Return-path: Received: from mail-wi0-f179.google.com ([209.85.212.179]:51686 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757684Ab3KHQyU (ORCPT ); Fri, 8 Nov 2013 11:54:20 -0500 Received: by mail-wi0-f179.google.com with SMTP id hm2so1219263wib.6 for ; Fri, 08 Nov 2013 08:54:18 -0800 (PST) Date: Fri, 8 Nov 2013 17:54:02 +0100 From: Karl Beldan To: Felix Fietkau Cc: Johannes Berg , linux-wireless Subject: Re: [PATCH 2/2] mac80211: minstrel_ht: do not sample unsupported rates Message-ID: <20131108165402.GB26361@magnum.frso.rivierawaves.com> (sfid-20131108_175423_979436_D18FABC1) References: <1383928473-798-1-git-send-email-karl.beldan@gmail.com> <1383928473-798-2-git-send-email-karl.beldan@gmail.com> <527D14B7.3090204@openwrt.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: <527D14B7.3090204@openwrt.org> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Fri, Nov 08, 2013 at 05:43:35PM +0100, Felix Fietkau wrote: > On 2013-11-08 17:34, Karl Beldan wrote: > > From: Karl Beldan > > > > ATM minstrel_ht does not check whether the sampling rate is supported. > > Unsupported rates attempts can trigger when there are holes between > > supported MCSes belonging to the same group (e.g many devices are > > capable of MCS32 without being capable of MCS33->MCS39). > > This change replaces an unsupported sample index with the fls of the > > bitfield of supported indexes. > > This is not a problem in minstrel which fills a per STA sample table > > with only supported rates (though only at init). > > > > Signed-off-by: Karl Beldan > > --- > > net/mac80211/rc80211_minstrel_ht.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c > > index aeec401..1b835ad 100644 > > --- a/net/mac80211/rc80211_minstrel_ht.c > > +++ b/net/mac80211/rc80211_minstrel_ht.c > > @@ -703,6 +703,8 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi) > > > > mg = &mi->groups[mi->sample_group]; > > sample_idx = sample_table[mg->column][mg->index]; > > + if (!(mg->supported & BIT(sample_idx))) > > + sample_idx = fls(sample_idx) - 1; > You probably meant fls(mg->supported) - 1 here, however I think a better Arf, yes. > approach would be to just skip the sample attempt. If there are fewer > rates in a group, we can run fewer sample attempts on it. > Agreed :) I was skimming through minstrel before leaving for the week-end because I had planned to put in shape a hack I did a while ago for vht in minstrel monday is a holiday here and I have absolutely nothing planned. Karl