Re: [PATCH 08/13] net: convert drivers to paged frag API.

On Fri, 2011-07-22 at 15:12 +0100, David Miller wrote:

From: Ian Campbell <redacted>
Date: Fri, 22 Jul 2011 14:17:28 +0100

quoted

-				put_dma(tx->index,eni_dev->dma,&j,(unsigned long)
-				    skb_shinfo(skb)->frags[i].page + skb_shinfo(skb)->frags[i].page_offset,
+				put_dma(tx->index,eni_dev->dma,&j,
+				    (unsigned long)skb_frag_address(&skb_shinfo(skb)->frags[i]),

This is not an equivalent transformation.

skb_frag_address() does a page_address() on the frag page, but that is
not what the code was doing here previously.

It's possible the code was buggy, but you can't do a fix like that
amidst what is supposed to be a semantically NOP transformation.

Ouch, you are absolutely right, I didn't spot that, sorry.

The original code does look pretty bogus though, indexing off a struct
page * like that -- CC'ing the ATM maintainer + list.

Ian.

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