Re: [PATCH net v2 3/6] net: bcm4908_enet: release the TX ring on stop

[Florian Fainelli <florian.fainelli@broadcom.com>]

On 11/12/26 11:50, Kordian Chmielewski wrote:
> bcm4908_enet_stop() disables the TX DMA but leaves the ring as it is:
> the skbs that poll_tx() has not freed yet stay mapped and are never
> freed, and the descriptors the DMA has not sent yet keep
> DMA_CTL_STATUS_OWN. The skbs, the socket memory they hold and their
> mappings leak. The next open starts the indexes from 0 again over
> those descriptors, so the DMA may send stale frames from before the
> stop, and if the first descriptor still has OWN, start_xmit() stops
> the queue before it enables the DMA, with nothing left to wake it.
> 
> Wait for the TX DMA channel to stop, as is already done for RX, then
> unmap and free the skbs between read_idx and write_idx, and clear the
> TX descriptors when the ring is initialised. A descriptor that
> start_xmit() is about to use then never carries OWN, so drop the check
> that stopped the queue on one. The RX helper's timeout warning said
> TX; make it say RX.
> 
> Found by reading the code; I have not seen these on the hardware.
> 
> Fixes: 4feffeadbcb2 ("net: broadcom: bcm4908enet: add BCM4908 controller driver")
> Signed-off-by: Kordian Chmielewski <kudzo51@gmail.com>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian