Re: [PATCH v6] wifi: mt76: mt7915: add wds support when wed is enabled

[Qu Shengyu <wiagn233@outlook.com>]

Hello Felix,

Sorry to bother but any updates on this? I remember that you’ve agreed to take over this patch on IRC.

Best regards,
Shengyu

> 在 2024年9月9日，00:27，Shengyu Qu <wiagn233@outlook.com> 写道：
> 
> 
>> 
>>> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/main.c b/drivers/net/wireless/mediatek/mt76/mt7915/main.c
>>> index 049223df9beb1..dc4d87e004a0f 100644
>>> --- a/drivers/net/wireless/mediatek/mt76/mt7915/main.c
>>> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/main.c
>>> @@ -745,8 +745,15 @@ int mt7915_mac_sta_add(struct mt76_dev *mdev, struct ieee80211_vif *vif,
>>>       bool ext_phy = mvif->phy != &dev->phy;
>>>       int ret, idx;
>>>       u32 addr;
>>> +    u8 flags = MT76_WED_DEFAULT;
>>> -    idx = mt76_wcid_alloc(dev->mt76.wcid_mask, MT7915_WTBL_STA);
>>> +    if (mtk_wed_device_active(&dev->mt76.mmio.wed) &&
>>> +        !is_mt7915(&dev->mt76)) {
>>> +        flags = test_bit(MT_WCID_FLAG_4ADDR, &msta->wcid.flags) ?
>>> +               MT76_WED_WDS_ACTIVE : MT76_WED_ACTIVE;
>>> +    }
>>> +
>>> +    idx = __mt76_wcid_alloc(mdev->wcid_mask, MT7915_WTBL_STA, flags);
>>>       if (idx < 0)
>>>           return -ENOSPC;
>> I'd prefer to replace the mt76_wcid_alloc flags argument with an explicit start offset argument.
> 
> Hi Felix,
> 
> I'm not really familiar with mt76 code, just a enthusiast that wants to
> make WDS+WED working. So I'm not sure how to do this correctly... Maybe
> it's better for you to take over this patch, sorry.
> 
>>> @@ -1201,12 +1208,27 @@ static void mt7915_sta_set_4addr(struct ieee80211_hw *hw,
>>>   {
>>>       struct mt7915_dev *dev = mt7915_hw_dev(hw);
>>>       struct mt7915_sta *msta = (struct mt7915_sta *)sta->drv_priv;
>>> +    int min = MT76_WED_WDS_MIN, max = MT76_WED_WDS_MAX;
>>>       if (enabled)
>>>           set_bit(MT_WCID_FLAG_4ADDR, &msta->wcid.flags);
>>>       else
>>>           clear_bit(MT_WCID_FLAG_4ADDR, &msta->wcid.flags);
>>> +    if (mtk_wed_device_active(&dev->mt76.mmio.wed) &&
>>> +        !is_mt7915(&dev->mt76) &&
>>> +        (msta->wcid.idx < min || msta->wcid.idx > max - 1)) {
>>> +        struct ieee80211_sta *pre_sta;
>>> +
>>> +        pre_sta = kzalloc(sizeof(*sta) + sizeof(*msta), GFP_KERNEL);
>>> +        mt76_sta_pre_rcu_remove(hw, vif, sta);
>>> +        memmove(pre_sta, sta, sizeof(*sta) + sizeof(*msta));
>>> +        mt7915_sta_add(hw, vif, sta);
>>> +        synchronize_rcu();
>>> +        mt7915_sta_remove(hw, vif, pre_sta);
>>> +        kfree(pre_sta);
>>> +    }
>>> +
>>>       mt76_connac_mcu_wtbl_update_hdr_trans(&dev->mt76, vif, sta);
>>>   }
>>> 
>> In order to update the code based on my latest changes and to fix potential race conditions on tx/rx packets during the transition, please change to this order:
>> 1. copy the sta
>> 2. allocate a new wcid
>> 3. change the wcid index in the copied sta to the newly allocated wcid
>> 4. call mcu functions on the duplicate sta for creating the new sta entry.
>> 5. use rcu_assign_pointer to point dev->wcid[new_idx] at &msta->wcid
>> 6. swap wcid index between real sta and duplicated sta
>> 7. rcu_assign_pointer(dev->wcid[orig_idx], NULL)
>> 8. synchronize_rcu()
>> 9. call mcu functions to delete the duplicate sta's entry (points to old wcid after the swap)
>> 10. free the duplicated sta
> 
> Now, the mt7915_sta_set_4addr function looks like this(__mt76_wcid_alloc
> not modified), do you think it's acceptable?
> 
> static void mt7915_sta_set_4addr(struct ieee80211_hw *hw,
>                 struct ieee80211_vif *vif,
>                 struct ieee80211_sta *sta,
>                 bool enabled)
> {
>    struct mt7915_dev *dev = mt7915_hw_dev(hw);
>    struct mt7915_sta *msta = (struct mt7915_sta *)sta->drv_priv;
>    int min = MT76_WED_WDS_MIN, max = MT76_WED_WDS_MAX;
>    struct ieee80211_sta *pre_sta;
>    u8 flags = MT76_WED_DEFAULT;
>    int temp_idx;
> 
>    if (enabled)
>        set_bit(MT_WCID_FLAG_4ADDR, &msta->wcid.flags);
>    else
>        clear_bit(MT_WCID_FLAG_4ADDR, &msta->wcid.flags);
> 
>    if (!msta->wcid.sta)
>        return;
> 
>    if (mtk_wed_device_active(&dev->mt76.mmio.wed) &&
>        !is_mt7915(&dev->mt76) &&
>        (msta->wcid.idx < min || msta->wcid.idx > max - 1)) {
>        pre_sta = kzalloc(sizeof(*sta) + sizeof(*msta), GFP_KERNEL);
>        memmove(pre_sta, sta, sizeof(*sta) + sizeof(*msta));
>        if (mtk_wed_device_active(&dev->mt76.mmio.wed) &&
>            !is_mt7915(&dev->mt76)) {
>            flags = test_bit(MT_WCID_FLAG_4ADDR, &msta->wcid.flags) ?
>                MT76_WED_WDS_ACTIVE : MT76_WED_ACTIVE;
>        }
> 
>        temp_idx = __mt76_wcid_alloc(mdev->wcid_mask, MT7915_WTBL_STA, flags);
>        ((struct mt7915_sta *)pre_sta->drv_priv)->wcid.idx = temp_idx;
>        mt7915_sta_add(hw, vif, pre_sta);
>        rcu_assign_pointer(dev->mt76.wcid[temp_idx], &msta->wcid);
>        temp_idx = msta->wcid.idx;
>        msta->wcid.idx = ((struct mt7915_sta *)pre_sta->drv_priv)->wcid.idx;
>        ((struct mt7915_sta *)pre_sta->drv_priv)->wcid.idx = temp_idx;
>        rcu_assign_pointer(dev->mt76.wcid[temp_idx], NULL);
>        synchronize_rcu();
>        mt7915_sta_remove(hw, vif, pre_sta);
>        kfree(pre_sta);
>    }
> 
>    mt76_connac_mcu_wtbl_update_hdr_trans(&dev->mt76, vif, sta);
> }
> 
> Best regards,
> Shengyu
> 
>> This should allow mgmt tx/rx to work while the sta is being migrated to the new wcid entry.
>> - Felix
> <OpenPGP_0xE3520CC91929C8E7.asc>