netdev - Re: [Intel-wired-lan] [PATCH iwl-net] idpf: check error for register

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Message-ID: <20250216093658.GB1615191@kernel.org>
Date: Sun, 16 Feb 2025 09:36:58 +0000
From: Simon Horman <horms@...nel.org>
To: "Tantilov, Emil S" <emil.s.tantilov@...el.com>
Cc: intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
	decot@...gle.com, willemb@...gle.com, anthony.l.nguyen@...el.com,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, madhu.chittim@...el.com
Subject: Re: [Intel-wired-lan] [PATCH iwl-net] idpf: check error for
 register_netdev() on init

On Thu, Feb 13, 2025 at 12:39:03PM -0800, Tantilov, Emil S wrote:
> On 2/12/2025 10:21 AM, Simon Horman wrote:
> > On Mon, Feb 10, 2025 at 06:38:51PM -0800, Emil Tantilov wrote:
> > > Current init logic ignores the error code from register_netdev(),
> > > which will cause WARN_ON() on attempt to unregister it, if there was one,
> > > and there is no info for the user that the creation of the netdev failed.
> > > 
> > > WARNING: CPU: 89 PID: 6902 at net/core/dev.c:11512 unregister_netdevice_many_notify+0x211/0x1a10
> > > ...
> > > [ 3707.563641]  unregister_netdev+0x1c/0x30
> > > [ 3707.563656]  idpf_vport_dealloc+0x5cf/0xce0 [idpf]
> > > [ 3707.563684]  idpf_deinit_task+0xef/0x160 [idpf]
> > > [ 3707.563712]  idpf_vc_core_deinit+0x84/0x320 [idpf]
> > > [ 3707.563739]  idpf_remove+0xbf/0x780 [idpf]
> > > [ 3707.563769]  pci_device_remove+0xab/0x1e0
> > > [ 3707.563786]  device_release_driver_internal+0x371/0x530
> > > [ 3707.563803]  driver_detach+0xbf/0x180
> > > [ 3707.563816]  bus_remove_driver+0x11b/0x2a0
> > > [ 3707.563829]  pci_unregister_driver+0x2a/0x250
> > > 
> > > Introduce an error check and log the vport number and error code.
> > > On removal make sure to check VPORT_REG_NETDEV flag prior to calling
> > > unregister and free on the netdev.
> > > 
> > > Add local variables for idx, vport_config and netdev for readability.
> > > 
> > > Fixes: 0fe45467a104 ("idpf: add create vport and netdev configuration")
> > > Reviewed-by: Madhu Chittim <madhu.chittim@...el.com>
> > > Suggested-by: Tony Nguyen <anthony.l.nguyen@...el.com>
> > > Signed-off-by: Emil Tantilov <emil.s.tantilov@...el.com>
> > > ---
> > >   drivers/net/ethernet/intel/idpf/idpf_lib.c | 27 ++++++++++++++--------
> > >   1 file changed, 18 insertions(+), 9 deletions(-)
> > > 
> > > diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > 
> > ...
> > 
> > > @@ -1536,12 +1540,17 @@ void idpf_init_task(struct work_struct *work)
> > >   	}
> > >   	for (index = 0; index < adapter->max_vports; index++) {
> > > -		if (adapter->netdevs[index] &&
> > > -		    !test_bit(IDPF_VPORT_REG_NETDEV,
> > > -			      adapter->vport_config[index]->flags)) {
> > > -			register_netdev(adapter->netdevs[index]);
> > > -			set_bit(IDPF_VPORT_REG_NETDEV,
> > > -				adapter->vport_config[index]->flags);
> > > +		struct idpf_vport_config *vport_config = adapter->vport_config[index];
> > > +		struct net_device *netdev = adapter->netdevs[index];
> > > +
> > > +		if (netdev && !test_bit(IDPF_VPORT_REG_NETDEV, vport_config->flags)) {
> > > +			err = register_netdev(netdev);
> > > +			if (err) {
> > > +				dev_err(&pdev->dev, "failed to register netdev for vport %d: %pe\n",
> > > +					index, ERR_PTR(err));
> > > +				continue;
> > > +			}
> > > +			set_bit(IDPF_VPORT_REG_NETDEV, vport_config->flags);
> > >   		}
> > >   	}
> > 
> > Hi Emil,
> > 
> > I'm wondering if we could reduce indentation and lines longer
> > than 80 characters in the above like this (completely untested!):
> I was mostly trying to focus on the fix itself, since this patch is -net
> bound. The >80 line came about from the introduction of the local netdev and
> it seemed cleaner to keep it in one line. I can just split the check as in
> the original code.
> 
> > 
> > 
> > 	for (index = 0; index < adapter->max_vports; index++) {
> > 		struct idpf_vport_config *vport_config = adapter->vport_config[index];
> > 		struct net_device *netdev = adapter->netdevs[index];
> > 
> > 		if (!netdev ||
> > 		    test_bit(IDPF_VPORT_REG_NETDEV, vport_config->flags))
> > 		    continue;
> Again, because its mainly to add the error checking I am not sure if its OK
> to re-shuffle the logic.
> 
> > 
> > 		err = register_netdev(netdev);
> > 		if (err) {
> > 			dev_err(&pdev->dev, "failed to register netdev for vport %d: %pe\n",
> > 				index, ERR_PTR(err));
> > 			continue;
> > 		}
> > 		set_bit(IDPF_VPORT_REG_NETDEV, vport_config->flags);
> > 	}
> 
> Don't mind re-spinning (and testing) v2 with the proposed change, if it's
> not infringing on the guidelines for submission to -net.

Thanks,

I see your point about not wanting to change logic for a -net patch.

My feeling is that the change is trivial enough to fit within -net
boundaries. But if you think there is any risk of it regressing
then feel free to go with your original version.