Re: [PATCH 1/2] wifi: mt76: mt7996: disable beacons when going offchannel

[Ben Greear <greearb@candelatech.com>]

On 8/13/25 05:11, Felix Fietkau wrote:
> Avoid leaking beacons on unrelated channels during scanning/roc
> 
> Fixes: c56d6edebc1f ("wifi: mt76: mt7996: use emulated hardware scan support")
> Reported-by: Chad Monroe <chad.monroe@adtran.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>   .../net/wireless/mediatek/mt76/mt7996/mac.c   | 46 +++++++++++--------
>   .../net/wireless/mediatek/mt76/mt7996/main.c  |  5 ++
>   .../net/wireless/mediatek/mt76/mt7996/mcu.c   | 11 +++--
>   .../wireless/mediatek/mt76/mt7996/mt7996.h    |  1 +
>   4 files changed, 42 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
> index 6333a064c4f7..d3d3b96f7dd2 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
> @@ -1698,17 +1698,37 @@ mt7996_wait_reset_state(struct mt7996_dev *dev, u32 state)
>   static void
>   mt7996_update_vif_beacon(void *priv, u8 *mac, struct ieee80211_vif *vif)
>   {
> -	struct ieee80211_hw *hw = priv;
> +	struct ieee80211_bss_conf *link_conf;
> +	struct mt7996_phy *phy = priv;
> +	struct mt7996_dev *dev = phy->dev;
> +	unsigned int link_id;
> +
>   
>   	switch (vif->type) {
>   	case NL80211_IFTYPE_MESH_POINT:
>   	case NL80211_IFTYPE_ADHOC:
>   	case NL80211_IFTYPE_AP:
> -		mt7996_mcu_add_beacon(hw, vif, &vif->bss_conf);
>   		break;
>   	default:
> -		break;
> +		return;
>   	}
> +
> +	for_each_vif_active_link(vif, link_conf, link_id) {
> +		struct mt7996_vif_link *link;
> +
> +		link = mt7996_vif_link(dev, vif, link_id);
> +		if (link->phy != phy)
> +			continue;
> +
> +		mt7996_mcu_add_beacon(dev->mt76.hw, vif, link_conf);
> +	}

Hello Felix,

We attempted to backport this into our tree, and we found that 'link'
in the code above is NULL sometimes and we were seeing crashes.  Adding
a check for null seems to have fixed it.

Possibly this does not happen in upstream code, so just FYI.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com