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 EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal);
  32
  33 /*
  34  * fence context counter: each execution context should have its own
  35  * fence context, this allows checking if fences belong to the same
  36  * context or not. One device can have multiple separate contexts,
  37  * and they're used if some engine can run independently of another.
  38  */
  39 static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(0);
  40
  41 /**
  42  * dma_fence_context_alloc - allocate an array of fence contexts
  43  * @num:        [in]    amount of contexts to allocate
  44  *
  45  * This function will return the first index of the number of fences allocated.
  46  * The fence context is used for setting fence->context to a unique number.
  47  */
  48 u64 dma_fence_context_alloc(unsigned num)
  49 {
  50         BUG_ON(!num);
  51         return atomic64_add_return(num, &dma_fence_context_counter) - num;
  52 }
  53 EXPORT_SYMBOL(dma_fence_context_alloc);
  54
  55 /**
  56  * dma_fence_signal_locked - signal completion of a fence
  57  * @fence: the fence to signal
  58  *
  59  * Signal completion for software callbacks on a fence, this will unblock
  60  * dma_fence_wait() calls and run all the callbacks added with
  61  * dma_fence_add_callback(). Can be called multiple times, but since a fence
  62  * can only go from unsignaled to signaled state, it will only be effective
  63  * the first time.
  64  *
  65  * Unlike dma_fence_signal, this function must be called with fence->lock held.
  66  */
  67 int dma_fence_signal_locked(struct dma_fence *fence)
  68 {
  69         struct dma_fence_cb *cur, *tmp;
  70         int ret = 0;
  71
  72         lockdep_assert_held(fence->lock);
  73
  74         if (WARN_ON(!fence))
  75                 return -EINVAL;
  76
  77         if (!ktime_to_ns(fence->timestamp)) {
  78                 fence->timestamp = ktime_get();
  79                 smp_mb__before_atomic();
  80         }
  81
  82         if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
  83                 ret = -EINVAL;
  84
  85                 /*
  86                  * we might have raced with the unlocked dma_fence_signal,
  87                  * still run through all callbacks
  88                  */
  89         } else
  90                 trace_dma_fence_signaled(fence);
  91
  92         list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
  93                 list_del_init(&cur->node);
  94                 cur->func(fence, cur);
  95         }
  96         return ret;
  97 }
  98 EXPORT_SYMBOL(dma_fence_signal_locked);
  99
 100 /**
 101  * dma_fence_signal - signal completion of a fence
 102  * @fence: the fence to signal
 103  *
 104  * Signal completion for software callbacks on a fence, this will unblock
 105  * dma_fence_wait() calls and run all the callbacks added with
 106  * dma_fence_add_callback(). Can be called multiple times, but since a fence
 107  * can only go from unsignaled to signaled state, it will only be effective
 108  * the first time.
 109  */
 110 int dma_fence_signal(struct dma_fence *fence)
 111 {
 112         unsigned long flags;
 113
 114         if (!fence)
 115                 return -EINVAL;
 116
 117         if (!ktime_to_ns(fence->timestamp)) {
 118                 fence->timestamp = ktime_get();
 119                 smp_mb__before_atomic();
 120         }
 121
 122         if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 123                 return -EINVAL;
 124
 125         trace_dma_fence_signaled(fence);
 126
 127         if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
 128                 struct dma_fence_cb *cur, *tmp;
 129
 130                 spin_lock_irqsave(fence->lock, flags);
 131                 list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
 132                         list_del_init(&cur->node);
 133                         cur->func(fence, cur);
 134                 }
 135                 spin_unlock_irqrestore(fence->lock, flags);
 136         }
 137         return 0;
 138 }
 139 EXPORT_SYMBOL(dma_fence_signal);
 140
 141 /**
 142  * dma_fence_wait_timeout - sleep until the fence gets signaled
 143  * or until timeout elapses
 144  * @fence:      [in]    the fence to wait on
 145  * @intr:       [in]    if true, do an interruptible wait
 146  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 147  *
 148  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 149  * remaining timeout in jiffies on success. Other error values may be
 150  * returned on custom implementations.
 151  *
 152  * Performs a synchronous wait on this fence. It is assumed the caller
 153  * directly or indirectly (buf-mgr between reservation and committing)
 154  * holds a reference to the fence, otherwise the fence might be
 155  * freed before return, resulting in undefined behavior.
