From: Ajit Khaparde <ajitkhaparde@gmail.com>
To: "Morten Brørup" <mb@smartsharesystems.com>
Cc: Olivier Matz <olivier.matz@6wind.com>,
dev@dpdk.org, andrew.rybchenko@oktetlabs.ru,
konstantin.ananyev@intel.com, stable@dpdk.org
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH v2] mbuf: fix reset on mbuf free
Date: Fri, 18 Dec 2020 15:33:41 -0800 [thread overview]
Message-ID: <CAD6mc5YTFp64f5+05J4PcZg2KpMjg6LWLzVd+8vpShJssgOrcg@mail.gmail.com> (raw)
In-Reply-To: <98CBD80474FA8B44BF855DF32C47DC35C614E2@smartserver.smartshare.dk>
On Fri, Dec 18, 2020 at 5:18 AM Morten Brørup <mb@smartsharesystems.com> wrote:
>
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Olivier Matz
> >
> > m->nb_seg must be reset on mbuf free whatever the value of m->next,
> > because it can happen that m->nb_seg is != 1. For instance in this
> > case:
> >
> > m1 = rte_pktmbuf_alloc(mp);
> > rte_pktmbuf_append(m1, 500);
> > m2 = rte_pktmbuf_alloc(mp);
> > rte_pktmbuf_append(m2, 500);
> > rte_pktmbuf_chain(m1, m2);
> > m0 = rte_pktmbuf_alloc(mp);
> > rte_pktmbuf_append(m0, 500);
> > rte_pktmbuf_chain(m0, m1);
> >
> > As rte_pktmbuf_chain() does not reset nb_seg in the initial m1
> > segment (this is not required), after this code the mbuf chain
> > have 3 segments:
> > - m0: next=m1, nb_seg=3
> > - m1: next=m2, nb_seg=2
> > - m2: next=NULL, nb_seg=1
> >
> > Then split this chain between m1 and m2, it would result in 2 packets:
> > - first packet
> > - m0: next=m1, nb_seg=3
> > - m1: next=m2, nb_seg=2
>
> I think you mean:
>
> - m0: next=m1, nb_seg=2 //< nb_seg corrected
> - m1: next=NULL, nb_seg=2 //< next corrected
>
> > - second packet
> > - m2: next=NULL, nb_seg=1
> >
> > Freeing the first packet will not restore nb_seg=1 in the second
> > segment. This is an issue because it is expected that mbufs stored
> > in pool have their nb_seg field set to 1.
> >
> > Fixes: 8f094a9ac5d7 ("mbuf: set mbuf fields while in pool")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
>
> The code looks good, so:
> Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
next prev parent reply other threads:[~2020-12-18 23:33 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-04 17:00 [dpdk-stable] [PATCH] " Olivier Matz
2020-11-05 0:15 ` Ananyev, Konstantin
2020-11-05 7:46 ` Olivier Matz
2020-11-05 8:33 ` [dpdk-stable] [dpdk-dev] " Morten Brørup
2020-11-05 9:03 ` Olivier Matz
2020-11-05 9:09 ` Andrew Rybchenko
2020-11-08 7:25 ` Ali Alnubani
2020-12-18 12:52 ` [dpdk-stable] [PATCH v2] " Olivier Matz
2020-12-18 13:18 ` [dpdk-stable] [dpdk-dev] " Morten Brørup
2020-12-18 23:33 ` Ajit Khaparde [this message]
2021-01-06 13:33 ` [dpdk-stable] [PATCH v3] " Olivier Matz
2021-01-10 9:28 ` Ali Alnubani
2021-01-11 13:14 ` Ananyev, Konstantin
2021-01-13 13:27 ` [dpdk-stable] [PATCH v4] " Olivier Matz
2021-01-15 13:59 ` David Marchand
2021-01-15 18:39 ` Ali Alnubani
2021-01-18 17:52 ` Ali Alnubani
2021-01-19 8:32 ` Olivier Matz
2021-01-19 8:53 ` Morten Brørup
2021-01-19 12:00 ` Ferruh Yigit
2021-01-19 12:27 ` [dpdk-stable] [dpdk-dev] " Morten Brørup
2021-01-19 14:03 ` Ferruh Yigit
2021-01-19 14:21 ` Morten Brørup
2021-01-21 9:15 ` Ferruh Yigit
2021-01-19 14:04 ` [dpdk-stable] " Slava Ovsiienko
2021-07-24 8:47 ` [dpdk-stable] [dpdk-dev] " Thomas Monjalon
2021-07-30 12:36 ` Olivier Matz
2021-07-30 14:35 ` Morten Brørup
2021-07-30 14:54 ` Thomas Monjalon
2021-07-30 15:14 ` Olivier Matz
2021-07-30 15:23 ` Morten Brørup
2021-01-21 9:19 ` [dpdk-stable] " Ferruh Yigit
2021-01-21 9:29 ` [dpdk-stable] [dpdk-dev] " Morten Brørup
2021-01-21 16:35 ` [dpdk-stable] [dpdklab] " Lincoln Lavoie
2021-01-23 8:57 ` [dpdk-stable] [dpdk-dev] [dpdklab] " Morten Brørup
2021-01-25 17:00 ` Brandon Lo
2021-01-25 18:42 ` [dpdk-stable] [dpdklab] RE: [dpdk-dev] " Ferruh Yigit
2021-06-15 13:56 ` [dpdk-stable] " Morten Brørup
2021-09-29 21:37 ` [dpdk-stable] [PATCH v5] " Olivier Matz
2021-09-30 13:27 ` Ali Alnubani
2021-10-21 9:18 ` [dpdk-stable] [dpdk-dev] " David Marchand
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