doc/examples/hlist/cds_hlist_add_head_rcu.c

   1 // SPDX-FileCopyrightText: 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   2 //
   3 // SPDX-License-Identifier: MIT
   4
   5 /*
   6  * This example shows how to add into a non-circular linked-list safely
   7  * against concurrent RCU traversals.
   8  */
   9
  10 #include <stdio.h>
  11
  12 #include <urcu/urcu-memb.h>     /* Userspace RCU flavor */
  13 #include <urcu/rcuhlist.h>      /* RCU hlist */
  14 #include <urcu/compiler.h>      /* For CAA_ARRAY_SIZE */
  15
  16 /*
  17  * Nodes populated into the list.
  18  */
  19 struct mynode {
  20         int value;                      /* Node content */
  21         struct cds_hlist_node node;     /* Linked-list chaining */
  22 };
  23
  24 int main(void)
  25 {
  26         int values[] = { -5, 42, 36, 24, };
  27         CDS_HLIST_HEAD(mylist);         /* Defines an empty hlist head */
  28         unsigned int i;
  29         int ret = 0;
  30         struct mynode *node;
  31
  32         /*
  33          * Adding nodes to the linked-list. Safe against concurrent
  34          * RCU traversals, require mutual exclusion with list updates.
  35          */
  36         for (i = 0; i < CAA_ARRAY_SIZE(values); i++) {
  37                 node = malloc(sizeof(*node));
  38                 if (!node) {
  39                         ret = -1;
  40                         goto end;
  41                 }
  42                 node->value = values[i];
  43                 cds_hlist_add_head_rcu(&node->node, &mylist);
  44         }
  45
  46         /*
  47          * Just show the list content. This is _not_ an RCU-safe
  48          * iteration on the list.
  49          */
  50         printf("mylist content:");
  51         cds_hlist_for_each_entry_2(node, &mylist, node) {
  52                 printf(" %d", node->value);
  53         }
  54         printf("\n");
  55 end:
  56         return ret;
  57 }