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 #include <linux/sched/signal.h>
  26
  27 #define CREATE_TRACE_POINTS
  28 #include <trace/events/dma_fence.h>
  29
  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         WARN_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 (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
  78                 ret = -EINVAL;
  79
  80                 /*
  81                  * we might have raced with the unlocked dma_fence_signal,
  82                  * still run through all callbacks
  83                  */
  84         } else {
  85                 fence->timestamp = ktime_get();
  86                 set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
  87                 trace_dma_fence_signaled(fence);
  88         }
  89
  90         list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
  91                 list_del_init(&cur->node);
  92                 cur->func(fence, cur);
  93         }
  94         return ret;
  95 }
  96 EXPORT_SYMBOL(dma_fence_signal_locked);
  97
  98 /**
  99  * dma_fence_signal - signal completion of a fence
 100  * @fence: the fence to signal
 101  *
 102  * Signal completion for software callbacks on a fence, this will unblock
 103  * dma_fence_wait() calls and run all the callbacks added with
 104  * dma_fence_add_callback(). Can be called multiple times, but since a fence
 105  * can only go from unsignaled to signaled state, it will only be effective
 106  * the first time.
 107  */
 108 int dma_fence_signal(struct dma_fence *fence)
 109 {
 110         unsigned long flags;
 111
 112         if (!fence)
 113                 return -EINVAL;
 114
 115         if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 116                 return -EINVAL;
 117
 118         fence->timestamp = ktime_get();
 119         set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
 120         trace_dma_fence_signaled(fence);
 121
 122         if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
 123                 struct dma_fence_cb *cur, *tmp;
 124
 125                 spin_lock_irqsave(fence->lock, flags);
 126                 list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
 127                         list_del_init(&cur->node);
 128                         cur->func(fence, cur);
 129                 }
 130                 spin_unlock_irqrestore(fence->lock, flags);
 131         }
 132         return 0;
 133 }
 134 EXPORT_SYMBOL(dma_fence_signal);
 135
 136 /**
 137  * dma_fence_wait_timeout - sleep until the fence gets signaled
 138  * or until timeout elapses
 139  * @fence:      [in]    the fence to wait on
 140  * @intr:       [in]    if true, do an interruptible wait
 141  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 142  *
 143  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 144  * remaining timeout in jiffies on success. Other error values may be
 145  * returned on custom implementations.
 146  *
 147  * Performs a synchronous wait on this fence. It is assumed the caller
 148  * directly or indirectly (buf-mgr between reservation and committing)
 149  * holds a reference to the fence, otherwise the fence might be
 150  * freed before return, resulting in undefined behavior.
 151  */
 152 signed long
 153 dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
 154 {
 155         signed long ret;
 156
 157         if (WARN_ON(timeout < 0))
 158                 return -EINVAL;
 159
 160         trace_dma_fence_wait_start(fence);
 161         if (fence->ops->wait)
 162                 ret = fence->ops->wait(fence, intr, timeout);
 163         else
 164                 ret = dma_fence_default_wait(fence, intr, timeout);
 165         trace_dma_fence_wait_end(fence);
 166         return ret;
 167 }
 168 EXPORT_SYMBOL(dma_fence_wait_timeout);
 169
 170 void dma_fence_release(struct kref *kref)
 171 {
 172         struct dma_fence *fence =
 173                 container_of(kref, struct dma_fence, refcount);
 174
 175         trace_dma_fence_destroy(fence);
 176
 177         /* Failed to signal before release, could be a refcounting issue */
 178         WARN_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 /**
 188  * dma_fence_free - default release function for &dma_fence.
 189  * @fence: fence to release
 190  *
 191  * This is the default implementation for &dma_fence_ops.release. It calls
 192  * kfree_rcu() on @fence.
