I am probably repeating something youve seen/know already.
The cleanup is to break up the code so it is functionally more readable
from a perspective of the 4 distinct parts in ->hard_start_xmit():
a) packet formatting (example: vlan, mss, descriptor counting, etc.)
b) chip-specific formatting
c) enqueueing the packet on a DMA ring
d) IO operations to complete packet transmit, tell DMA engine to chew
on, tx completion interrupts, set last tx time, etc.
Each of those steps sitting in different functions accumulates state
that is used in the next steps. cb stores this state because it a
scratchpad the driver owns. You could create some other structure and
pass it around the iteration, but why waste more bytes.
batching work. Thats how we started this discussion ;-> I would like,
once converted the driver to remove LLTX, to do #a without holding the
tx lock. This stands on its own even without batching. Then of course,
once all this is in such good shape it makes it easier to add the
batching code because i could reuse the now functionalized steps.
I hope that provides reasonable and good explanation ;->
cheers,
jamal
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