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_annotate_wait_on);
  31 EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit);
  32 EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal);
  33
  34 /*
  35  * fence context counter: each execution context should have its own
  36  * fence context, this allows checking if fences belong to the same
  37  * context or not. One device can have multiple separate contexts,
  38  * and they're used if some engine can run independently of another.
  39  */
  40 static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(0);
  41
  42 /**
  43  * dma_fence_context_alloc - allocate an array of fence contexts
  44  * @num:        [in]    amount of contexts to allocate
  45  *
  46  * This function will return the first index of the number of fences allocated.
  47  * The fence context is used for setting fence->context to a unique number.
  48  */
  49 u64 dma_fence_context_alloc(unsigned num)
  50 {
  51         BUG_ON(!num);
  52         return atomic64_add_return(num, &dma_fence_context_counter) - num;
  53 }
  54 EXPORT_SYMBOL(dma_fence_context_alloc);
  55
  56 /**
  57  * dma_fence_signal_locked - signal completion of a fence
  58  * @fence: the fence to signal
  59  *
  60  * Signal completion for software callbacks on a fence, this will unblock
  61  * dma_fence_wait() calls and run all the callbacks added with
  62  * dma_fence_add_callback(). Can be called multiple times, but since a fence
  63  * can only go from unsignaled to signaled state, it will only be effective
  64  * the first time.
  65  *
  66  * Unlike dma_fence_signal, this function must be called with fence->lock held.
  67  */
  68 int dma_fence_signal_locked(struct dma_fence *fence)
  69 {
  70         struct dma_fence_cb *cur, *tmp;
  71         int ret = 0;
  72
  73         lockdep_assert_held(fence->lock);
  74
  75         if (WARN_ON(!fence))
  76                 return -EINVAL;
  77
  78         if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
  79                 ret = -EINVAL;
  80
  81                 /*
  82                  * we might have raced with the unlocked dma_fence_signal,
  83                  * still run through all callbacks
  84                  */
  85         } else {
  86                 fence->timestamp = ktime_get();
  87                 set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
  88                 trace_dma_fence_signaled(fence);
  89         }
  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 (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 117                 return -EINVAL;
 118
 119         fence->timestamp = ktime_get();
 120         set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
 121         trace_dma_fence_signaled(fence);
 122
 123         if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
 124                 struct dma_fence_cb *cur, *tmp;
 125
 126                 spin_lock_irqsave(fence->lock, flags);
 127                 list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
 128                         list_del_init(&cur->node);
 129                         cur->func(fence, cur);
 130                 }
 131                 spin_unlock_irqrestore(fence->lock, flags);
 132         }
 133         return 0;
 134 }
 135 EXPORT_SYMBOL(dma_fence_signal);
 136
 137 /**
 138  * dma_fence_wait_timeout - sleep until the fence gets signaled
 139  * or until timeout elapses
 140  * @fence:      [in]    the fence to wait on
 141  * @intr:       [in]    if true, do an interruptible wait
 142  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 143  *
 144  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 145  * remaining timeout in jiffies on success. Other error values may be
 146  * returned on custom implementations.
 147  *
 148  * Performs a synchronous wait on this fence. It is assumed the caller
 149  * directly or indirectly (buf-mgr between reservation and committing)
 150  * holds a reference to the fence, otherwise the fence might be
 151  * freed before return, resulting in undefined behavior.
