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         ret = fence->ops->wait(fence, intr, timeout);
 162         trace_dma_fence_wait_end(fence);
 163         return ret;
 164 }
 165 EXPORT_SYMBOL(dma_fence_wait_timeout);
 166
 167 void dma_fence_release(struct kref *kref)
 168 {
 169         struct dma_fence *fence =
 170                 container_of(kref, struct dma_fence, refcount);
 171
 172         trace_dma_fence_destroy(fence);
 173
 174         WARN_ON(!list_empty(&fence->cb_list));
 175
 176         if (fence->ops->release)
 177                 fence->ops->release(fence);
 178         else
 179                 dma_fence_free(fence);
 180 }
 181 EXPORT_SYMBOL(dma_fence_release);
 182
 183 void dma_fence_free(struct dma_fence *fence)
 184 {
 185         kfree_rcu(fence, rcu);
 186 }
 187 EXPORT_SYMBOL(dma_fence_free);
 188
 189 /**
 190  * dma_fence_enable_sw_signaling - enable signaling on fence
 191  * @fence:      [in]    the fence to enable
 192  *
 193  * this will request for sw signaling to be enabled, to make the fence
 194  * complete as soon as possible
 195  */
 196 void dma_fence_enable_sw_signaling(struct dma_fence *fence)
 197 {
 198         unsigned long flags;
 199
 200         if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 201                               &fence->flags) &&
 202             !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 203                 trace_dma_fence_enable_signal(fence);
 204
 205                 spin_lock_irqsave(fence->lock, flags);
 206
 207                 if (!fence->ops->enable_signaling(fence))
 208                         dma_fence_signal_locked(fence);
 209
 210                 spin_unlock_irqrestore(fence->lock, flags);
 211         }
 212 }
 213 EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
 214
 215 /**
 216  * dma_fence_add_callback - add a callback to be called when the fence
 217  * is signaled
 218  * @fence:      [in]    the fence to wait on
 219  * @cb:         [in]    the callback to register
 220  * @func:       [in]    the function to call
 221  *
 222  * cb will be initialized by dma_fence_add_callback, no initialization
 223  * by the caller is required. Any number of callbacks can be registered
 224  * to a fence, but a callback can only be registered to one fence at a time.
 225  *
 226  * Note that the callback can be called from an atomic context.  If
 227  * fence is already signaled, this function will return -ENOENT (and
 228  * *not* call the callback)
 229  *
 230  * Add a software callback to the fence. Same restrictions apply to
 231  * refcount as it does to dma_fence_wait, however the caller doesn't need to
 232  * keep a refcount to fence afterwards: when software access is enabled,
 233  * the creator of the fence is required to keep the fence alive until
 234  * after it signals with dma_fence_signal. The callback itself can be called
 235  * from irq context.
 236  *
 237  * Returns 0 in case of success, -ENOENT if the fence is already signaled
 238  * and -EINVAL in case of error.
 239  */
 240 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
 241                            dma_fence_func_t func)
 242 {
 243         unsigned long flags;
 244         int ret = 0;
 245         bool was_set;
 246
 247         if (WARN_ON(!fence || !func))
 248                 return -EINVAL;
 249
 250         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 251                 INIT_LIST_HEAD(&cb->node);
 252                 return -ENOENT;
 253         }
 254
 255         spin_lock_irqsave(fence->lock, flags);
 256
 257         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 258                                    &fence->flags);
 259
 260         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 261                 ret = -ENOENT;
 262         else if (!was_set) {
 263                 trace_dma_fence_enable_signal(fence);
 264
 265                 if (!fence->ops->enable_signaling(fence)) {
 266                         dma_fence_signal_locked(fence);
 267                         ret = -ENOENT;
 268                 }
 269         }
 270
 271         if (!ret) {
 272                 cb->func = func;
 273                 list_add_tail(&cb->node, &fence->cb_list);
 274         } else
 275                 INIT_LIST_HEAD(&cb->node);
 276         spin_unlock_irqrestore(fence->lock, flags);
 277
 278         return ret;
 279 }
 280 EXPORT_SYMBOL(dma_fence_add_callback);
 281
 282 /**
 283  * dma_fence_get_status - returns the status upon completion
 284  * @fence: [in] the dma_fence to query
 285  *
 286  * This wraps dma_fence_get_status_locked() to return the error status
 287  * condition on a signaled fence. See dma_fence_get_status_locked() for more
 288  * details.
 289  *
 290  * Returns 0 if the fence has not yet been signaled, 1 if the fence has
 291  * been signaled without an error condition, or a negative error code
 292  * if the fence has been completed in err.
