Re: [PATCH net-next v9 00/17] net: macb: implement context swapping

[Théo Lebrun]

On Wed Aug 12, 2026 at 10:03 AM CEST, Théo Lebrun wrote:
> MACB has a pretty primitive approach to buffer management. They are all
> stored in `struct macb *bp`. On operations that require buffer realloc
> (set_ringparam & change_mtu at the moment), the only option is to close
> the interface, change our global state and re-open the interface.
>
> Two issues:
> - It doesn't fly on memory pressured systems; we free our precious
>   buffers and don't manage to reallocate fully, meaning our machine
>   just lost its network access.
> - Anecdotally, it is pretty slow because it implies a full PHY reinit.
>
> Instead, we shall:
>  - allocate a new context (including buffers) first
>  - if it fails, early return without any impact to the interface
>  - stop interface
>  - update global state (bp, netdev, etc)
>  - pass newly allocated buffer pointers to the hardware
>  - start interface
>  - free old context
>
> This is what we implement here. Both .set_ringparam() and
> .ndo_change_mtu() are covered by this series. In the future,
> at least .set_channels() [0], XDP [1] and XSK [2] would benefit.

Sorry for the insistence, but do we have a chance of seeing this merged
before the next merge window? Context swapping is a nice feature to get
into v7.3 and it would allow us to send XDP (& XSK) series that are
dependent on context swapping.

Thanks!

Have a nice week-end,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com