[RFC PATCH] ath11k: add ath11k_mac_op_flush_sta to properly flush pending packets

[Florian Maurer]

On Tue, 2025-10-07 at 14:38 +0200, Sebastian Gottschall wrote:
> Am 07.10.2025 um 10:11 schrieb Florian Maurer:
> 
> > When a STA is marked as no longer authorized, if the driver doesn't
> > implement flush_sta(), mac80211 calls ieee80211_flush_queues() to
> > flush hardware queues to avoid sending unencrypted frames.
> > 
> > This has became a problem for ath11k because ieee80211_flush_queues()
> > will stop all traffic and call ath11k_flush, which waits until the
> > whole HW queue is empty. In a busy environment this will trigger a
> > timeout warning and stalls other STAs.
> > 
> > Fix this by implementing flush_sta method using WMI command to flush
> > frames of a specific STA.
> > Flushed frames will be marked as discard in tx complete indication.
> > 
> > warning print "ath11k c000000.wifi: failed to flush transmit queue 0"
> > was observed on various openwrt devices, and is fixed through this patch.
> > 
> > Signed-off-by: Florian Maurer <f.maurer at outlook.de>
> > Tested-by: Florian Maurer  <f.maurer at outlook.de>
> > Co-authored-by: Benjamin Berg <benjamin at sipsolutions.net>
> > Tested-by: Flole <flole at flole.de>
> > ---
> > We tested this patch and it solved the problem of flushing the transmit
> > queues taking too long when the AP is busy.
> > We did not confirm if this flush is implemented to guarantee that no
> > unencrypted frames are sent out on station removal.
> > Could someone with more knowledge about the firmware behavior check
> > wether this approach is feasible or if a different approach should be
> > taken.
> > It is not clear to me if the approach taken in "wifi: ath10k: Flush
> > only requested txq in ath10k_flush()" might be better.
> > https://lore.kernel.org/linux-wireless/01d859e8e574a1f5d0b916333fe0b5cda859af9b.1732293922.git.repk@triplefau.lt/
> > 
> > Regards
> > Florian
> > 
> >   drivers/net/wireless/ath/ath11k/mac.c | 19 +++++++++++++++++++
> >   1 file changed, 19 insertions(+)
> > 
> > diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
> > index 106e2530b64e..a94649edd4ed 100644
> > --- a/drivers/net/wireless/ath/ath11k/mac.c
> > +++ b/drivers/net/wireless/ath/ath11k/mac.c
> > @@ -8330,6 +8330,24 @@ static void ath11k_mac_op_flush(struct ieee80211_hw *hw, struct ieee80211_vif *v
> >   	ath11k_mac_flush_tx_complete(ar);
> >   }
> >   
> > +static void ath11k_mac_op_flush_sta(struct ieee80211_hw *hw,
> > +							struct ieee80211_vif *vif,
> > +			    			struct ieee80211_sta *sta)
> > +{
> > +	struct ath11k_vif *arvif = (void *)vif->drv_priv;
> > +	struct ath11k *ar = hw->priv;
> > +	struct peer_flush_params params = {
> > +		.peer_tid_bitmap = 0xFF,
> > +		.vdev_id = arvif->vdev_id,
> > +	};
> > +	int ret = 0;
> > +
> > +	ret = ath11k_wmi_send_peer_flush_tids_cmd(ar, sta->addr, &params);
> > +	if (ret)
> > +		ath11k_warn(ar->ab, "failed to flush sta (sta %pM)\n",
> > +			    sta->addr);
> > +}
> > +
> >   static bool
> >   ath11k_mac_has_single_legacy_rate(struct ath11k *ar,
> >   				  enum nl80211_band band,
> > @@ -9920,6 +9938,7 @@ static const struct ieee80211_ops ath11k_ops = {
> >   	.set_bitrate_mask		= ath11k_mac_op_set_bitrate_mask,
> >   	.get_survey			= ath11k_mac_op_get_survey,
> >   	.flush				= ath11k_mac_op_flush,
> > +	.flush_sta			= ath11k_mac_op_flush_sta,
> >   	.sta_statistics			= ath11k_mac_op_sta_statistics,
> >   	CFG80211_TESTMODE_CMD(ath11k_tm_cmd)
> >   
> why is peer_tid_bitmap 0xff instead of 0xffffffff?
When setting it to 0xffffffff it fails with:
Assertion !CHK_TID_FLG(ptid, WAL_TID_IN_SCHEDQ) failedparam0 :zero,
param1 :zero, param2 :zero.
leading to a device reboot. See:
https://github.com/openwrt/openwrt/pull/20293#issuecomment-3367037471
It works with 0xffff though, but I don't quite know what the firmware
does/expects here. Maybe someone with more information can help.