 293  */
 294 int dma_fence_get_status(struct dma_fence *fence)
 295 {
 296         unsigned long flags;
 297         int status;
 298
 299         spin_lock_irqsave(fence->lock, flags);
 300         status = dma_fence_get_status_locked(fence);
 301         spin_unlock_irqrestore(fence->lock, flags);
 302
 303         return status;
 304 }
 305 EXPORT_SYMBOL(dma_fence_get_status);
 306
 307 /**
 308  * dma_fence_remove_callback - remove a callback from the signaling list
 309  * @fence:      [in]    the fence to wait on
 310  * @cb:         [in]    the callback to remove
 311  *
 312  * Remove a previously queued callback from the fence. This function returns
 313  * true if the callback is successfully removed, or false if the fence has
 314  * already been signaled.
 315  *
 316  * *WARNING*:
 317  * Cancelling a callback should only be done if you really know what you're
 318  * doing, since deadlocks and race conditions could occur all too easily. For
 319  * this reason, it should only ever be done on hardware lockup recovery,
 320  * with a reference held to the fence.
 321  */
 322 bool
 323 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
 324 {
 325         unsigned long flags;
 326         bool ret;
 327
 328         spin_lock_irqsave(fence->lock, flags);
 329
 330         ret = !list_empty(&cb->node);
 331         if (ret)
 332                 list_del_init(&cb->node);
 333
 334         spin_unlock_irqrestore(fence->lock, flags);
 335
 336         return ret;
 337 }
 338 EXPORT_SYMBOL(dma_fence_remove_callback);
 339
 340 struct default_wait_cb {
 341         struct dma_fence_cb base;
 342         struct task_struct *task;
 343 };
 344
 345 static void
 346 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 347 {
 348         struct default_wait_cb *wait =
 349                 container_of(cb, struct default_wait_cb, base);
 350
 351         wake_up_state(wait->task, TASK_NORMAL);
 352 }
 353
 354 /**
 355  * dma_fence_default_wait - default sleep until the fence gets signaled
 356  * or until timeout elapses
 357  * @fence:      [in]    the fence to wait on
 358  * @intr:       [in]    if true, do an interruptible wait
 359  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 360  *
 361  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 362  * remaining timeout in jiffies on success. If timeout is zero the value one is
 363  * returned if the fence is already signaled for consistency with other
 364  * functions taking a jiffies timeout.
 365  */
 366 signed long
 367 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
 368 {
 369         struct default_wait_cb cb;
 370         unsigned long flags;
 371         signed long ret = timeout ? timeout : 1;
 372         bool was_set;
 373
 374         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 375                 return ret;
 376
 377         spin_lock_irqsave(fence->lock, flags);
 378
 379         if (intr && signal_pending(current)) {
 380                 ret = -ERESTARTSYS;
 381                 goto out;
 382         }
 383
 384         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 385                                    &fence->flags);
 386
 387         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 388                 goto out;
 389
 390         if (!was_set) {
 391                 trace_dma_fence_enable_signal(fence);
 392
 393                 if (!fence->ops->enable_signaling(fence)) {
 394                         dma_fence_signal_locked(fence);
 395                         goto out;
 396                 }
 397         }
 398
 399         if (!timeout) {
 400                 ret = 0;
 401                 goto out;
 402         }
 403
 404         cb.base.func = dma_fence_default_wait_cb;
 405         cb.task = current;
 406         list_add(&cb.base.node, &fence->cb_list);
 407
 408         while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
 409                 if (intr)
 410                         __set_current_state(TASK_INTERRUPTIBLE);
 411                 else
 412                         __set_current_state(TASK_UNINTERRUPTIBLE);
 413                 spin_unlock_irqrestore(fence->lock, flags);
 414
 415                 ret = schedule_timeout(ret);
 416
 417                 spin_lock_irqsave(fence->lock, flags);
 418                 if (ret > 0 && intr && signal_pending(current))
 419                         ret = -ERESTARTSYS;
 420         }
 421
 422         if (!list_empty(&cb.base.node))
 423                 list_del(&cb.base.node);
 424         __set_current_state(TASK_RUNNING);
 425
 426 out:
 427         spin_unlock_irqrestore(fence->lock, flags);
 428         return ret;
 429 }
 430 EXPORT_SYMBOL(dma_fence_default_wait);
 431
 432 static bool
 433 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
 434                             uint32_t *idx)
 435 {
 436         int i;
 437
 438         for (i = 0; i < count; ++i) {
 439                 struct dma_fence *fence = fences[i];
 440                 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 441                         if (idx)
 442                                 *idx = i;
 443                         return true;
 444                 }
 445         }
 446         return false;
 447 }
 448
 449 /**
 450  * dma_fence_wait_any_timeout - sleep until any fence gets signaled
 451  * or until timeout elapses
 452  * @fences:     [in]    array of fences to wait on
 453  * @count:      [in]    number of fences to wait on
 454  * @intr:       [in]    if true, do an interruptible wait
 455  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 456  * @idx:       [out]    the first signaled fence index, meaningful only on
 457  *                      positive return
 458  *
 459  * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
 460  * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
 461  * on success.
