From mboxrd@z Thu Jan  1 00:00:00 1970
From: zhouyangchao <zhouyates@gmail.com>
Subject: Re: [PATCH] net/bnx2x: reserve enough headroom for mbuf
	prepend
Date: Thu, 08 Mar 2018 05:57:09 +0000
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 <4a1a34a8-87a9-5776-dfeb-1be4fe59eb12@intel.com>
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Cc: dev@dpdk.org, harish.patil@cavium.com, rasesh.mody@cavium.com
To: Ferruh Yigit <ferruh.yigit@intel.com>
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When allocating a new mbuf for Rx, the value of m->data_off should be
reset to its default value (RTE_PKTMBUF_HEADROOM), instead of reusing
the previous undefined value, which could cause the packet to have a too
small or too high headroom.

On Mon, Mar 5, 2018 at 11:28 PM Ferruh Yigit <ferruh.yigit@intel.com> wrote:

> On 2/6/2018 11:21 AM, zhouyangchao wrote:
>
> Can you please provide more information why this patch is needed?
>
> > Signed-off-by: Yangchao Zhou <zhouyates@gmail.com>
> > ---
> >  drivers/net/bnx2x/bnx2x_rxtx.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/bnx2x/bnx2x_rxtx.c
> b/drivers/net/bnx2x/bnx2x_rxtx.c
> > index a0d4ac9..d8a3225 100644
> > --- a/drivers/net/bnx2x/bnx2x_rxtx.c
> > +++ b/drivers/net/bnx2x/bnx2x_rxtx.c
> > @@ -140,7 +140,8 @@ bnx2x_dev_rx_queue_setup(struct rte_eth_dev *dev,
> >                       return -ENOMEM;
> >               }
> >               rxq->sw_ring[idx] = mbuf;
> > -             rxq->rx_ring[idx] = mbuf->buf_iova;
> > +             rxq->rx_ring[idx] =
> > +                     rte_cpu_to_le_64(rte_mbuf_data_iova_default(mbuf));
> >       }
> >       rxq->pkt_first_seg = NULL;
> >       rxq->pkt_last_seg = NULL;
> > @@ -400,7 +401,8 @@ bnx2x_recv_pkts(void *p_rxq, struct rte_mbuf
> **rx_pkts, uint16_t nb_pkts)
> >
> >               rx_mb = rxq->sw_ring[bd_cons];
> >               rxq->sw_ring[bd_cons] = new_mb;
> > -             rxq->rx_ring[bd_prod] = new_mb->buf_iova;
> > +             rxq->rx_ring[bd_prod] =
> > +
>  rte_cpu_to_le_64(rte_mbuf_data_iova_default(new_mb));
> >
> >               rx_pref = NEXT_RX_BD(bd_cons) & MAX_RX_BD(rxq);
> >               rte_prefetch0(rxq->sw_ring[rx_pref]);
> > @@ -409,7 +411,7 @@ bnx2x_recv_pkts(void *p_rxq, struct rte_mbuf
> **rx_pkts, uint16_t nb_pkts)
> >                       rte_prefetch0(&rxq->sw_ring[rx_pref]);
> >               }
> >
> > -             rx_mb->data_off = pad;
> > +             rx_mb->data_off = pad + RTE_PKTMBUF_HEADROOM;
> >               rx_mb->nb_segs = 1;
> >               rx_mb->next = NULL;
> >               rx_mb->pkt_len = rx_mb->data_len = len;
> >
>
>