linux-kernel - Re: [net,v2,1/2] net: liquidio: Fix off-by-one error in setup_nic

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Message-ID: <aXeOl5D7BR-xnEgm@horms.kernel.org>
Date: Mon, 26 Jan 2026 15:56:07 +0000
From: Simon Horman <horms@...nel.org>
To: zilin@....edu.cn
Cc: davem@...emloft.net, andrew+netdev@...n.ch, jianhao.xu@....edu.cn,
	kuba@...nel.org, kory.maincent@...tlin.com,
	marco.crivellari@...e.com, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org, vadim.fedorenko@...ux.dev,
	edumazet@...gle.com, pabeni@...hat.com
Subject: Re: [net,v2,1/2] net: liquidio: Fix off-by-one error in
 setup_nic_devices() cleanup

On Mon, Jan 26, 2026 at 03:50:39PM +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: Fix off-by-one error in setup_nic_devices() cleanup
> 
> This patch changes the cleanup loop from while(i--) to do{}while(i--)
> to ensure that when a device fails to initialize, it gets cleaned up
> along with all previously initialized devices.
> 
> > diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c b/drivers/net/ethernet/cavium/liquidio/lio_main.c
> > index 0732440eeacd..3ba2806f5d1e 100644
> > --- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
> > +++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
> > @@ -3765,11 +3765,11 @@ static int setup_nic_devices(struct octeon_device *octeon_dev)
> >
> >  setup_nic_dev_free:
> >
> > -	while (i--) {
> > +	do {
> >  		dev_err(&octeon_dev->pci_dev->dev,
> >  			"NIC ifidx:%d Setup failed\n", i);
> >  		liquidio_destroy_nic_device(octeon_dev, i);
> > -	}
> > +	} while (i--);
> 
> In lio_main.c, setup_nic_devices() can also reach setup_nic_dev_free from
> the devlink_alloc() failure path after the main for loop completes. At that
> point i equals ifcount (the loop counter has been incremented past the last
> valid device).
> 
> With the do-while change, the first iteration will call
> liquidio_destroy_nic_device(octeon_dev, ifcount) for a device index that
> was never initialized. The function has a guard for NULL netdev so it will
> not crash, but it will print a spurious error message about a device that
> never existed.
> 
> The fix works correctly for failures within the loop (which is the case
> described in the commit message), but is there a way to handle the
> post-loop devlink_alloc() failure case without printing the spurious
> error message?

Sorry for not realising this when I made this suggestion in
my review of v1.

Also, I would suggest splitting this patch in two: one patch
per driver.