Despite the 'RTS thr:off' setting a wireshark trace of IBSS
traffic with HT40 mode enabled between two ath9k cards revealed
some RTS/CTS traffic.
Debug and code analysis showed that most places setting
IEEE80211_TX_RC_USE_RTS_CTS respect the RTS strategy by
evaluating rts_threshold, e.g. net/mac80211/tx.c:
698 /* set up RTS protection if desired */
699 if (len > tx->local->hw.wiphy->rts_threshold) {
700 txrc.rts = true;
701 }
702
703 info->control.use_rts = txrc.rts;
or drivers/net/wireless/ath/ath9k/xmit.c
1238 /*
1239 * Handle RTS threshold for unaggregated HT frames.
1240 */
1241 if (bf_isampdu(bf) && !bf_isaggr(bf) &&
1242 (rates[i].flags & IEEE80211_TX_RC_MCS) &&
1243 unlikely(rts_thresh != (u32) -1)) {
1244 if (!rts_thresh || (len > rts_thresh))
1245 rts = true;
1246 }
The only place setting IEEE80211_TX_RC_USE_RTS_CTS unconditionally
was found in net/mac80211/rc80211_minstrel_ht.c.
As the use_rts value is only calculated after hitting the minstrel_ht code
preferre to not set IEEE80211_TX_RC_USE_RTS_CTS (and overruling the
RTS threshold setting) for the fallback rates case.
Signed-off-by: Peter Seiderer <ps.report@xxxxxxx>
---
Changes v1 -> v2:
- change from 'respect RTS threshold setting' to 'do not set RTS/CTS
flag for fallback rates' (see commit message for reasoning)
---
net/mac80211/rc80211_minstrel_ht.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index 72b44d4c42d0..f151acbe7bf5 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -1355,11 +1355,9 @@ minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
/* enable RTS/CTS if needed:
* - if station is in dynamic SMPS (and streams > 1)
- * - for fallback rates, to increase chances of getting through
*/
- if (offset > 0 ||
- (mi->sta->smps_mode == IEEE80211_SMPS_DYNAMIC &&
- group->streams > 1)) {
+ if (mi->sta->smps_mode == IEEE80211_SMPS_DYNAMIC &&
+ group->streams > 1) {
ratetbl->rate[offset].count = ratetbl->rate[offset].count_rts;
flags |= IEEE80211_TX_RC_USE_RTS_CTS;
}
--
2.33.1