 152  */
 153 signed long
 154 dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
 155 {
 156         signed long ret;
 157
 158         if (WARN_ON(timeout < 0))
 159                 return -EINVAL;
 160
 161         trace_dma_fence_wait_start(fence);
 162         ret = fence->ops->wait(fence, intr, timeout);
 163         trace_dma_fence_wait_end(fence);
 164         return ret;
 165 }
 166 EXPORT_SYMBOL(dma_fence_wait_timeout);
 167
 168 void dma_fence_release(struct kref *kref)
 169 {
 170         struct dma_fence *fence =
 171                 container_of(kref, struct dma_fence, refcount);
 172
 173         trace_dma_fence_destroy(fence);
 174
 175         BUG_ON(!list_empty(&fence->cb_list));
 176
 177         if (fence->ops->release)
 178                 fence->ops->release(fence);
 179         else
 180                 dma_fence_free(fence);
 181 }
 182 EXPORT_SYMBOL(dma_fence_release);
 183
 184 void dma_fence_free(struct dma_fence *fence)
 185 {
 186         kfree_rcu(fence, rcu);
 187 }
 188 EXPORT_SYMBOL(dma_fence_free);
 189
 190 /**
 191  * dma_fence_enable_sw_signaling - enable signaling on fence
 192  * @fence:      [in]    the fence to enable
 193  *
 194  * this will request for sw signaling to be enabled, to make the fence
 195  * complete as soon as possible
 196  */
 197 void dma_fence_enable_sw_signaling(struct dma_fence *fence)
 198 {
 199         unsigned long flags;
 200
 201         if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 202                               &fence->flags) &&
 203             !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 204                 trace_dma_fence_enable_signal(fence);
 205
 206                 spin_lock_irqsave(fence->lock, flags);
 207
 208                 if (!fence->ops->enable_signaling(fence))
 209                         dma_fence_signal_locked(fence);
 210
 211                 spin_unlock_irqrestore(fence->lock, flags);
 212         }
 213 }
 214 EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
 215
 216 /**
 217  * dma_fence_add_callback - add a callback to be called when the fence
 218  * is signaled
 219  * @fence:      [in]    the fence to wait on
 220  * @cb:         [in]    the callback to register
 221  * @func:       [in]    the function to call
 222  *
 223  * cb will be initialized by dma_fence_add_callback, no initialization
 224  * by the caller is required. Any number of callbacks can be registered
 225  * to a fence, but a callback can only be registered to one fence at a time.
 226  *
 227  * Note that the callback can be called from an atomic context.  If
 228  * fence is already signaled, this function will return -ENOENT (and
 229  * *not* call the callback)
 230  *
 231  * Add a software callback to the fence. Same restrictions apply to
 232  * refcount as it does to dma_fence_wait, however the caller doesn't need to
 233  * keep a refcount to fence afterwards: when software access is enabled,
 234  * the creator of the fence is required to keep the fence alive until
 235  * after it signals with dma_fence_signal. The callback itself can be called
 236  * from irq context.
 237  *
 238  * Returns 0 in case of success, -ENOENT if the fence is already signaled
 239  * and -EINVAL in case of error.
 240  */
 241 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
 242                            dma_fence_func_t func)
 243 {
 244         unsigned long flags;
 245         int ret = 0;
 246         bool was_set;
 247
 248         if (WARN_ON(!fence || !func))
 249                 return -EINVAL;
 250
 251         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 252                 INIT_LIST_HEAD(&cb->node);
 253                 return -ENOENT;
 254         }
 255
 256         spin_lock_irqsave(fence->lock, flags);
 257
 258         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 259                                    &fence->flags);
 260
 261         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 262                 ret = -ENOENT;
 263         else if (!was_set) {
 264                 trace_dma_fence_enable_signal(fence);
 265
 266                 if (!fence->ops->enable_signaling(fence)) {
 267                         dma_fence_signal_locked(fence);
 268                         ret = -ENOENT;
 269                 }
 270         }
 271
 272         if (!ret) {
 273                 cb->func = func;
 274                 list_add_tail(&cb->node, &fence->cb_list);
 275         } else
 276                 INIT_LIST_HEAD(&cb->node);
 277         spin_unlock_irqrestore(fence->lock, flags);
 278
 279         return ret;
 280 }
 281 EXPORT_SYMBOL(dma_fence_add_callback);
 282
 283 /**
 284  * dma_fence_get_status - returns the status upon completion
 285  * @fence: [in] the dma_fence to query
 286  *
 287  * This wraps dma_fence_get_status_locked() to return the error status
 288  * condition on a signaled fence. See dma_fence_get_status_locked() for more
 289  * details.
 290  *
 291  * Returns 0 if the fence has not yet been signaled, 1 if the fence has
 292  * been signaled without an error condition, or a negative error code
 293  * if the fence has been completed in err.
 294  */
 295 int dma_fence_get_status(struct dma_fence *fence)
 296 {
 297         unsigned long flags;
 298         int status;
 299
 300         spin_lock_irqsave(fence->lock, flags);
 301         status = dma_fence_get_status_locked(fence);
 302         spin_unlock_irqrestore(fence->lock, flags);
 303
 304         return status;
 305 }
 306 EXPORT_SYMBOL(dma_fence_get_status);
 307
 308 /**
 309  * dma_fence_remove_callback - remove a callback from the signaling list
 310  * @fence:      [in]    the fence to wait on
 311  * @cb:         [in]    the callback to remove
 312  *
 313  * Remove a previously queued callback from the fence. This function returns
 314  * true if the callback is successfully removed, or false if the fence has
 315  * already been signaled.
