net: mctp: usblib: Move TX transfer processing to mctp-usblib

With the RX processing in mctp-usblib, add TX processing alongside.

To accommodate packed transfers in DSP0283, where a transfer may contain
multiple MCTP packets, we move to a split process for the transmit API:

 * push: create a new transmit context, and add a skb to it.

 * send: callback to the driver implementation to send the (possibly
   multi-packet) USB transfer

 * complete: update skb accounting and release the tx context

The actual multi-packet transfer implementation will be added in the
next change; no tx context persists beyond the single send at present.
However, we use an anchor in the host driver implementation to track the
submitted TX urb when necessary.

While we're here, fix an inconsistency between tx and rx stats: both
should not include the transport header.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://patch.msgid.link/20260724-dev-mctp-usb-1-1-v5-5-e66bbba0dbdc@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jeremy Kerr 2026-07-24 13:15:26 +08:00 • committed by Jakub Kicinski
commit aadf5ed03e
3 changed files with 292 additions and 64 deletions