Re: [PATCH v3 net-next 08/14] mlx4: use order-0 pages for RX

@@ -137,13 +137,17 @@ static int mlx4_en_prepare_rx_desc(struct mlx4_en_priv *priv,
 	struct mlx4_en_rx_desc *rx_desc = ring->buf + (index * ring->stride);
 	struct mlx4_en_rx_alloc *frags = ring->rx_info +
 					(index << priv->log_rx_info);
+
 	if (ring->page_cache.index > 0) {
+		spin_lock(&ring->page_cache.lock);
+
 		/* XDP uses a single page per frame */
 		if (!frags->page) {
 			ring->page_cache.index--;
 			frags->page = ring->page_cache.buf[ring->page_cache.index].page;
 			frags->dma  = ring->page_cache.buf[ring->page_cache.index].dma;
 		}
+		spin_unlock(&ring->page_cache.lock);
 		frags->page_offset = XDP_PACKET_HEADROOM;
 		rx_desc->data[0].addr = cpu_to_be64(frags->dma +
 						    XDP_PACKET_HEADROOM);

@@ -277,6 +281,7 @@ int mlx4_en_create_rx_ring(struct mlx4_en_priv *priv,
 		}
 	}
 
+	spin_lock_init(&ring->page_cache.lock);
 	ring->prod = 0;
 	ring->cons = 0;
 	ring->size = size;

@@ -419,10 +424,13 @@ bool mlx4_en_rx_recycle(struct mlx4_en_rx_ring *ring,
 
 	if (cache->index >= MLX4_EN_CACHE_SIZE)
 		return false;
-
-	cache->buf[cache->index].page = frame->page;
-	cache->buf[cache->index].dma = frame->dma;
-	cache->index++;
+	spin_lock(&cache->lock);
+	if (cache->index < MLX4_EN_CACHE_SIZE) {
+		cache->buf[cache->index].page = frame->page;
+		cache->buf[cache->index].dma = frame->dma;
+		cache->index++;
+	}
+	spin_unlock(&cache->lock);
 	return true;
 }
 

@@ -258,7 +258,8 @@ struct mlx4_en_rx_alloc {
 #define MLX4_EN_CACHE_SIZE (2 * NAPI_POLL_WEIGHT)
 
 struct mlx4_en_page_cache {
-	u32 index;
+	u32			index;
+	spinlock_t		lock;
 	struct {
 		struct page	*page;
 		dma_addr_t	dma;