Re: ethernet device xmit function is not gettting called

[Ravi Kumar <ravivsn@rocsys.com>]

Hi Syed,
comments inline
syedk wrote:

> hi ravi,
>  your net driver doesn't fit into a proper net driver reasons being:
The driver has no problems except I did not checked the pointer 
reference to oldiph, in one case it was referring to NULL.

> 1)what is the char driver doing in a net driver
Why not we use character device? Infact its not character device in net 
driver but netdevice in a character device. I am creating netdevice from 
a character device. Using Character device, I will have better control 
over netdevice. Alternately it can be controlled using ifconfig.

> 2)dev->priv is being typecasted to test_struct and assigned to
> test_struct c; which itself has net_device variable:
Yes, I require that dev structure.

> Please remember that dev->priv is used for holding private data like the
> statistics etc.,
In my case, its test_struct, The driver is experimental and to prove the 
concept.

>  Please go thru skeleton of a sample net driver in
>
> /usr/src/linux-2.4.x/drivers/net/pci-skeleton.c
> /usr/src/linux-2.4.x/drivers/net/loopback.c
>
> Hope this helps
> Regards
> Syed
>
> On Mon, 2004-06-28 at 18:48, Ravi Kumar wrote:
>  
>
> > Hi,
> > I wrote a module to create dummy ethernet device, the intention is to 
> > add it to a bridge and transmit modified packets. I get ethernet device 
> > created but its xmit function is not called when the bridge receives a 
> > packet.
> >
> > I feel I have missed some information to register netdevice.
> >
> > To add to bridge I did the following:
> > brctl addbr br0
> > brctl addif bro eth0
> > brctl addif br0 firsteth0
> > ifconfig etho 0.0.0.0
> > ifconfig bro 172.16.2.100 up
> >
> > When I try to add IP address to firsteth0, I get a kernel panic!!
> > Can we give IP to dummy ethernet device?
> >
> > Please help, I am given little time to complete this :( I am attaching 
> > the code for the dummy ethernet device.
> > -Ravi
> > ----
> >
> >    
>
>  
>
> > #ifndef __KERNEL__
> > #   define __KERNEL__
> > #endif
> >
> > #ifndef MODULE
> > #  define MODULE
> > #endif
> >
> > #define DEVNAME "firsteth"
> >
> > #include <linux/module.h>
> > #include <linux/kernel.h>
> > #include <linux/fs.h>
> > #include <linux/slab.h>
> >
> > #include <linux/netdevice.h>
> > #include <linux/if_ether.h>
> > #include <linux/rtnetlink.h>
> > #include <linux/if_arp.h>
> >
> > /* netfilters related */
> > #include <linux/netfilter.h>
> > #include <linux/netfilter_ipv4.h>
> >
> > #include <linux/in.h>
> > #include <linux/udp.h>
> > #include <net/ip.h>
> >
> > int test_open(struct inode *,struct file *);
> > int test_release(struct inode *,struct file*);
> >
> >
> > struct test_struct{
> > 	struct net_device *dev;
> > 	char name[IFNAMSIZ];
> > 	
> > };
> >
> > struct file_operations test_fop={
> > llseek:  	NULL,
> > read:   	NULL,
> > write:  	NULL,
> > ioctl:  	NULL,
> > open:   	test_open,
> > release: 	test_release,
> > };
> >
> >
> > struct test_struct pTestStruct;
> >
> > 	
> > static int testdev_xmit(struct sk_buff *skb, struct net_device *dev)
> > {
> > 	struct iphdr *oldiph;
> > 	unsigned char tos=0;
> > 	unsigned short df =0;
> > 	unsigned char ttl;
> > 	
> > 	printk(KERN_INFO " In xmit function\n");
> > 	oldiph = (skb->protocol==htons(ETH_P_IP))
> > 	           ? (struct iphdr*)(skb->data+ETH_HLEN)
> > 	           : NULL;
> > 	
> >        tos = oldiph->tos;
> >        df = oldiph->frag_off;
> >        ttl = oldiph->ttl;
> > 	printk(KERN_INFO"src IP: %x dst IP: %x , protocol %d \n",ntohl(oldiph->saddr), ntohl(oldiph->daddr),oldiph->protocol);
> >      
> > 	return 0;
> > }
> >
> > int test_open(struct inode *inode, struct file *filep)
> > {
> > 	MOD_INC_USE_COUNT;
