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mac80211: add minstrel fixes that fix mt76 issues in legacy mode

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Remove deferred sampling code which does not work well with rate tables +
probing.
Fix tx status handling if the first invalid rate idx is not set to -1

Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Felix Fietkau 2020-11-11 19:49:54 +01:00
parent bf3158b620
commit 0bb5d39b7a
2 changed files with 122 additions and 0 deletions
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96
package/kernel/mac80211/patches/subsys/334-mac80211-minstrel-remove-deferred-sampling-code.patch Normal file
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@ -0,0 +1,96 @@
From: Felix Fietkau <nbd@nbd.name>
Date: Wed, 11 Nov 2020 19:17:44 +0100
Subject: [PATCH] mac80211: minstrel: remove deferred sampling code
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>
---
--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -287,12 +287,6 @@ 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 / (mp->new_avg ? 2 : 1)))
minstrel_update_stats(mp, mi);
@@ -367,7 +361,7 @@ 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;
@@ -376,7 +370,6 @@ 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) {
@@ -401,19 +394,8 @@ 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;
@@ -433,6 +415,7 @@ 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
@@ -126,7 +126,6 @@ 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;

26
package/kernel/mac80211/patches/subsys/335-mac80211-minstrel-fix-tx-status-processing-corner-ca.patch Normal file
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From: Felix Fietkau <nbd@nbd.name>
Date: Wed, 11 Nov 2020 19:25:39 +0100
Subject: [PATCH] mac80211: minstrel: fix tx status processing corner case
Some drivers fill the status rate list without setting the rate index after
the final rate to -1. minstrel_ht already deals with this, but minstrel
doesn't, which causes it to get stuck at the lowest rate on these drivers.
Fix this by checking the count as well.
Cc: stable@vger.kernel.org
Fixes: cccf129f820e ("mac80211: add the 'minstrel' rate control algorithm")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -274,7 +274,7 @@ minstrel_tx_status(void *priv, struct ie
success = !!(info->flags & IEEE80211_TX_STAT_ACK);
for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
- if (ar[i].idx < 0)
+ if (ar[i].idx < 0 || !ar[i].count)
break;
ndx = rix_to_ndx(mi, ar[i].idx);