linux-kernel - RE: [Intel-wired-lan] [PATCH 5/5] idpf: skip stopping/opening vport if it is NULL during HW reset

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Message-ID: <IA3PR11MB89860A2DFF318912A58FF8E4E582A@IA3PR11MB8986.namprd11.prod.outlook.com>
Date: Fri, 9 Jan 2026 06:10:19 +0000
From: "Loktionov, Aleksandr" <aleksandr.loktionov@...el.com>
To: "Loktionov, Aleksandr" <aleksandr.loktionov@...el.com>, Li Li
	<boolli@...gle.com>, "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
	"Kitszel, Przemyslaw" <przemyslaw.kitszel@...el.com>, "David S. Miller"
	<davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Eric Dumazet
	<edumazet@...gle.com>, "intel-wired-lan@...ts.osuosl.org"
	<intel-wired-lan@...ts.osuosl.org>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "David
 Decotigny" <decot@...gle.com>, "Singhai, Anjali" <anjali.singhai@...el.com>,
	"Samudrala, Sridhar" <sridhar.samudrala@...el.com>, Brian Vazquez
	<brianvv@...gle.com>, "Tantilov, Emil S" <emil.s.tantilov@...el.com>
Subject: RE: [Intel-wired-lan] [PATCH 5/5] idpf: skip stopping/opening vport
 if it is NULL during HW reset



> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf
> Of Loktionov, Aleksandr
> Sent: Friday, January 9, 2026 7:07 AM
> To: Li Li <boolli@...gle.com>; Nguyen, Anthony L
> <anthony.l.nguyen@...el.com>; Kitszel, Przemyslaw
> <przemyslaw.kitszel@...el.com>; David S. Miller <davem@...emloft.net>;
> Jakub Kicinski <kuba@...nel.org>; Eric Dumazet <edumazet@...gle.com>;
> intel-wired-lan@...ts.osuosl.org
> Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org; David
> Decotigny <decot@...gle.com>; Singhai, Anjali
> <anjali.singhai@...el.com>; Samudrala, Sridhar
> <sridhar.samudrala@...el.com>; Brian Vazquez <brianvv@...gle.com>;
> Tantilov, Emil S <emil.s.tantilov@...el.com>
> Subject: Re: [Intel-wired-lan] [PATCH 5/5] idpf: skip stopping/opening
> vport if it is NULL during HW reset
> 
> 
> 
> > -----Original Message-----
> > From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf
> > Of Li Li via Intel-wired-lan
> > Sent: Wednesday, January 7, 2026 2:05 AM
> > To: Nguyen, Anthony L <anthony.l.nguyen@...el.com>; Kitszel,
> > Przemyslaw <przemyslaw.kitszel@...el.com>; David S. Miller
> > <davem@...emloft.net>; Jakub Kicinski <kuba@...nel.org>; Eric
> Dumazet
> > <edumazet@...gle.com>; intel-wired-lan@...ts.osuosl.org
> > Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org; David
> > Decotigny <decot@...gle.com>; Singhai, Anjali
> > <anjali.singhai@...el.com>; Samudrala, Sridhar
> > <sridhar.samudrala@...el.com>; Brian Vazquez <brianvv@...gle.com>;
> Li
> > Li <boolli@...gle.com>; Tantilov, Emil S <emil.s.tantilov@...el.com>
> > Subject: [Intel-wired-lan] [PATCH 5/5] idpf: skip stopping/opening
> > vport if it is NULL during HW reset
> >
> > When an idpf HW reset is triggered, it clears the vport but does not
> > clear the netdev held by vport:
> >
> >     // In idpf_vport_dealloc() called by idpf_init_hard_reset(),
> >     // idpf_init_hard_reset() sets IDPF_HR_RESET_IN_PROG, so
> >     // idpf_decfg_netdev() doesn't get called.
> >     if (!test_bit(IDPF_HR_RESET_IN_PROG, adapter->flags))
> >         idpf_decfg_netdev(vport);
> >     // idpf_decfg_netdev() would clear netdev but it isn't called:
> >     unregister_netdev(vport->netdev);
> >     free_netdev(vport->netdev);
> >     vport->netdev = NULL;
> >     // Later in idpf_init_hard_reset(), the vport is cleared:
> >     kfree(adapter->vports);
> >     adapter->vports = NULL;
> >
> > During an idpf HW reset, when userspace restarts the network
> service,
> > the vport associated with the netdev is NULL, and so a kernel panic
> > would
> > happen:
> >
> > [ 1791.669339] BUG: kernel NULL pointer dereference, address:
> > 0000000000000070 ...
> > [ 1791.717130] RIP: 0010:idpf_vport_stop+0x16/0x1c0
> >
> > This can be reproduced reliably by injecting a TX timeout to cause
> an
> > idpf HW reset, and injecting a virtchnl error to cause the HW reset
> to
> > fail and retry, while running "service network restart" in
> userspace.
> >
> > With this patch applied, we see the following error but no kernel
> > panics anymore:
> >
> > [  181.409483] idpf 0000:05:00.0 eth1: mtu not changed due to no
> vport
> > innetdev RTNETLINK answers: Bad address ...
"innetdev" -> "in netdev"

> > [  181.913644] idpf 0000:05:00.0 eth1: not stopping vport because it
> > is NULL [  181.938675] idpf 0000:05:00.0 eth1: mtu not changed due
> to
> > no vport in netdev ...
> > [  242.849499] idpf 0000:05:00.0 eth1: not opening vport because it
> is
> > NULL ...
> > [  304.289364] idpf 0000:05:00.0 eth0: not opening vport because it
> is
> > NULL
> >
> > Signed-off-by: Li Li <boolli@...gle.com>
> > ---
> >  drivers/net/ethernet/intel/idpf/idpf_lib.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > index 53b31989722a7..a9a556499262b 100644
> > --- a/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > +++ b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > @@ -1021,6 +1021,8 @@ static void idpf_vport_stop(struct idpf_vport
> > *vport, bool rtnl)
> >   */
> >  static int idpf_stop(struct net_device *netdev)  {
> > +	if (!netdev)
> > +		return 0;
> >  	struct idpf_netdev_priv *np = netdev_priv(netdev);
> >  	struct idpf_vport *vport;
> >
> > @@ -1029,9 +1031,14 @@ static int idpf_stop(struct net_device
> > *netdev)
> >
> >  	idpf_vport_ctrl_lock(netdev);
> >  	vport = idpf_netdev_to_vport(netdev);
> > +	if (!vport) {
> > +		netdev_err(netdev, "not stopping vport because it is
> > NULL");
> Please don't forget to add trailing '\n'.
> 
> > +		goto unlock;
> > +	}
> >
> >  	idpf_vport_stop(vport, false);
> >
> > +unlock:
> >  	idpf_vport_ctrl_unlock(netdev);
> >
> >  	return 0;
> > @@ -2301,6 +2308,11 @@ static int idpf_open(struct net_device
> > *netdev)
> >
> >  	idpf_vport_ctrl_lock(netdev);
> >  	vport = idpf_netdev_to_vport(netdev);
> > +	if (!vport) {
> > +		netdev_err(netdev, "not opening vport because it is
> > NULL");
> Please don't forget to add trailing '\n', here too.
> 
> > +		err = -EFAULT;
> > +		goto unlock;
> > +	}
> >
> >  	err = idpf_set_real_num_queues(vport);
> >  	if (err)
> > --
> > 2.52.0.351.gbe84eed79e-goog
> 
> Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@...el.com>