Subject: Re: [PATCH net v2 1/1] mlxbf_gige: Fix kernel panic at shutdown

From: Maciej Fijalkowski <[email-masked]>
Date: Mon, 12 Jun 2023 13:34:49 +0200

On Sun, Jun 11, 2023 at 09:11:25PM +0300, Leon Romanovsky wrote:
> On Wed, Jun 07, 2023 at 10:03:35AM -0400, Asmaa Mnebhi wrote:
> > There is a race condition happening during shutdown due to pending napi transactions.
> > Since mlxbf_gige_poll is still running, it tries to access a NULL pointer and as a
> > result causes a kernel panic.
> > To fix this during shutdown, invoke mlxbf_gige_remove to disable and dequeue napi.
> > 
> > Fixes: f92e1869d74e ("Add Mellanox BlueField Gigabit Ethernet driver")
> > Signed-off-by: Asmaa Mnebhi <[email-masked]>
> > ---
> >  .../net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c    | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c
> > index 694de9513b9f..609d038b034e 100644
> > --- a/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c
> > +++ b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c
> > @@ -475,6 +475,9 @@ static int mlxbf_gige_remove(struct platform_device *pdev)
> >  {
> >  	struct mlxbf_gige *priv = platform_get_drvdata(pdev);
> >  
> > +	if (!priv)
> > +		return 0;
> > +
> 
> How can this check be correct? You are removing mlxbf_gige driver, priv
> should be always exist here.

Asmaa please include v1->v2 diff next time.

Leon, look at v1 discussion:
https://lore.kernel.org/netdev/[email-masked]/

> 
> >  	unregister_netdev(priv->netdev);
> >  	phy_disconnect(priv->netdev->phydev);
> >  	mlxbf_gige_mdio_remove(priv);
> > @@ -485,10 +488,7 @@ static int mlxbf_gige_remove(struct platform_device *pdev)
> >  
> >  static void mlxbf_gige_shutdown(struct platform_device *pdev)
> >  {
> > -	struct mlxbf_gige *priv = platform_get_drvdata(pdev);
> > -
> > -	writeq(0, priv->base + MLXBF_GIGE_INT_EN);
> > -	mlxbf_gige_clean_port(priv);
> > +	mlxbf_gige_remove(pdev);
> >  }
> >  
> >  static const struct acpi_device_id __maybe_unused mlxbf_gige_acpi_match[] = {
> > -- 
> > 2.30.1
> > 
> > 
>