netdev - Re: [PATCH net v2] bnxt_en: update xdp_rxq

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Message-ID: <CAMArcTUyvwTL15MtT5rPugfJL2JrgJvUibWwXF6TAuPPXHd2yg@mail.gmail.com>
Date: Wed, 24 Jul 2024 02:37:35 +0900
From: Taehee Yoo <ap420073@...il.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: michael.chan@...adcom.com, somnath.kotur@...adcom.com, kuba@...nel.org, 
	dw@...idwei.uk, netdev@...r.kernel.org, horms@...nel.org, edumazet@...gle.com, 
	davem@...emloft.net
Subject: Re: [PATCH net v2] bnxt_en: update xdp_rxq_info in queue restart logic

On Tue, Jul 23, 2024 at 7:59 PM Paolo Abeni <pabeni@...hat.com> wrote:
>

Hi Paolo,
Thanks a lot for the review!

> On 7/21/24 07:35, Taehee Yoo wrote:
> > When the netdev_rx_queue_restart() restarts queues, the bnxt_en driver
> > updates(creates and deletes) a page_pool.
> > But it doesn't update xdp_rxq_info, so the xdp_rxq_info is still
> > connected to an old page_pool.
> > So, bnxt_rx_ring_info->page_pool indicates a new page_pool, but
> > bnxt_rx_ring_info->xdp_rxq is still connected to an old page_pool.
> >
> > An old page_pool is no longer used so it is supposed to be
> > deleted by page_pool_destroy() but it isn't.
> > Because the xdp_rxq_info is holding the reference count for it and the
> > xdp_rxq_info is not updated, an old page_pool will not be deleted in
> > the queue restart logic.
> >
> > Before restarting 1 queue:
> > ./tools/net/ynl/samples/page-pool
> > enp10s0f1np1[6] page pools: 4 (zombies: 0)
> >       refs: 8192 bytes: 33554432 (refs: 0 bytes: 0)
> >       recycling: 0.0% (alloc: 128:8048 recycle: 0:0)
> >
> > After restarting 1 queue:
> > ./tools/net/ynl/samples/page-pool
> > enp10s0f1np1[6] page pools: 5 (zombies: 0)
> >       refs: 10240 bytes: 41943040 (refs: 0 bytes: 0)
> >       recycling: 20.0% (alloc: 160:10080 recycle: 1920:128)
> >
> > Before restarting queues, an interface has 4 page_pools.
> > After restarting one queue, an interface has 5 page_pools, but it
> > should be 4, not 5.
> > The reason is that queue restarting logic creates a new page_pool and
> > an old page_pool is not deleted due to the absence of an update of
> > xdp_rxq_info logic.
> >
> > Fixes: 2d694c27d32e ("bnxt_en: implement netdev_queue_mgmt_ops")
> > Signed-off-by: Taehee Yoo <ap420073@...il.com>
>
> @Michael: looks good?
>
> > @@ -15018,6 +15019,16 @@ static int bnxt_queue_mem_alloc(struct net_device *dev, void *qmem, int idx)
> >       if (rc)
> >               return rc;
> >
> > +     rc = xdp_rxq_info_reg(&clone->xdp_rxq, bp->dev, idx, 0);
> > +     if (rc < 0)
> > +             goto err_page_pool_destroy;
> > +
> > +     rc = xdp_rxq_info_reg_mem_model(&clone->xdp_rxq,
> > +                                     MEM_TYPE_PAGE_POOL,
> > +                                     clone->page_pool);
> > +     if (rc)
> > +             goto err_rxq_info_unreg;
> > +
> >       ring = &clone->rx_ring_struct;
> >       rc = bnxt_alloc_ring(bp, &ring->ring_mem);
> >       if (rc)
>
> Side note for a possible 'net-next' follow-up: there is quite a bit of
> duplicated code shared by both bnxt_queue_mem_alloc() and
> bnxt_alloc_rx_rings(), that is likely worth a common helper.
>

Yes, I agree with you.
I will try to refactor it after the merge window.

Thanks a lot!
Taehee Yoo


> Thanks,
>
> Paolo
>