URL: https://linuxfr.org/forums/programmation-c--2/posts/generic-netlink
Title: Generic Netlink
Authors: Doude
Date: 2007年11月13日T15:42:43+01:00
Tags: 
Score: 0
Salut,
J'essaye de me servir des fonctionnalités de la Generic Netlink pour dialoguer entre mon module noyau et des processus utilisateurs.
Je me suis inspirer de la doc [http://www.linux-foundation.org/en/Net:Generic_Netlink_HOWTO](http://www.linux-foundation.org/en/Net:Generic_Netlink_HOWTO) et de code du noyau (taskstats.c, acpi.c) pour reproduire un exemple de base avant de l'incorporer dans mon module.
Mais je n'arrive pas à faire fonctionner cet exemple de base :
 
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <net/sock.h>
 #include <linux/netlink.h>
 #include <linux/version.h>
 
 #include <linux/rtnetlink.h>
 #include <net/genetlink.h>
 
 enum {
 £spaces£	£/spaces£DOC_EXMPL_C_UNSPEC = 0,
 £spaces£	£/spaces£DOC_EXMPL_C_ECHO,
 £spaces£	£/spaces£__DOC_EXMPL_C_MAX,
 };
 #define DOC_EXMPL_C_MAX (__DOC_EXMPL_C_MAX - 1)
 
 enum {
 £spaces£	£/spaces£DOC_EXMPL_A_UNSPEC = 0,
 £spaces£	£/spaces£DOC_EXMPL_A_MSG,
 £spaces£	£/spaces£__DOC_EXMPL_A_MAX,
 };
 #define DOC_EXMPL_A_MAX (__DOC_EXMPL_A_MAX - 1)
 
 static struct genl_family doc_exmpl_gnl_family = {
 £spaces£ £/spaces£.id = GENL_ID_GENERATE,
 £spaces£ £/spaces£.name = "DOC_EXMPL",
 £spaces£ £/spaces£.version = 1,
 £spaces£ £/spaces£.maxattr = DOC_EXMPL_A_MAX,
 };
 
 static struct genl_multicast_group event_mcgrp_echo = {
 £spaces£	£/spaces£.name = "mc_group_echo",
 };
 
 struct test {
 £spaces£	£/spaces£char name[15];
 £spaces£	£/spaces£u32 num;
 };
 
 int send(void) {
 £spaces£	£/spaces£struct sk_buff *skb;
 £spaces£	£/spaces£int rc = 0, size;
 £spaces£	£/spaces£void *msg_head;
 
 £spaces£	£/spaces£size = nla_total_size(0);
 £spaces£	£/spaces£printk("size = %i\n", size);
 
 £spaces£	£/spaces£skb = genlmsg_new(size, GFP_KERNEL);
 £spaces£	£/spaces£if (skb == NULL) {
 £spaces£		£/spaces£printk("error on genlmsg_new\n");
 £spaces£		£/spaces£return -ENOMEM;
 £spaces£	£/spaces£}
 
 £spaces£	£/spaces£/* create the message headers */
 £spaces£	£/spaces£msg_head = genlmsg_put(skb, 0, 0, &doc_exmpl_gnl_family, 0, DOC_EXMPL_C_ECHO);
 £spaces£	£/spaces£if (msg_head == NULL) {
 £spaces£		£/spaces£printk("error on genlmsg_put\n");
 £spaces£		£/spaces£rc = -ENOMEM;
 £spaces£		£/spaces£goto failure;
 £spaces£	£/spaces£}
 
 £spaces£	£/spaces£/* finalize the message */
 £spaces£	£/spaces£rc = genlmsg_end(skb, msg_head);
 £spaces£	£/spaces£if (rc < 0) {
 £spaces£		£/spaces£printk("error on genlmsg_end\n");
 £spaces£		£/spaces£goto failure;
 £spaces£	£/spaces£}
 £spaces£	£/spaces£
 £spaces£	£/spaces£rc = genlmsg_multicast(skb, 0, event_mcgrp_echo.id, GFP_KERNEL);
 £spaces£	£/spaces£if (rc != 0) {
 £spaces£		£/spaces£printk("error on genlmsg_multicast %i\n", rc);
 £spaces£		£/spaces£goto failure;
 £spaces£	£/spaces£}
 
 £spaces£	£/spaces£return rc;
 
 failure:
 £spaces£	£/spaces£printk("Failure\n");
 £spaces£	£/spaces£nlmsg_free(skb);
 £spaces£	£/spaces£genl_unregister_family(&doc_exmpl_gnl_family);
 £spaces£	£/spaces£return rc;
 }
 
 int init_mod(void) {
 £spaces£	£/spaces£int err = 0;
 
 £spaces£	£/spaces£err = genl_register_family(&doc_exmpl_gnl_family);
 £spaces£	£/spaces£if (err < 0) {
 £spaces£		£/spaces£printk("Error register family\n");
 £spaces£		£/spaces£return err;
 £spaces£	£/spaces£}
 
 £spaces£	£/spaces£printk("Family id : %i\n", doc_exmpl_gnl_family.id);
 £spaces£	£/spaces£
 £spaces£	£/spaces£err = genl_register_mc_group(&doc_exmpl_gnl_family, &event_mcgrp_echo);
 
 £spaces£	£/spaces£if (err) {
 £spaces£		£/spaces£genl_unregister_family(&doc_exmpl_gnl_family);
 £spaces£		£/spaces£printk("error register multicast group \n");
 £spaces£		£/spaces£return err;
 £spaces£	£/spaces£}
 
 £spaces£	£/spaces£err = send();
 
 £spaces£	£/spaces£return err;
 }
 
 static void __exit exit_mod(void) {
 £spaces£	£/spaces£genl_unregister_family(&doc_exmpl_gnl_family);
 £spaces£	£/spaces£printk(KERN_INFO "Goodbye\n");
 }
 
 module_init(init_mod);
 module_exit(exit_mod);
 
 MODULE_LICENSE("GPL");
Je travail avec un noyau 2.6.23 et sur deux architecture différentes (x86, armv5b)
Sur le x86, la fonction "genlmsg_multicast" me retourne l'erreur ESRCH
Sur la carte arm, la fonction "genlmsg_put" retourne une pointeur NULL.
Une idée du problème, un oublis ... ?
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