Please read again, that isn't the suggestion being discussed.
What's being discussed is having the top of the transmit call path
getting a socket "buffer" pointer, that it can feed back into the
packet input path directly. Loopback would return buffer pointers
from ->hard_start_xmit() instead of passing them netif_rx(). The top
of the transmit call path, upon getting a non-NULL buffer returned,
would pass it to netif_receive_skb().
We're not talking about sockets, although that is another idea (which
I'm working on a patch for, and I have a mechanism for what you refer
to as "path validation").
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