Re: [PATCH 1/1] net: mvpp2: fix XDP rx queues registering

[John Fastabend <john.fastabend@gmail.com>]

Jakub Kicinski wrote:
> On Mon, 6 Dec 2021 15:42:47 +0000 Russell King (Oracle) wrote:
> > On Mon, Dec 06, 2021 at 04:37:20PM +0100, Emmanuel Deloget wrote:
> > > On 10/11/2021 15:41, Louis Amas wrote:  
> > > > The registration of XDP queue information is incorrect because the
> > > > RX queue id we use is invalid. When port->id == 0 it appears to works
> > > > as expected yet it's no longer the case when port->id != 0.
> > > > 
> > > > When we register the XDP rx queue information (using
> > > > xdp_rxq_info_reg() in function mvpp2_rxq_init()) we tell them to use
> > > > rxq->id as the queue id. This value iscomputed as:
> > > > rxq->id = port->id * max_rxq_count + queue_id
> > > > 
> > > > where max_rxq_count depends on the device version. In the MB case,
> > > > this value is 32, meaning that rx queues on eth2 are numbered from
> > > > 32 to 35 - there are four of them.
> > > > 
> > > > Clearly, this is not the per-port queue id that XDP is expecting:
> > > > it wants a value in the range [0..3]. It shall directly use queue_id
> > > > which is stored in rxq->logic_rxq -- so let's use that value instead.
> > > > 
> > > > This is consistent with the remaining part of the code in
> > > > mvpp2_rxq_init().
> 
> > > Is there any update on this patch ? Without it, XDP only partially work on a
> > > MACCHIATOBin (read: it works on some ports, not on others, as described in
> > > our analysis sent together with the original patch).  
> > 
> > I suspect if you *didn't* thread your updated patch to your previous
> > submission, then it would end up with a separate entry in
> > patchwork.kernel.org,
> 
> Indeed, it's easier to keep track of patches which weren't posted 
> as a reply in a thread, at least for me.
> 
> > and the netdev maintainers will notice that the
> > patch is ready for inclusion, having been reviewed by Marcin.
> 
> In this case I _think_ it was dropped because it didn't apply.
> 
> Please rebase on top of net/master and repost if the changes is still
> needed.

Also I would add the detailed description to the actual commit not below
the "--" lines. Capturing that in the log will be useful for future
reference if we ever hit similar issue here or elsewhere.

Otherwise for patch,

Acked-by: John Fastabend <john.fastabend@gmail.com>