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         /* Failed to signal before release, could be a refcounting issue */
 175         WARN_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 /**
 185  * dma_fence_free - default release function for &dma_fence.
 186  * @fence: fence to release
 187  *
 188  * This is the default implementation for &dma_fence_ops.release. It calls
 189  * kfree_rcu() on @fence.
 190  */
 191 void dma_fence_free(struct dma_fence *fence)
 192 {
 193         kfree_rcu(fence, rcu);
 194 }
 195 EXPORT_SYMBOL(dma_fence_free);
 196
 197 /**
 198  * dma_fence_enable_sw_signaling - enable signaling on fence
 199  * @fence:      [in]    the fence to enable
 200  *
 201  * this will request for sw signaling to be enabled, to make the fence
 202  * complete as soon as possible
 203  */
 204 void dma_fence_enable_sw_signaling(struct dma_fence *fence)
 205 {
 206         unsigned long flags;
 207
 208         if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 209                               &fence->flags) &&
 210             !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 211                 trace_dma_fence_enable_signal(fence);
 212
 213                 spin_lock_irqsave(fence->lock, flags);
 214
 215                 if (!fence->ops->enable_signaling(fence))
 216                         dma_fence_signal_locked(fence);
 217
 218                 spin_unlock_irqrestore(fence->lock, flags);
 219         }
 220 }
 221 EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
 222
 223 /**
 224  * dma_fence_add_callback - add a callback to be called when the fence
 225  * is signaled
 226  * @fence:      [in]    the fence to wait on
 227  * @cb:         [in]    the callback to register
 228  * @func:       [in]    the function to call
 229  *
 230  * cb will be initialized by dma_fence_add_callback, no initialization
 231  * by the caller is required. Any number of callbacks can be registered
 232  * to a fence, but a callback can only be registered to one fence at a time.
 233  *
 234  * Note that the callback can be called from an atomic context.  If
 235  * fence is already signaled, this function will return -ENOENT (and
 236  * *not* call the callback)
 237  *
 238  * Add a software callback to the fence. Same restrictions apply to
 239  * refcount as it does to dma_fence_wait, however the caller doesn't need to
 240  * keep a refcount to fence afterwards: when software access is enabled,
 241  * the creator of the fence is required to keep the fence alive until
 242  * after it signals with dma_fence_signal. The callback itself can be called
 243  * from irq context.
 244  *
 245  * Returns 0 in case of success, -ENOENT if the fence is already signaled
 246  * and -EINVAL in case of error.
 247  */
 248 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
 249                            dma_fence_func_t func)
 250 {
 251         unsigned long flags;
 252         int ret = 0;
 253         bool was_set;
 254
 255         if (WARN_ON(!fence || !func))
 256                 return -EINVAL;
 257
 258         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 259                 INIT_LIST_HEAD(&cb->node);
 260                 return -ENOENT;
 261         }
 262
 263         spin_lock_irqsave(fence->lock, flags);
 264
 265         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 266                                    &fence->flags);
 267
 268         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 269                 ret = -ENOENT;
 270         else if (!was_set) {
 271                 trace_dma_fence_enable_signal(fence);
 272
 273                 if (!fence->ops->enable_signaling(fence)) {
 274                         dma_fence_signal_locked(fence);
 275                         ret = -ENOENT;
 276                 }
 277         }
 278
 279         if (!ret) {
 280                 cb->func = func;
 281                 list_add_tail(&cb->node, &fence->cb_list);
 282         } else
 283                 INIT_LIST_HEAD(&cb->node);
 284         spin_unlock_irqrestore(fence->lock, flags);
 285
 286         return ret;
 287 }
 288 EXPORT_SYMBOL(dma_fence_add_callback);
 289
 290 /**
 291  * dma_fence_get_status - returns the status upon completion
 292  * @fence: [in] the dma_fence to query
 293  *
 294  * This wraps dma_fence_get_status_locked() to return the error status
 295  * condition on a signaled fence. See dma_fence_get_status_locked() for more
 296  * details.
 297  *
 298  * Returns 0 if the fence has not yet been signaled, 1 if the fence has
 299  * been signaled without an error condition, or a negative error code
 300  * if the fence has been completed in err.