 156  */
 157 signed long
 158 dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
 159 {
 160         signed long ret;
 161
 162         if (WARN_ON(timeout < 0))
 163                 return -EINVAL;
 164
 165         trace_dma_fence_wait_start(fence);
 166         ret = fence->ops->wait(fence, intr, timeout);
 167         trace_dma_fence_wait_end(fence);
 168         return ret;
 169 }
 170 EXPORT_SYMBOL(dma_fence_wait_timeout);
 171
 172 void dma_fence_release(struct kref *kref)
 173 {
 174         struct dma_fence *fence =
 175                 container_of(kref, struct dma_fence, refcount);
 176
 177         trace_dma_fence_destroy(fence);
 178
 179         BUG_ON(!list_empty(&fence->cb_list));
 180
 181         if (fence->ops->release)
 182                 fence->ops->release(fence);
 183         else
 184                 dma_fence_free(fence);
 185 }
 186 EXPORT_SYMBOL(dma_fence_release);
 187
 188 void dma_fence_free(struct dma_fence *fence)
 189 {
 190         kfree_rcu(fence, rcu);
 191 }
 192 EXPORT_SYMBOL(dma_fence_free);
 193
 194 /**
 195  * dma_fence_enable_sw_signaling - enable signaling on fence
 196  * @fence:      [in]    the fence to enable
 197  *
 198  * this will request for sw signaling to be enabled, to make the fence
 199  * complete as soon as possible
 200  */
 201 void dma_fence_enable_sw_signaling(struct dma_fence *fence)
 202 {
 203         unsigned long flags;
 204
 205         if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 206                               &fence->flags) &&
 207             !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 208                 trace_dma_fence_enable_signal(fence);
 209
 210                 spin_lock_irqsave(fence->lock, flags);
 211
 212                 if (!fence->ops->enable_signaling(fence))
 213                         dma_fence_signal_locked(fence);
 214
 215                 spin_unlock_irqrestore(fence->lock, flags);
 216         }
 217 }
 218 EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
 219
 220 /**
 221  * dma_fence_add_callback - add a callback to be called when the fence
 222  * is signaled
 223  * @fence:      [in]    the fence to wait on
 224  * @cb:         [in]    the callback to register
 225  * @func:       [in]    the function to call
 226  *
 227  * cb will be initialized by dma_fence_add_callback, no initialization
 228  * by the caller is required. Any number of callbacks can be registered
 229  * to a fence, but a callback can only be registered to one fence at a time.
 230  *
 231  * Note that the callback can be called from an atomic context.  If
 232  * fence is already signaled, this function will return -ENOENT (and
 233  * *not* call the callback)
 234  *
 235  * Add a software callback to the fence. Same restrictions apply to
 236  * refcount as it does to dma_fence_wait, however the caller doesn't need to
 237  * keep a refcount to fence afterwards: when software access is enabled,
 238  * the creator of the fence is required to keep the fence alive until
 239  * after it signals with dma_fence_signal. The callback itself can be called
 240  * from irq context.
 241  *
 242  */
 243 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
 244                            dma_fence_func_t func)
 245 {
 246         unsigned long flags;
 247         int ret = 0;
 248         bool was_set;
 249
 250         if (WARN_ON(!fence || !func))
 251                 return -EINVAL;
 252
 253         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 254                 INIT_LIST_HEAD(&cb->node);
 255                 return -ENOENT;
 256         }
 257
 258         spin_lock_irqsave(fence->lock, flags);
 259
 260         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 261                                    &fence->flags);
 262
 263         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 264                 ret = -ENOENT;
 265         else if (!was_set) {
 266                 trace_dma_fence_enable_signal(fence);
 267
 268                 if (!fence->ops->enable_signaling(fence)) {
 269                         dma_fence_signal_locked(fence);
 270                         ret = -ENOENT;
 271                 }
 272         }
 273
 274         if (!ret) {
 275                 cb->func = func;
 276                 list_add_tail(&cb->node, &fence->cb_list);
 277         } else
 278                 INIT_LIST_HEAD(&cb->node);
 279         spin_unlock_irqrestore(fence->lock, flags);
 280
 281         return ret;
 282 }
 283 EXPORT_SYMBOL(dma_fence_add_callback);
 284
 285 /**
 286  * dma_fence_get_status - returns the status upon completion
 287  * @fence: [in] the dma_fence to query
 288  *
 289  * This wraps dma_fence_get_status_locked() to return the error status
 290  * condition on a signaled fence. See dma_fence_get_status_locked() for more
 291  * details.
 292  *
 293  * Returns 0 if the fence has not yet been signaled, 1 if the fence has
 294  * been signaled without an error condition, or a negative error code
 295  * if the fence has been completed in err.
