Re: [PATCH] net: amd: xgbe: fix possible sleep-in-atomic-context bugs in xgbe_powerdown()

[Jia-Ju Bai]

On 2019/12/19 5:26, David Miller wrote:
> From: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
> Date: Wed, 18 Dec 2019 22:01:02 +0800
>
> > @@ -1257,17 +1257,18 @@ int xgbe_powerdown(struct net_device *netdev, unsigned int caller)
> >   	netif_tx_stop_all_queues(netdev);
> >   
> >   	xgbe_stop_timers(pdata);
> > -	flush_workqueue(pdata->dev_workqueue);
> >   
> >   	hw_if->powerdown_tx(pdata);
> >   	hw_if->powerdown_rx(pdata);
> >   
> > -	xgbe_napi_disable(pdata, 0);
> > -
> >   	pdata->power_down = 1;
> >   
> >   	spin_unlock_irqrestore(&pdata->lock, flags);
> >   
> > +	flush_workqueue(pdata->dev_workqueue);
> > +
> > +	xgbe_napi_disable(pdata, 0);
> > +
> Nope, this doesn't work at all.
>
> You can't leave NAPI enabled, and thus packet processing, after the TX
> and RX units of the chip have been powered down.

Looking at the code, only xgbe_powerup() and xgbe_powerdown() use the 
spinlock "pdata->lock".
How about change the spinlock to a mutex?


Best wishes,
Jia-Ju Bai