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Date:   Mon, 2 Mar 2020 13:43:17 -0800
From:   Bjorn Andersson <bjorn.andersson@linaro.org>
To:     Mathieu Poirier <mathieu.poirier@linaro.org>
Cc:     nikita.shubin@maquefel.me, Nikita Shubin <NShubin@topcon.com>,
        Ohad Ben-Cohen <ohad@wizery.com>,
        linux-remoteproc <linux-remoteproc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] remoteproc: error on kick missing
Message-ID: <20200302214317.GI210720@yoga>
References: <20200228110804.25822-1-nikita.shubin@maquefel.me>
 <CANLsYkyDsJaxO_37qTjEP+aeQju8W2+jhHFRF7+oifBMqJqyng@mail.gmail.com>
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On Mon 02 Mar 09:44 PST 2020, Mathieu Poirier wrote:

> Hi Nikita,
> 
> On Fri, 28 Feb 2020 at 04:07, <nikita.shubin@maquefel.me> wrote:
> >
> > From: Nikita Shubin <NShubin@topcon.com>
> >
> > .kick method not set in rproc_ops will result in:
> >
> > 8<--- cut here ---
> > Unable to handle kernel NULL pointer dereference
> >
> > in rproc_virtio_notify, after firmware loading.
> 
> There wasn't any kernel stack trace?  What platform was this observed
> on? I'm afraid we won't be able to move forward with this patch
> without one, or more information on what is happening.
> 
> >
> > refuse to register an rproc-induced virtio device if no kick method was
> > defined for rproc.
> >
> > Signed-off-by: Nikita Shubin <NShubin@topcon.com>
> > ---

Nikita, please include "v2" in the subject and add here (below the ---)
short summary of what changes since v1.

> >  drivers/remoteproc/remoteproc_virtio.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
> > index 8c07cb2ca8ba..31a62a0b470e 100644
> > --- a/drivers/remoteproc/remoteproc_virtio.c
> > +++ b/drivers/remoteproc/remoteproc_virtio.c
> > @@ -334,6 +334,13 @@ int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
> >         struct rproc_mem_entry *mem;
> >         int ret;
> >
> > +       if (rproc->ops->kick == NULL) {
> > +               ret = -EINVAL;
> > +               dev_err(dev, ".kick method not defined for %s",
> > +                               rproc->name);
> > +               goto out;
> > +       }
> 
> I think it would be better to use WARN_ONCE() in rproc_virtio_notify()
> than prevent a virtio device from being added.  But again I will need
> more information on this case to know for sure.
> 

I reviewed v1 and afaict there's no way rproc->ops->kick would change
and that things wouldn't work without a kick.

So I requested that it should be checked during initialization instead.
Please let me know if I missed some case.

Regards,
Bjorn

> Thanks,
> Mathieu
> 
> > +
> >         /* Try to find dedicated vdev buffer carveout */
> >         mem = rproc_find_carveout_by_name(rproc, "vdev%dbuffer", rvdev->index);
> >         if (mem) {
> > --
> > 2.24.1
> >