netdev - Re: [PATCH net v1] octeon_ep: initialise control mbox tasks before using APIs

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Date: Mon, 4 Dec 2023 23:13:24 +0100
From: Michal Schmidt <mschmidt@...hat.com>
To: Shinas Rasheed <srasheed@...vell.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, hgani@...vell.com, 
	vimleshk@...vell.com, egallen@...hat.com, pabeni@...hat.com, horms@...nel.org, 
	kuba@...nel.org, davem@...emloft.net, wizhao@...hat.com, konguyen@...hat.com, 
	Veerasenareddy Burru <vburru@...vell.com>, Sathesh Edara <sedara@...vell.com>, 
	Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH net v1] octeon_ep: initialise control mbox tasks before
 using APIs

On Mon, Dec 4, 2023 at 11:10 PM Michal Schmidt <mschmidt@...hat.com> wrote:
>
> On Sat, Dec 2, 2023 at 4:08 PM Shinas Rasheed <srasheed@...vell.com> wrote:
> > Do INIT_WORK for the various workqueue tasks before the first
> > invocation of any control net APIs. Since octep_ctrl_net_get_info
> > was called before the control net receive work task was even
> > initialised, the function call wasn't returning actual firmware
> > info queried from Octeon.
>
> It might be more accurate to say that octep_ctrl_net_get_info depends
> on the processing of OEI events. This happens in intr_poll_task.
> That's why intr_poll_task needs to be queued earlier.
> Did octep_send_mbox_req previously always fail with EAGAIN after
          ^^^^^^^^^^^^^^^^^^^^^
I meant octep_ctrl_net_get_info here.

> running into the 500 ms timeout in octep_send_mbox_req?
>
> Apropos octep_send_mbox_req... I think it has a race. "d" is put on
> the ctrl_req_wait_list after sending the request to the hardware. If
> the response arrives quickly, "d" might not yet be on the list when
> process_mbox_resp looks for it.
> Also, what protects ctrl_req_wait_list from concurrent access?
>
> Michal
>
> > Fixes: 8d6198a14e2b ("octeon_ep: support to fetch firmware info")
> > Signed-off-by: Shinas Rasheed <srasheed@...vell.com>
> > ---
> >  .../net/ethernet/marvell/octeon_ep/octep_main.c    | 14 +++++++-------
> >  1 file changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/marvell/octeon_ep/octep_main.c b/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
> > index 552970c7dec0..3e7bfd3e0f56 100644
> > --- a/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
> > +++ b/drivers/net/ethernet/marvell/octeon_ep/octep_main.c
> > @@ -1193,6 +1193,13 @@ int octep_device_setup(struct octep_device *oct)
> >         if (ret)
> >                 return ret;
> >
> > +       INIT_WORK(&oct->tx_timeout_task, octep_tx_timeout_task);
> > +       INIT_WORK(&oct->ctrl_mbox_task, octep_ctrl_mbox_task);
> > +       INIT_DELAYED_WORK(&oct->intr_poll_task, octep_intr_poll_task);
> > +       oct->poll_non_ioq_intr = true;
> > +       queue_delayed_work(octep_wq, &oct->intr_poll_task,
> > +                          msecs_to_jiffies(OCTEP_INTR_POLL_TIME_MSECS));
> > +
> >         atomic_set(&oct->hb_miss_cnt, 0);
> >         INIT_DELAYED_WORK(&oct->hb_task, octep_hb_timeout_task);
> >
> > @@ -1333,13 +1340,6 @@ static int octep_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> >         queue_delayed_work(octep_wq, &octep_dev->hb_task,
> >                            msecs_to_jiffies(octep_dev->conf->fw_info.hb_interval));
> >
> > -       INIT_WORK(&octep_dev->tx_timeout_task, octep_tx_timeout_task);
> > -       INIT_WORK(&octep_dev->ctrl_mbox_task, octep_ctrl_mbox_task);
> > -       INIT_DELAYED_WORK(&octep_dev->intr_poll_task, octep_intr_poll_task);
> > -       octep_dev->poll_non_ioq_intr = true;
> > -       queue_delayed_work(octep_wq, &octep_dev->intr_poll_task,
> > -                          msecs_to_jiffies(OCTEP_INTR_POLL_TIME_MSECS));
> > -
> >         netdev->netdev_ops = &octep_netdev_ops;
> >         octep_set_ethtool_ops(netdev);
> >         netif_carrier_off(netdev);
> > --
> > 2.25.1
> >