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

   1 /*
   2  * dma-fence-array: aggregate fences to be waited together
   3  *
   4  * Copyright (C) 2016 Collabora Ltd
   5  * Copyright (C) 2016 Advanced Micro Devices, Inc.
   6  * Authors:
   7  *      Gustavo Padovan <gustavo@padovan.org>
   8  *      Christian König <christian.koenig@amd.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License version 2 as published by
  12  * the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope that it will be useful, but WITHOUT
  15  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  17  * more details.
  18  */
  19
  20 #include <linux/export.h>
  21 #include <linux/slab.h>
  22 #include <linux/dma-fence-array.h>
  23
  24 static const char *dma_fence_array_get_driver_name(struct dma_fence *fence)
  25 {
  26         return "dma_fence_array";
  27 }
  28
  29 static const char *dma_fence_array_get_timeline_name(struct dma_fence *fence)
  30 {
  31         return "unbound";
  32 }
  33
  34 static void dma_fence_array_cb_func(struct dma_fence *f,
  35                                     struct dma_fence_cb *cb)
  36 {
  37         struct dma_fence_array_cb *array_cb =
  38                 container_of(cb, struct dma_fence_array_cb, cb);
  39         struct dma_fence_array *array = array_cb->array;
  40
  41         if (atomic_dec_and_test(&array->num_pending))
  42                 dma_fence_signal(&array->base);
  43         dma_fence_put(&array->base);
  44 }
  45
  46 static bool dma_fence_array_enable_signaling(struct dma_fence *fence)
  47 {
  48         struct dma_fence_array *array = to_dma_fence_array(fence);
  49         struct dma_fence_array_cb *cb = (void *)(&array[1]);
  50         unsigned i;
  51
  52         for (i = 0; i < array->num_fences; ++i) {
  53                 cb[i].array = array;
  54                 /*
  55                  * As we may report that the fence is signaled before all
  56                  * callbacks are complete, we need to take an additional
  57                  * reference count on the array so that we do not free it too
  58                  * early. The core fence handling will only hold the reference
  59                  * until we signal the array as complete (but that is now
  60                  * insufficient).
  61                  */
  62                 dma_fence_get(&array->base);
  63                 if (dma_fence_add_callback(array->fences[i], &cb[i].cb,
  64                                            dma_fence_array_cb_func)) {
  65                         dma_fence_put(&array->base);
  66                         if (atomic_dec_and_test(&array->num_pending))
  67                                 return false;
  68                 }
  69         }
  70
  71         return true;
  72 }
  73
  74 static bool dma_fence_array_signaled(struct dma_fence *fence)
  75 {
  76         struct dma_fence_array *array = to_dma_fence_array(fence);
  77
  78         return atomic_read(&array->num_pending) <= 0;
  79 }
  80
  81 static void dma_fence_array_release(struct dma_fence *fence)
  82 {
  83         struct dma_fence_array *array = to_dma_fence_array(fence);
  84         unsigned i;
  85
  86         for (i = 0; i < array->num_fences; ++i)
  87                 dma_fence_put(array->fences[i]);
  88
  89         kfree(array->fences);
  90         dma_fence_free(fence);
  91 }
  92
  93 const struct dma_fence_ops dma_fence_array_ops = {
  94         .get_driver_name = dma_fence_array_get_driver_name,
  95         .get_timeline_name = dma_fence_array_get_timeline_name,
  96         .enable_signaling = dma_fence_array_enable_signaling,
  97         .signaled = dma_fence_array_signaled,
  98         .wait = dma_fence_default_wait,
  99         .release = dma_fence_array_release,
 100 };
 101 EXPORT_SYMBOL(dma_fence_array_ops);
 102
 103 /**
 104  * dma_fence_array_create - Create a custom fence array
 105  * @num_fences:         [in]    number of fences to add in the array
 106  * @fences:             [in]    array containing the fences
 107  * @context:            [in]    fence context to use
 108  * @seqno:              [in]    sequence number to use
 109  * @signal_on_any:      [in]    signal on any fence in the array
 110  *
 111  * Allocate a dma_fence_array object and initialize the base fence with
 112  * dma_fence_init().
 113  * In case of error it returns NULL.
 114  *
 115  * The caller should allocate the fences array with num_fences size
 116  * and fill it with the fences it wants to add to the object. Ownership of this
 117  * array is taken and dma_fence_put() is used on each fence on release.
 118  *
 119  * If @signal_on_any is true the fence array signals if any fence in the array
 120  * signals, otherwise it signals when all fences in the array signal.
 121  */
 122 struct dma_fence_array *dma_fence_array_create(int num_fences,
 123                                                struct dma_fence **fences,
 124                                                u64 context, unsigned seqno,
 125                                                bool signal_on_any)
 126 {
 127         struct dma_fence_array *array;
 128         size_t size = sizeof(*array);
 129
 130         /* Allocate the callback structures behind the array. */
 131         size += num_fences * sizeof(struct dma_fence_array_cb);
 132         array = kzalloc(size, GFP_KERNEL);
 133         if (!array)
 134                 return NULL;
 135
 136         spin_lock_init(&array->lock);
 137         dma_fence_init(&array->base, &dma_fence_array_ops, &array->lock,
 138                        context, seqno);
 139
 140         array->num_fences = num_fences;
 141         atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
 142         array->fences = fences;
 143
 144         return array;
 145 }
 146 EXPORT_SYMBOL(dma_fence_array_create);