linux-kernel - RE: [PATCH v2 net-next 12/14] net: fec: add fec_alloc_rxq_buffers

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Message-ID:
 <PAXPR04MB8510A564C6DE0459BC7E2A46888AA@PAXPR04MB8510.eurprd04.prod.outlook.com>
Date: Sat, 17 Jan 2026 02:16:18 +0000
From: Wei Fang <wei.fang@....com>
To: Frank Li <frank.li@....com>
CC: Shenwei Wang <shenwei.wang@....com>, Clark Wang <xiaoning.wang@....com>,
	"andrew+netdev@...n.ch" <andrew+netdev@...n.ch>, "davem@...emloft.net"
	<davem@...emloft.net>, "edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"ast@...nel.org" <ast@...nel.org>, "daniel@...earbox.net"
	<daniel@...earbox.net>, "hawk@...nel.org" <hawk@...nel.org>,
	"john.fastabend@...il.com" <john.fastabend@...il.com>, "sdf@...ichev.me"
	<sdf@...ichev.me>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>, "bpf@...r.kernel.org"
	<bpf@...r.kernel.org>
Subject: RE: [PATCH v2 net-next 12/14] net: fec: add
 fec_alloc_rxq_buffers_pp() to allocate buffers from page pool

> On Fri, Jan 16, 2026 at 03:40:25PM +0800, Wei Fang wrote:
> > Currently, the buffers of RX queue are allocated from the page pool.
> > In the subsequent patches to support XDP zero copy, the RX buffers
> > will be allocated from the UMEM. Therefore, extract
> > fec_alloc_rxq_buffers_pp() from fec_enet_alloc_rxq_buffers() and we
> > will add another helper to allocate RX buffers from UMEM for the XDP zero
> copy mode.
> >
> > Signed-off-by: Wei Fang <wei.fang@....com>
> > ---
> >  drivers/net/ethernet/freescale/fec_main.c | 78
> > ++++++++++++++++-------
> >  1 file changed, 54 insertions(+), 24 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/freescale/fec_main.c
> > b/drivers/net/ethernet/freescale/fec_main.c
> > index a418f0153d43..68aa94dd9487 100644
> > --- a/drivers/net/ethernet/freescale/fec_main.c
> > +++ b/drivers/net/ethernet/freescale/fec_main.c
> > @@ -3435,6 +3435,24 @@ static void fec_xdp_rxq_info_unreg(struct
> fec_enet_priv_rx_q *rxq)
> >  	}
> >  }
> >
> > +static void fec_free_rxq_buffers(struct fec_enet_priv_rx_q *rxq) {
> > +	int i;
> > +
> > +	for (i = 0; i < rxq->bd.ring_size; i++) {
> > +		struct page *page = rxq->rx_buf[i];
> > +
> > +		if (!page)
> > +			continue;
> > +
> > +		page_pool_put_full_page(rxq->page_pool, page, false);
> > +		rxq->rx_buf[i] = NULL;
> > +	}
> > +
> > +	page_pool_destroy(rxq->page_pool);
> > +	rxq->page_pool = NULL;
> > +}
> > +
> >  static void fec_enet_free_buffers(struct net_device *ndev)  {
> >  	struct fec_enet_private *fep = netdev_priv(ndev); @@ -3448,16
> > +3466,10 @@ static void fec_enet_free_buffers(struct net_device *ndev)
> >  		rxq = fep->rx_queue[q];
> >
> >  		fec_xdp_rxq_info_unreg(rxq);
> > -
> > -		for (i = 0; i < rxq->bd.ring_size; i++)
> > -			page_pool_put_full_page(rxq->page_pool, rxq->rx_buf[i],
> > -						false);
> > +		fec_free_rxq_buffers(rxq);
> >
> >  		for (i = 0; i < XDP_STATS_TOTAL; i++)
> >  			rxq->stats[i] = 0;
> > -
> > -		page_pool_destroy(rxq->page_pool);
> > -		rxq->page_pool = NULL;
> >  	}
> >
> >  	for (q = 0; q < fep->num_tx_queues; q++) { @@ -3556,22 +3568,18 @@
> > static int fec_enet_alloc_queue(struct net_device *ndev)
> >  	return ret;
> >  }
> >
> > -static int
> > -fec_enet_alloc_rxq_buffers(struct net_device *ndev, unsigned int
> > queue)
> > +static int fec_alloc_rxq_buffers_pp(struct fec_enet_private *fep,
> > +				    struct fec_enet_priv_rx_q *rxq)
> >  {
> > -	struct fec_enet_private *fep = netdev_priv(ndev);
> > -	struct fec_enet_priv_rx_q *rxq;
> > +	struct bufdesc *bdp = rxq->bd.base;
> >  	dma_addr_t phys_addr;
> > -	struct bufdesc	*bdp;
> >  	struct page *page;
> >  	int i, err;
> >
> > -	rxq = fep->rx_queue[queue];
> > -	bdp = rxq->bd.base;
> > -
> >  	err = fec_enet_create_page_pool(fep, rxq);
> >  	if (err < 0) {
> > -		netdev_err(ndev, "%s failed queue %d (%d)\n", __func__, queue, err);
> > +		netdev_err(fep->netdev, "%s failed queue %d (%d)\n",
> > +			   __func__, rxq->bd.qid, err);
> >  		return err;
> >  	}
> >
> > @@ -3590,8 +3598,10 @@ fec_enet_alloc_rxq_buffers(struct net_device
> > *ndev, unsigned int queue)
> >
> >  	for (i = 0; i < rxq->bd.ring_size; i++) {
> >  		page = page_pool_dev_alloc_pages(rxq->page_pool);
> > -		if (!page)
> > -			goto err_alloc;
> > +		if (!page) {
> > +			err = -ENOMEM;
> > +			goto free_rx_buffers;
> 
> look like this part is bug fix, miss set err to -ENOMEM
> 

This is not a bug fix, the previous logic returned "-ENOMEM" directly
at the err_alloc label, see below.

err_alloc:
	fec_enet_free_buffers(ndev);
	return -ENOMEM;