test0r
8cd10f487c
The original Patch I refused EVERY 5 GHz scan request unconditionally
(req->n_channels > 0 && band == NL80211_BAND_5GHZ). This eliminated
the Pattern A storm but also broke 5 GHz association entirely:
NM / wpa_supplicant iterates a freq_list when a connection profile
specifies 802-11-wireless.band=a, issuing per-frequency single-channel
scans to find the BSS before associating. Those single-channel scans
were also refused by our guard, so the BSS was never seen and
'Wi-Fi network could not be found' was the only outcome.
Tighten the guard: refuse only multi-channel 5 GHz scans (n_channels
> 1), which is the per-band-sweep pattern mac80211 issues internally
and the only one that triggers the firmware storm at the per-band
loop boundary. Single-channel 5 GHz scans pass through to firmware,
which generally accepts them -- and when they happen to be rejected,
the failure is isolated and doesn't cascade.
Verified on ohm with pkgrel=3 (srcversion BEB625FA7443171EA8D55F7):
- Pattern A count since boot: 0 (Phase 7 prediction still holds)
- iw dev wlan0 scan freq 5180 -> allowed
- iw dev wlan0 scan freq 5180 5200 ... -> refused -EOPNOTSUPP
- NM 'nmcli connection up' with band=a -> associated to BSSID
c0:25:06:e6:5b:33 on 5240 MHz / ch.48 in ~1 second
- TX bitrate 150 Mbit/s MCS 7 40MHz short-GI (vs 72.2 Mbit/s
HT20 on 2.4 GHz) -- ~2x throughput recovered
The change is a single byte (> 0 -> > 1) plus comment update; the
test confirmation above is what motivates it.
Refs: besser#1 (closed but tracked for follow-up like this), original
Patch I sha 093a503.