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

[Ferruh Yigit]

On 2/1/2023 2:34 AM, Jiawen Wu wrote:
> On Friday, January 27, 2023 11:36 PM, Ferruh Yigit wrote:
>> 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.
>>
> 
> It is indeed a problem, I will fix it.
> 
>> 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.
>>
> 
> There is a macro that defines the conversion to limit 16K.
> 
> #define PKTLEN(v)     ROUND_OVER(v, 14, 10)
> #define ROUND_OVER(x, maxbits, unitbits) \
> 	((x) >= 1 << (maxbits) ? 0 : (x) >> (unitbits))
> 

ack