 296  */
 297 int dma_fence_get_status(struct dma_fence *fence)
 298 {
 299         unsigned long flags;
 300         int status;
 301
 302         spin_lock_irqsave(fence->lock, flags);
 303         status = dma_fence_get_status_locked(fence);
 304         spin_unlock_irqrestore(fence->lock, flags);
 305
 306         return status;
 307 }
 308 EXPORT_SYMBOL(dma_fence_get_status);
 309
 310 /**
 311  * dma_fence_remove_callback - remove a callback from the signaling list
 312  * @fence:      [in]    the fence to wait on
 313  * @cb:         [in]    the callback to remove
 314  *
 315  * Remove a previously queued callback from the fence. This function returns
 316  * true if the callback is successfully removed, or false if the fence has
 317  * already been signaled.
 318  *
 319  * *WARNING*:
 320  * Cancelling a callback should only be done if you really know what you're
 321  * doing, since deadlocks and race conditions could occur all too easily. For
 322  * this reason, it should only ever be done on hardware lockup recovery,
 323  * with a reference held to the fence.
 324  */
 325 bool
 326 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
 327 {
 328         unsigned long flags;
 329         bool ret;
 330
 331         spin_lock_irqsave(fence->lock, flags);
 332
 333         ret = !list_empty(&cb->node);
 334         if (ret)
 335                 list_del_init(&cb->node);
 336
 337         spin_unlock_irqrestore(fence->lock, flags);
 338
 339         return ret;
 340 }
 341 EXPORT_SYMBOL(dma_fence_remove_callback);
 342
 343 struct default_wait_cb {
 344         struct dma_fence_cb base;
 345         struct task_struct *task;
 346 };
 347
 348 static void
 349 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 350 {
 351         struct default_wait_cb *wait =
 352                 container_of(cb, struct default_wait_cb, base);
 353
 354         wake_up_state(wait->task, TASK_NORMAL);
 355 }
 356
 357 /**
 358  * dma_fence_default_wait - default sleep until the fence gets signaled
 359  * or until timeout elapses
 360  * @fence:      [in]    the fence to wait on
 361  * @intr:       [in]    if true, do an interruptible wait
 362  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 363  *
 364  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 365  * remaining timeout in jiffies on success. If timeout is zero the value one is
 366  * returned if the fence is already signaled for consistency with other
 367  * functions taking a jiffies timeout.
 368  */
 369 signed long
 370 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
 371 {
 372         struct default_wait_cb cb;
 373         unsigned long flags;
 374         signed long ret = timeout ? timeout : 1;
 375         bool was_set;
 376
 377         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 378                 return ret;
 379
 380         spin_lock_irqsave(fence->lock, flags);
 381
 382         if (intr && signal_pending(current)) {
 383                 ret = -ERESTARTSYS;
 384                 goto out;
 385         }
 386
 387         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 388                                    &fence->flags);
 389
 390         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 391                 goto out;
 392
 393         if (!was_set) {
 394                 trace_dma_fence_enable_signal(fence);
 395
 396                 if (!fence->ops->enable_signaling(fence)) {
 397                         dma_fence_signal_locked(fence);
 398                         goto out;
 399                 }
 400         }
 401
 402         cb.base.func = dma_fence_default_wait_cb;
 403         cb.task = current;
 404         list_add(&cb.base.node, &fence->cb_list);
 405
 406         while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
 407                 if (intr)
 408                         __set_current_state(TASK_INTERRUPTIBLE);
 409                 else
 410                         __set_current_state(TASK_UNINTERRUPTIBLE);
 411                 spin_unlock_irqrestore(fence->lock, flags);
 412
 413                 ret = schedule_timeout(ret);
 414
 415                 spin_lock_irqsave(fence->lock, flags);
 416                 if (ret > 0 && intr && signal_pending(current))
 417                         ret = -ERESTARTSYS;
 418         }
 419
 420         if (!list_empty(&cb.base.node))
 421                 list_del(&cb.base.node);
 422         __set_current_state(TASK_RUNNING);
 423
 424 out:
 425         spin_unlock_irqrestore(fence->lock, flags);
 426         return ret;
 427 }
 428 EXPORT_SYMBOL(dma_fence_default_wait);
 429
 430 static bool
 431 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
 432                             uint32_t *idx)
 433 {
 434         int i;
 435
 436         for (i = 0; i < count; ++i) {
 437                 struct dma_fence *fence = fences[i];
 438                 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 439                         if (idx)
 440                                 *idx = i;
 441                         return true;
 442                 }
 443         }
 444         return false;
 445 }
 446
 447 /**
 448  * dma_fence_wait_any_timeout - sleep until any fence gets signaled
 449  * or until timeout elapses
 450  * @fences:     [in]    array of fences to wait on
 451  * @count:      [in]    number of fences to wait on
 452  * @intr:       [in]    if true, do an interruptible wait
 453  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 454  * @idx:       [out]    the first signaled fence index, meaningful only on
 455  *                      positive return
 456  *
 457  * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
 458  * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
 459  * on success.
