
 471                         ret = -EINVAL;
 472                         goto fence_rm_cb;
 473                 }
 474
 475                 cb[i].task = current;
 476                 if (dma_fence_add_callback(fence, &cb[i].base,
 477                                            dma_fence_default_wait_cb)) {
 478                         /* This fence is already signaled */
 479                         if (idx)
 480                                 *idx = i;
 481                         goto fence_rm_cb;
 482                 }
 483         }
 484
 485         while (ret > 0) {
 486                 if (intr)
 487                         set_current_state(TASK_INTERRUPTIBLE);
 488                 else
 489                         set_current_state(TASK_UNINTERRUPTIBLE);
 490
 491                 if (dma_fence_test_signaled_any(fences, count, idx))
 492                         break;
 493
 494                 ret = schedule_timeout(ret);
 495
 496                 if (ret > 0 && intr && signal_pending(current))
 497                         ret = -ERESTARTSYS;
 498         }
 499
 500         __set_current_state(TASK_RUNNING);
 501
 502 fence_rm_cb:
 503         while (i-- > 0)
 504                 dma_fence_remove_callback(fences[i], &cb[i].base);
 505
 506 err_free_cb:
 507         kfree(cb);
 508
 509         return ret;
 510 }
 511 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
 512
 513 /**
 514  * dma_fence_init - Initialize a custom fence.
 515  * @fence:      [in]    the fence to initialize
 516  * @ops:        [in]    the dma_fence_ops for operations on this fence
 517  * @lock:       [in]    the irqsafe spinlock to use for locking this fence
 518  * @context:    [in]    the execution context this fence is run on
 519  * @seqno:      [in]    a linear increasing sequence number for this context
 520  *
 521  * Initializes an allocated fence, the caller doesn't have to keep its
 522  * refcount after committing with this fence, but it will need to hold a
 523  * refcount again if dma_fence_ops.enable_signaling gets called. This can
 524  * be used for other implementing other types of fence.
 525  *
 526  * context and seqno are used for easy comparison between fences, allowing
 527  * to check which fence is later by simply using dma_fence_later.
 528  */
 529 void
 530 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 531                spinlock_t *lock, u64 context, unsigned seqno)
 532 {
 533         BUG_ON(!lock);
 534         BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
 535                !ops->get_driver_name || !ops->get_timeline_name);
 536
 537         kref_init(&fence->refcount);
 538         fence->ops = ops;
 539         INIT_LIST_HEAD(&fence->cb_list);
 540         fence->lock = lock;
 541         fence->context = context;
 542         fence->seqno = seqno;
 543         fence->flags = 0UL;
 544
 545         trace_dma_fence_init(fence);
 546 }
 547 EXPORT_SYMBOL(dma_fence_init);