Subject: Re: [bpf-next V5 PATCH 11/15] page_pool: refurbish version of page_pool code

From: Jesper Dangaard Brouer <[email-masked]>
Date: Mon, 26 Mar 2018 16:09:25 +0200

On Fri, 23 Mar 2018 06:28:13 -0700
Eric Dumazet <[email-masked]> wrote:

> On 03/23/2018 05:18 AM, Jesper Dangaard Brouer wrote:
> 
> > +
> > +	/* Note, below struct compat code was primarily needed when
> > +	 * page_pool code lived under MM-tree control, given mmots and
> > +	 * net-next trees progress in very different rates.
> > +	 *
> > +	 * Allow kernel devel trees and driver to progress at different rates
> > +	 */
> > +	param_copy_sz = PAGE_POOL_PARAMS_SIZE;
> > +	memset(&pool->p, 0, param_copy_sz);
> > +	if (params->size < param_copy_sz) {
> > +		/* Older module calling newer kernel, handled by only
> > +		 * copying supplied size, and keep remaining params zero
> > +		 */
> > +		param_copy_sz = params->size;
> > +	} else if (params->size > param_copy_sz) {
> > +		/* Newer module calling older kernel. Need to validate
> > +		 * no new features were requested.
> > +		 */
> > +		unsigned char *addr = (unsigned char *)params + param_copy_sz;
> > +		unsigned char *end  = (unsigned char *)params + params->size;
> > +
> > +		for (; addr < end; addr++) {
> > +			if (*addr != 0)
> > +				return -E2BIG;
> > +		}
> > +	}  
> 
> I do not see the need for this part.

Okay, then I'll just drop it.
I'm considering changing page_pool_create() to just take everything
as parameters.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer