From: Felix Fietkau nbd@nbd.name
commit 4fe40b8e1566dad04c87fbf299049a1d0d4bd58d upstream.
Deferring sampling attempts to the second stage has some bad interactions with drivers that process the rate table in hardware and use the probe flag to indicate probing packets (e.g. most mt76 drivers). On affected drivers it can lead to probing not working at all.
If the link conditions turn worse, it might not be such a good idea to do a lot of sampling for lower rates in this case.
Fix this by simply skipping the sample attempt instead of deferring it, but keep the checks that would allow it to be sampled if it was skipped too often, but only if it has less than 95% success probability.
Also ensure that IEEE80211_TX_CTL_RATE_CTRL_PROBE is set for all probing packets.
Cc: stable@vger.kernel.org Fixes: cccf129f820e ("mac80211: add the 'minstrel' rate control algorithm") Signed-off-by: Felix Fietkau nbd@nbd.name Link: https://lore.kernel.org/r/20201111183359.43528-2-nbd@nbd.name Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/mac80211/rc80211_minstrel.c | 25 ++++--------------------- net/mac80211/rc80211_minstrel.h | 1 - 2 files changed, 4 insertions(+), 22 deletions(-)
--- a/net/mac80211/rc80211_minstrel.c +++ b/net/mac80211/rc80211_minstrel.c @@ -289,12 +289,6 @@ minstrel_tx_status(void *priv, struct ie mi->r[ndx].stats.success += success; }
- if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0)) - mi->sample_packets++; - - if (mi->sample_deferred > 0) - mi->sample_deferred--; - if (time_after(jiffies, mi->last_stats_update + (mp->update_interval * HZ) / 1000)) minstrel_update_stats(mp, mi); @@ -373,7 +367,7 @@ minstrel_get_rate(void *priv, struct iee return;
delta = (mi->total_packets * sampling_ratio / 100) - - (mi->sample_packets + mi->sample_deferred / 2); + mi->sample_packets;
/* delta < 0: no sampling required */ prev_sample = mi->prev_sample; @@ -382,7 +376,6 @@ minstrel_get_rate(void *priv, struct iee return;
if (mi->total_packets >= 10000) { - mi->sample_deferred = 0; mi->sample_packets = 0; mi->total_packets = 0; } else if (delta > mi->n_rates * 2) { @@ -407,19 +400,8 @@ minstrel_get_rate(void *priv, struct iee * rate sampling method should be used. * Respect such rates that are not sampled for 20 interations. */ - if (mrr_capable && - msr->perfect_tx_time > mr->perfect_tx_time && - msr->stats.sample_skipped < 20) { - /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark - * packets that have the sampling rate deferred to the - * second MRR stage. Increase the sample counter only - * if the deferred sample rate was actually used. - * Use the sample_deferred counter to make sure that - * the sampling is not done in large bursts */ - info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE; - rate++; - mi->sample_deferred++; - } else { + if (msr->perfect_tx_time < mr->perfect_tx_time || + msr->stats.sample_skipped >= 20) { if (!msr->sample_limit) return;
@@ -439,6 +421,7 @@ minstrel_get_rate(void *priv, struct iee
rate->idx = mi->r[ndx].rix; rate->count = minstrel_get_retry_count(&mi->r[ndx], info); + info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE; }
--- a/net/mac80211/rc80211_minstrel.h +++ b/net/mac80211/rc80211_minstrel.h @@ -98,7 +98,6 @@ struct minstrel_sta_info { u8 max_prob_rate; unsigned int total_packets; unsigned int sample_packets; - int sample_deferred;
unsigned int sample_row; unsigned int sample_column;