Re: [dpdk-dev] [PATCH] app/testpmd: fix error detection in MTU command

["Iremonger, Bernard" <bernard.iremonger@intel.com>]

Hi Shy

> -----Original Message-----
> From: Shy Shyman <shys@mellanox.com>
> Sent: Monday, May 18, 2020 10:27 AM
> To: dev@dpdk.org
> Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Xing, Beilei
> <beilei.xing@intel.com>; Iremonger, Bernard
> <bernard.iremonger@intel.com>; xavier.huwei@huawei.com
> Subject: [PATCH] app/testpmd: fix error detection in MTU command
> 
> MTU is used in testpmd to set the maximum payload size for packets.
> According to testpmd, the setting influnce RX only.
> In rte_ethdev there's no relation between MTU setting and JUMBO offload
> or rx_max_pkt_len.
> 
> The previous fix in patch referenced below was meant to update the
> correlated variables of max_pkt_len and JUMBO offload, but by doing so it
> assumes that MTU setting can only exist when JUMBO offload supported in
> the device. For example fail-safe device does supports set MTU and doesn't

Typo: supports should be support

> support JUMBO offload, and in this case, though set MTU succeed an error
> mesage still printed  since the JUMBO packet offload is disabled.

Typo: mesage  should be message

> The fix separates the two conditions to make sure the error triggers  
> A warning message is provided in this special case to alert the user.
> 
> Fixes: 150c9ac2df13 ("app/testpmd: update Rx offload after setting MTU")
> Cc: xavier.huwei@huawei.com

Should the patch be backported to 20.02 ?(ie add Cc: stable@dpdk.org)

> 
> Signed-off-by: Shy Shyman <shys@mellanox.com>
> ---
>  app/test-pmd/config.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c index
> 5381207cc..73b53c50b 100644
> --- a/app/test-pmd/config.c
> +++ b/app/test-pmd/config.c
> @@ -1277,8 +1277,9 @@ port_mtu_set(portid_t port_id, uint16_t mtu)
>  		return;
>  	}
>  	diag = rte_eth_dev_set_mtu(port_id, mtu);
> -	if (diag == 0 &&
> -	    dev_info.rx_offload_capa & DEV_RX_OFFLOAD_JUMBO_FRAME) {
> +	if (diag)
> +		printf("Set MTU failed. diag=%d\n", diag);
> +	else if (dev_info.rx_offload_capa &
> DEV_RX_OFFLOAD_JUMBO_FRAME) {
>  		/*
>  		 * Ether overhead in driver is equal to the difference of
>  		 * max_rx_pktlen and max_mtu in rte_eth_dev_info when
> the @@ -1293,10 +1294,9 @@ port_mtu_set(portid_t port_id, uint16_t mtu)
>  		} else
>  			rte_port->dev_conf.rxmode.offloads &=
> 
> 	~DEV_RX_OFFLOAD_JUMBO_FRAME;
> -
> -		return;
> -	}
> -	printf("Set MTU failed. diag=%d\n", diag);
> +	} else
> +		printf("WARNING: MTU was set while jumbo frame offload
> is"
> +			" not supported by the device\n");
>  }
> 
>  /* Generic flow management functions. */
> --
> 2.21.0

Otherwise 

Acked-by: Bernard Iremonger <bernard.iremonger@intel.com>