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References: <20221221200513.676744-1-nfrayer@baylibre.com> <66ef2f70-9405-fe09-7927-143084286d1b@gmail.com>
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From:   Nicolas Frayer <nfrayer@baylibre.com>
Date:   Fri, 30 Dec 2022 01:04:57 +0100
Message-ID: <CANyCTtR-6ooPBPyNdnDe+qUMDUHVUyrHc=2sk8noXzmcurbqag@mail.gmail.com>
Subject: Re: [PATCH] soc: ti: k3-ringacc: Add try_module_get() to k3_dmaring_request_dual_ring()
To:     =?UTF-8?Q?P=C3=A9ter_Ujfalusi?= <peter.ujfalusi@gmail.com>
Cc:     nm@ti.com, ssantosh@kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, grygorii.strashko@ti.com,
        khilman@baylibre.com, mkorpershoek@baylibre.com
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Le sam. 24 d=C3=A9c. 2022 =C3=A0 23:01, P=C3=A9ter Ujfalusi
<peter.ujfalusi@gmail.com> a =C3=A9crit :
>
> Hi Nicolas,
>
> On 21/12/2022 22:05, Nicolas Frayer wrote:
> > When the k3 ring accelerator driver has been modified to add module bui=
ld
> > support, try_module_get() and module_put() have been added to update th=
e
> > module refcnt. One code path has not been updated and it has introduced
> > an issue where the refcnt is decremented by module_put() in
> > k3_ringacc_ring_free() without being incremented previously.
> > Adding try_module_get() to k3_dmaring_request_dual_ring() ensures the
> > refcnt is kept up to date.
>
> Good catch!
> I had never had my hands on a device with DMSS (BCDMA/PKDMA) and the
> original module support was developed and tested on devices with UDMA.
>
> can you add the fixes tag along with my reviewed by tag?
>
> Fixes: c07f216a8b72 ("soc: ti: k3-ringacc: Allow the driver to be built a=
s module")
> Reviewed-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
>
> >
> > Signed-off-by: Nicolas Frayer <nfrayer@baylibre.com>
> > ---
> >   drivers/soc/ti/k3-ringacc.c | 7 +++++++
> >   1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/soc/ti/k3-ringacc.c b/drivers/soc/ti/k3-ringacc.c
> > index e01e4d815230a..8f131368a7586 100644
> > --- a/drivers/soc/ti/k3-ringacc.c
> > +++ b/drivers/soc/ti/k3-ringacc.c
> > @@ -406,6 +406,11 @@ static int k3_dmaring_request_dual_ring(struct k3_=
ringacc *ringacc, int fwd_id,
> >
> >       mutex_lock(&ringacc->req_lock);
> >
> > +     if (!try_module_get(ringacc->dev->driver->owner)) {
> > +             ret =3D -EINVAL;
> > +             goto err_module_get;
> > +     }
> > +
> >       if (test_bit(fwd_id, ringacc->rings_inuse)) {
> >               ret =3D -EBUSY;
> >               goto error;
> > @@ -421,6 +426,8 @@ static int k3_dmaring_request_dual_ring(struct k3_r=
ingacc *ringacc, int fwd_id,
> >       return 0;
> >
> >   error:
> > +     module_put(ringacc->dev->driver->owner);
> > +err_module_get:
> >       mutex_unlock(&ringacc->req_lock);
> >       return ret;
> >   }
>
> --
> P=C3=A9ter
Thanks Peter, I'll send a v2 with the tags.