 462  *
 463  * Synchronous waits for the first fence in the array to be signaled. The
 464  * caller needs to hold a reference to all fences in the array, otherwise a
 465  * fence might be freed before return, resulting in undefined behavior.
 466  */
 467 signed long
 468 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 469                            bool intr, signed long timeout, uint32_t *idx)
 470 {
 471         struct default_wait_cb *cb;
 472         signed long ret = timeout;
 473         unsigned i;
 474
 475         if (WARN_ON(!fences || !count || timeout < 0))
 476                 return -EINVAL;
 477
 478         if (timeout == 0) {
 479                 for (i = 0; i < count; ++i)
 480                         if (dma_fence_is_signaled(fences[i])) {
 481                                 if (idx)
 482                                         *idx = i;
 483                                 return 1;
 484                         }
 485
 486                 return 0;
 487         }
 488
 489         cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
 490         if (cb == NULL) {
 491                 ret = -ENOMEM;
 492                 goto err_free_cb;
 493         }
 494
 495         for (i = 0; i < count; ++i) {
 496                 struct dma_fence *fence = fences[i];
 497
 498                 if (fence->ops->wait != dma_fence_default_wait) {
 499                         ret = -EINVAL;
 500                         goto fence_rm_cb;
 501                 }
 502
 503                 cb[i].task = current;
 504                 if (dma_fence_add_callback(fence, &cb[i].base,
 505                                            dma_fence_default_wait_cb)) {
 506                         /* This fence is already signaled */
 507                         if (idx)
 508                                 *idx = i;
 509                         goto fence_rm_cb;
 510                 }
 511         }
 512
 513         while (ret > 0) {
 514                 if (intr)
 515                         set_current_state(TASK_INTERRUPTIBLE);
 516                 else
 517                         set_current_state(TASK_UNINTERRUPTIBLE);
 518
 519                 if (dma_fence_test_signaled_any(fences, count, idx))
 520                         break;
 521
 522                 ret = schedule_timeout(ret);
 523
 524                 if (ret > 0 && intr && signal_pending(current))
 525                         ret = -ERESTARTSYS;
 526         }
 527
 528         __set_current_state(TASK_RUNNING);
 529
 530 fence_rm_cb:
 531         while (i-- > 0)
 532                 dma_fence_remove_callback(fences[i], &cb[i].base);
 533
 534 err_free_cb:
 535         kfree(cb);
 536
 537         return ret;
 538 }
 539 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
 540
 541 /**
 542  * dma_fence_init - Initialize a custom fence.
 543  * @fence:      [in]    the fence to initialize
 544  * @ops:        [in]    the dma_fence_ops for operations on this fence
 545  * @lock:       [in]    the irqsafe spinlock to use for locking this fence
 546  * @context:    [in]    the execution context this fence is run on
 547  * @seqno:      [in]    a linear increasing sequence number for this context
 548  *
 549  * Initializes an allocated fence, the caller doesn't have to keep its
 550  * refcount after committing with this fence, but it will need to hold a
 551  * refcount again if dma_fence_ops.enable_signaling gets called. This can
 552  * be used for other implementing other types of fence.
 553  *
 554  * context and seqno are used for easy comparison between fences, allowing
 555  * to check which fence is later by simply using dma_fence_later.
 556  */
 557 void
 558 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 559                spinlock_t *lock, u64 context, unsigned seqno)
 560 {
 561         BUG_ON(!lock);
 562         BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
 563                !ops->get_driver_name || !ops->get_timeline_name);
 564
 565         kref_init(&fence->refcount);
 566         fence->ops = ops;
 567         INIT_LIST_HEAD(&fence->cb_list);
 568         fence->lock = lock;
 569         fence->context = context;
 570         fence->seqno = seqno;
 571         fence->flags = 0UL;
 572         fence->error = 0;
 573
 574         trace_dma_fence_init(fence);
 575 }
 576 EXPORT_SYMBOL(dma_fence_init);