drivers/dma-buf/fence-array.c

   1 /*
   2  * 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/fence-array.h>
  23
  24 static void fence_array_cb_func(struct fence *f, struct fence_cb *cb);
  25
  26 static const char *fence_array_get_driver_name(struct fence *fence)
  27 {
  28         return "fence_array";
  29 }
  30
  31 static const char *fence_array_get_timeline_name(struct fence *fence)
  32 {
  33         return "unbound";
  34 }
  35
  36 static void fence_array_cb_func(struct fence *f, struct fence_cb *cb)
  37 {
  38         struct fence_array_cb *array_cb =
  39                 container_of(cb, struct fence_array_cb, cb);
  40         struct fence_array *array = array_cb->array;
  41
  42         if (atomic_dec_and_test(&array->num_pending))
  43                 fence_signal(&array->base);
  44         fence_put(&array->base);
  45 }
  46
  47 static bool fence_array_enable_signaling(struct fence *fence)
  48 {
  49         struct fence_array *array = to_fence_array(fence);
  50         struct fence_array_cb *cb = (void *)(&array[1]);
  51         unsigned i;
  52
  53         for (i = 0; i < array->num_fences; ++i) {
  54                 cb[i].array = array;
  55                 /*
  56                  * As we may report that the fence is signaled before all
  57                  * callbacks are complete, we need to take an additional
  58                  * reference count on the array so that we do not free it too
  59                  * early. The core fence handling will only hold the reference
  60                  * until we signal the array as complete (but that is now
  61                  * insufficient).
  62                  */
  63                 fence_get(&array->base);
  64                 if (fence_add_callback(array->fences[i], &cb[i].cb,
  65                                        fence_array_cb_func)) {
  66                         fence_put(&array->base);
  67                         if (atomic_dec_and_test(&array->num_pending))
  68                                 return false;
  69                 }
  70         }
  71
  72         return true;
  73 }
  74
  75 static bool fence_array_signaled(struct fence *fence)
  76 {
  77         struct fence_array *array = to_fence_array(fence);
  78
  79         return atomic_read(&array->num_pending) <= 0;
  80 }
  81
  82 static void fence_array_release(struct fence *fence)
  83 {
  84         struct fence_array *array = to_fence_array(fence);
  85         unsigned i;
  86
  87         for (i = 0; i < array->num_fences; ++i)
  88                 fence_put(array->fences[i]);
  89
  90         kfree(array->fences);
  91         fence_free(fence);
  92 }
  93
  94 const struct fence_ops fence_array_ops = {
  95         .get_driver_name = fence_array_get_driver_name,
  96         .get_timeline_name = fence_array_get_timeline_name,
  97         .enable_signaling = fence_array_enable_signaling,
  98         .signaled = fence_array_signaled,
  99         .wait = fence_default_wait,
 100         .release = fence_array_release,
 101 };
 102
 103 /**
 104  * 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 fence_array object and initialize the base fence with fence_init().
 112  * In case of error it returns NULL.
 113  *
 114  * The caller should allocte the fences array with num_fences size
 115  * and fill it with the fences it wants to add to the object. Ownership of this
 116  * array is take and fence_put() is used on each fence on release.
 117  *
 118  * If @signal_on_any is true the fence array signals if any fence in the array
 119  * signals, otherwise it signals when all fences in the array signal.
 120  */
 121 struct fence_array *fence_array_create(int num_fences, struct fence **fences,
 122                                        u64 context, unsigned seqno,
 123                                        bool signal_on_any)
 124 {
 125         struct fence_array *array;
 126         size_t size = sizeof(*array);
 127
 128         /* Allocate the callback structures behind the array. */
 129         size += num_fences * sizeof(struct fence_array_cb);
 130         array = kzalloc(size, GFP_KERNEL);
 131         if (!array)
 132                 return NULL;
 133
 134         spin_lock_init(&array->lock);
 135         fence_init(&array->base, &fence_array_ops, &array->lock,
 136                    context, seqno);
 137
 138         array->num_fences = num_fences;
 139         atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
 140         array->fences = fences;
 141
 142         return array;
 143 }
 144 EXPORT_SYMBOL(fence_array_create);