Re: [PATCH v3 net-next 14/15] net: enetc: add PSI-to-VSI link status notification support for VF

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Race condition in `enetc_vf_probe` causes permanent loss of carrier state if the interface is brought UP immediately by userspace.
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commit 14cc725fe4ebcb6942ed2c3904878d85a508f30f
Author: Wei Fang <wei.fang@nxp.com>

net: enetc: add PSI-to-VSI link status notification support for VF

This commit adds infrastructure for ENETC v4 VFs to track PF link
status changes via the PSI-to-VSI messaging channel. It implements
a dedicated MSI-X vector and workqueue to parse notifications and
update the carrier state accordingly.

[ ... ]

> diff --git a/drivers/net/ethernet/freescale/enetc/enetc_vf.c b/drivers/net/ethernet/freescale/enetc/enetc_vf.c
> --- a/drivers/net/ethernet/freescale/enetc/enetc_vf.c
> +++ b/drivers/net/ethernet/freescale/enetc/enetc_vf.c

[ ... ]

> @@ -520,15 +718,33 @@ static int enetc_vf_probe(struct pci_dev *pdev,
>  		goto err_alloc_msix;
>  	}
>  
> +	err = enetc_vf_wq_task_init(si);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to init workqueue\n");
> +		goto err_wq_init;
> +	}
> +
> +	err = enetc_vf_register_msg_msix(si);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to register msg irq\n");
> +		goto err_register_msg_msix;
> +	}
> +
>  	err = register_netdev(ndev);
>  	if (err)
>  		goto err_reg_netdev;
>  
> +	/* Enable message received interrupt */
> +	enetc_vf_enable_mr_int(si);
>  	netif_carrier_off(ndev);

[Severity: High]
This isn't a bug introduced by this patch, but this is a pre-existing 
issue that appears to be exacerbated by the new asynchronous message 
handling.

Could this sequence in enetc_vf_probe() cause a permanent loss of the
carrier state if the interface is brought up immediately by userspace?

Once register_netdev() exposes the device to userspace, the rtnl_lock
is dropped. If userspace reacts to the registration and brings the
interface up immediately, enetc_open() will run and successfully register
the link status notifier.

The PF then replies with the initial link status, queuing the msg_task
workqueue which calls netif_carrier_on().

Concurrently, enetc_vf_probe() resumes and unconditionally calls
netif_carrier_off(). If the workqueue wins the race, netif_carrier_off()
will overwrite the valid on state with off, severing the link without any
notification until the next physical link flap or a manual restart.

Should netif_carrier_off() be called before register_netdev() to prevent
this condition?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260831025441.635045-1-wei.fang@oss.nxp.com?part=14