wifi: mt76: add memory barrier to SDIO queue kick

Ensure the entry has been fully updated before SDIO bus worker access
it. This patch would fix potential memory risk in both mt7663s and
mt7921s.

Fixes: 764dee47e2c1 ("mt76: sdio: move common code in mt76_sdio module")
Signed-off-by: Deren Wu <deren.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/drivers/net/wireless/mediatek/mt76/sdio.c b/drivers/net/wireless/mediatek/mt76/sdio.c
index 228bc7d45011c0f65e6dc0e79f81c33681aa1ff7..419723118ded8e3f187aa2887d987b2697b48bb0 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/sdio.c
+++ b/drivers/net/wireless/mediatek/mt76/sdio.c
@@ -562,6 +562,10 @@ mt76s_tx_queue_skb_raw(struct mt76_dev *dev, struct mt76_queue *q,
 
        q->entry[q->head].buf_sz = len;
        q->entry[q->head].skb = skb;
+
+       /* ensure the entry fully updated before bus access */
+       smp_wmb();
+
        q->head = (q->head + 1) % q->ndesc;
        q->queued++;