Re: [PATCH net v2 2/3] net: macb: propagate RX ring refill errors

[Nicolai Buchwitz <nb@tipi-net.de>]

On 25.9.2026 15:59, Théo Lebrun wrote:
> gem_rx_refill() is responsible for Rx SKB allocation, including at 
> open,
> but its prototype indicates a void return value.
> 
> Therefore we change the code to propagate allocation and DMA mapping
> errors back up the stack, making sure the open fails if no descriptors
> were allocated. Change all those to return errno-style ints:
>  - gem_rx_refill()
>  - its parent gem_init_rx_ring()
>  - its grand-parent gem_init_rings()
>  - the macbgem_ops.mog_init_rings function pointer
>  - its grand-uncle macb_init_rings()
> 
> We tolerate some allocation failures: we accept running with the rx 
> ring
> only partially filled with successful descriptors. It is important we
> refuse the zero-valid-descriptor case: nothing would ever trigger a
> refill, which only happens once a frame has been received.
> 
> Theoretical bugfix, never encountered in practice. To reproduce,
> introduce memory pressure (less than 512 SKBs of free memory) and open
> the interface. I expect the last queue to be unusable because it has
> zero usable rx buffers.
> 
> Note that other callers of refill (resume, HRESP error task, NAPI)
> cannot do anything useful with that error and keep their best-effort
> refill, hoping it will improve.
> 
> Fixes: 4df95131ea80 ("net/macb: change RX path for GEM")
> Cc: stable@vger.kernel.org
> Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
> ---

> [...]

Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>

Thanks,
Nicolai