 316  *
 317  * *WARNING*:
 318  * Cancelling a callback should only be done if you really know what you're
 319  * doing, since deadlocks and race conditions could occur all too easily. For
 320  * this reason, it should only ever be done on hardware lockup recovery,
 321  * with a reference held to the fence.
 322  */
 323 bool
 324 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
 325 {
 326         unsigned long flags;
 327         bool ret;
 328
 329         spin_lock_irqsave(fence->lock, flags);
 330
 331         ret = !list_empty(&cb->node);
 332         if (ret)
 333                 list_del_init(&cb->node);
 334
 335         spin_unlock_irqrestore(fence->lock, flags);
 336
 337         return ret;
 338 }
 339 EXPORT_SYMBOL(dma_fence_remove_callback);
 340
 341 struct default_wait_cb {
 342         struct dma_fence_cb base;
 343         struct task_struct *task;
 344 };
 345
 346 static void
 347 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 348 {
 349         struct default_wait_cb *wait =
 350                 container_of(cb, struct default_wait_cb, base);
 351
 352         wake_up_state(wait->task, TASK_NORMAL);
 353 }
 354
 355 /**
 356  * dma_fence_default_wait - default sleep until the fence gets signaled
 357  * or until timeout elapses
 358  * @fence:      [in]    the fence to wait on
 359  * @intr:       [in]    if true, do an interruptible wait
 360  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 361  *
 362  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 363  * remaining timeout in jiffies on success. If timeout is zero the value one is
 364  * returned if the fence is already signaled for consistency with other
 365  * functions taking a jiffies timeout.
 366  */
 367 signed long
 368 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
 369 {
 370         struct default_wait_cb cb;
 371         unsigned long flags;
 372         signed long ret = timeout ? timeout : 1;
 373         bool was_set;
 374
 375         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 376                 return ret;
 377
 378         spin_lock_irqsave(fence->lock, flags);
 379
 380         if (intr && signal_pending(current)) {
 381                 ret = -ERESTARTSYS;
 382                 goto out;
 383         }
 384
 385         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 386                                    &fence->flags);
 387
 388         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 389                 goto out;
 390
 391         if (!was_set) {
 392                 trace_dma_fence_enable_signal(fence);
 393
 394                 if (!fence->ops->enable_signaling(fence)) {
 395                         dma_fence_signal_locked(fence);
 396                         goto out;
 397                 }
 398         }
 399
 400         if (!timeout) {
 401                 ret = 0;
 402                 goto out;
 403         }
 404
 405         cb.base.func = dma_fence_default_wait_cb;
 406         cb.task = current;
 407         list_add(&cb.base.node, &fence->cb_list);
 408
 409         while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
 410                 if (intr)
 411                         __set_current_state(TASK_INTERRUPTIBLE);
 412                 else
 413                         __set_current_state(TASK_UNINTERRUPTIBLE);
 414                 spin_unlock_irqrestore(fence->lock, flags);
 415
 416                 ret = schedule_timeout(ret);
 417
 418                 spin_lock_irqsave(fence->lock, flags);
 419                 if (ret > 0 && intr && signal_pending(current))
 420                         ret = -ERESTARTSYS;
 421         }
 422
 423         if (!list_empty(&cb.base.node))
 424                 list_del(&cb.base.node);
 425         __set_current_state(TASK_RUNNING);
 426
 427 out:
 428         spin_unlock_irqrestore(fence->lock, flags);
 429         return ret;
 430 }
 431 EXPORT_SYMBOL(dma_fence_default_wait);
 432
 433 static bool
 434 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
 435                             uint32_t *idx)
 436 {
 437         int i;
 438
 439         for (i = 0; i < count; ++i) {
 440                 struct dma_fence *fence = fences[i];
 441                 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 442                         if (idx)
 443                                 *idx = i;
 444                         return true;
 445                 }
 446         }
 447         return false;
 448 }
 449
 450 /**
 451  * dma_fence_wait_any_timeout - sleep until any fence gets signaled
 452  * or until timeout elapses
 453  * @fences:     [in]    array of fences to wait on
 454  * @count:      [in]    number of fences to wait on
 455  * @intr:       [in]    if true, do an interruptible wait
 456  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 457  * @idx:       [out]    the first signaled fence index, meaningful only on
 458  *                      positive return
 459  *
 460  * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
 461  * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
 462  * on success.
