drivers/gpu/drm/i915/i915_sw_fence.c

   1 /*
   2  * (C) Copyright 2016 Intel Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; version 2
   7  * of the License.
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/dma-fence.h>
  12 #include <linux/reservation.h>
  13
  14 #include "i915_sw_fence.h"
  15
  16 #define I915_SW_FENCE_FLAG_ALLOC BIT(3) /* after WQ_FLAG_* for safety */
  17
  18 static DEFINE_SPINLOCK(i915_sw_fence_lock);
  19
  20 static int __i915_sw_fence_notify(struct i915_sw_fence *fence,
  21                                   enum i915_sw_fence_notify state)
  22 {
  23         i915_sw_fence_notify_t fn;
  24
  25         fn = (i915_sw_fence_notify_t)(fence->flags & I915_SW_FENCE_MASK);
  26         return fn(fence, state);
  27 }
  28
  29 static void i915_sw_fence_free(struct kref *kref)
  30 {
  31         struct i915_sw_fence *fence = container_of(kref, typeof(*fence), kref);
  32
  33         WARN_ON(atomic_read(&fence->pending) > 0);
  34
  35         if (fence->flags & I915_SW_FENCE_MASK)
  36                 __i915_sw_fence_notify(fence, FENCE_FREE);
  37         else
  38                 kfree(fence);
  39 }
  40
  41 static void i915_sw_fence_put(struct i915_sw_fence *fence)
  42 {
  43         kref_put(&fence->kref, i915_sw_fence_free);
  44 }
  45
  46 static struct i915_sw_fence *i915_sw_fence_get(struct i915_sw_fence *fence)
  47 {
  48         kref_get(&fence->kref);
  49         return fence;
  50 }
  51
  52 static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
  53                                         struct list_head *continuation)
  54 {
  55         wait_queue_head_t *x = &fence->wait;
  56         wait_queue_t *pos, *next;
  57         unsigned long flags;
  58
  59         atomic_set_release(&fence->pending, -1); /* 0 -> -1 [done] */
  60
  61         /*
  62          * To prevent unbounded recursion as we traverse the graph of
  63          * i915_sw_fences, we move the task_list from this, the next ready
  64          * fence, to the tail of the original fence's task_list
  65          * (and so added to the list to be woken).
  66          */
  67
  68         spin_lock_irqsave_nested(&x->lock, flags, 1 + !!continuation);
  69         if (continuation) {
  70                 list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
  71                         if (pos->func == autoremove_wake_function)
  72                                 pos->func(pos, TASK_NORMAL, 0, continuation);
  73                         else
  74                                 list_move_tail(&pos->task_list, continuation);
  75                 }
  76         } else {
  77                 LIST_HEAD(extra);
  78
  79                 do {
  80                         list_for_each_entry_safe(pos, next,
  81                                                  &x->task_list, task_list)
  82                                 pos->func(pos, TASK_NORMAL, 0, &extra);
  83
  84                         if (list_empty(&extra))
  85                                 break;
  86
  87                         list_splice_tail_init(&extra, &x->task_list);
  88                 } while (1);
  89         }
  90         spin_unlock_irqrestore(&x->lock, flags);
  91 }
  92
  93 static void __i915_sw_fence_complete(struct i915_sw_fence *fence,
  94                                      struct list_head *continuation)
  95 {
  96         if (!atomic_dec_and_test(&fence->pending))
  97                 return;
  98
  99         if (fence->flags & I915_SW_FENCE_MASK &&
 100             __i915_sw_fence_notify(fence, FENCE_COMPLETE) != NOTIFY_DONE)
 101                 return;
 102
 103         __i915_sw_fence_wake_up_all(fence, continuation);
 104 }
 105
 106 static void i915_sw_fence_complete(struct i915_sw_fence *fence)
 107 {
 108         if (WARN_ON(i915_sw_fence_done(fence)))
 109                 return;
 110
 111         __i915_sw_fence_complete(fence, NULL);
 112 }
 113
 114 static void i915_sw_fence_await(struct i915_sw_fence *fence)
 115 {
 116         WARN_ON(atomic_inc_return(&fence->pending) <= 1);
 117 }
 118
 119 void i915_sw_fence_init(struct i915_sw_fence *fence, i915_sw_fence_notify_t fn)
 120 {
 121         BUG_ON((unsigned long)fn & ~I915_SW_FENCE_MASK);
 122
 123         init_waitqueue_head(&fence->wait);
 124         kref_init(&fence->kref);
 125         atomic_set(&fence->pending, 1);
 126         fence->flags = (unsigned long)fn;
 127 }
 128
 129 void i915_sw_fence_commit(struct i915_sw_fence *fence)
 130 {
 131         i915_sw_fence_complete(fence);
 132         i915_sw_fence_put(fence);
 133 }
 134
 135 static int i915_sw_fence_wake(wait_queue_t *wq, unsigned mode, int flags, void *key)
 136 {
 137         list_del(&wq->task_list);
