OK, understand now.
Thanks,
Dong
-----Original Message-----
From: Ananyev, Konstantin
Sent: Wednesday, November 14, 2018 19:19
To: Wang, Dong1 <dong1.w...@intel.com>; Lipiec, Herakliusz
<herakliusz.lip...@intel.com>; dev@dpdk.org
Cc: tho...@monjalon.net; Burakov, Anatoly <anatoly.bura...@intel.com>;
sta...@dpdk.org
Subject: RE: [PATCH v2] example/ipv4_multicast: fix app hanging when using clone
> -----Original Message-----
> From: Wang, Dong1
> Sent: Wednesday, November 14, 2018 11:06 AM
> To: Ananyev, Konstantin <konstantin.anan...@intel.com>; Lipiec,
> Herakliusz <herakliusz.lip...@intel.com>; dev@dpdk.org
> Cc: tho...@monjalon.net; Burakov, Anatoly <anatoly.bura...@intel.com>;
> sta...@dpdk.org
> Subject: RE: [PATCH v2] example/ipv4_multicast: fix app hanging when
> using clone
>
> Hi Konstantin & Herakliusz,
>
> In mcast_out_pkt(), new header added and to be the first segment. Driver will
> check first segment's ol_flags when sending mbuf.
It will check for *TX* flags.
TX flags are not set in cloned mbuf (only RX ones).
> So why new first segment didn't inherit old one's ol_flags?
Because they are RX flags and they don't' really belong to new packet we are
going to send.
Also, as that bug shows it is error prone.
> This function already copied other mbuf fields from old one.
And from my perspective it is not needed and better be removed.
Though it is a subject of different patch probably.
>
> Since this is an example and reference code, hope developer can reuse
> it smoothly. If they didn't notice ol_flags not be copied because ol_flags is
> not changed in this example, they may take some time to debug their
> application.
For that scenario it is not needed.
Surely when user linking two packets manually (as we are doing here) it is his
responsibility to update the mbuf fileds properly.
I think this is obvious thing and probably already mentioned in the docs.
Konstantin
>
> This is a tiny change to the patch, I hope it cloud be done.
>
> Thanks,
> Dong
>
> -----Original Message-----
> From: Ananyev, Konstantin
> Sent: Wednesday, November 14, 2018 18:18
> To: Wang, Dong1 <dong1.w...@intel.com>; Lipiec, Herakliusz
> <herakliusz.lip...@intel.com>; dev@dpdk.org
> Cc: tho...@monjalon.net; Burakov, Anatoly <anatoly.bura...@intel.com>;
> sta...@dpdk.org
> Subject: RE: [PATCH v2] example/ipv4_multicast: fix app hanging when
> using clone
>
>
> >
> > Hi Konstantin,
> >
> > In this example, no flags be set by user, so no need to copy flags from
> > original mbuf.
>
> Then why to bother?
>
> > I'm thinking about some DPDK developers may create their own
> > application based on this example, they add some flags before packet be
> > cloned.
>
> Hmm you receive a packet change l2 header and transmit it.
> What flags you might need to copy from original header considering that only
> RX flags would be set at present moment?
> If you let say want to insert vlan tag (or so), then you'll have to set new
> TX flags.
> Again, for timestamp you'll need to copy the timestamp value too, which we
> don't support in that example.
> Konstantin
>
> >
> > Regards,
> > Dong
> >
> > -----Original Message-----
> > From: Ananyev, Konstantin
> > Sent: Wednesday, November 14, 2018 17:03
> > To: Wang, Dong1 <dong1.w...@intel.com>; Lipiec, Herakliusz
> > <herakliusz.lip...@intel.com>; dev@dpdk.org
> > Cc: tho...@monjalon.net; Burakov, Anatoly
> > <anatoly.bura...@intel.com>; sta...@dpdk.org
> > Subject: RE: [PATCH v2] example/ipv4_multicast: fix app hanging when
> > using clone
> >
> > Hi Dong,
> >
> > > Hi Herakliusz,
> > >
> > > Since pkt->ol_flags might set some other bits except
> > > IND_ATTACHED_MBUF, how about set its value to original
> > > pkt->ol_flag
> >
> > It could be done, but not sure what is the point?
> > Which flags you think we need to copy from cloned mbuf (segment #2) to new
> > header?
> > Konstantin
> >
> > >
> > > Regards,
> > > Dong
> > >
> > > -----Original Message-----
> > > From: Lipiec, Herakliusz
> > > Sent: Tuesday, November 13, 2018 19:49
> > > To: dev@dpdk.org
> > > Cc: Ananyev, Konstantin <konstantin.anan...@intel.com>; Wang,
> > > Dong1 <dong1.w...@intel.com>; tho...@monjalon.net; Burakov,
> > > Anatoly <anatoly.bura...@intel.com>; Lipiec, Herakliusz
> > > <herakliusz.lip...@intel.com>; sta...@dpdk.org
> > > Subject: [PATCH v2] example/ipv4_multicast: fix app hanging when
> > > using clone
> > >
> > > The ipv4_multicast sample application was dropping packets when
> > > using mbuf clone. When creating an L2 header and copying metadata
> > > from the source packet, the ol_flags were also copied along with
> > > all the other metadata. Because the cloned packet had
> > > IND_ATTACHED_MBUF
> > flag set in its ol_flags, this caused the packets to never be freed when
> > using rte_pktmbuf_free.
> > > Since copying ol_flags from the cloned packet is not necessary in the
> > > first place, just don't do it.
> > >
> > > Fixes: af75078fece3 ("first public release")
> > > CC: sta...@dpdk.org
> > >
> > > Reported-by: Wang Dong <dong1.w...@intel.com>
> > > Signed-off-by: Herakliusz Lipiec <herakliusz.lip...@intel.com>
> > > ---
> > > doc/guides/sample_app_ug/ipv4_multicast.rst | 1 -
> > > examples/ipv4_multicast/main.c | 2 --
> > > 2 files changed, 3 deletions(-)
> > >
> > > diff --git a/doc/guides/sample_app_ug/ipv4_multicast.rst
> > > b/doc/guides/sample_app_ug/ipv4_multicast.rst
> > > index ce1474ec7..f6efa7f6f 100644
> > > --- a/doc/guides/sample_app_ug/ipv4_multicast.rst
> > > +++ b/doc/guides/sample_app_ug/ipv4_multicast.rst
> > > @@ -319,7 +319,6 @@ It is the mcast_out_pkt() function that performs the
> > > packet duplication (either
> > > hdr->pkt.in_port = pkt->pkt.in_port;
> > > hdr->pkt.vlan_macip = pkt->pkt.vlan_macip;
> > > hdr->pkt.hash = pkt->pkt.hash;
> > > - hdr->ol_flags = pkt->ol_flags;
> > > rte_mbuf_sanity_check(hdr, RTE_MBUF_PKT, 1);
> > >
> > > return hdr;
> > > diff --git a/examples/ipv4_multicast/main.c
> > > b/examples/ipv4_multicast/main.c index 4073a4907..428ca4694 100644
> > > --- a/examples/ipv4_multicast/main.c
> > > +++ b/examples/ipv4_multicast/main.c
> > > @@ -266,8 +266,6 @@ mcast_out_pkt(struct rte_mbuf *pkt, int use_clone)
> > > hdr->tx_offload = pkt->tx_offload;
> > > hdr->hash = pkt->hash;
> > >
> > > - hdr->ol_flags = pkt->ol_flags;
> > > -
> > > __rte_mbuf_sanity_check(hdr, 1);
> > > return hdr;
> > > }
> > > --
> > > 2.17.1
