Subject: Re: [net-next PATCH V2 1/3] mm: add dma_addr_t to struct page

From: Jesper Dangaard Brouer <[email-masked]>
Date: Tue, 12 Feb 2019 19:19:17 +0100

On Tue, 12 Feb 2019 10:05:39 -0800
Florian Fainelli <[email-masked]> wrote:

> On 2/12/19 6:49 AM, Jesper Dangaard Brouer wrote:
> > The page_pool API is using page->private to store DMA addresses.
> > As pointed out by David Miller we can't use that on 32-bit architectures
> > with 64-bit DMA
> > 
> > This patch adds a new dma_addr_t struct to allow storing DMA addresses
> > 
> > Signed-off-by: Jesper Dangaard Brouer <[email-masked]>
> > Signed-off-by: Ilias Apalodimas <[email-masked]>
> > Acked-by: Andrew Morton <[email-masked]>
> > ---
> >  include/linux/mm_types.h |    7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> > index 2c471a2c43fa..581737bd0878 100644
> > --- a/include/linux/mm_types.h
> > +++ b/include/linux/mm_types.h
> > @@ -95,6 +95,13 @@ struct page {
> >  			 */
> >  			unsigned long private;
> >  		};
> > +		struct {	/* page_pool used by netstack */
> > +			/**
> > +			 * @dma_addr: page_pool requires a 64-bit value even on
> > +			 * 32-bit architectures.
> > +			 */  
> 
> Nit: might require? dma_addr_t, as you mention in the commit may have a
> different size based on CONFIG_ARCH_DMA_ADDR_T_64BIT.

So you want me to change the comment to be:

/**
 * @dma_addr: might require a 64-bit value even on
 * 32-bit architectures.
 */

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