Re: [PATCH] ar9170usb: fix panic triggered by undersized rxstream buffer

[Zhu Yi <yi.zhu@intel.com>]

On Wed, 2010-03-24 at 09:59 +0800, Johannes Berg wrote:
> On Tue, 2010-03-23 at 21:51 +0100, Christian Lamparter wrote:
> > While ar9170's USB transport packet size is currently set to 8KiB,
> > the PHY is capable of receiving AMPDUs with up to 64KiB.
> > Such a large frame will be split over several rx URBs and
> > exceed the previously allocated space for rx stream reconstruction.
> > 
> > This patch increases the buffer size to 64KiB which is
> > in fact the phy & rx stream designed size limit.
> 
> That's a pretty high order allocation, you may want to paged allocation
> -- you'll end up doing a order 5 allocation here!

Yup, order-5 given the struct skb_shared_info overhead in __alloc_skb().
If the URBs are split over, you probably don't need to allocate such a
big chunk of memory in one go. You just need to connect them into a
paged skb later before pushing to mac80211. BTW, I've moved the
skb_linearize() from iwlwifi to mac80211. Will submit the patches today.

Thanks,
-yi