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From:   Jason Wang <jasowang@redhat.com>
Date:   Thu, 10 Nov 2022 11:47:33 +0800
Message-ID: <CACGkMEuQTob8DYwYAa20-3SdHWoZJ+EnxJCKm+xR4_gUHRcd8g@mail.gmail.com>
Subject: Re: [PATCH] virtio_pci: modify ENOENT to EINVAL
To:     Angus Chen <angus.chen@jaguarmicro.com>
Cc:     "mst@redhat.com" <mst@redhat.com>,
        "virtualization@lists.linux-foundation.org" 
        <virtualization@lists.linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "lingshan.zhu@intel.com" <lingshan.zhu@intel.com>
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On Thu, Nov 10, 2022 at 11:31 AM Angus Chen <angus.chen@jaguarmicro.com> wrote:
>
> Hi Jason.
>
> > -----Original Message-----
> > From: Jason Wang <jasowang@redhat.com>
> > Sent: Wednesday, November 2, 2022 1:34 PM
> > To: Angus Chen <angus.chen@jaguarmicro.com>
> > Cc: mst@redhat.com; virtualization@lists.linux-foundation.org;
> > linux-kernel@vger.kernel.org; lingshan.zhu@intel.com
> > Subject: Re: [PATCH] virtio_pci: modify ENOENT to EINVAL
> >
> > On Tue, Nov 1, 2022 at 7:17 PM Angus Chen <angus.chen@jaguarmicro.com>
> > wrote:
> > >
> > > Virtio_crypto use max_data_queues+1 to setup vqs,
> > > we use vp_modern_get_num_queues to protect the vq range in setup_vq.
> > > We could enter index >= vp_modern_get_num_queues(mdev) in setup_vq
> > > if common->num_queues is not set well,and it return -ENOENT.
> > > It is better to use -EINVAL instead.
> >
> > I'm not sure I get this. It would be better to describe:
> >
> > 1) what kind of issues can we see if we return -ENOENT
> > 2) why -EINVAL can help in this case
> >
> > Thanks
> Thank you for your reply.
> We use a robot to test our dpu to get the return value of probe.
>  We often get ENOENT form ' setup_vq ' function because of device error.
> Most of time, my device can't handle queue_enable well.
> This time,we get 'ENOENT' because the device set max_data_queues bigger than num_queues.

Ok, I see, ENOENT is not very popular on linux but I'm not sure it's
worth bothering.

>
> I think EINVAL is used when the value of some parameter is wrong.
> Btw,it not a big deal,I can modify the robot to workaround.

Btw, the error code is not a part of the ABI, so depending on that is
kind of fragile.

Thanks

>
> >
> > >
> > > Signed-off-by: Angus Chen <angus.chen@jaguarmicro.com>
> > > ---
> > >  drivers/virtio/virtio_pci_modern.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/virtio/virtio_pci_modern.c
> > b/drivers/virtio/virtio_pci_modern.c
> > > index c3b9f2761849..edf2e18014cd 100644
> > > --- a/drivers/virtio/virtio_pci_modern.c
> > > +++ b/drivers/virtio/virtio_pci_modern.c
> > > @@ -303,7 +303,7 @@ static struct virtqueue *setup_vq(struct
> > virtio_pci_device *vp_dev,
> > >         int err;
> > >
> > >         if (index >= vp_modern_get_num_queues(mdev))
> > > -               return ERR_PTR(-ENOENT);
> > > +               return ERR_PTR(-EINVAL);
> > >
> > >         /* Check if queue is either not available or already active. */
> > >         num = vp_modern_get_queue_size(mdev, index);
> > > --
> > > 2.25.1
> > >
>