Re: [PATCH v2 1/3] net/ark: support secondary process

[Ed Czeck <ed.czeck@atomicrules.com>]

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Hi ferruh,
We have limited support for secondary processes.  This patch simply avoids
corrupting the FPGA state if a secondary process attaches.
Improved support for secondary processes is on our list, but we need a
strong customer driver for this feature.
An update patch is following soon.
Thanks for the review.
Ed.

On Mon, Feb 20, 2023 at 9:17 AM Ferruh Yigit <ferruh.yigit@amd.com> wrote:

> On 2/17/2023 9:59 PM, Ed Czeck wrote:
> > From: John Miller <john.miller@atomicrules.com>
> >
> > disable device configuration for secondary processes
> >
> > Signed-off-by: John Miller <john.miller@atomicrules.com>
> > ---
> > v2:
> > * Use standard logging
> > ---
> >  drivers/net/ark/ark_ethdev.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/ark/ark_ethdev.c b/drivers/net/ark/ark_ethdev.c
> > index b2995427c8..d237e80cf4 100644
> > --- a/drivers/net/ark/ark_ethdev.c
> > +++ b/drivers/net/ark/ark_ethdev.c
> > @@ -147,6 +147,9 @@ eth_ark_pci_probe(struct rte_pci_driver *pci_drv
> __rte_unused,
> >       struct rte_eth_dev *eth_dev;
> >       int ret;
> >
> > +     if (rte_eal_process_type() == RTE_PROC_SECONDARY)
> > +             ARK_PMD_LOG(DEBUG, "ARK probed by secondary process\n");
> > +
> >       eth_dev = rte_eth_dev_pci_allocate(pci_dev, sizeof(struct
> ark_adapter));
> >
> >       if (eth_dev == NULL)
> > @@ -385,9 +388,11 @@ eth_ark_dev_init(struct rte_eth_dev *dev)
> >                   0xcafef00d, ark->sysctrl.t32[4], __func__);
> >
> >       /* We are a single function multi-port device. */
> > -     ret = ark_config_device(dev);
> > -     if (ret)
> > -             return -1;
> > +     if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
> > +             ret = ark_config_device(dev);
> > +             if (ret)
> > +                     return -1;
> > +     }
>
>
> Hi Ed,
>
> As far as I can see both primary and secondary process continues to run
> after this point, and below there are a few places that updates
> 'eth_dev->data'.
>
> 'eth_dev->data' is shared between primary and secondaries, so each
> secondary will be overwriting the shared data.
> Better usage is shared data only updated by primary process and
> secondary processes use available values.
> But 'eth_dev' is process specific and all primary and shared processes
> must set fields of this struct.
>
> You may need to re-order calls in function to make secondary quit after
> 'eth_dev' fields updated and before 'eth_dev->data' updated, to make
> sure secondaries don't update shared data.
>
> >
> >       dev->dev_ops = &ark_eth_dev_ops;
> >       dev->rx_queue_count = eth_ark_dev_rx_queue_count;
>
>

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