This past week started with me mindlessly chasing down memory bugs after having gotten WinDBG up and running. A particularly annoying bug involved an lwIP protocol control block being dereferenced by lwIP after it had been freed. I could not find a place in my drivere where I tried to use a dead PCB pointer, so I looked deeper. I did some stepping through of code, and read more of lwIP's source code.
Assigning Clusters Part 2
I can't believe week seven has already passed! Adding assigned clusters to data runs turned out to be more challenging than I anticipated, but I made steady progress on it throughout the week and have it working now (as far as I can tell). Fixing the problems with LargeMcb.c in week 1 came full-circle, as I relied on a map control block to simplify my task considerably.
I'll start this report from the good news. After starting GSoC's coding period, I was doing fixes and improvements of hub layer and was not repeating tests which was done by me in community bonding period (results provided in my first blog post). So by the end of this week I decided to test surprise-removal on VBox with 2k3 working with our USB stack. As result I saw that crashes on device removal (physical) are gone! Even more after connection again, the USB flash and also composite device were performing well.
Last week ended with Art going through decompiled assembly to find a bug for me, because the stack trace in the kernel debugger was pointing me to the wrong line in the C source code. It turns out that the problem was a NULL pointer dereference in the RECEIVE callback. As always in programming, a lot of effort went into catching a small oversight.
With that leftover bug from last week resolved, I moved on to my tasks for this week - more debugging, a code review done by Thomas Faber, and finally setting up WinDBG.
This week was rewarding, because I got some things done that I've been wanting to do for a while.
I wrote some code which can assign clusters by updating the $BITMAP file. As I mentioned last week, this is half of the equation for extending the allocation size of a non-resident file. I'm still working on the other half, which involves storing the assigned clusters in data runs.