Return-path: Received: from mail022-1.exch022.serverdata.net ([64.78.22.98]:48559 "EHLO mail022-1.exch022.serverdata.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751592Ab2LTNRv (ORCPT ); Thu, 20 Dec 2012 08:17:51 -0500 Message-ID: <50D30FFB.9030003@posedge.com> (sfid-20121220_141755_917337_3233B37B) Date: Thu, 20 Dec 2012 18:47:47 +0530 From: Chaitanya MIME-Version: 1.0 To: Johannes Berg CC: linux-wireless Subject: Re: [RFC] mac80211: Fix MAX MTU Calculation References: <201212201236.qBKCakFZ011657@chaitanya-desktop> <50D307FD.9010508@posedge.com> <1356008873.10029.13.camel@jlt4.sipsolutions.net> In-Reply-To: <1356008873.10029.13.camel@jlt4.sipsolutions.net> Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thursday 20 December 2012 06:37 PM, Johannes Berg wrote: > On Thu, 2012-12-20 at 18:13 +0530, Chaitanya wrote: >> Fix the MTU calculation, we should check for data_len+ mesh hdr len >> and shouldn't include any header lengths. >> >> ToDo: Get the MAX_DATA_LEN based on driver's AMSDU capability. >> >> Signed-off-by: T Krishna Chaitanya >> >> --- >> >> net/mac80211/iface.c | 17 ++++++++++++++++- >> 1 files changed, 16 insertions(+), 1 deletions(-) >> >> diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c >> index 54fb7f9..da74ef9 100644 >> --- a/net/mac80211/iface.c >> +++ b/net/mac80211/iface.c >> @@ -214,8 +214,23 @@ static int ieee80211_change_mtu(struct net_device *dev, int new_mtu) >> >> /* FIX: what would be proper limits for MTU? >> * This interface uses 802.3 frames. */ >> + /* Fixed: MTU needn't worry about headers*/ >> + >> + /* 802.11-2012: 8.2.3: The maximum frame body size is determined by >> + 1. The maximum MSDU size (2304 octets), >> + 2. plus the length of the Mesh Control field (6, 12, or 18 octets) >> + if present, >> + 3. the maximum unencrypted MMPDU size excluding the MAC header and >> + FCS (2304 octets) or >> + 4. the maximum A- MSDU size (3839 or 7935 octets), >> + plus any overhead from security encapsulation. >> + Note1: IEEE80211_MAX_DATA_LEN doesnt include any headers (2304), >> + so it can be used directly+ Mesh HDR Len >> + Note2: In Other places (like skb_alloc) its handled properly. >> + */ >> + > ok so the comment style is wrong, you shouldn't list changelog-type > things in comments ("Fixed: ...") etc. > > I also don't understand why we should add the mesh length? It seems that > this is really just the maximum MSDU size, i.e. 2304 octets. > > johannes > Ok, will change the comments. So shall i remove the comments for FIX as well (or) should i retain them? As for WLAN is concerned the mesh header is part of data (MSDU) hence the standard says the MSDU can be Maximum of 2304 + Any Mesh Control Field. (#2 above).