ieee80211_emulate_remove_chanctx() calls _ieee80211_hw_conf_chan() after
the last channel context has been removed. With no context left,
ieee80211_calc_hw_conf_chan() falls back to the default channel, so the
driver is switched to a channel nobody asked for, and the next context
switches it again.
A monitor interface retunes by removing its context and adding a new
one, so every retune costs the driver two channel changes. Nothing is
transmitting or receiving without a context, and the new context sets
the channel, so the extra reconfiguration is unnecessary. Keep clearing
radar_enabled so the next configuration starts clean.
Measured on an AR9271 (ath9k_htc), where a channel change is a full chip
reset over USB, hopping across the 13 channels in 2.4 GHz, 1000 hops:
drv_config calls median hop p95 hop
before 2006 123.5 ms 183 ms
after 1006 92.0 ms 105 ms
Delivery of injected frames to a second card was 99.1% before and 98.3%
after (3863 and 3835 of 3900).
Assisted-by: Claude:claude-fable-5-1
Signed-off-by: Nerijus Bendžiūnas <nerijus.bendziunas@gmail.com>
---
Changes in v2:
- Add the Assisted-by tag.
- Rewrite the commit message and shorten the in-code comment. No change
to the code.
net/mac80211/main.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index a59837b9f480..643d59e878c9 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -289,9 +289,12 @@ void ieee80211_emulate_remove_chanctx(struct ieee80211_hw *hw,
{
struct ieee80211_local *local = hw_to_local(hw);
+ /*
+ * No context is left, so there is nothing to configure; the next
+ * context sets the channel. Reconfiguring here would switch the
+ * driver to the default channel only to switch it again.
+ */
local->hw.conf.radar_enabled = false;
-
- _ieee80211_hw_conf_chan(local, NULL);
}
EXPORT_SYMBOL(ieee80211_emulate_remove_chanctx);
base-commit: ca800a9302764c445de0da0e84d2252400a770ee
--
2.55.0