linux-kernel - Re: [Intel-wired-lan] [PATCH] ice/ptp: fix the PTP worker retrying indefinitely if the link went down

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Date:   Thu, 19 Jan 2023 21:08:01 +0100
From:   Daniel Vacek <neelx@...hat.com>
To:     Jacob Keller <jacob.e.keller@...el.com>
Cc:     Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Richard Cochran <richardcochran@...il.com>,
        "Kolacinski, Karol" <karol.kolacinski@...el.com>,
        Siddaraju <siddaraju.dh@...el.com>,
        "Michalik, Michal" <michal.michalik@...el.com>,
        netdev@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Intel-wired-lan] [PATCH] ice/ptp: fix the PTP worker retrying
 indefinitely if the link went down

On Thu, Jan 19, 2023 at 8:25 PM Jacob Keller <jacob.e.keller@...el.com> wrote:
> On 1/19/2023 1:38 AM, Daniel Vacek wrote:
> > On Wed, Jan 18, 2023 at 11:22 PM Jacob Keller <jacob.e.keller@...el.com> wrote:
> >> On 1/18/2023 2:11 PM, Daniel Vacek wrote:
> >>> On Wed, Jan 18, 2023 at 9:59 PM Jacob Keller <jacob.e.keller@...el.com> wrote:
> >>>> On 1/18/2023 7:14 AM, Daniel Vacek wrote:
> >>>> 1) request tx timestamp
> >>>> 2) timestamp occurs
> >>>> 3) link goes down while processing
> >>>
> >>> I was thinking this is the case we got reported. But then again, I'm
> >>> not really experienced in this field.
> >>>
> >>
> >> I think it might be, or at least something similar to this.
> >>
> >> I think that can be fixed with the link check you added. I think we
> >> actually have a copy of the current link status in the ice_ptp or
> >> ice_ptp_tx structure which could be used instead of having to check back
> >> to the other structure.
> >
> > If you're talking about ptp_port->link_up that one is always false no
> > matter the actual NIC link status. First I wanted to use it but
> > checking all the 8 devices available in the dump data it just does not
> > match the net_dev->state or the port_info->phy.link_info.link_info
> >
> > crash> net_device.name,state 0xff48df6f0c553000
> >   name = "ens1f1",
> >   state = 0x7,    // DOWN
> > crash> ice_port_info.phy.link_info.link_info 0xff48df6f05dca018
> >   phy.link_info.link_info = 0xc0,    // DOWN
> > crash> ice_ptp_port.port_num,link_up 0xff48df6f05dd44e0
> >   port_num = 0x1
> >   link_up = 0x0,    // False
> >
> > crash> net_device.name,state 0xff48df6f25e3f000
> >   name = "ens1f0",
> >   state = 0x3,    // UP
> > crash> ice_port_info.phy.link_info.link_info 0xff48df6f070a3018
> >   phy.link_info.link_info = 0xe1,    // UP
> > crash> ice_ptp_port.port_num,link_up 0xff48df6f063184e0
> >   port_num = 0x0
> >   link_up = 0x0,    // False
> >
> > crash> ice_ptp_port.port_num,link_up 0xff48df6f25b844e0
> >   port_num = 0x2
> >   link_up = 0x0,    // False even this device is UP
> > crash> ice_ptp_port.port_num,link_up 0xff48df6f140384e0
> >   port_num = 0x3
> >   link_up = 0x0,    // False even this device is UP
> > crash> ice_ptp_port.port_num,link_up 0xff48df6f055044e0
> >   port_num = 0x0
> >   link_up = 0x0,    // False even this device is UP
> > crash> ice_ptp_port.port_num,link_up 0xff48df6f251cc4e0
> >   port_num = 0x1
> >   link_up = 0x0,
> > crash> ice_ptp_port.port_num,link_up 0xff48df6f33a9c4e0
> >   port_num = 0x2
> >   link_up = 0x0,
> > crash> ice_ptp_port.port_num,link_up 0xff48df6f3bb7c4e0
> >   port_num = 0x3
> >   link_up = 0x0,
> >
> > In other words, the ice_ptp_port.link_up is always false and cannot be
> > used. That's why I had to fall back to
> > hw->port_info->phy.link_info.link_info
> >
>
> Hmm. We call ice_ptp_link_change in ice_link_event which is called from
> ice_handle_link_event...
>
> In ice_link_event, a local link_up field is set based on
> phy_info->link_info.link_info & ICE_AQ_LINK_UP
>
> What kernel are you testing on? Does it include 6b1ff5d39228 ("ice:
> always call ice_ptp_link_change and make it void")?
>
> Prior to this commit the field was only valid for E822 devices, but I
> fixed that as it was used for other checks as well.
>
> I am guessing that the Red Hat kernel you are using lacks several of
> these clean ups and fixes.

Yeah, makes perfect sense. We don't have that commit in 8.4. All the data
I have and present here are from 4.18.0-305.49.1.rt7.121.el8_4.x86_64

> For the current code in the net-next kernel I believe we can safely use
> the ptp_port->link_up field.

I'll fix that up and drop you a v3. Thank you for the review.

--nX

> Thanks,
> Jake