[PATCH] wifi: mt76: mt7921: fix skb leak by txs missing in AMSDU

[Sean Wang]

Hi, Deren

On Mon, May 15, 2023 at 7:21 AM Deren Wu <deren.wu at mediatek.com> wrote:
>
> txs may be dropped if the frame is aggregated in AMSDU. When the problem
> shows up, some SKBs would be hold in driver to cause network stopped
> temporarily. Even if the problem can be recovered by txs timeout handling,
> mt7921 still need to disable txs in AMSDU to avoid this issue.
>
> Cc: stable at vger.kernel.org
> Fixes: 182071cdd594 ("mt76: connac: move connac2_mac_write_txwi in mt76_connac module")

The patch with the identifier "182071cdd594 ("mt76: connac: move
connac2_mac_write_txwi in mt76_connac module") was merely a
refactoring patch and not the root cause of the issue. Therefore, I
believe it would be more appropriate to address and rectify the patch
"163f4d22c118 ("mt76: mt7921: add MAC support") instead. This will
ensure downstream branches are better informed about the necessary fix
and can accurately backport the patch.

> Reviewed-by: Shayne Chen <shayne.chen at mediatek.com>
> Signed-off-by: Deren Wu <deren.wu at mediatek.com>
> ---
>  drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c b/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
> index ee0fbfcd07d6..56c42ee1178c 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
> @@ -495,6 +495,7 @@ void mt76_connac2_mac_write_txwi(struct mt76_dev *dev, __le32 *txwi,
>                                     BSS_CHANGED_BEACON_ENABLED));
>         bool inband_disc = !!(changed & (BSS_CHANGED_UNSOL_BCAST_PROBE_RESP |
>                                          BSS_CHANGED_FILS_DISCOVERY));
> +       bool amsdu_en = wcid->amsdu;
>
>         if (vif) {
>                 struct mt76_vif *mvif = (struct mt76_vif *)vif->drv_priv;
> @@ -554,12 +555,14 @@ void mt76_connac2_mac_write_txwi(struct mt76_dev *dev, __le32 *txwi,
>         txwi[4] = 0;
>
>         val = FIELD_PREP(MT_TXD5_PID, pid);
> -       if (pid >= MT_PACKET_ID_FIRST)
> +       if (pid >= MT_PACKET_ID_FIRST) {
>                 val |= MT_TXD5_TX_STATUS_HOST;
> +               amsdu_en &= !is_mt7921(dev);
> +       }
>
>         txwi[5] = cpu_to_le32(val);
>         txwi[6] = 0;
> -       txwi[7] = wcid->amsdu ? cpu_to_le32(MT_TXD7_HW_AMSDU) : 0;
> +       txwi[7] = amsdu_en ? cpu_to_le32(MT_TXD7_HW_AMSDU) : 0;
>
>         if (is_8023)
>                 mt76_connac2_mac_write_txwi_8023(txwi, skb, wcid);
> --
> 2.18.0
>