 301  */
 302 int dma_fence_get_status(struct dma_fence *fence)
 303 {
 304         unsigned long flags;
 305         int status;
 306
 307         spin_lock_irqsave(fence->lock, flags);
 308         status = dma_fence_get_status_locked(fence);
 309         spin_unlock_irqrestore(fence->lock, flags);
 310
 311         return status;
 312 }
 313 EXPORT_SYMBOL(dma_fence_get_status);
 314
 315 /**
 316  * dma_fence_remove_callback - remove a callback from the signaling list
 317  * @fence:      [in]    the fence to wait on
 318  * @cb:         [in]    the callback to remove
 319  *
 320  * Remove a previously queued callback from the fence. This function returns
 321  * true if the callback is successfully removed, or false if the fence has
 322  * already been signaled.
 323  *
 324  * *WARNING*:
 325  * Cancelling a callback should only be done if you really know what you're
 326  * doing, since deadlocks and race conditions could occur all too easily. For
 327  * this reason, it should only ever be done on hardware lockup recovery,
 328  * with a reference held to the fence.
 329  */
 330 bool
 331 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
 332 {
 333         unsigned long flags;
 334         bool ret;
 335
 336         spin_lock_irqsave(fence->lock, flags);
 337
 338         ret = !list_empty(&cb->node);
 339         if (ret)
 340                 list_del_init(&cb->node);
 341
 342         spin_unlock_irqrestore(fence->lock, flags);
 343
 344         return ret;
 345 }
 346 EXPORT_SYMBOL(dma_fence_remove_callback);
 347
 348 struct default_wait_cb {
 349         struct dma_fence_cb base;
 350         struct task_struct *task;
 351 };
 352
 353 static void
 354 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 355 {
 356         struct default_wait_cb *wait =
 357                 container_of(cb, struct default_wait_cb, base);
 358
 359         wake_up_state(wait->task, TASK_NORMAL);
 360 }
 361
 362 /**
 363  * dma_fence_default_wait - default sleep until the fence gets signaled
 364  * or until timeout elapses
 365  * @fence:      [in]    the fence to wait on
 366  * @intr:       [in]    if true, do an interruptible wait
 367  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 368  *
 369  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
 370  * remaining timeout in jiffies on success. If timeout is zero the value one is
 371  * returned if the fence is already signaled for consistency with other
 372  * functions taking a jiffies timeout.
 373  */
 374 signed long
 375 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
 376 {
 377         struct default_wait_cb cb;
 378         unsigned long flags;
 379         signed long ret = timeout ? timeout : 1;
 380         bool was_set;
 381
 382         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 383                 return ret;
 384
 385         spin_lock_irqsave(fence->lock, flags);
 386
 387         if (intr && signal_pending(current)) {
 388                 ret = -ERESTARTSYS;
 389                 goto out;
 390         }
 391
 392         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 393                                    &fence->flags);
 394
 395         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
 396                 goto out;
 397
 398         if (!was_set) {
 399                 trace_dma_fence_enable_signal(fence);
 400
 401                 if (!fence->ops->enable_signaling(fence)) {
 402                         dma_fence_signal_locked(fence);
 403                         goto out;
 404                 }
 405         }
 406
 407         if (!timeout) {
 408                 ret = 0;
 409                 goto out;
 410         }
 411
 412         cb.base.func = dma_fence_default_wait_cb;
 413         cb.task = current;
 414         list_add(&cb.base.node, &fence->cb_list);
 415
 416         while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
 417                 if (intr)
 418                         __set_current_state(TASK_INTERRUPTIBLE);
 419                 else
 420                         __set_current_state(TASK_UNINTERRUPTIBLE);
 421                 spin_unlock_irqrestore(fence->lock, flags);
 422
 423                 ret = schedule_timeout(ret);
 424
 425                 spin_lock_irqsave(fence->lock, flags);
 426                 if (ret > 0 && intr && signal_pending(current))
 427                         ret = -ERESTARTSYS;
 428         }
 429
 430         if (!list_empty(&cb.base.node))
 431                 list_del(&cb.base.node);
 432         __set_current_state(TASK_RUNNING);
 433
 434 out:
 435         spin_unlock_irqrestore(fence->lock, flags);
 436         return ret;
 437 }
 438 EXPORT_SYMBOL(dma_fence_default_wait);
 439
 440 static bool
 441 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
 442                             uint32_t *idx)
 443 {
 444         int i;
 445
 446         for (i = 0; i < count; ++i) {
 447                 struct dma_fence *fence = fences[i];
 448                 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 449                         if (idx)
 450                                 *idx = i;
 451                         return true;
 452                 }
 453         }
 454         return false;
 455 }
 456
 457 /**
 458  * dma_fence_wait_any_timeout - sleep until any fence gets signaled
 459  * or until timeout elapses
 460  * @fences:     [in]    array of fences to wait on
 461  * @count:      [in]    number of fences to wait on
 462  * @intr:       [in]    if true, do an interruptible wait
 463  * @timeout:    [in]    timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
 464  * @idx:       [out]    the first signaled fence index, meaningful only on
 465  *                      positive return
 466  *
 467  * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
 468  * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
 469  * on success.