> > 	return 0;
> > }
> >
> > int test_release(struct inode *inode, struct file *filep)
> > {
> > 	MOD_DEC_USE_COUNT;
> > 	return 0;
> > }
> >
> > int testdev_open(struct net_device *dev)
> > {
> > 	MOD_INC_USE_COUNT;
> > 	return 0;
> > }
> >
> > int testdev_close(struct net_device *dev)
> > {
> > 	unregister_netdev(dev);
> > 	MOD_DEC_USE_COUNT;
> > 	return 0;
> > }
> > //t test_ioctl(struct inode *inode, 
> > static int test_init_dev(struct net_device *dev)
> > {
> > 	struct test_struct *c;
> >
> > 	printk(KERN_INFO "in test_init_dev\n");
> > 	
> > 	c = (struct test_struct *)dev->priv;
> > 	if(!c)
> > 		return -ENODEV;
> >
> > 	memset(c,0,sizeof(struct test_struct));
> >        c->dev = dev;
> >
> >       // ether_setup(dev);	
> > 	dev->open  = testdev_open;
> > 	dev->stop  = testdev_close;
> > 	dev->hard_start_xmit        = testdev_xmit;
> > 	dev->mtu   = ETH_DATA_LEN - sizeof(struct udphdr) - sizeof(struct iphdr) ;
> >        dev_init_buffers(dev);
> >
> > 	printk(KERN_INFO "completed test_init_dev\n");
> > 	return 0;
> > }
> >
> > int init_module(void)
> > {
> > 	int result,i;
> >        struct net_device *tempDev;
> > 	struct test_struct *temp_struct;
> >        char devname[25]; // Remove the hardcode
> >
> > 	
> > 	 for(i=0;i<99;i++)
> > 	 {
> >           sprintf(devname,"firseth%d",i);
> >           if(__dev_get_by_name(devname) == NULL)
> > 	     break;
> > 	 }
> >         if(i==100)
> > 	      return -ENFILE;
> >         printk(KERN_INFO "********MACOUDP TUNNEL******\n");	 
> > 	
> > 	temp_struct = (struct test_struct *)kmalloc(sizeof(struct test_struct),GFP_KERNEL);
> > 	if(!temp_struct)
> > 	{
> > 		printk(KERN_ERR "error in allocating memory\n");
> > 		return -ENOMEM;
> > 	}
> > 	result = register_chrdev(244,"testdrv",&test_fop);
> > 	if( result !=  0 ){
> > 		printk(KERN_WARNING "test: cant get major\n");
> > 		return result;
> > 	}
> > 	i=0;
> >        memset(temp_struct,0,sizeof(struct test_struct));
> > 	//sprintf(temp_struct->name, DEVNAME "%d",i);
> > 	tempDev = (struct net_device *)kmalloc(sizeof(struct net_device),GFP_KERNEL);
> > 	if( !tempDev)
> > 	{
> > 		printk(KERN_ERR "kmalloc faied\n");
> > 		return -ENOMEM;
> > 	}
> > 	memset(tempDev,0,sizeof(struct net_device));
> > 	temp_struct->dev = tempDev;
> > 	temp_struct->dev->priv = &pTestStruct;
> > 	temp_struct->dev->next = NULL;
> > 	temp_struct->dev->base_addr=0;
> > 	temp_struct->dev->init = test_init_dev;
> >   
> > 	temp_struct->dev->dev_addr[0]=0xFC;
> > 	temp_struct->dev->dev_addr[1]=0xFC;
> > 	temp_struct->dev->dev_addr[2]=0xA;
> > 	temp_struct->dev->dev_addr[3]=0xB;
> > 	temp_struct->dev->dev_addr[4]=0xC;
> >        temp_struct->dev->addr_len = ETH_ALEN;
> > 	i = dev_alloc_name(temp_struct->dev,"firsteth%d");
> > 	if(i < 0 )
> > 	{
> > 		printk(KERN_ERR "cant allocate device\n");
> > 		return -ENODEV;
> > 	}
> >        ether_setup(temp_struct->dev);	
> > 	rtnl_lock();
> > 	printk(KERN_INFO "Before calling register_netdevice\n");
> > 	i = register_netdevice((temp_struct->dev));
> > 	rtnl_unlock();
> > 	memcpy(&pTestStruct,temp_struct,sizeof(struct test_struct));
> > 	if( i < 0 ){
> > 		printk(KERN_ERR "register netdevice failed\n");
> >                return -1;
> > 	}
> > 	return 0;
> > }
> >
> > void cleanup_module(void)
> > {
> >        rtnl_lock();
> > 	unregister_netdevice(pTestStruct.dev);
> > 	rtnl_unlock();
> > 	unregister_chrdev(244,"testdrv");
> > }
> >
> >
> >
> >
> >
> >
> >    
>
>
>
> --
> Kernelnewbies: Help each other learn about the Linux kernel.
> Archive:       http://mail.nl.linux.org/kernelnewbies/
> FAQ:           http://kernelnewbies.org/faq/
>
>  




--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive:       http://mail.nl.linux.org/kernelnewbies/
FAQ:           http://kernelnewbies.org/faq/