netdev - Re: [PATCH net-next v2 1/2] net: store netdevs in an xarray

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Date: Fri, 28 Jul 2023 07:53:04 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
	pabeni@...hat.com, sd@...asysnail.net
Subject: Re: [PATCH net-next v2 1/2] net: store netdevs in an xarray

On Thu, Jul 27, 2023 at 08:45:19AM -0700, Jakub Kicinski wrote:
> On Thu, 27 Jul 2023 16:08:24 +0300 Leon Romanovsky wrote:
> > > +	if (!ifindex)
> > > +		err = xa_alloc_cyclic(&net->dev_by_index, &ifindex, NULL,
> > > +				      xa_limit_31b, &net->ifindex, GFP_KERNEL);
> > > +	else
> > > +		err = xa_insert(&net->dev_by_index, ifindex, NULL, GFP_KERNEL);
> > > +	if (err < 0)
> > > +		return err;
> > > +
> > > +	return ifindex;  
> > 
> > ifindex is now u32, but you return it as int. In potential, you can
> > return valid ifindex which will be treated as error.
> > 
> > You should ensure that ifindex doesn't have signed bit on.
> 
> I'm feeding xa_alloc_cyclic() xa_limit_31b, which should take care 
> of that, no?

And what about xa_insert() call? Is it safe?