Help me get up to speed, please.

Linux kernel crew,

I sent this message to [email protected] but that mailing list appears to be rather inactive compared to this one. As I've mentioned below, I'm new to linux kernel- programming. I've used linux for years, mainly because I love how easy it is to do all sorts of cool networking things. I would really like to get involved with linux kernel programming, but first I'm going to need to get up to speed with a few things. I'd like to learn the linux networking stacks inside and out. So, I posted the message below to the linux-net mailing list. Please forgive me if you are a member of both that list and this one and are therefore getting two copies. Please lend any help you can.

Thanks,
Josh

-----------------------------------------------------------

I'm new to this mailing list, and to linux kernel programming. I'm trying to get a really good grasp on what happens to packets from when they arrive until they are pushed to user-space applications. For now I'm just assuming I am receiving a TCP packet.

I've read almost all the online docs I can find, but most don't get down and dirty enough for what I'm trying to figure out. For example,
http://www.gnumonks.org/ftp/pub/doc/packet-journey-2.4.html. I also have troubles with running into docs referring to the 2.0 or 2.2 kernels and interrupt bottom halves, which it seems are not in the 2.4 network code (softirqs instead).

I'd like to create a list of the functions (in order) that are called from the time of sk_buff creation/allocation until the buffer is free'd (kfree_skb). I'd really like to track an sk_buff throughout it's 'lifespan' in the linux kernel. So far I think I understand the following, which isn't much...

Linux network drivers all register themselves with the kernel through a register_netdev() call. Lots of structures are allocated and initialized. It seems that most sk_buffs come into existence during an interrupt routine in a NIC card driver (i.e. /usr/src/linux/drivers/net/pci-skeleton.c, netdrv_rx_interrupt()), which does the following...

netif_rx(skb) is called, which performs the following...

__skb_queue_tail(&queue->input_pkt_queue,skb); dev.c, line 1255

which puts the sk_buff into the incoming packet queue of one of the processors, which is really a member of the softnet_data[] array.

it has something to do with 2.4's new softirqs, but I don't really have a good grasp on that yet.

Please help me fill in where my knowledge is lacking. Also, PLEASE correct any mistakes you see in my understanding so far.

Thanks,
Joshua Stewart

[email protected]