Re: [PATCH V3] mac80211: fix paged defragmentation

["John W. Linville" <linville@tuxdriver.com>]

On Tue, May 11, 2010 at 11:22:11AM -0700, Abhijeet Kolekar wrote:
> Paged RX skb patch broke the defragmentation. We need to read hdr again
> after linearization.
> 
> It fixes following bug
> http://bugzilla.intellinuxwireless.org/show_bug.cgi?id=2194
> 
> Signed-off-by: Zhu, Yi <yi.zhu@intel.com>
> Signed-off-by: Abhijeet Kolekar <abhijeet.kolekar@intel.com>
> ---
> v2: Changed hdr reading.
> v3: Added more comments.
>  net/mac80211/rx.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
> index 9a08f2c..6e2a7bc 100644
> --- a/net/mac80211/rx.c
> +++ b/net/mac80211/rx.c
> @@ -1253,6 +1253,12 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
>  	if (skb_linearize(rx->skb))
>  		return RX_DROP_UNUSABLE;
>  
> +	/*
> +	 *  skb_linearize() might change the skb->data and
> +	 *  previously cached variables (in this case, hdr) need to
> +	 *  be refreshed with the new data.
> +	 */
> +	hdr = (struct ieee80211_hdr *)rx->skb->data;
>  	seq = (sc & IEEE80211_SCTL_SEQ) >> 4;
>  
>  	if (frag == 0) {

And what about making sure the compiler doesn't optimize this away?

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.