Right - the famous 30 instructions are in the hardware interrupt path, and responsible for putting the packet on the correct process's queue and waking that process up. As the original post says:
The TCP protocol processing is done as we remove packets
from the queue & copy their data to user space (and since
we're in process context, it's possible to do a
checksum-and-copy).
The TCP protocol processing mentioned here done in process context is certainly not covered by the 30 instructions.
