drivers/dma-buf/dma-fence-array.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * dma-fence-array: aggregate fences to be waited together
   4  *
   5  * Copyright (C) 2016 Collabora Ltd
   6  * Copyright (C) 2016 Advanced Micro Devices, Inc.
   7  * Authors:
   8  *      Gustavo Padovan <gustavo@padovan.org>
   9  *      Christian König <christian.koenig@amd.com>
  10  */
  11
  12 #include <linux/export.h>
  13 #include <linux/slab.h>
  14 #include <linux/dma-fence-array.h>
  15
  16 #define PENDING_ERROR 1
  17
  18 static const char *dma_fence_array_get_driver_name(struct dma_fence *fence)
  19 {
  20         return "dma_fence_array";
  21 }
  22
  23 static const char *dma_fence_array_get_timeline_name(struct dma_fence *fence)
  24 {
  25         return "unbound";
  26 }
  27
  28 static void dma_fence_array_set_pending_error(struct dma_fence_array *array,
  29                                               int error)
  30 {
  31         /*
  32          * Propagate the first error reported by any of our fences, but only
  33          * before we ourselves are signaled.
  34          */
  35         if (error)
  36                 cmpxchg(&array->base.error, PENDING_ERROR, error);
  37 }
  38
  39 static void dma_fence_array_clear_pending_error(struct dma_fence_array *array)
  40 {
  41         /* Clear the error flag if not actually set. */
  42         cmpxchg(&array->base.error, PENDING_ERROR, 0);
  43 }
  44
  45 static void irq_dma_fence_array_work(struct irq_work *wrk)
  46 {
  47         struct dma_fence_array *array = container_of(wrk, typeof(*array), work);
  48
  49         dma_fence_array_clear_pending_error(array);
  50
  51         dma_fence_signal(&array->base);
  52         dma_fence_put(&array->base);
  53 }
  54
  55 static void dma_fence_array_cb_func(struct dma_fence *f,
  56                                     struct dma_fence_cb *cb)
  57 {
  58         struct dma_fence_array_cb *array_cb =
  59                 container_of(cb, struct dma_fence_array_cb, cb);
  60         struct dma_fence_array *array = array_cb->array;
  61
  62         dma_fence_array_set_pending_error(array, f->error);
  63
  64         if (atomic_dec_and_test(&array->num_pending))
  65                 irq_work_queue(&array->work);
  66         else
  67                 dma_fence_put(&array->base);
  68 }
  69
  70 static bool dma_fence_array_enable_signaling(struct dma_fence *fence)
  71 {
  72         struct dma_fence_array *array = to_dma_fence_array(fence);
  73         struct dma_fence_array_cb *cb = (void *)(&array[1]);
  74         unsigned i;
  75
  76         for (i = 0; i < array->num_fences; ++i) {
  77                 cb[i].array = array;
  78                 /*
  79                  * As we may report that the fence is signaled before all
  80                  * callbacks are complete, we need to take an additional
  81                  * reference count on the array so that we do not free it too
  82                  * early. The core fence handling will only hold the reference
  83                  * until we signal the array as complete (but that is now
  84                  * insufficient).
  85                  */
  86                 dma_fence_get(&array->base);
  87                 if (dma_fence_add_callback(array->fences[i], &cb[i].cb,
  88                                            dma_fence_array_cb_func)) {
  89                         int error = array->fences[i]->error;
  90
  91                         dma_fence_array_set_pending_error(array, error);
  92                         dma_fence_put(&array->base);
  93                         if (atomic_dec_and_test(&array->num_pending)) {
  94                                 dma_fence_array_clear_pending_error(array);
  95                                 return false;
  96                         }
  97                 }
  98         }
  99
 100         return true;
 101 }
 102
 103 static bool dma_fence_array_signaled(struct dma_fence *fence)
 104 {
 105         struct dma_fence_array *array = to_dma_fence_array(fence);
 106
 107         if (atomic_read(&array->num_pending) > 0)
 108                 return false;
 109
 110         dma_fence_array_clear_pending_error(array);
 111         return true;
 112 }
 113
 114 static void dma_fence_array_release(struct dma_fence *fence)
 115 {
 116         struct dma_fence_array *array = to_dma_fence_array(fence);
 117         unsigned i;
 118
 119         for (i = 0; i < array->num_fences; ++i)
 120                 dma_fence_put(array->fences[i]);
 121
 122         kfree(array->fences);
 123         dma_fence_free(fence);
 124 }
 125
 126 const struct dma_fence_ops dma_fence_array_ops = {
 127         .get_driver_name = dma_fence_array_get_driver_name,
 128         .get_timeline_name = dma_fence_array_get_timeline_name,
 129         .enable_signaling = dma_fence_array_enable_signaling,
 130         .signaled = dma_fence_array_signaled,
 131         .release = dma_fence_array_release,
 132 };
 133 EXPORT_SYMBOL(dma_fence_array_ops);
 134
 135 /**
 136  * dma_fence_array_create - Create a custom fence array
 137  * @num_fences:         [in]    number of fences to add in the array
 138  * @fences:             [in]    array containing the fences
 139  * @context:            [in]    fence context to use
 140  * @seqno:              [in]    sequence number to use
 141  * @signal_on_any:      [in]    signal on any fence in the array
 142  *
 143  * Allocate a dma_fence_array object and initialize the base fence with
 144  * dma_fence_init().