 470  *
 471  * Synchronous waits for the first fence in the array to be signaled. The
 472  * caller needs to hold a reference to all fences in the array, otherwise a
 473  * fence might be freed before return, resulting in undefined behavior.
 474  */
 475 signed long
 476 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 477                            bool intr, signed long timeout, uint32_t *idx)
 478 {
 479         struct default_wait_cb *cb;
 480         signed long ret = timeout;
 481         unsigned i;
 482
 483         if (WARN_ON(!fences || !count || timeout < 0))
 484                 return -EINVAL;
 485
 486         if (timeout == 0) {
 487                 for (i = 0; i < count; ++i)
 488                         if (dma_fence_is_signaled(fences[i])) {
 489                                 if (idx)
 490                                         *idx = i;
 491                                 return 1;
 492                         }
 493
 494                 return 0;
 495         }
 496
 497         cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
 498         if (cb == NULL) {
 499                 ret = -ENOMEM;
 500                 goto err_free_cb;
 501         }
 502
 503         for (i = 0; i < count; ++i) {
 504                 struct dma_fence *fence = fences[i];
 505
 506                 if (fence->ops->wait != dma_fence_default_wait) {
 507                         ret = -EINVAL;
 508                         goto fence_rm_cb;
 509                 }
 510
 511                 cb[i].task = current;
 512                 if (dma_fence_add_callback(fence, &cb[i].base,
 513                                            dma_fence_default_wait_cb)) {
 514                         /* This fence is already signaled */
 515                         if (idx)
 516                                 *idx = i;
 517                         goto fence_rm_cb;
 518                 }
 519         }
 520
 521         while (ret > 0) {
 522                 if (intr)
 523                         set_current_state(TASK_INTERRUPTIBLE);
 524                 else
 525                         set_current_state(TASK_UNINTERRUPTIBLE);
 526
 527                 if (dma_fence_test_signaled_any(fences, count, idx))
 528                         break;
 529
 530                 ret = schedule_timeout(ret);
 531
 532                 if (ret > 0 && intr && signal_pending(current))
 533                         ret = -ERESTARTSYS;
 534         }
 535
 536         __set_current_state(TASK_RUNNING);
 537
 538 fence_rm_cb:
 539         while (i-- > 0)
 540                 dma_fence_remove_callback(fences[i], &cb[i].base);
 541
 542 err_free_cb:
 543         kfree(cb);
 544
 545         return ret;
 546 }
 547 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
 548
 549 /**
 550  * dma_fence_init - Initialize a custom fence.
 551  * @fence:      [in]    the fence to initialize
 552  * @ops:        [in]    the dma_fence_ops for operations on this fence
 553  * @lock:       [in]    the irqsafe spinlock to use for locking this fence
 554  * @context:    [in]    the execution context this fence is run on
 555  * @seqno:      [in]    a linear increasing sequence number for this context
 556  *
 557  * Initializes an allocated fence, the caller doesn't have to keep its
 558  * refcount after committing with this fence, but it will need to hold a
 559  * refcount again if dma_fence_ops.enable_signaling gets called. This can
 560  * be used for other implementing other types of fence.
 561  *
 562  * context and seqno are used for easy comparison between fences, allowing
 563  * to check which fence is later by simply using dma_fence_later.
 564  */
 565 void
 566 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
 567                spinlock_t *lock, u64 context, unsigned seqno)
 568 {
 569         BUG_ON(!lock);
 570         BUG_ON(!ops || !ops->wait ||
 571                !ops->get_driver_name || !ops->get_timeline_name);
 572
 573         kref_init(&fence->refcount);
 574         fence->ops = ops;
 575         INIT_LIST_HEAD(&fence->cb_list);
 576         fence->lock = lock;
 577         fence->context = context;
 578         fence->seqno = seqno;
 579         fence->flags = 0UL;
 580         fence->error = 0;
 581
 582         if (!ops->enable_signaling)
 583                 set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 584                         &fence->flags);
 585
 586         trace_dma_fence_init(fence);
 587 }
 588 EXPORT_SYMBOL(dma_fence_init);