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Code Issues Releases Packages Activity

wifi: mac80211: queue frames while off-channel

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Drivers without FAST_XMIT and hardware scan support currently drop TX
frames during software scanning while being off-channel. This happens
in ieee80211_tx_h_check_assoc() before frames reach internal TX queue.

Move the off-channel check to invoke_tx_handlers_late(), after
ieee80211_queue_skb(). Frames can then remain queued and be transmitted
when the interface returns on-channel. This how TX works currently when
code goes via ieee80211_xmit_fast() path.

Below is rt2x00 driver ping output example while scanning, before and
after the fix. After the fix, packets are no longer lost. Some have
increased latency, what is expected behavior.

BEFORE:
64 bytes from 192.168.0.1: icmp_seq=29 ttl=64 time=3.61 ms
64 bytes from 192.168.0.1: icmp_seq=31 ttl=64 time=3.33 ms # Missed 30
64 bytes from 192.168.0.1: icmp_seq=32 ttl=64 time=4.03 ms
64 bytes from 192.168.0.1: icmp_seq=34 ttl=64 time=3.10 ms # Missed 33
64 bytes from 192.168.0.1: icmp_seq=36 ttl=64 time=3.04 ms # Missed 35
64 bytes from 192.168.0.1: icmp_seq=38 ttl=64 time=3.05 ms # Missed 37
64 bytes from 192.168.0.1: icmp_seq=40 ttl=64 time=4.14 ms # Missed 39
64 bytes from 192.168.0.1: icmp_seq=41 ttl=64 time=4.50 ms

AFTER:
64 bytes from 192.168.0.1: icmp_seq=29 ttl=64 time=3.40 ms
64 bytes from 192.168.0.1: icmp_seq=30 ttl=64 time=6.10 ms
64 bytes from 192.168.0.1: icmp_seq=31 ttl=64 time=4.69 ms
64 bytes from 192.168.0.1: icmp_seq=32 ttl=64 time=4.49 ms
64 bytes from 192.168.0.1: icmp_seq=33 ttl=64 time=148 ms
64 bytes from 192.168.0.1: icmp_seq=34 ttl=64 time=6.83 ms
64 bytes from 192.168.0.1: icmp_seq=35 ttl=64 time=8.66 ms
64 bytes from 192.168.0.1: icmp_seq=36 ttl=64 time=13.0 ms
64 bytes from 192.168.0.1: icmp_seq=37 ttl=64 time=4.78 ms
64 bytes from 192.168.0.1: icmp_seq=38 ttl=64 time=3.85 ms

Cc: <stable@vger.kernel.org>
Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Link: https://patch.msgid.link/20260908124651.2995-1-stf_xl@wp.pl
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Stanislaw Gruszka 2026-09-08 14:46:51 +02:00 • committed by Johannes Berg
commit 13e51269b6
1 changed files with 28 additions and 24 deletions
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