 145  * In case of error it returns NULL.
 146  *
 147  * The caller should allocate the fences array with num_fences size
 148  * and fill it with the fences it wants to add to the object. Ownership of this
 149  * array is taken and dma_fence_put() is used on each fence on release.
 150  *
 151  * If @signal_on_any is true the fence array signals if any fence in the array
 152  * signals, otherwise it signals when all fences in the array signal.
 153  */
 154 struct dma_fence_array *dma_fence_array_create(int num_fences,
 155                                                struct dma_fence **fences,
 156                                                u64 context, unsigned seqno,
 157                                                bool signal_on_any)
 158 {
 159         struct dma_fence_array *array;
 160         size_t size = sizeof(*array);
 161
 162         WARN_ON(!num_fences || !fences);
 163
 164         /* Allocate the callback structures behind the array. */
 165         size += num_fences * sizeof(struct dma_fence_array_cb);
 166         array = kzalloc(size, GFP_KERNEL);
 167         if (!array)
 168                 return NULL;
 169
 170         spin_lock_init(&array->lock);
 171         dma_fence_init(&array->base, &dma_fence_array_ops, &array->lock,
 172                        context, seqno);
 173         init_irq_work(&array->work, irq_dma_fence_array_work);
 174
 175         array->num_fences = num_fences;
 176         atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
 177         array->fences = fences;
 178
 179         array->base.error = PENDING_ERROR;
 180
 181         /*
 182          * dma_fence_array objects should never contain any other fence
 183          * containers or otherwise we run into recursion and potential kernel
 184          * stack overflow on operations on the dma_fence_array.
 185          *
 186          * The correct way of handling this is to flatten out the array by the
 187          * caller instead.
 188          *
 189          * Enforce this here by checking that we don't create a dma_fence_array
 190          * with any container inside.
 191          */
 192         while (num_fences--)
 193                 WARN_ON(dma_fence_is_container(fences[num_fences]));
 194
 195         return array;
 196 }
 197 EXPORT_SYMBOL(dma_fence_array_create);
 198
 199 /**
 200  * dma_fence_match_context - Check if all fences are from the given context
 201  * @fence:              [in]    fence or fence array
 202  * @context:            [in]    fence context to check all fences against
 203  *
 204  * Checks the provided fence or, for a fence array, all fences in the array
 205  * against the given context. Returns false if any fence is from a different
 206  * context.
 207  */
 208 bool dma_fence_match_context(struct dma_fence *fence, u64 context)
 209 {
 210         struct dma_fence_array *array = to_dma_fence_array(fence);
 211         unsigned i;
 212
 213         if (!dma_fence_is_array(fence))
 214                 return fence->context == context;
 215
 216         for (i = 0; i < array->num_fences; i++) {
 217                 if (array->fences[i]->context != context)
 218                         return false;
 219         }
 220
 221         return true;
 222 }
 223 EXPORT_SYMBOL(dma_fence_match_context);
 224
 225 struct dma_fence *dma_fence_array_first(struct dma_fence *head)
 226 {
 227         struct dma_fence_array *array;
 228
 229         if (!head)
 230                 return NULL;
 231
 232         array = to_dma_fence_array(head);
 233         if (!array)
 234                 return head;
 235
 236         if (!array->num_fences)
 237                 return NULL;
 238
 239         return array->fences[0];
 240 }
 241 EXPORT_SYMBOL(dma_fence_array_first);
 242
 243 struct dma_fence *dma_fence_array_next(struct dma_fence *head,
 244                                        unsigned int index)
 245 {
 246         struct dma_fence_array *array = to_dma_fence_array(head);
 247
 248         if (!array || index >= array->num_fences)
 249                 return NULL;
 250
 251         return array->fences[index];
 252 }
 253 EXPORT_SYMBOL(dma_fence_array_next);