该楼层疑似违规已被系统折叠 隐藏此楼查看此楼

最近在学习netlink，用来实现用户层和内核的通信，在写内核部分代码时，遇到一个奇怪的问题：

每次卸载完模块后，必须修改协议号(NETLINK_TEST),netlink_kernel_create(&init_net,NETLINK_TEST,&cfg);才能成功，不修改协议号，一直创建内核sock失败，

哪位大佬帮帮忙！！！所用平台Ubuntu16.04+linux内核4.15.0-46-generic内核代码如下

[code=c]#include

#include

#include

#include#define MAX_MSG_LEN 1024

//#define USER_PID 66666

#define NETLINK_TEST 21 //proto number

static struct sock* g_sk_nl_k = NULL;

static struct nlmsghdr *g_nlh = NULL; //will contain user's pid,data and so on//static int g_nlmsg_pid = USER_PID;//static void revFromApp(struct sk_buff* skb);//send msg to app

int sendToApp(char *pmsg){

struct nlmsghdr *nlh = NULL;

struct sk_buff *nl_skb_out = NULL;

int ret;

ret= -1; if(!pmsg){

printk("Msg is null,send msg failed!\n");

return -1;

} if(!g_sk_nl_k){

printk("User's pid is'n known,send msg failed!\n");

return -1;

}

nl_skb_out = nlmsg_new(MAX_MSG_LEN,0);//Allocate a new skb to send a new netlink message to nl_APP

//nl_skb_out = alloc_skb(NLMSG_SPACE(MAX_MSG_LEN), GFP_ATOMIC);

if(!nl_skb_out){

printk("Allocate new skb failed,send msg failed!\n");

return -1;

}

nlh = nlmsg_put(nl_skb_out,0,0,0,MAX_MSG_LEN,0);

if(nlh == NULL){

printk("nlmsg_put failaure!\n");

nlmsg_free(nl_skb_out);

return -1;

} NETLINK_CB(nl_skb_out).creds.pid = 0;

//NETLINK_CB(nl_skb_out).dst_group = 0;

memcpy(NLMSG_DATA(nlh), pmsg, strlen(pmsg));

//ret = nlmsg;

ret = netlink_unicast(g_sk_nl_k, nl_skb_out,g_nlh->nlmsg_pid, MSG_DONTWAIT);//USER_PID

if(ret < 0){

printk("nlmsg_unicast failaure!\n");

nlmsg_free(nl_skb_out);

return -1;

}

nlmsg_free(nl_skb_out);

return 0;

}//receive msg from app(only run one time if no loop)

static void revFromApp(struct sk_buff* skb){

char * msgFromApp = NULL;

char * str0 = "msg from kernel";

//struct nlmsghdr *nlh; turn to gloabe

g_nlh=(struct nlmsghdr*)(skb->data); //nlh message from shb's data...(sk_buff:unsigned char *data)

//nlh = nlmsg_hdr(skb);

msgFromApp = nlmsg_data(g_nlh);//get data from struct nlmsghdr *nlh;

//test

printk("msg:%s\n",msgFromApp);

sendToApp(str0);

}struct netlink_kernel_cfg cfg = {

.input=revFromApp,

};//create socket

int netlinkCreate(void){

g_sk_nl_k = netlink_kernel_create(&init_net,NETLINK_TEST,&cfg);

if(!g_sk_nl_k){

printk("Error creating socket!\n");

return -1;

}

return 0;

}//close socket

void netlinkClose(struct sock* sk_nl_k){

if(!sk_nl_k){

//sock_release(sk_nl_k->sk_socket);

netlink_kernel_release(sk_nl_k);

//sk_nl_k = NULL;

}

}//netlink open

static int __init netlink_init(void){

int ret = -1;

ret = netlinkCreate();//get struct sock* g_sk_nl_k

if(ret < 0){

printk("Netlink open failed!\n");

return -1;

}

printk("Netlink open !\n");

return 0;

}//netlink close

static void __exit netlink_exit(void){

//netlink_kernel_release(g_sk_nl_k);

//printk("Netlink close0!\n");

netlinkClose(g_sk_nl_k);

printk("Netlink close1!\n");

}module_init(netlink_init);

module_exit(netlink_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("ysx"); [/code]makefile如下

[code=c]

ifneq ($(KERNELRELEASE),)obj-m :=nldrv.o

#obj-m += hello.oelseKDIR :=/lib/modules/$(shell uname -r)/buildall:

make -C $(KDIR) M=$(PWD) modules

clean:

rm -f *.ko *.o *.mod.o *.mod.c *.symvers *.orderendif

[/code]