Re: [PATCH net-next-2.6] e1000: save skb counts in TX to avoid cache misses

[Jeff Kirsher <jeffrey.t.kirsher@intel.com>]

[-- Attachment #1: Type: text/plain, Size: 1186 bytes --]

On Thu, 2011-08-25 at 17:39 -0700, Dean Nelson wrote:
> Virtual Machines with emulated e1000 network adapter running on
> Parallels'
> server were seeing kernel panics due to the e1000 driver dereferencing
> an
> unexpected NULL pointer retrieved from buffer_info->skb.
> 
> The problem has been addressed for the e1000e driver, but not for the
> e1000.
> Since the two drivers share similar code in the affected area, a port
> of the
> following e1000e driver commit solves the issue for the e1000 driver:
> 
> commit 9ed318d546a29d7a591dbe648fd1a2efe3be1180
> Author: Tom Herbert <therbert@google.com>
> Date:   Wed May 5 14:02:27 2010 +0000
> 
>     e1000e: save skb counts in TX to avoid cache misses
> 
>     In e1000_tx_map, precompute number of segements and bytecounts
> which
>     are derived from fields in skb; these are stored in buffer_info.
> When
>     cleaning tx in e1000_clean_tx_irq use the values in the associated
>     buffer_info for statistics counting, this eliminates cache misses
>     on skb fields.
> 
> 
> Signed-off-by: Dean Nelson <dnelson@redhat.com> 

Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Looks fine.

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 490 bytes --]