From: Mathieu Desnoyers Date: Fri, 21 Jun 2013 18:22:32 +0000 (-0400) Subject: doc/examples: cds_list_for_each_rcu X-Git-Tag: v0.8.0~53 X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=17fb31883652e28774dbb148f7237382de3ab504;p=urcu.git doc/examples: cds_list_for_each_rcu Signed-off-by: Mathieu Desnoyers --- diff --git a/.gitignore b/.gitignore index 01611b4..9c4597d 100644 --- a/.gitignore +++ b/.gitignore @@ -76,6 +76,7 @@ tests/*.log doc/examples/list/cds_list_add_rcu doc/examples/list/cds_list_add_tail_rcu doc/examples/list/cds_list_del_rcu +doc/examples/list/cds_list_for_each_rcu doc/examples/list/cds_list_for_each_entry_rcu doc/examples/list/cds_list_replace_rcu diff --git a/doc/examples/Makefile.am b/doc/examples/Makefile.am index b6ad791..af03be8 100644 --- a/doc/examples/Makefile.am +++ b/doc/examples/Makefile.am @@ -16,11 +16,13 @@ dist_doc_examples_list_DATA = \ list/Makefile.cds_list_add_rcu \ list/Makefile.cds_list_add_tail_rcu \ list/Makefile.cds_list_del_rcu \ + list/Makefile.cds_list_for_each_rcu \ list/Makefile.cds_list_for_each_entry_rcu \ list/Makefile.cds_list_replace_rcu \ list/cds_list_add_rcu.c \ list/cds_list_add_tail_rcu.c \ list/cds_list_del_rcu.c \ + list/cds_list_for_each_rcu.c \ list/cds_list_for_each_entry_rcu.c \ list/cds_list_replace_rcu.c diff --git a/doc/examples/list/Makefile b/doc/examples/list/Makefile index e62a883..c291efe 100644 --- a/doc/examples/list/Makefile +++ b/doc/examples/list/Makefile @@ -15,6 +15,7 @@ all: $(MAKE) -f Makefile.cds_list_add_rcu $(MAKE) -f Makefile.cds_list_add_tail_rcu $(MAKE) -f Makefile.cds_list_del_rcu + $(MAKE) -f Makefile.cds_list_for_each_rcu $(MAKE) -f Makefile.cds_list_for_each_entry_rcu $(MAKE) -f Makefile.cds_list_replace_rcu @@ -23,5 +24,6 @@ clean: $(MAKE) -f Makefile.cds_list_add_rcu clean $(MAKE) -f Makefile.cds_list_add_tail_rcu clean $(MAKE) -f Makefile.cds_list_del_rcu clean + $(MAKE) -f Makefile.cds_list_for_each_rcu $(MAKE) -f Makefile.cds_list_for_each_entry_rcu $(MAKE) -f Makefile.cds_list_replace_rcu clean diff --git a/doc/examples/list/Makefile.cds_list_for_each_rcu b/doc/examples/list/Makefile.cds_list_for_each_rcu new file mode 100644 index 0000000..3a81db4 --- /dev/null +++ b/doc/examples/list/Makefile.cds_list_for_each_rcu @@ -0,0 +1,20 @@ +# Copyright (C) 2013 Mathieu Desnoyers +# +# THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED +# OR IMPLIED. ANY USE IS AT YOUR OWN RISK. +# +# Permission is hereby granted to use or copy this program for any +# purpose, provided the above notices are retained on all copies. +# Permission to modify the code and to distribute modified code is +# granted, provided the above notices are retained, and a notice that +# the code was modified is included with the above copyright notice. +# +# This makefile is purposefully kept simple to support GNU and BSD make. + +EXAMPLE_NAME = cds_list_for_each_rcu + +SOURCES = $(EXAMPLE_NAME).c +OBJECTS = $(EXAMPLE_NAME).o +BINARY = $(EXAMPLE_NAME) + +include ../Makefile.examples.template diff --git a/doc/examples/list/cds_list_for_each_rcu.c b/doc/examples/list/cds_list_for_each_rcu.c new file mode 100644 index 0000000..5de6bcf --- /dev/null +++ b/doc/examples/list/cds_list_for_each_rcu.c @@ -0,0 +1,90 @@ +/* + * Copyright (C) 2013 Mathieu Desnoyers + * + * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED + * OR IMPLIED. ANY USE IS AT YOUR OWN RISK. + * + * Permission is hereby granted to use or copy this program for any + * purpose, provided the above notices are retained on all copies. + * Permission to modify the code and to distribute modified code is + * granted, provided the above notices are retained, and a notice that + * the code was modified is included with the above copyright notice. + * + * This example shows how to to a RCU linked list traversal, safely + * against concurrent RCU updates. cds_list_for_each_rcu() iterates on + * struct cds_list_head, and thus, either caa_container_of() or + * cds_list_entry() are needed to access the container structure. + */ + +#include + +#include /* Userspace RCU flavor */ +#include /* RCU list */ +#include /* For CAA_ARRAY_SIZE */ + +/* + * Nodes populated into the list. + */ +struct mynode { + int value; /* Node content */ + struct cds_list_head node; /* Linked-list chaining */ +}; + +int main(int argc, char **argv) +{ + int values[] = { -5, 42, 36, 24, }; + CDS_LIST_HEAD(mylist); /* Defines an empty list head */ + unsigned int i; + int ret = 0; + struct cds_list_head *pos; + + /* + * Each thread need using RCU read-side need to be explicitely + * registered. + */ + rcu_register_thread(); + + /* + * Adding nodes to the linked-list. Safe against concurrent + * RCU traversals, require mutual exclusion with list updates. + */ + for (i = 0; i < CAA_ARRAY_SIZE(values); i++) { + struct mynode *node; + + node = malloc(sizeof(*node)); + if (!node) { + ret = -1; + goto end; + } + node->value = values[i]; + cds_list_add_tail_rcu(&node->node, &mylist); + } + + /* + * RCU-safe iteration on the list. + */ + printf("mylist content:"); + + /* + * Surround the RCU read-side critical section with rcu_read_lock() + * and rcu_read_unlock(). + */ + rcu_read_lock(); + + /* + * This traversal can be performed concurrently with RCU + * updates. + */ + cds_list_for_each_rcu(pos, &mylist) { + struct mynode *node = cds_list_entry(pos, struct mynode, node); + + printf(" %d", node->value); + } + + rcu_read_unlock(); + + printf("\n"); +end: + rcu_unregister_thread(); + return ret; +}