[RTnet-developers] rtskb_acquire

[Jorge A. <j-a...@cr...>]

Hello Jan.

Can you please give me a description of wath is done in the rtskb_acquire function in the rtskb.c file line 463.

The rtnet is crashing with an SIG=11 in this function when i pass the cloned rtskb to the ETH_P_ALL socket.

My clone function is the following:
/** Clone a rtskb to another, allocating a rtskb for the copy  */
int rtskb_clone(struct rtskb *rtskb_1,struct rtskb *rtskb_2,struct rtskb_queue *pool)
{

    rtskb_1 = alloc_rtskb(rtskb_2->len,pool);
    if(rtskb_1 == NULL)
        return -ENOMEM;
    
    
    memcpy(rtskb_1->data, rtskb_2->data, rtskb_2->len );
    rtskb_1->len        = rtskb_2->len;
    rtskb_1->time_stamp = rtskb_2->time_stamp;
    rtskb_1->rtdev      = rtskb_2->rtdev;
    rtskb_1->protocol   = rtskb_2->protocol;
    
    return 0;
}

I check the path between the driver and the stack manager and only find that these fields are necessary.

the task manager does the following for the clone rtskb:

            list_for_each_entry(pt_entry, &rt_packets[hash], list_entry)
            {
                rt_printk("List entry protocol= %d %d name = %d\n",
                          ntohs(pt_entry->type),hash,strncmp(pt_entry->name,"PACKET_SOCKET",13));
                //the "PACKET_SOCKET" string is defined in line 188 of file af_packet.c
                //this string should be replaced by a #define declaration
                if ( likely(ntohs(pt_entry->type) == hash && 
                            (strncmp(pt_entry->name,"PACKET_SOCKET",13) == 0 )))
                {
                    rtdm_lock_put_irqrestore(&rt_packets_lock, context);
//                     rt_printk("List entry 1 \n");
                    
                    sock   = container_of(pt_entry, struct rtsocket,
                                           prot.packet.packet_type);
                    
                    rtdm_lock_get_irqsave(&rt_packets_lock, context);
                    err = rtskb_clone(clone_skb, skb, &sock->skb_pool);
                    rtdm_lock_put_irqrestore(&rt_packets_lock, context);
                    if(err != 0)
                    {
                        break;
                    }
                        
                    rtskb_queue_head(&sock->skb_pool,clone_skb);
                    //queue the message to fifo head here
                    
                    
                    rtdm_lock_get_irqsave(&rt_packets_lock, context);
                    pt_entry->refcount++;
                    rtdm_lock_put_irqrestore(&rt_packets_lock, context);
//                         rt_printk("List entry 2 \n");
                    err = pt_entry->handler(clone_skb, pt_entry);
//                         rt_printk("List entry 3 \n");
                    rtdm_lock_get_irqsave(&rt_packets_lock, context);
                    pt_entry->refcount--;
                    rtdm_lock_put_irqrestore(&rt_packets_lock, context);

                }
            }


I'm not sure if the cloned rtskb shoul be inserted in the queue head or not.


thanks
-- 
Jorge Almeida
j-a...@cr...
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