 193  */
 194 void dma_fence_free(struct dma_fence *fence)
 195 {
 196         kfree_rcu(fence, rcu);
 197 }
 198 EXPORT_SYMBOL(dma_fence_free);
 199
 200 /**
 201  * dma_fence_enable_sw_signaling - enable signaling on fence
 202  * @fence:      [in]    the fence to enable
 203  *
 204  * this will request for sw signaling to be enabled, to make the fence
 205  * complete as soon as possible
 206  */
 207 void dma_fence_enable_sw_signaling(struct dma_fence *fence)
 208 {
 209         unsigned long flags;
 210
 211         if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 212                               &fence->flags) &&
 213             !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 214                 trace_dma_fence_enable_signal(fence);
 215
 216                 spin_lock_irqsave(fence->lock, flags);
 217
 218                 if (!fence->ops->enable_signaling(fence))
 219                         dma_fence_signal_locked(fence);
 220
 221                 spin_unlock_irqrestore(fence->lock, flags);
 222         }
 223 }
 224 EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
 225
 226 /**
 227  * dma_fence_add_callback - add a callback to be called when the fence
 228  * is signaled
 229  * @fence:      [in]    the fence to wait on
 230  * @cb:         [in]    the callback to register
 231  * @func:       [in]    the function to call
 232  *
 233  * cb will be initialized by dma_fence_add_callback, no initialization
 234  * by the caller is required. Any number of callbacks can be registered
 235  * to a fence, but a callback can only be registered to one fence at a time.
 236  *
 237  * Note that the callback can be called from an atomic context.  If
 238  * fence is already signaled, this function will return -ENOENT (and
 239  * *not* call the callback)
 240  *
 241  * Add a software callback to the fence. Same restrictions apply to
 242  * refcount as it does to dma_fence_wait, however the caller doesn't need to
 243  * keep a refcount to fence afterwards: when software access is enabled,
 244  * the creator of the fence is required to keep the fence alive until
 245  * after it signals with dma_fence_signal. The callback itself can be called
 246  * from irq context.
 247  *
 248  * Returns 0 in case of success, -ENOENT if the fence is already signaled
 249  * and -EINVAL in case of error.
 250  */
 251 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
 252                            dma_fence_func_t func)
 253 {
 254         unsigned long flags;
 255         int ret = 0;
 256         bool was_set;
 257
 258         if (WARN_ON(!fence || !func))
 259                 return -EINVAL;
 260
 261         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 262                 INIT_LIST_HEAD(&cb->node);
 263                 return -ENOENT;
 264         }
 265
 266         spin_lock_irqsave(fence->lock, flags);
 267
 268         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 269                                    &fence->flags);
 270
 271         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 272                 ret = -ENOENT;
 273         else if (!was_set) {
 274                 trace_dma_fence_enable_signal(fence);
 275
 276                 if (!fence->ops->enable_signaling(fence)) {
 277                         dma_fence_signal_locked(fence);
 278                         ret = -ENOENT;
 279                 }
 280         }
 281
 282         if (!ret) {
 283                 cb->func = func;
 284                 list_add_tail(&cb->node, &fence->cb_list);
 285         } else
 286                 INIT_LIST_HEAD(&cb->node);
 287         spin_unlock_irqrestore(fence->lock, flags);
 288
 289         return ret;
 290 }
 291 EXPORT_SYMBOL(dma_fence_add_callback);
 292
 293 /**
 294  * dma_fence_get_status - returns the status upon completion
 295  * @fence: [in] the dma_fence to query
 296  *
 297  * This wraps dma_fence_get_status_locked() to return the error status
 298  * condition on a signaled fence. See dma_fence_get_status_locked() for more
 299  * details.
 300  *
 301  * Returns 0 if the fence has not yet been signaled, 1 if the fence has
 302  * been signaled without an error condition, or a negative error code
 303  * if the fence has been completed in err.
 304  */
 305 int dma_fence_get_status(struct dma_fence *fence)
 306 {
 307         unsigned long flags;
 308         int status;
 309
 310         spin_lock_irqsave(fence->lock, flags);
 311         status = dma_fence_get_status_locked(fence);
 312         spin_unlock_irqrestore(fence->lock, flags);
 313
 314         return status;
 315 }
 316 EXPORT_SYMBOL(dma_fence_get_status);
 317
 318 /**
 319  * dma_fence_remove_callback - remove a callback from the signaling list
 320  * @fence:      [in]    the fence to wait on
 321  * @cb:         [in]    the callback to remove
 322  *
 323  * Remove a previously queued callback from the fence. This function returns
 324  * true if the callback is successfully removed, or false if the fence has
 325  * already been signaled.
