netdev - Re: [net,v2,2/2] net: liquidio: Initialize netdev pointer before queue setup

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Message-Id: <20260127101136.960753-1-zilin@seu.edu.cn>
Date: Tue, 27 Jan 2026 10:11:36 +0000
From: Zilin Guan <zilin@....edu.cn>
To: horms@...nel.org
Cc: andrew+netdev@...n.ch,
	davem@...emloft.net,
	edumazet@...gle.com,
	jianhao.xu@....edu.cn,
	kory.maincent@...tlin.com,
	kuba@...nel.org,
	linux-kernel@...r.kernel.org,
	marco.crivellari@...e.com,
	netdev@...r.kernel.org,
	pabeni@...hat.com,
	vadim.fedorenko@...ux.dev,
	zilin@....edu.cn
Subject: Re: [net,v2,2/2] net: liquidio: Initialize netdev pointer before queue setup

On Mon, Jan 26, 2026 at 03:52:52PM +0000, Simon Horman wrote:
> On Mon, Jan 26, 2026 at 03:49:41PM +0000, Simon Horman wrote:
> > This is an AI-generated review of your patch. The human sending this
> > email has considered the AI review valid, or at least plausible.
> > 
> > For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
> > ---
> > net: liquidio: Initialize netdev pointer before queue setup
> > 
> > This patch moves the initialization of lio and props structures earlier
> > in setup_nic_devices() so that props->netdev is set before calling
> > netif_set_real_num_rx_queues() and netif_set_real_num_tx_queues(). The
> > intent is to fix a memory leak where the allocated netdev would not be
> > freed if queue setup fails.
> > 
> > > diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c b/drivers/net/ethernet/cavium/liquidio/lio_main.c
> > > index 3ba2806f5d1e..2383f0173a54 100644
> > > --- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
> > > +++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
> > > @@ -3505,6 +3505,16 @@ static int setup_nic_devices(struct octeon_device *octeon_dev)
> > >  		 */
> > >  		netdev->netdev_ops = &lionetdevops;
> > >
> > > +		lio = GET_LIO(netdev);
> > > +
> > > +		memset(lio, 0, sizeof(struct lio));
> > > +
> > > +		lio->ifidx = ifidx_or_pfnum;
> > > +
> > > +		props = &octeon_dev->props[i];
> > > +		props->gmxport = resp->cfg_info.linfo.gmxport;
> > > +		props->netdev = netdev;
> > 
> > Moving this initialization earlier fixes the memory leak, but now if
> > netif_set_real_num_rx_queues() or netif_set_real_num_tx_queues() fails
> > below, the cleanup path in liquidio_destroy_nic_device() will proceed
> > further than before since props->netdev is no longer NULL.
> > 
> > Previously, when queue setup failed, liquidio_destroy_nic_device() would
> > return early at the "if (!netdev)" check. Now it continues and calls
> > cleanup_rx_oom_poll_fn().
> > 
> > In cleanup_rx_oom_poll_fn() (lio_core.c), the code does:
> > 
> >     struct lio *lio = GET_LIO(netdev);
> >     struct octeon_device *oct = lio->oct_dev;
> >     ...
> >     for (q_no = 0; q_no < oct->num_oqs; q_no++) {
> > 
> > Since lio->oct_dev is not assigned until much later in setup_nic_devices()
> > (around line 3602), it will be NULL after the memset above. Would this
> > cause a NULL pointer dereference when cleanup_rx_oom_poll_fn() tries to
> > access oct->num_oqs?
> > 
> > > +
> > >  		retval = netif_set_real_num_rx_queues(netdev, num_oqueues);
> > >  		if (retval) {
> > >  			dev_err(&octeon_dev->pci_dev->dev,
> > 
> > [ ... ]
> 
> Strangely the AI review did not pick this up for v1.
> (And neither did I.)

Hi Simon,

Apologies for missing this dependency.

I will update the code to initialize lio->oct_dev alongside props->netdev
to prevent NULL pointer dereference in cleanup_rx_oom_poll_fn().

Thanks,
Zilin