[PATCH 1/8] net/txgbe: fix Rx buffer size in configure register

[Ferruh Yigit]

On 1/18/2023 6:00 AM, Jiawen Wu wrote:
> When round up buffer size to 1K, to configure the register, hardware will
> receive packets exceeding the buffer size in LRO mode. It will cause a
> segment fault in the receive function.
> 
> Fixes: be797cbf4582 ("net/txgbe: add Rx and Tx init")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Jiawen Wu <jiawenwu at trustnetic.com>
> ---
>  drivers/net/txgbe/txgbe_rxtx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/txgbe/txgbe_rxtx.c b/drivers/net/txgbe/txgbe_rxtx.c
> index ac1bba08a3..ae70ca3beb 100644
> --- a/drivers/net/txgbe/txgbe_rxtx.c
> +++ b/drivers/net/txgbe/txgbe_rxtx.c
> @@ -4382,7 +4382,7 @@ txgbe_dev_rx_init(struct rte_eth_dev *dev)
>  		 */
>  		buf_size = (uint16_t)(rte_pktmbuf_data_room_size(rxq->mb_pool) -
>  			RTE_PKTMBUF_HEADROOM);
> -		buf_size = ROUND_UP(buf_size, 0x1 << 10);
> +		buf_size = ROUND_DOWN(buf_size, 0x1 << 10);
>  		srrctl |= TXGBE_RXCFG_PKTLEN(buf_size);
>  

What if 'buf_size' is less than 1K, won't 'ROUND_DOWN' make it 0, and I
assume setting 0 to register may cause problem.

And according to the code comment for 'buf_size' [1], buffer size can't
be more than 16K, but technically 'buf_size' can be more than 16K.
Does the HW constrain values larger than 16K? If not the 'buf_size'
value needs to be checked against the 16K limit.




[1]
 /*
  * Configure the RX buffer size in the PKTLEN field of
  * the RXCFG register of the queue.
  * The value is in 1 KB resolution. Valid values can be from
  * 1 KB to 16 KB.
  */