 326  *
 327  * *WARNING*:
 328  * Cancelling a callback should only be done if you really know what you're
 329  * doing, since deadlocks and race conditions could occur all too easily. For
 330  * this reason, it should only ever be done on hardware lockup recovery,
 331  * with a reference held to the fence.
 332  */
 333 bool
 334 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
 335 {
 336         unsigned long flags;
 337         bool ret;
 338
 339         spin_lock_irqsave(fence->lock, flags);
 340
 341         ret = !list_empty(&cb->node);
 342         if (ret)
 343                 list_del_init(&cb->node);
 344
 345         spin_unlock_irqrestore(fence->lock, flags);
 346
 347         return ret;
 348 }
 349 EXPORT_SYMBOL(dma_fence_remove_callback);
 350
 351 struct default_wait_cb {
 352         struct dma_fence_cb base;
 353         struct task_struct *task;
 354 };
 355
 356 static void
 357 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 358 {
 359         struct default_wait_cb *wait =
 360                 container_of(cb, struct default_wait_cb, base);
 361
 362         wake_up_state(wait->task, TASK_NORMAL);
 363 }
 364
 365 /**
 366  * dma_fence_default_wait - default sleep until the fence gets signaled
 367  * or until timeout elapses
 368  * @fence:      [in]    the fence to wait on
 369  * @intr:       [in]    if true, do an interruptible wait
 370  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 371  *
 372  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 373  * remaining timeout in jiffies on success. If timeout is zero the value one is
 374  * returned if the fence is already signaled for consistency with other
 375  * functions taking a jiffies timeout.
 376  */
 377 signed long
 378 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
 379 {
 380         struct default_wait_cb cb;
 381         unsigned long flags;
 382         signed long ret = timeout ? timeout : 1;
 383         bool was_set;
 384
 385         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 386                 return ret;
 387
 388         spin_lock_irqsave(fence->lock, flags);
 389
 390         if (intr && signal_pending(current)) {
 391                 ret = -ERESTARTSYS;
 392                 goto out;
 393         }
 394
 395         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 396                                    &fence->flags);
 397
 398         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 399                 goto out;
 400
 401         if (!was_set) {
 402                 trace_dma_fence_enable_signal(fence);
 403
 404                 if (!fence->ops->enable_signaling(fence)) {
 405                         dma_fence_signal_locked(fence);
 406                         goto out;
 407                 }
 408         }
 409
 410         if (!timeout) {
 411                 ret = 0;
 412                 goto out;
 413         }
 414
 415         cb.base.func = dma_fence_default_wait_cb;
 416         cb.task = current;
 417         list_add(&cb.base.node, &fence->cb_list);
 418
 419         while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
 420                 if (intr)
 421                         __set_current_state(TASK_INTERRUPTIBLE);
 422                 else
 423                         __set_current_state(TASK_UNINTERRUPTIBLE);
 424                 spin_unlock_irqrestore(fence->lock, flags);
 425
 426                 ret = schedule_timeout(ret);
 427
 428                 spin_lock_irqsave(fence->lock, flags);
 429                 if (ret > 0 && intr && signal_pending(current))
 430                         ret = -ERESTARTSYS;
 431         }
 432
 433         if (!list_empty(&cb.base.node))
 434                 list_del(&cb.base.node);
 435         __set_current_state(TASK_RUNNING);
 436
 437 out:
 438         spin_unlock_irqrestore(fence->lock, flags);
 439         return ret;
 440 }
 441 EXPORT_SYMBOL(dma_fence_default_wait);
 442
 443 static bool
 444 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
 445                             uint32_t *idx)
 446 {
 447         int i;
 448
 449         for (i = 0; i < count; ++i) {
 450                 struct dma_fence *fence = fences[i];
 451                 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 452                         if (idx)
 453                                 *idx = i;
 454                         return true;
 455                 }
 456         }
 457         return false;
 458 }
 459
 460 /**
 461  * dma_fence_wait_any_timeout - sleep until any fence gets signaled
 462  * or until timeout elapses
 463  * @fences:     [in]    array of fences to wait on
 464  * @count:      [in]    number of fences to wait on
 465  * @intr:       [in]    if true, do an interruptible wait
 466  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 467  * @idx:       [out]    the first signaled fence index, meaningful only on
 468  *                      positive return
 469  *
 470  * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
 471  * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
 472  * on success.
 473  *
 474  * Synchronous waits for the first fence in the array to be signaled. The
 475  * caller needs to hold a reference to all fences in the array, otherwise a
 476  * fence might be freed before return, resulting in undefined behavior.
 477  */
 478 signed long
 479 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 480                            bool intr, signed long timeout, uint32_t *idx)
 481 {
 482         struct default_wait_cb *cb;
 483         signed long ret = timeout;
 484         unsigned i;
 485
 486         if (WARN_ON(!fences || !count || timeout < 0))
 487                 return -EINVAL;
 488
 489         if (timeout == 0) {
 490                 for (i = 0; i < count; ++i)
 491                         if (dma_fence_is_signaled(fences[i])) {
 492                                 if (idx)
 493                                         *idx = i;
 494                                 return 1;
 495                         }
 496
 497                 return 0;
 498         }
 499
 500         cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
 501         if (cb == NULL) {
 502                 ret = -ENOMEM;
 503                 goto err_free_cb;
 504         }
 505
 506         for (i = 0; i < count; ++i) {
 507                 struct dma_fence *fence = fences[i];
 508
 509                 cb[i].task = current;
 510                 if (dma_fence_add_callback(fence, &cb[i].base,
 511                                            dma_fence_default_wait_cb)) {
 512                         /* This fence is already signaled */
 513                         if (idx)
 514                                 *idx = i;
 515                         goto fence_rm_cb;
 516                 }
 517         }
 518
 519         while (ret > 0) {
 520                 if (intr)
 521                         set_current_state(TASK_INTERRUPTIBLE);
 522                 else
 523                         set_current_state(TASK_UNINTERRUPTIBLE);
 524
 525                 if (dma_fence_test_signaled_any(fences, count, idx))
 526                         break;
 527
 528                 ret = schedule_timeout(ret);
 529
 530                 if (ret > 0 && intr && signal_pending(current))
 531                         ret = -ERESTARTSYS;
 532         }
 533
 534         __set_current_state(TASK_RUNNING);
 535
 536 fence_rm_cb:
 537         while (i-- > 0)
 538                 dma_fence_remove_callback(fences[i], &cb[i].base);
 539
 540 err_free_cb:
 541         kfree(cb);
 542
 543         return ret;
 544 }
 545 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
 546
 547 /**
 548  * dma_fence_init - Initialize a custom fence.
 549  * @fence:      [in]    the fence to initialize
 550  * @ops:        [in]    the dma_fence_ops for operations on this fence
 551  * @lock:       [in]    the irqsafe spinlock to use for locking this fence
 552  * @context:    [in]    the execution context this fence is run on
 553  * @seqno:      [in]    a linear increasing sequence number for this context
 554  *
 555  * Initializes an allocated fence, the caller doesn't have to keep its
 556  * refcount after committing with this fence, but it will need to hold a
 557  * refcount again if dma_fence_ops.enable_signaling gets called. This can
 558  * be used for other implementing other types of fence.
 559  *
 560  * context and seqno are used for easy comparison between fences, allowing
 561  * to check which fence is later by simply using dma_fence_later.
 562  */
 563 void
 564 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 565                spinlock_t *lock, u64 context, unsigned seqno)
 566 {
 567         BUG_ON(!lock);
 568         BUG_ON(!ops || !ops->wait ||
 569                !ops->get_driver_name || !ops->get_timeline_name);
 570
 571         kref_init(&fence->refcount);
 572         fence->ops = ops;
 573         INIT_LIST_HEAD(&fence->cb_list);
 574         fence->lock = lock;
 575         fence->context = context;
 576         fence->seqno = seqno;
 577         fence->flags = 0UL;
 578         fence->error = 0;
 579
 580         if (!ops->enable_signaling)
 581                 set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 582                         &fence->flags);
 583
 584         trace_dma_fence_init(fence);
 585 }
 586 EXPORT_SYMBOL(dma_fence_init);