 460  *
 461  * Synchronous waits for the first fence in the array to be signaled. The
 462  * caller needs to hold a reference to all fences in the array, otherwise a
 463  * fence might be freed before return, resulting in undefined behavior.
 464  */
 465 signed long
 466 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 467                            bool intr, signed long timeout, uint32_t *idx)
 468 {
 469         struct default_wait_cb *cb;
 470         signed long ret = timeout;
 471         unsigned i;
 472
 473         if (WARN_ON(!fences || !count || timeout < 0))
 474                 return -EINVAL;
 475
 476         if (timeout == 0) {
 477                 for (i = 0; i < count; ++i)
 478                         if (dma_fence_is_signaled(fences[i])) {
 479                                 if (idx)
 480                                         *idx = i;
 481                                 return 1;
 482                         }
 483
 484                 return 0;
 485         }
 486
 487         cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
 488         if (cb == NULL) {
 489                 ret = -ENOMEM;
 490                 goto err_free_cb;
 491         }
 492
 493         for (i = 0; i < count; ++i) {
 494                 struct dma_fence *fence = fences[i];
 495
 496                 if (fence->ops->wait != dma_fence_default_wait) {
 497                         ret = -EINVAL;
 498                         goto fence_rm_cb;
 499                 }
 500
 501                 cb[i].task = current;
 502                 if (dma_fence_add_callback(fence, &cb[i].base,
 503                                            dma_fence_default_wait_cb)) {
 504                         /* This fence is already signaled */
 505                         if (idx)
 506                                 *idx = i;
 507                         goto fence_rm_cb;
 508                 }
 509         }
 510
 511         while (ret > 0) {
 512                 if (intr)
 513                         set_current_state(TASK_INTERRUPTIBLE);
 514                 else
 515                         set_current_state(TASK_UNINTERRUPTIBLE);
 516
 517                 if (dma_fence_test_signaled_any(fences, count, idx))
 518                         break;
 519
 520                 ret = schedule_timeout(ret);
 521
 522                 if (ret > 0 && intr && signal_pending(current))
 523                         ret = -ERESTARTSYS;
 524         }
 525
 526         __set_current_state(TASK_RUNNING);
 527
 528 fence_rm_cb:
 529         while (i-- > 0)
 530                 dma_fence_remove_callback(fences[i], &cb[i].base);
 531
 532 err_free_cb:
 533         kfree(cb);
 534
 535         return ret;
 536 }
 537 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
 538
 539 /**
 540  * dma_fence_init - Initialize a custom fence.
 541  * @fence:      [in]    the fence to initialize
 542  * @ops:        [in]    the dma_fence_ops for operations on this fence
 543  * @lock:       [in]    the irqsafe spinlock to use for locking this fence
 544  * @context:    [in]    the execution context this fence is run on
 545  * @seqno:      [in]    a linear increasing sequence number for this context
 546  *
 547  * Initializes an allocated fence, the caller doesn't have to keep its
 548  * refcount after committing with this fence, but it will need to hold a
 549  * refcount again if dma_fence_ops.enable_signaling gets called. This can
 550  * be used for other implementing other types of fence.
 551  *
 552  * context and seqno are used for easy comparison between fences, allowing
 553  * to check which fence is later by simply using dma_fence_later.
 554  */
 555 void
 556 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 557                spinlock_t *lock, u64 context, unsigned seqno)
 558 {
 559         BUG_ON(!lock);
 560         BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
 561                !ops->get_driver_name || !ops->get_timeline_name);
 562
 563         kref_init(&fence->refcount);
 564         fence->ops = ops;
 565         INIT_LIST_HEAD(&fence->cb_list);
 566         fence->lock = lock;
 567         fence->context = context;
 568         fence->seqno = seqno;
 569         fence->flags = 0UL;
 570         fence->error = 0;
 571
 572         trace_dma_fence_init(fence);
 573 }
 574 EXPORT_SYMBOL(dma_fence_init);