Re: [dpdk-dev] [RFC] lib/librte_ether: add a return value for MAC set ops

[Olivier Matz <olivier.matz@6wind.com>]

Hi Wenzhuo,

On Thu, Jan 25, 2018 at 10:46:57AM +0800, Wenzhuo Lu wrote:
> Setting the default MAC address may fail on many NICs.
> But the ops return void. So, even it failed, RTE changes
> the MAC address and APP doesn't know the failure.
> 
> It's not real patch, just show the idea to add a return
> value for the ops.

Thank you for taking care of this. I had some plans to work
on it too, as discussed here:
https://dpdk.org/dev/patchwork/patch/32284/

I noticed that some PMDs try to manage the error case by
themselve by overriding the mac address in ethdev->data.
See for instance qede_mac_addr_set().

With your patch, these PMDs should be modified. No PMD
should change the value of eth_dev->data->mac_addrs.

> BTW,
> Seems we should do the same thing for
> rte_eth_dev_mac_addr_remove as it also has chance to fail
> in PMD layer.

Agree.

> Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
> ---
>  drivers/net/i40e/i40e_ethdev_vf.c  | 12 +++++++-----
>  lib/librte_ether/rte_ethdev.c      |  7 +++++--
>  lib/librte_ether/rte_ethdev.h      |  1 +
>  lib/librte_ether/rte_ethdev_core.h |  2 +-
>  4 files changed, 14 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/i40e/i40e_ethdev_vf.c b/drivers/net/i40e/i40e_ethdev_vf.c
> index 6ac3f8c..1d3898b 100644
> --- a/drivers/net/i40e/i40e_ethdev_vf.c
> +++ b/drivers/net/i40e/i40e_ethdev_vf.c
> @@ -120,8 +120,8 @@ static int i40evf_dev_rss_hash_update(struct rte_eth_dev *dev,
>  static int i40evf_dev_rss_hash_conf_get(struct rte_eth_dev *dev,
>  					struct rte_eth_rss_conf *rss_conf);
>  static int i40evf_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu);
> -static void i40evf_set_default_mac_addr(struct rte_eth_dev *dev,
> -					struct ether_addr *mac_addr);
> +static int i40evf_set_default_mac_addr(struct rte_eth_dev *dev,
> +				       struct ether_addr *mac_addr);
>  static int
>  i40evf_dev_rx_queue_intr_enable(struct rte_eth_dev *dev, uint16_t queue_id);
>  static int
> @@ -2655,7 +2655,7 @@ static int eth_i40evf_pci_remove(struct rte_pci_device *pci_dev)
>  	return ret;
>  }
>  
> -static void
> +static int
>  i40evf_set_default_mac_addr(struct rte_eth_dev *dev,
>  			    struct ether_addr *mac_addr)
>  {
> @@ -2664,15 +2664,17 @@ static int eth_i40evf_pci_remove(struct rte_pci_device *pci_dev)
>  
>  	if (!is_valid_assigned_ether_addr(mac_addr)) {
>  		PMD_DRV_LOG(ERR, "Tried to set invalid MAC address.");
> -		return;
> +		return -1;
>  	}
>  
>  	if (vf->flags & I40E_FLAG_VF_MAC_BY_PF)
> -		return;
> +		return -1;
>  

I wonder if returning -errno wouldn't be better?


>  	i40evf_del_mac_addr_by_addr(dev, (struct ether_addr *)hw->mac.addr);
>  
>  	i40evf_add_mac_addr(dev, mac_addr, 0, 0);
>  
>  	ether_addr_copy(mac_addr, (struct ether_addr *)hw->mac.addr);
> +
> +	return 0;
>  }
> diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
> index f285ba2..869c960 100644
> --- a/lib/librte_ether/rte_ethdev.c
> +++ b/lib/librte_ether/rte_ethdev.c
> @@ -2816,6 +2816,7 @@ struct rte_eth_dev *
>  rte_eth_dev_default_mac_addr_set(uint16_t port_id, struct ether_addr *addr)
>  {
>  	struct rte_eth_dev *dev;
> +	int ret;
>  
>  	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
>  
> @@ -2825,11 +2826,13 @@ struct rte_eth_dev *
>  	dev = &rte_eth_devices[port_id];
>  	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->mac_addr_set, -ENOTSUP);
>  
> +	ret = (*dev->dev_ops->mac_addr_set)(dev, addr);
> +	if (ret)
> +		return -EPERM;
> +

And here, we could return the return code of the PMD ops instead of
-EPERM, I think it can give better idea of the error cause.


>  	/* Update default address in NIC data structure */
>  	ether_addr_copy(addr, &dev->data->mac_addrs[0]);
>  
> -	(*dev->dev_ops->mac_addr_set)(dev, addr);
> -
>  	return 0;
>  }
>  
> diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> index ccf4a15..e3355cc 100644
> --- a/lib/librte_ether/rte_ethdev.h
> +++ b/lib/librte_ether/rte_ethdev.h
> @@ -2616,6 +2616,7 @@ int rte_eth_dev_mac_addr_add(uint16_t port_id, struct ether_addr *mac_addr,
>   *   - (-ENOTSUP) if hardware doesn't support.
>   *   - (-ENODEV) if *port* invalid.
>   *   - (-EINVAL) if MAC address is invalid.
> + *   - (-EPERM) if the default MAC address cannot be changed.

Here, I suggest:

  - (-errno) for any other error returned by the PMD


Thanks
Olivier