Re: [PATCH] lib/mempool : rte_mempool_avail_count, fixing return bigger than mempool size

[Yasin CANER <yasinncaner@gmail.com>]

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Hello,

I found a second free command in my code and removed it. David pointed to
the right .

On the other hand, do you think we need to avoid miscalculations? Is it
better to patch it or not?

or it needs to be aware of the second free command.

Sharing more information about env.

# ethtool -i mgmt
driver: virtio_net
version: 1.0.0
firmware-version:
expansion-rom-version:
bus-info: 0000:00:03.0
supports-statistics: yes
supports-test: no
supports-eeprom-access: no
supports-register-dump: no
supports-priv-flags: no

NAME="Ubuntu"
VERSION="20.04.4 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.4 LTS"
VERSION_ID="20.04"

Linux spgw-dpdk 5.4.0-146-generic #163-Ubuntu SMP Fri Mar 17 18:26:02 UTC
2023 x86_64 x86_64 x86_64 GNU/Linux



Best regards.

Morten Brørup <mb@smartsharesystems.com>, 17 May 2023 Çar, 15:23 tarihinde
şunu yazdı:

> > From: David Marchand [mailto:david.marchand@redhat.com]
> > Sent: Wednesday, 17 May 2023 13.53
> >
> > On Wed, May 17, 2023 at 11:05 AM Morten Brørup <mb@smartsharesystems.com
> >
> > wrote:
> > > > On Tue, 16 May 2023 13:41:46 +0000
> > > > Yasin CANER <yasinncaner@gmail.com> wrote:
> > > >
> > > > > From: Yasin CANER <yasin.caner@ulakhaberlesme.com.tr>
> > > > >
> > > > > after a while working rte_mempool_avail_count function returns
> bigger
> > > > > than mempool size that cause miscalculation
> rte_mempool_in_use_count.
> > > > >
> > > > > it helps to avoid miscalculation rte_mempool_in_use_count.
> >
> > Is this issue reproduced with an application of the reporter, or a
> > DPDK in-tree application?
> >
> >
> > > > >
> > > > > Bugzilla ID: 1229
> > > > >
> > > > > Signed-off-by: Yasin CANER <yasin.caner@ulakhaberlesme.com.tr>
> > > >
> > > > An alternative that avoids some code duplication.
> > > >
> > > > diff --git a/lib/mempool/rte_mempool.c b/lib/mempool/rte_mempool.c
> > > > index cf5dea2304a7..2406b112e7b0 100644
> > > > --- a/lib/mempool/rte_mempool.c
> > > > +++ b/lib/mempool/rte_mempool.c
> > > > @@ -1010,7 +1010,7 @@ rte_mempool_avail_count(const struct
> rte_mempool
> > > > *mp)
> > > >         count = rte_mempool_ops_get_count(mp);
> > > >
> > > >         if (mp->cache_size == 0)
> > > > -               return count;
> > > > +               goto exit;
> > >
> > > This bug can only occur here (i.e. with cache_size==0) if
> > rte_mempool_ops_get_count() returns an incorrect value. The bug should be
> > fixed there instead.
> > >
> > >
> > >
> > > MB (continued): The bug must be in the underlying mempool driver. I
> took a
> > look at the ring and stack drivers, and they seem fine.
> >
> > Or it could indicate a double free (or equivalent) issue from the
> > application (either through direct call to mempool API, or indirectly
> > like sending/freeing an already sent/freed packet for example).
>
> Good point, David.
>
> @Yasin, if you build DPDK and your application with
> RTE_LIBRTE_MEMPOOL_DEBUG set in config/rte_config.h, the mempool cookies
> should catch any double frees.
>
>

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