Re: [dpdk-dev] [PATCH] net/i40e: force promiscuous state after VF reset

["Zhang, Xiao" <xiao.zhang@intel.com>]

> -----Original Message-----
> From: Eelco Chaudron <echaudro@redhat.com>
> Sent: Friday, October 25, 2019 5:24 PM
> To: Xing, Beilei <beilei.xing@intel.com>; Zhang, Xiao <xiao.zhang@intel.com>
> Cc: Zhang, Qi Z <qi.z.zhang@intel.com>; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] net/i40e: force promiscuous state after VF
> reset
> 
> 
> 
> On 17 Oct 2019, at 8:34, Xing, Beilei wrote:
> 
> >> On 17 Sep 2019, at 9:40, Eelco Chaudron wrote:
> >>
> >>> Even though the device reset is successful, disabling promiscuous
> >>> mode might not always succeed, causing enabling it after reset to
> >>> fail.
> >>> This would happen when the kernel driver requires a reset of the VF.
> >>>
> >>> This patch resets the internal state, so next time promiscuous mode
> >>> is configured it will be enabled.
> >>>
> >>> Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
> >>> ---
> >>>  drivers/net/i40e/i40e_ethdev_vf.c | 10 ++++++++++
> >>>  1 file changed, 10 insertions(+)
> >>>
> >>> diff --git a/drivers/net/i40e/i40e_ethdev_vf.c
> >>> b/drivers/net/i40e/i40e_ethdev_vf.c
> >>> index 551f6fa..e0f99a4 100644
> >>> --- a/drivers/net/i40e/i40e_ethdev_vf.c
> >>> +++ b/drivers/net/i40e/i40e_ethdev_vf.c
> >>> @@ -2276,11 +2276,21 @@ static int eth_i40evf_pci_remove(struct
> >>> rte_pci_device *pci_dev)  i40evf_dev_reset(struct rte_eth_dev *dev)
> >>> {
> >>>  	int ret;
> >>> +	struct i40e_vf *vf =
> >>> I40EVF_DEV_PRIVATE_TO_VF(dev->data->dev_private);
> >>>
> >>>  	ret = i40evf_dev_uninit(dev);
> >>>  	if (ret)
> >>>  		return ret;
> >>>
> >>> +	/*
> >>> +	 * Even though the device reset is successful disabling
> >>> promiscuous
> >>> +	 * mode might not always succeed, causing enabling it after reset
> >>> to
> >
> > I think we need to root cause why fail to disable promiscuous mode and
> > try to fix it first.
> 
> I’ve copied in Xiao who helped me identify the issue in your driver.
> 
> The issue is because the change from kernel pf was not synced to DPDK vf during
> the closing period of reset, so we get this failure. Xiao can you add more details?
> 

The root cause is when kernel pf generate DPDK vf reset event, the flag 
vf->promisc_unicast_enabled will not be cleared but promiscuous mode is
disabled. When trying to enable promiscuous mode next time by calling 
i40evf_dev_promiscuous_enable won't work because it will check the 
vf->promisc_unicast_enabled flag first.

static int
i40evf_dev_promiscuous_enable(struct rte_eth_dev *dev)
{
...
    /* If enabled, just return */
    if (vf->promisc_unicast_enabled)
        return 0;
...
}

Hi Eelco,

I think you may need add more detailed message in the commit log or comments.

> 
> >>> +	 * fail. This would happen when the kernel driver requires a reset
> >>> +	 * of the VF.
> >>> +	 */
> >>> +	if (rte_eal_process_type() == RTE_PROC_PRIMARY)
> >>> +		vf->promisc_unicast_enabled = FALSE;
> >>> +
> >>>  	ret = i40evf_dev_init(dev);
> >>>
> >>>  	return ret;
> >>> --
> >>> 1.8.3.1