Re: [PATCH v3 4/6] net/nfb: use process private variable for internal data

Stephen Hemminger
2026-01-20T16:12:33Z

On Tue, 20 Jan 2026 15:13:58 +0100
Martin Spinler <spinler@cesnet.cz> wrote:

> On Mon, 2026-01-19 at 16:13 -0800, Stephen Hemminger wrote:
> > > Internal structures of libnfb can't be shared between processes.
> > > Move these structures from dev_private to process_private, which allows
> > > secondary process to correctly initialize and uninitialize the eth_dev.
> > >
> > >
> > > diff --git a/drivers/net/nfb/nfb.h b/drivers/net/nfb/nfb.h
> > > index 917b830283..09d4b7da5f 100644
> > > --- a/drivers/net/nfb/nfb.h
> > > +++ b/drivers/net/nfb/nfb.h
> > > @@ -48,7 +48,9 @@ struct pmd_internals {
> > > struct nc_rxmac *rxmac[RTE_MAX_NC_RXMAC];
> > > struct nc_txmac *txmac[RTE_MAX_NC_TXMAC];
> > > struct nfb_device *nfb;
> > > +};
> > >
> > > +struct pmd_priv {
> > > uint16_t max_rx_queues;
> > > uint16_t max_tx_queues;
> > > };
> >
> > Where does max_rx_queues get populated in the secondary process?
> > What if either process calls configure to change number of queues?
> >
> > Don't see other drivers splitting structure here.
>
> The NFB PMD must use separate handles for each process (each process
> has its own FILE* and mmap handles from libnfb). However, some data,
> such as max_rx_queues, is constant and can still be stored in shared
> memory (and inited by RTE_PROC_PRIMARY).
>
> The pmd_priv is stored in data->dev_private, so it is shared between
> processes. However, your comment pointed at the opposite issue, that
> the nfb_eth_dev_init() assigns to the (pmd_)priv->max_rx_queues in both
> process types (duplicate assignment).
> I will fix this by moving those assignments to the RTE_PROC_PRIMARY-
> only block.
>
> By the way, this partial diff shows the struct pmd_internals being
> split into the new struct pmd_priv. Semantically, however, the struct
> pmd_internals is the new one, is newly alocated and holds the
> process_private data.
>
> Does that make it better sense now?

Yes thanks, you might want to add a comment for future readers