Re: [PATCH 1/2] hw/net/net_tx_pkt: add function to check pkt->max_raw_frags

[Mauro Matteo Cascella]

On Tue, Jul 28, 2020 at 6:06 AM Jason Wang <jasowang@redhat.com> wrote:
>
>
> On 2020/7/28 上午1:08, Mauro Matteo Cascella wrote:
> > This patch introduces a new function in hw/net/net_tx_pkt.{c,h} to check the
> > current data fragment against the maximum number of data fragments.
>
>
> I wonder whether it's better to do the check in
> net_tx_pkt_add_raw_fragment() and fail there.

Given the assertion, I assumed the caller is responsible for the
check, but moving the check in net_tx_pkt_add_raw_fragment() totally
makes sense to me.

> Btw, I find net_tx_pkt_add_raw_fragment() does not unmap dma when
> returning to true, is this a bug?

Isn't it unmapped in net_tx_pkt_reset()?

> Thanks
>
>
> >
> > Reported-by: Ziming Zhang <ezrakiez@gmail.com>
> > Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
> > ---
> >   hw/net/net_tx_pkt.c | 5 +++++
> >   hw/net/net_tx_pkt.h | 8 ++++++++
> >   2 files changed, 13 insertions(+)
> >
> > diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
> > index 9560e4a49e..d035618f2c 100644
> > --- a/hw/net/net_tx_pkt.c
> > +++ b/hw/net/net_tx_pkt.c
> > @@ -400,6 +400,11 @@ bool net_tx_pkt_add_raw_fragment(struct NetTxPkt *pkt, 
> > hwaddr pa,
> >       }
> >   }
> >
> > +bool net_tx_pkt_exceed_max_fragments(struct NetTxPkt *pkt)
> > +{
> > +    return pkt->raw_frags >= pkt->max_raw_frags;
> > +}
> > +
> >   bool net_tx_pkt_has_fragments(struct NetTxPkt *pkt)
> >   {
> >       return pkt->raw_frags > 0;
> > diff --git a/hw/net/net_tx_pkt.h b/hw/net/net_tx_pkt.h
> > index 4ec8bbe9bd..e2ee46ae03 100644
> > --- a/hw/net/net_tx_pkt.h
> > +++ b/hw/net/net_tx_pkt.h
> > @@ -179,6 +179,14 @@ bool net_tx_pkt_send_loopback(struct NetTxPkt *pkt, 
> > NetClientState *nc);
> >    */
> >   bool net_tx_pkt_parse(struct NetTxPkt *pkt);
> >
> > +/**
> > +* indicates if the current data fragment exceeds max_raw_frags
> > +*
> > +* @pkt:            packet
> > +*
> > +*/
> > +bool net_tx_pkt_exceed_max_fragments(struct NetTxPkt *pkt);
> > +
> >   /**
> >   * indicates if there are data fragments held by this packet object.
> >   *
>

-- 
Mauro Matteo Cascella, Red Hat Product Security
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