Hi,

Im not sure if this is the right forum for this thread
Sorry if it isn't.

Im trying to make some changes to slow start.
For this i need to have 4 new variables per connection.

I added these members in the tcp_sock structure in tcp.h
Im doing initializations in tcp_ipv4.c and tcp.c and then using
these variables in the slow_start function in tcp_cong.c

This is my first time doing any sort of kernel programming/hacking.

Now when i compile the kernel, it compiles fine. However when i try to boot my system, i get a kernel panic in tcp_v4_destroy_sock and tcp_v6_destroy sock. I am not sure if its because i added new members to the tcp_sock structure since i dont have issues if i remove all my other code changes except for the member declarations in tcp.h for tcp_sock.

I am not sure what the issue is or how to go about debugging it.

Im working on the 2.6.22 kernel.

Any help would be much appreciated.

Thanks !
-A.

It is possible to get such an effect this way. There's casting between struct sock and struct tcp_sock. Probably you should see the problem by just looking at the two structures. If not, use tcp_v4_destroy_sock. It's not a very complicated function (tcp_ipv4.c) and you can add your debug inside. It will probbaly crash the first time it's run, so the amount of debug is not important - add as much as you want. Print the situation before and after all functions run in tcp_v4_destroy_sock and you should see what's wrong really fast.

Sorry for the late response and Thanks a lot Mara.

Well actually, I dont really know what caused the issue. Compiling each modified file individually somehow eliminated the problem. Whats even stranger is that now if I modify any file and compile it or even do a make clean and recompile the kernel, i dont seem to face any issues.

However, I did figure out that the tcp_sock structure provides for some private space for each pluggable module. I ended up using that even though my modifications were to the common to all slow start code which is built in. :-).