netdev - Re: [PATCH net-next v7 1/8] bnxt_en: Add auxiliary driver support

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Date:   Sat, 14 Jan 2023 12:39:09 -0800
From:   Ajit Khaparde <ajit.khaparde@...adcom.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     andrew.gospodarek@...adcom.com, davem@...emloft.net,
        edumazet@...gle.com, jgg@...pe.ca, leon@...nel.org,
        linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
        michael.chan@...adcom.com, netdev@...r.kernel.org,
        pabeni@...hat.com, selvin.xavier@...adcom.com,
        Leon Romanovsky <leonro@...dia.com>
Subject: Re: [PATCH net-next v7 1/8] bnxt_en: Add auxiliary driver support

On Fri, Jan 13, 2023 at 10:10 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Thu, 12 Jan 2023 12:29:32 -0800 Ajit Khaparde wrote:
> > Add auxiliary driver support.
> > An auxiliary device will be created if the hardware indicates
> > support for RDMA.
> > The bnxt_ulp_probe() function has been removed and a new
> > bnxt_rdma_aux_device_add() function has been added.
> > The bnxt_free_msix_vecs() and bnxt_req_msix_vecs() will now hold
> > the RTNL lock when they call the bnxt_close_nic()and bnxt_open_nic()
> > since the device close and open need to be protected under RTNL lock.
> > The operations between the bnxt_en and bnxt_re will be protected
> > using the en_ops_lock.
> > This will be used by the bnxt_re driver in a follow-on patch
> > to create ROCE interfaces.
>
> > --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> > +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> > @@ -13178,6 +13178,9 @@ static void bnxt_remove_one(struct pci_dev *pdev)
> >       struct net_device *dev = pci_get_drvdata(pdev);
> >       struct bnxt *bp = netdev_priv(dev);
> >
> > +     bnxt_rdma_aux_device_uninit(bp);
> > +     bnxt_aux_dev_free(bp);
>
> You still free bp->aux_dev synchronously..
>
> > +void bnxt_aux_dev_free(struct bnxt *bp)
> > +{
> > +     kfree(bp->aux_dev);
>
> .. here. Which is called on .remove of the PCI device.
>
> > +     bp->aux_dev = NULL;
> > +}
> > +
> > +static struct bnxt_aux_dev *bnxt_aux_dev_alloc(struct bnxt *bp)
> > +{
> > +     return kzalloc(sizeof(struct bnxt_aux_dev), GFP_KERNEL);
> > +}
> > +
> > +void bnxt_rdma_aux_device_uninit(struct bnxt *bp)
> > +{
> > +     struct bnxt_aux_dev *bnxt_adev;
> > +     struct auxiliary_device *adev;
> > +
> > +     /* Skip if no auxiliary device init was done. */
> > +     if (!(bp->flags & BNXT_FLAG_ROCE_CAP))
> > +             return;
> > +
> > +     bnxt_adev = bp->aux_dev;
> > +     adev = &bnxt_adev->aux_dev;
> > +     auxiliary_device_delete(adev);
> > +     auxiliary_device_uninit(adev);
> > +     if (bnxt_adev->id >= 0)
> > +             ida_free(&bnxt_aux_dev_ids, bnxt_adev->id);
> > +}
> > +
> > +static void bnxt_aux_dev_release(struct device *dev)
> > +{
> > +     struct bnxt_aux_dev *bnxt_adev =
> > +             container_of(dev, struct bnxt_aux_dev, aux_dev.dev);
> > +     struct bnxt *bp = netdev_priv(bnxt_adev->edev->net);
> > +
> > +     bnxt_adev->edev->en_ops = NULL;
> > +     kfree(bnxt_adev->edev);
>
> And yet the reference counted "release" function accesses the bp->adev
> like it must exist.
>
> This seems odd to me - why do we need refcounting on devices at all
> if we can free them synchronously? To be clear - I'm not sure this is
> wrong, just seems odd.
I followed the existing implementations in that regard. Thanks

>
> > +     bnxt_adev->edev = NULL;
> > +     bp->edev = NULL;
> > +}

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