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From:   Ioana Ciornei <ioana.ciornei@nxp.com>
To:     Leo Li <leoyang.li@nxp.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Youri Querry <youri.querry_1@nxp.com>
Subject: RE: [PATCH net] soc: fsl: dpio: properly compute the consumer index
Thread-Topic: [PATCH net] soc: fsl: dpio: properly compute the consumer index
Thread-Index: AQHWIxnwftGr9QjI3EaSI/Mop7aGF6iZ8TmAgAAAJpA=
Date:   Tue, 5 May 2020 20:30:29 +0000
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> Subject: RE: [PATCH net] soc: fsl: dpio: properly compute the consumer in=
dex
>=20
>=20
>=20
> > -----Original Message-----
> > From: Ioana Ciornei <ioana.ciornei@nxp.com>
> > Sent: Tuesday, May 5, 2020 3:14 PM
> > To: davem@davemloft.net; netdev@vger.kernel.org; linux-
> > kernel@vger.kernel.org
> > Cc: Youri Querry <youri.querry_1@nxp.com>; Leo Li
> > <leoyang.li@nxp.com>; Ioana Ciornei <ioana.ciornei@nxp.com>
> > Subject: [PATCH net] soc: fsl: dpio: properly compute the consumer
> > index
> >
> > Mask the consumer index before using it. Without this, we would be
> > writing frame descriptors beyond the ring size supported by the QBMAN b=
lock.
> >
> > Fixes: 3b2abda7d28c ("soc: fsl: dpio: Replace QMAN array mode with
> > ring mode enqueue")
> > Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
>=20
> If you would like it go through net tree.
>=20
> Acked-by: Li Yang <leoyang.li@nxp.com>
>=20
> > ---
> >
> > I am sending this fix through the net tree since the bug manifests
> > itself only on net-next and not the soc trees. This way it would be
> > easier to integrate this sooner rather than later.
>=20
> Since the description of the patch says it fixes a patch included from so=
c tree, it
> is not very clear why this problem only exists on net-next.
>=20

The problem is only observed when we enqueue multiple frame descriptors at =
once, which is happening only with my latest patch set on net-next that add=
s this for the XDP_REDIRECT path.=20

> >
> >  drivers/soc/fsl/dpio/qbman-portal.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/soc/fsl/dpio/qbman-portal.c
> > b/drivers/soc/fsl/dpio/qbman-portal.c
> > index 804b8ba9bf5c..23a1377971f4 100644
> > --- a/drivers/soc/fsl/dpio/qbman-portal.c
> > +++ b/drivers/soc/fsl/dpio/qbman-portal.c
> > @@ -669,6 +669,7 @@ int qbman_swp_enqueue_multiple_direct(struct
> > qbman_swp *s,
> >  		eqcr_ci =3D s->eqcr.ci;
> >  		p =3D s->addr_cena + QBMAN_CENA_SWP_EQCR_CI;
> >  		s->eqcr.ci =3D qbman_read_register(s,
> QBMAN_CINH_SWP_EQCR_CI);
> > +		s->eqcr.ci &=3D full_mask;
> >
> >  		s->eqcr.available =3D qm_cyc_diff(s->eqcr.pi_ring_size,
> >  					eqcr_ci, s->eqcr.ci);
> > --
> > 2.17.1