linux-kernel - Re: [PATCH] vdpa/mlx5: Extract correct pointer from driver data

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Message-ID: <20210216124540.GA94503@mtl-vdi-166.wap.labs.mlnx>
Date:   Tue, 16 Feb 2021 14:45:40 +0200
From:   Eli Cohen <elic@...dia.com>
To:     Leon Romanovsky <leon@...nel.org>
CC:     <mst@...hat.com>, <jasowang@...hat.com>,
        <linux-kernel@...r.kernel.org>,
        <virtualization@...ts.linux-foundation.org>,
        <netdev@...r.kernel.org>, <si-wei.liu@...cle.com>
Subject: Re: [PATCH] vdpa/mlx5: Extract correct pointer from driver data

On Tue, Feb 16, 2021 at 09:37:34AM +0200, Leon Romanovsky wrote:
> On Tue, Feb 16, 2021 at 08:42:26AM +0200, Eli Cohen wrote:
> > On Tue, Feb 16, 2021 at 08:35:51AM +0200, Leon Romanovsky wrote:
> > > On Tue, Feb 16, 2021 at 07:50:22AM +0200, Eli Cohen wrote:
> > > > struct mlx5_vdpa_net pointer was stored in drvdata. Extract it as well
> > > > in mlx5v_remove().
> > > >
> > > > Fixes: 74c9729dd892 ("vdpa/mlx5: Connect mlx5_vdpa to auxiliary bus")
> > > > Signed-off-by: Eli Cohen <elic@...dia.com>
> > > > ---
> > > >  drivers/vdpa/mlx5/net/mlx5_vnet.c | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > > index 6b0a42183622..4103d3b64a2a 100644
> > > > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > > @@ -2036,9 +2036,9 @@ static int mlx5v_probe(struct auxiliary_device *adev,
> > > >
> > > >  static void mlx5v_remove(struct auxiliary_device *adev)
> > > >  {
> > > > -	struct mlx5_vdpa_dev *mvdev = dev_get_drvdata(&adev->dev);
> > > > +	struct mlx5_vdpa_net *ndev = dev_get_drvdata(&adev->dev);
> > > >
> > > > -	vdpa_unregister_device(&mvdev->vdev);
> > > > +	vdpa_unregister_device(&ndev->mvdev.vdev);
> > > >  }
> > >
> > > IMHO, The more correct solution is to fix dev_set_drvdata() call,
> > > because we are regustering/unregistering/allocating "struct mlx5_vdpa_dev".
> > >
> >
> > We're allocating "struct mlx5_vdpa_net". "struct mlx5_vdpa_dev" is just
> > a member field of "struct mlx5_vdpa_net".
> 
> I referred to these lines in the mlx5v_probe():
>   1986         err = mlx5_vdpa_alloc_resources(&ndev->mvdev);
>   1987         if (err)
>   1988                 goto err_mtu;
>   1989
>   1990         err = alloc_resources(ndev);
>   1991         if (err)
>   1992                 goto err_res;
>   1993
>   1994         err = vdpa_register_device(&mvdev->vdev);
> 
> So mlx5v_remove() is better to be symmetrical.
> 

It's "struct mlx5_vdpa_net" that is being allocated here so it makes
sense to set this pointer as the the driver data.

> Thanks
> 
> >
> > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > index 88dde3455bfd..079b8fe669af 100644
> > > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > @@ -1995,7 +1995,7 @@ static int mlx5v_probe(struct auxiliary_device *adev,
> > >  	if (err)
> > >  		goto err_reg;
> > >
> > > -	dev_set_drvdata(&adev->dev, ndev);
> > > +	dev_set_drvdata(&adev->dev, mvdev);
> > >  	return 0;
> > >
> > >  err_reg:
> > >
> > > >
> > > >  static const struct auxiliary_device_id mlx5v_id_table[] = {
> > >
> > > > --
> > > > 2.29.2
> > > >