From: David Marchand <david.marchand@redhat.com>
To: Fengnan Chang <changfengnan@bytedance.com>,
olivier.matz@6wind.com, andrew.rybchenko@oktetlabs.ru
Cc: dev@dpdk.org, "Morten Brørup" <mb@smartsharesystems.com>
Subject: Re: [External] Re: [PATCH] mempool: fix rte_mempool_avail_count may segment fault when used in multiprocess
Date: Tue, 15 Nov 2022 08:47:15 +0100 [thread overview]
Message-ID: <CAJFAV8whTd+WGi4-hDyCNWvXbQ701Q4EH=LfkBajFGh0apRmbQ@mail.gmail.com> (raw)
In-Reply-To: <CAPFOzZveHKPs3Ue3WUCBjibaAmmOEAvVFAcgF7UxMFyNhPrsng@mail.gmail.com>
On Tue, Nov 15, 2022 at 2:51 AM Fengnan Chang
<changfengnan@bytedance.com> wrote:
>
> David Marchand <david.marchand@redhat.com> 于2022年11月15日周二 04:44写道:
> >
> > On Mon, Nov 14, 2022 at 9:13 AM changfengnan <changfengnan@bytedance.com> wrote:
> > >
> > > rte_mempool_create put tailq entry into rte_mempool_tailq list before
> > > populate, and pool_data set when populate. So in multi process, if
> > > process A create mempool, and process B can get mempool through
> > > rte_mempool_lookup before pool_data set, if B call rte_mempool_lookup,
> > > it will cause segment fault.
> >
> > I fail to see how pool_data impacts rte_mempool_lookup.
> > Something is fishy about this commitlog.
>
> oh, it's my fault about this commit. correct: if B can get mempool through
> rte_mempool_lookup before pool_data set, and call rte_mempool_avail_count,
> it will cause segment fault.
Ok, now it makes more sense :-).
>
> >
> >
> > > Fix this by put tailq entry into rte_mempool_tailq after populate.
> >
> > Moving tailq manipulation to rte_mempool_create only, is probably incorrect.
> > An application is allowed to call rte_mempool_create_empty() and
> > rte_mempool_populate().
> >
> > I did not look in depth, but It is likely the reason why testpmd (as
> > run with devtools/test-null.sh) won't pass anymore.
> > The CI reported this issue in various envs.
> >
> > We can't take this patch.
>
> Yeah, this version makes CI fail.
> I didn't notice rte_mempool_create_empty will called directly before, maybe
> add a new flag bit to indicate when to put tailq entry into rte_mempool_tailq
> list is a better way. If no better idea, I'll send a new version.
I don't think we need an other flag.
Can we "publish" the mempool at the mempool_ops_alloc_once stage?
>
> >
> >
> > >
> > > Signed-off-by: changfengnan <changfengnan@bytedance.com>
> >
> > Please use your real name.
>
> It's my real name.
Sorry, I meant your full name, like Fengnan Chang <changfengnan@bytedance.com>
--
David Marchand
next prev parent reply other threads:[~2022-11-15 7:47 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-14 7:14 changfengnan
2022-11-14 9:55 ` Morten Brørup
2022-11-14 11:23 ` changfengnan
2022-11-14 20:43 ` David Marchand
2022-11-15 1:51 ` [External] " Fengnan Chang
2022-11-15 7:23 ` Morten Brørup
2022-11-15 7:47 ` David Marchand [this message]
2022-11-15 8:29 ` Olivier Matz
2022-11-15 11:30 ` Fengnan Chang
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