Return-path: Received: from mail-iy0-f194.google.com ([209.85.210.194]:41354 "EHLO mail-iy0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755112Ab1AGB5n convert rfc822-to-8bit (ORCPT ); Thu, 6 Jan 2011 20:57:43 -0500 Received: by iyf40 with SMTP id 40so7631710iyf.1 for ; Thu, 06 Jan 2011 17:57:43 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1294363427.2704.23.camel@edumazet-laptop> References: <1294361165-15308-1-git-send-email-greearb@candelatech.com> <201101070205.00886.chunkeey@googlemail.com> <1294363427.2704.23.camel@edumazet-laptop> From: "Luis R. Rodriguez" Date: Thu, 6 Jan 2011 17:57:22 -0800 Message-ID: Subject: Re: [PATCH 1/3] ath9k: Decrease skb size to fit into one page. To: Eric Dumazet Cc: Christian Lamparter , greearb@candelatech.com, linux-wireless@vger.kernel.org, ath9k-devel@venema.h4ckr.net Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thu, Jan 6, 2011 at 5:23 PM, Eric Dumazet wrote: > Le vendredi 07 janvier 2011 à 02:04 +0100, Christian Lamparter a écrit : >> On Friday 07 January 2011 01:46:03 greearb@candelatech.com wrote: >> > From: Ben Greear >> > >> > Patch is from Eric Dumazet, as described here: >> > https://patchwork.kernel.org/patch/104271/ >> > >> > Reported-by: Michael Guntsche >> > Signed-off-by: Eric Dumazet >> > Signed-off-by: Ben Greear >> > --- >> > >> > NOTE:  This needs review by ath9k and/or other informed >> > people. >> >> Does the hardware support vector-i/o for rx (like for instance iwlagn)? >> Else, this change would break A-MSDU rx - which is a mandatory feature >> (although, not very popular) of 802.11n - >> >> See for example 802.11n-2009 9.7c: >> >> "Support for the reception of an A-MSDU, where [...], is mandatory for >> an HT STA" >> >> And 7.1.2 "The maximum frame body size is determined by the maximum >> MSDU size (2304 octets) OR the maximum A-MSDU (3839 or 7935 octets, >> depending upon the STA's capability), plus any overhead from security >> encapsulation. > > Then, only solution is to mark this broken, and perform a copy of each > received frame, to keep a order-1 buffer(s) allocated for hardware. -ENOTPOSSIBLE -- its an WFA requirement to RX AMSDU. > Its too easy to have memory allocation failures for high order pages and > freeze the card. Can't we us paged RX skbs, which mac80211 supports now? See 2f301227a1ede57504694e1f64839839f5737cac and friends. Luis