Re: [PATCH net] ptp: netc: fix potential interrupt storm caused by incorrect unbind order

[Vadim Fedorenko <vadim.fedorenko@linux.dev>]

On 24/07/2026 07:51, wei.fang@oss.nxp.com wrote:
> From: Wei Fang <wei.fang@nxp.com>
> 
> In netc_timer_remove(), hardware interrupts are disabled by clearing
> TMR_TEMASK before ptp_clock_unregister() is called. This may cause a
> race condition during driver unbind that could leave hardware interrupts
> active. For example, a concurrent PTP_CLK_REQ_EXTTS ioctl can re-enable
> TMR_TEMASK after it has been cleared, leaving a pending hardware
> interrupt when the driver unbinds.
> 
> Since the NETC Timer does not support PCIe FLR, hardware state is not
> reset during probe. When the driver is rebound and the IRQ is registered,
> the pending interrupt fires immediately. At that point priv->tmr_emask
> is still zero, so netc_timer_isr() does not clear the interrupt status
> and unconditionally returns IRQ_HANDLED, resulting in an uninterruptible
> infinite interrupt storm.
> 
> Therefore, move ptp_clock_unregister() before the register writes that
> clear NETC_TMR_TEMASK and NETC_TMR_CTRL. This guarantees that no
> in-flight or concurrent ioctl can re-enable hardware interrupts, so no
> pending interrupt is left when the driver unbinds.
> 
> Fixes: 671e266835b8 ("ptp: netc: add periodic pulse output support")
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Closes: https://sashiko.dev/#/patchset/20260720012508.23227-1-wei.fang%40oss.nxp.com
> Signed-off-by: Wei Fang <wei.fang@nxp.com>
> ---
>   drivers/ptp/ptp_netc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/ptp/ptp_netc.c b/drivers/ptp/ptp_netc.c
> index 5e381c354d74..3bab86afe8e2 100644
> --- a/drivers/ptp/ptp_netc.c
> +++ b/drivers/ptp/ptp_netc.c
> @@ -1019,9 +1019,9 @@ static void netc_timer_remove(struct pci_dev *pdev)
>   {
>   	struct netc_timer *priv = pci_get_drvdata(pdev);
>   
> +	ptp_clock_unregister(priv->clock);
>   	netc_timer_wr(priv, NETC_TMR_TEMASK, 0);
>   	netc_timer_wr(priv, NETC_TMR_CTRL, 0);
> -	ptp_clock_unregister(priv->clock);
>   	netc_timer_free_msix_irq(priv);
>   	netc_timer_pci_remove(pdev);
>   }

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>