Return-path: Received: from he.sipsolutions.net ([78.46.109.217]:48714 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752473Ab0D0Rzs (ORCPT ); Tue, 27 Apr 2010 13:55:48 -0400 Subject: Re: [PATCH 1/1] mac80211: fix rts threshold check From: Johannes Berg To: shanyu.zhao@intel.com Cc: linux-wireless@vger.kernel.org In-Reply-To: <1272392112-28301-1-git-send-email-shanyu.zhao@intel.com> References: <1272392112-28301-1-git-send-email-shanyu.zhao@intel.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 27 Apr 2010 19:55:45 +0200 Message-ID: <1272390945.3549.39.camel@jlt3.sipsolutions.net> Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Tue, 2010-04-27 at 11:15 -0700, shanyu.zhao@intel.com wrote: > From: Shanyu Zhao > > Currently whenever rts thresold is set, every packet will use RTS > protection no matter its size exceeds the threshold or not. This is > due to a bug in the rts threshold check. > if (len > tx->local->hw.wiphy->rts_threshold) { > txrc.rts = rts = true; > } > Basically it is comparing an int (len) and a u32 (rts_threshold), > and the variable len is assigned as: > len = min_t(int, tx->skb->len + FCS_LEN, > tx->local->hw.wiphy->frag_threshold); > However, when frag_threshold is "-1", len is always "-1", which is > 0xffffffff therefore rts is always set to true. D'oh. Good catch. Reviewed-by: Johannes Berg > CC: stable@kernel.org > > Signed-off-by: Shanyu Zhao > --- > net/mac80211/tx.c | 5 +++-- > 1 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c > index e2aa972..f3841f4 100644 > --- a/net/mac80211/tx.c > +++ b/net/mac80211/tx.c > @@ -593,7 +593,8 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx) > struct ieee80211_hdr *hdr = (void *)tx->skb->data; > struct ieee80211_supported_band *sband; > struct ieee80211_rate *rate; > - int i, len; > + int i; > + u32 len; > bool inval = false, rts = false, short_preamble = false; > struct ieee80211_tx_rate_control txrc; > u32 sta_flags; > @@ -602,7 +603,7 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx) > > sband = tx->local->hw.wiphy->bands[tx->channel->band]; > > - len = min_t(int, tx->skb->len + FCS_LEN, > + len = min_t(u32, tx->skb->len + FCS_LEN, > tx->local->hw.wiphy->frag_threshold); > > /* set up the tx rate control struct we give the RC algo */