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Subject: Re: 3.7.8/amd64 full interrupt hangs due to iwlwifi under big nfs
 copies out
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Marc MERLIN <marc@merlins.org>, David Miller <davem@davemloft.net>,
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On Wed, 2013-02-20 at 18:01 +0100, Johannes Berg wrote:

> FWIW, I think just using order-0 pages and turning 8k A-MSDUs off by
> default makes more sense, A-MSDU is rarely used to begin with ...
> 

My suggested patch makes sure that if someone needs 8k A-MSDU, iwlwifi
still works correctly.

> Also, if we copy larger frames here, we should also take into account
> the (variable) 802.11 header length to avoid copying into a position
> where the IP header ends up being unaligned.

But the current code already has this problem (if its a problem at all,
as on x86 NET_IP_ALIGN is 0)

I only increase available tailroom in the skb. Right now there is enough
room for IP and tcp headers.