 463  *
 464  * Synchronous waits for the first fence in the array to be signaled. The
 465  * caller needs to hold a reference to all fences in the array, otherwise a
 466  * fence might be freed before return, resulting in undefined behavior.
 467  */
 468 signed long
 469 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 470                            bool intr, signed long timeout, uint32_t *idx)
 471 {
 472         struct default_wait_cb *cb;
 473         signed long ret = timeout;
 474         unsigned i;
 475
 476         if (WARN_ON(!fences || !count || timeout < 0))
 477                 return -EINVAL;
 478
 479         if (timeout == 0) {
 480                 for (i = 0; i < count; ++i)
 481                         if (dma_fence_is_signaled(fences[i])) {
 482                                 if (idx)
 483                                         *idx = i;
 484                                 return 1;
 485                         }
 486
 487                 return 0;
 488         }
 489
 490         cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
 491         if (cb == NULL) {
 492                 ret = -ENOMEM;
 493                 goto err_free_cb;
 494         }
 495
 496         for (i = 0; i < count; ++i) {
 497                 struct dma_fence *fence = fences[i];
 498
 499                 if (fence->ops->wait != dma_fence_default_wait) {
 500                         ret = -EINVAL;
 501                         goto fence_rm_cb;
 502                 }
 503
 504                 cb[i].task = current;
 505                 if (dma_fence_add_callback(fence, &cb[i].base,
 506                                            dma_fence_default_wait_cb)) {
 507                         /* This fence is already signaled */
 508                         if (idx)
 509                                 *idx = i;
 510                         goto fence_rm_cb;
 511                 }
 512         }
 513
 514         while (ret > 0) {
 515                 if (intr)
 516                         set_current_state(TASK_INTERRUPTIBLE);
 517                 else
 518                         set_current_state(TASK_UNINTERRUPTIBLE);
 519
 520                 if (dma_fence_test_signaled_any(fences, count, idx))
 521                         break;
 522
 523                 ret = schedule_timeout(ret);
 524
 525                 if (ret > 0 && intr && signal_pending(current))
 526                         ret = -ERESTARTSYS;
 527         }
 528
 529         __set_current_state(TASK_RUNNING);
 530
 531 fence_rm_cb:
 532         while (i-- > 0)
 533                 dma_fence_remove_callback(fences[i], &cb[i].base);
 534
 535 err_free_cb:
 536         kfree(cb);
 537
 538         return ret;
 539 }
 540 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
 541
 542 /**
 543  * dma_fence_init - Initialize a custom fence.
 544  * @fence:      [in]    the fence to initialize
 545  * @ops:        [in]    the dma_fence_ops for operations on this fence
 546  * @lock:       [in]    the irqsafe spinlock to use for locking this fence
 547  * @context:    [in]    the execution context this fence is run on
 548  * @seqno:      [in]    a linear increasing sequence number for this context
 549  *
 550  * Initializes an allocated fence, the caller doesn't have to keep its
 551  * refcount after committing with this fence, but it will need to hold a
 552  * refcount again if dma_fence_ops.enable_signaling gets called. This can
 553  * be used for other implementing other types of fence.
 554  *
 555  * context and seqno are used for easy comparison between fences, allowing
 556  * to check which fence is later by simply using dma_fence_later.
 557  */
 558 void
 559 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 560                spinlock_t *lock, u64 context, unsigned seqno)
 561 {
 562         BUG_ON(!lock);
 563         BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
 564                !ops->get_driver_name || !ops->get_timeline_name);
 565
 566         kref_init(&fence->refcount);
 567         fence->ops = ops;
 568         INIT_LIST_HEAD(&fence->cb_list);
 569         fence->lock = lock;
 570         fence->context = context;
 571         fence->seqno = seqno;
 572         fence->flags = 0UL;
 573         fence->error = 0;
 574
 575         trace_dma_fence_init(fence);
 576 }
 577 EXPORT_SYMBOL(dma_fence_init);