Re: [PATCH] net/tap: Bug fix to populate fds in secondary process

[kumaraparameshwaran rathinavel <kumaraparamesh92@gmail.com>]

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On Tue, Jan 18, 2022 at 9:51 PM Stephen Hemminger <
stephen@networkplumber.org> wrote:

> On Tue, 18 Jan 2022 05:22:19 +0000
> Kumara Parameshwaran <kparameshwar@vmware.com> wrote:
>
> > @Stephen Hemminger<mailto:stephen@networkplumber.org> This is process
> private as the tap fds are maintained in per process data structures. In
> existing scheme, the fds are opened by the primary during queue setup and
> exchanged to during secondary probe where the send_msg using SOL_SOCKET and
> SCM_RIGHTS would remap the corresponding fds to the secondary process. If
> the secondary process is coming up once the primary is initialised things
> would work fine, but it's a problem during hotplug of the tap device.
> >
> > Thanks,
> > Param.
> > ________________________________
> > From: Stephen Hemminger <stephen@networkplumber.org>
> > Sent: 18 January 2022 03:46
> > To: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
> > Cc: keith.wiles@intel.com <keith.wiles@intel.com>; dev@dpdk.org <
> dev@dpdk.org>; Kumara Parameshwaran <kparameshwar@vmware.com>
> > Subject: Re: [PATCH] net/tap: Bug fix to populate fds in secondary
> process
> >
> > On Fri, 26 Nov 2021 09:45:15 +0530
> > Kumara Parameshwaran <kumaraparamesh92@gmail.com> wrote:
> >
> > > +     ret = rte_eth_dev_get_port_by_name(request_param->port_name,
> &port_id);
> > > +     if (ret) {
> > > +             TAP_LOG(ERR, "Failed to get port id for %s",
> > > +                     request_param->port_name);
> > > +             return -1;
> > > +     }
> > > +     dev = &rte_eth_devices[port_id];
> > > +     process_private = dev->process_private;
> > > +     dev->data->nb_rx_queues = request_param->rxq_count;
> > > +     dev->data->nb_tx_queues = request_param->txq_count;
> >
> > Why is this necessary?  dev->data is already in memory shared between
> primary
> > and secondary process.
>
> > The question is about the two assignments that happen in secondary proces
> > that change dev->data->nb_rx_queues and dev->data->nb_tx_queues.  These
> are
> > shared and should not need to be modified here.
>
 Sure my bad. Misunderstood the comment. Yes, this should not be done, will
remove the assignments.

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