 138         __i915_sw_fence_complete(wq->private, key);
 139         i915_sw_fence_put(wq->private);
 140         if (wq->flags & I915_SW_FENCE_FLAG_ALLOC)
 141                 kfree(wq);
 142         return 0;
 143 }
 144
 145 static bool __i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 146                                     const struct i915_sw_fence * const signaler)
 147 {
 148         wait_queue_t *wq;
 149
 150         if (__test_and_set_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
 151                 return false;
 152
 153         if (fence == signaler)
 154                 return true;
 155
 156         list_for_each_entry(wq, &fence->wait.task_list, task_list) {
 157                 if (wq->func != i915_sw_fence_wake)
 158                         continue;
 159
 160                 if (__i915_sw_fence_check_if_after(wq->private, signaler))
 161                         return true;
 162         }
 163
 164         return false;
 165 }
 166
 167 static void __i915_sw_fence_clear_checked_bit(struct i915_sw_fence *fence)
 168 {
 169         wait_queue_t *wq;
 170
 171         if (!__test_and_clear_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
 172                 return;
 173
 174         list_for_each_entry(wq, &fence->wait.task_list, task_list) {
 175                 if (wq->func != i915_sw_fence_wake)
 176                         continue;
 177
 178                 __i915_sw_fence_clear_checked_bit(wq->private);
 179         }
 180 }
 181
 182 static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 183                                   const struct i915_sw_fence * const signaler)
 184 {
 185         unsigned long flags;
 186         bool err;
 187
 188         if (!IS_ENABLED(CONFIG_I915_SW_FENCE_CHECK_DAG))
 189                 return false;
 190
 191         spin_lock_irqsave(&i915_sw_fence_lock, flags);
 192         err = __i915_sw_fence_check_if_after(fence, signaler);
 193         __i915_sw_fence_clear_checked_bit(fence);
 194         spin_unlock_irqrestore(&i915_sw_fence_lock, flags);
 195
 196         return err;
 197 }
 198
 199 static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 200                                           struct i915_sw_fence *signaler,
 201                                           wait_queue_t *wq, gfp_t gfp)
 202 {
 203         unsigned long flags;
 204         int pending;
 205
 206         if (i915_sw_fence_done(signaler))
 207                 return 0;
 208
 209         /* The dependency graph must be acyclic. */
 210         if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
 211                 return -EINVAL;
 212
 213         pending = 0;
 214         if (!wq) {
 215                 wq = kmalloc(sizeof(*wq), gfp);
 216                 if (!wq) {
 217                         if (!gfpflags_allow_blocking(gfp))
 218                                 return -ENOMEM;
 219
 220                         i915_sw_fence_wait(signaler);
 221                         return 0;
 222                 }
 223
 224                 pending |= I915_SW_FENCE_FLAG_ALLOC;
 225         }
 226
 227         INIT_LIST_HEAD(&wq->task_list);
 228         wq->flags = pending;
 229         wq->func = i915_sw_fence_wake;
 230         wq->private = i915_sw_fence_get(fence);
 231
 232         i915_sw_fence_await(fence);
 233
 234         spin_lock_irqsave(&signaler->wait.lock, flags);
 235         if (likely(!i915_sw_fence_done(signaler))) {
 236                 __add_wait_queue_tail(&signaler->wait, wq);
 237                 pending = 1;
 238         } else {
 239                 i915_sw_fence_wake(wq, 0, 0, NULL);
 240                 pending = 0;
 241         }
 242         spin_unlock_irqrestore(&signaler->wait.lock, flags);
 243
 244         return pending;
 245 }
 246
 247 int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 248                                  struct i915_sw_fence *signaler,
 249                                  wait_queue_t *wq)
 250 {
 251         return __i915_sw_fence_await_sw_fence(fence, signaler, wq, 0);
 252 }
 253
 254 int i915_sw_fence_await_sw_fence_gfp(struct i915_sw_fence *fence,
 255                                      struct i915_sw_fence *signaler,
 256                                      gfp_t gfp)
 257 {
 258         return __i915_sw_fence_await_sw_fence(fence, signaler, NULL, gfp);
 259 }
 260
 261 struct i915_sw_dma_fence_cb {
 262         struct dma_fence_cb base;
 263         struct i915_sw_fence *fence;
 264         struct dma_fence *dma;
 265         struct timer_list timer;
 266 };
 267
 268 static void timer_i915_sw_fence_wake(unsigned long data)
 269 {
 270         struct i915_sw_dma_fence_cb *cb = (struct i915_sw_dma_fence_cb *)data;
