mt76: remove rx_page_lock

We can not run mt76u_alloc_buf() concurently, rx_tasklet is stooped
when mt76u_submit_rx_buffers(). We can remove rx_page_lock.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt76.h

@@ -138,7 +138,6 @@ struct mt76_queue {
 	dma_addr_t desc_dma;
 	struct sk_buff *rx_head;
 	struct page_frag_cache rx_page;
-	spinlock_t rx_page_lock;
 };
 
 struct mt76_sw_queue {

drivers/net/wireless/mediatek/mt76/usb.c

@@ -292,7 +292,6 @@ mt76u_fill_rx_sg(struct mt76_dev *dev, struct mt76u_buf *buf,
 	struct urb *urb = buf->urb;
 	int i;
 
-	spin_lock_bh(&q->rx_page_lock);
 	for (i = 0; i < nsgs; i++) {
 		struct page *page;
 		void *data;
@@ -306,7 +305,6 @@ mt76u_fill_rx_sg(struct mt76_dev *dev, struct mt76u_buf *buf,
 		offset = data - page_address(page);
 		sg_set_page(&urb->sg[i], page, sglen, offset);
 	}
-	spin_unlock_bh(&q->rx_page_lock);
 
 	if (i < nsgs) {
 		int j;
@@ -569,7 +567,6 @@ static int mt76u_alloc_rx(struct mt76_dev *dev)
 	if (!usb->mcu.data)
 		return -ENOMEM;
 
-	spin_lock_init(&q->rx_page_lock);
 	spin_lock_init(&q->lock);
 	q->entry = devm_kcalloc(dev->dev,
 				MT_NUM_RX_ENTRIES, sizeof(*q->entry),
@@ -597,15 +594,12 @@ static void mt76u_free_rx(struct mt76_dev *dev)
 	for (i = 0; i < q->ndesc; i++)
 		mt76u_buf_free(&q->entry[i].ubuf);
 
-	spin_lock_bh(&q->rx_page_lock);
 	if (!q->rx_page.va)
-		goto out;
+		return;
 
 	page = virt_to_page(q->rx_page.va);
 	__page_frag_cache_drain(page, q->rx_page.pagecnt_bias);
 	memset(&q->rx_page, 0, sizeof(q->rx_page));
-out:
-	spin_unlock_bh(&q->rx_page_lock);
 }
 
 static void mt76u_stop_rx(struct mt76_dev *dev)