That would tell you how many of the TODOs from that specific older kernel have been fixed. But in the intervening releases you could have TODOs come and go.

That would tell you how many of the TODOs from that specific older kernel have been fixed. But in the intervening releases you could have TODOs come and go. To find them all you would have to go through pretty much every kernel patch looking for something approximating the following regex (assuming you were looking at TODO comments and not +/- TODO files): ^-(?!--).*TODO This should show you all lines removed from source that contain TODO, which should get you in the ballpark.