 271
 272         printk(KERN_WARNING "asynchronous wait on fence %s:%s:%x timed out\n",
 273                cb->dma->ops->get_driver_name(cb->dma),
 274                cb->dma->ops->get_timeline_name(cb->dma),
 275                cb->dma->seqno);
 276         dma_fence_put(cb->dma);
 277         cb->dma = NULL;
 278
 279         i915_sw_fence_commit(cb->fence);
 280         cb->timer.function = NULL;
 281 }
 282
 283 static void dma_i915_sw_fence_wake(struct dma_fence *dma,
 284                                    struct dma_fence_cb *data)
 285 {
 286         struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
 287
 288         del_timer_sync(&cb->timer);
 289         if (cb->timer.function)
 290                 i915_sw_fence_commit(cb->fence);
 291         dma_fence_put(cb->dma);
 292
 293         kfree(cb);
 294 }
 295
 296 int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
 297                                   struct dma_fence *dma,
 298                                   unsigned long timeout,
 299                                   gfp_t gfp)
 300 {
 301         struct i915_sw_dma_fence_cb *cb;
 302         int ret;
 303
 304         if (dma_fence_is_signaled(dma))
 305                 return 0;
 306
 307         cb = kmalloc(sizeof(*cb), gfp);
 308         if (!cb) {
 309                 if (!gfpflags_allow_blocking(gfp))
 310                         return -ENOMEM;
 311
 312                 return dma_fence_wait(dma, false);
 313         }
 314
 315         cb->fence = i915_sw_fence_get(fence);
 316         i915_sw_fence_await(fence);
 317
 318         cb->dma = NULL;
 319         __setup_timer(&cb->timer,
 320                       timer_i915_sw_fence_wake, (unsigned long)cb,
 321                       TIMER_IRQSAFE);
 322         if (timeout) {
 323                 cb->dma = dma_fence_get(dma);
 324                 mod_timer(&cb->timer, round_jiffies_up(jiffies + timeout));
 325         }
 326
 327         ret = dma_fence_add_callback(dma, &cb->base, dma_i915_sw_fence_wake);
 328         if (ret == 0) {
 329                 ret = 1;
 330         } else {
 331                 dma_i915_sw_fence_wake(dma, &cb->base);
 332                 if (ret == -ENOENT) /* fence already signaled */
 333                         ret = 0;
 334         }
 335
 336         return ret;
 337 }
 338
 339 int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
 340                                     struct reservation_object *resv,
 341                                     const struct dma_fence_ops *exclude,
 342                                     bool write,
 343                                     unsigned long timeout,
 344                                     gfp_t gfp)
 345 {
 346         struct dma_fence *excl;
 347         int ret = 0, pending;
 348
 349         if (write) {
 350                 struct dma_fence **shared;
 351                 unsigned int count, i;
 352
 353                 ret = reservation_object_get_fences_rcu(resv,
 354                                                         &excl, &count, &shared);
 355                 if (ret)
 356                         return ret;
 357
 358                 for (i = 0; i < count; i++) {
 359                         if (shared[i]->ops == exclude)
 360                                 continue;
 361
 362                         pending = i915_sw_fence_await_dma_fence(fence,
 363                                                                 shared[i],
 364                                                                 timeout,
 365                                                                 gfp);
 366                         if (pending < 0) {
 367                                 ret = pending;
 368                                 break;
 369                         }
 370
 371                         ret |= pending;
 372                 }
 373
 374                 for (i = 0; i < count; i++)
 375                         dma_fence_put(shared[i]);
 376                 kfree(shared);
 377         } else {
 378                 excl = reservation_object_get_excl_rcu(resv);
 379         }
 380
 381         if (ret >= 0 && excl && excl->ops != exclude) {
 382                 pending = i915_sw_fence_await_dma_fence(fence,
 383                                                         excl,
 384                                                         timeout,
 385                                                         gfp);
 386                 if (pending < 0)
 387                         ret = pending;
 388                 else
 389                         ret |= pending;
 390         }
 391
 392         dma_fence_put(excl);
 393
 394         return ret;
 395 }