Re: [dpdk-dev] [PATCH] net/ixgbe: update data->eth_link status on start

[Chas Williams <3chas3@gmail.com>]

On Mon, Apr 2, 2018 at 8:40 AM, Zhang, Qi Z <qi.z.zhang@intel.com> wrote:
> Hi Williams:
>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Chas Williams
>> Sent: Saturday, March 31, 2018 1:22 AM
>> To: Zhang, Helin <helin.zhang@intel.com>
>> Cc: dev@dpdk.org; Lu, Wenzhuo <wenzhuo.lu@intel.com>; Ananyev,
>> Konstantin <konstantin.ananyev@intel.com>; Charles (Chas) Williams
>> <chas3@att.com>
>> Subject: Re: [dpdk-dev] [PATCH] net/ixgbe: update data->eth_link status on
>> start
>>
>> On Fri, Mar 30, 2018 at 12:30 PM, Zhang, Helin <helin.zhang@intel.com>
>> wrote:
>> >
>> >
>> >> -----Original Message-----
>> >> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Chas Williams
>> >> Sent: Wednesday, February 14, 2018 6:56 AM
>> >> To: dev@dpdk.org
>> >> Cc: Lu, Wenzhuo; Ananyev, Konstantin; Charles (Chas) Williams
>> >> Subject: [dpdk-dev] [PATCH] net/ixgbe: update data->eth_link status
>> >> on start
>> >>
>> >> From: "Charles (Chas) Williams" <chas3@att.com>
>> >>
>> >> dev->data->eth_link isn't updated until the first interrupt.  If a
>> >> link is carrier down, then this interrupt may never happen.  Before
>> >> we finished starting the PMD, call ixgbe_dev_link_update() to ensure we
>> have a valid status.
>> >>
>> >> Signed-off-by: Chas Williams <chas3@att.com>
>> >> ---
>> >>  drivers/net/ixgbe/ixgbe_ethdev.c | 4 ++++
>> >>  1 file changed, 4 insertions(+)
>> >>
>> >> diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c
>> >> b/drivers/net/ixgbe/ixgbe_ethdev.c
>> >> index 37eb668..27d29dc 100644
>> >> --- a/drivers/net/ixgbe/ixgbe_ethdev.c
>> >> +++ b/drivers/net/ixgbe/ixgbe_ethdev.c
>> >> @@ -2666,6 +2666,8 @@ ixgbe_dev_start(struct rte_eth_dev *dev)
>> >>       if (err)
>> >>               goto error;
>> >>
>> >> +     ixgbe_dev_link_update(dev, 0);
>> > It is called in rte_eth_dev_start() if lsc is not enabled, and it is
>> > not needed here to avoid any duplication.
>> > BTW, did you see any issue or just check the code? Thanks!
>>
>> Yes, I see an issue with bonding.  If LSC is enabled, then link_status isn't set
>> until the first interrupt to update the link status.  If a link is down, this
>> interrupt may never happen result in link_status being somewhat undefined.
>
> Is your issue only happened on VF?
> For PF, I saw ixgbe_check_link is called at ixgbe_dev_start, so link status is assume be updated.
> If you think it is just missed in VF, can you implemented this in the similar way as PF?

No, I don't believe it's isolated to VF.  ixgbe_check_link() doesn't
update (atomically write)
the dev->data->dev_link.  After .dev_start() finishes, I need the
link_status of the adapter to
be set.  I can't wait until I hope the first interrupt has happened
that would update
dev->data->dev_link.  How long would I wait?  I don't really care if
the link is down,
or up, or whatever, but it can't be partially filled in.  Bonding (in
802.3ad) wants the
links to be similarly configured.

>
> Regards
> Qi
>
>>
>> >
>> > /Helin
>> >
>> >> +
>> >>  skip_link_setup:
>> >>
>> >>       if (rte_intr_allow_others(intr_handle)) { @@ -5033,6 +5035,8 @@
>> >> ixgbevf_dev_start(struct rte_eth_dev *dev)
>> >>
>> >>       ixgbevf_dev_rxtx_start(dev);
>> >>
>> >> +     ixgbevf_dev_link_update(dev, 0);
>> >> +
>> >>       /* check and configure queue intr-vector mapping */
>> >>       if (rte_intr_cap_multiple(intr_handle) &&
>> >>           dev->data->dev_conf.intr_conf.rxq) {
>> >> --
>> >> 2.9.5
>> >