ice: Retrieve rx_buf in separate function

Introduce ice_get_rx_buf, which will fetch the Rx buffer and do the DMA
synchronization. Length of the packet that hardware Rx descriptor
contains is now read in ice_clean_rx_irq, so we can feed ice_get_rx_buf
with it and resign from rx_desc passed as argument in ice_fetch_rx_buf
and ice_add_rx_frag.
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ice/ice_txrx.c

@@ -499,8 +499,8 @@ static bool ice_page_is_reserved(struct page *page)
 /**
  * ice_add_rx_frag - Add contents of Rx buffer to sk_buff
  * @rx_buf: buffer containing page to add
- * @rx_desc: descriptor containing length of buffer written by hardware
  * @skb: sk_buf to place the data into
+ * @size: the length of the packet
  *
  * This function will add the data contained in rx_buf->page to the skb.
  * This is done either through a direct copy if the data in the buffer is
@@ -511,8 +511,8 @@ static bool ice_page_is_reserved(struct page *page)
  * true if the buffer can be reused by the adapter.
  */
 static bool
-ice_add_rx_frag(struct ice_rx_buf *rx_buf, union ice_32b_rx_flex_desc *rx_desc,
-		struct sk_buff *skb)
+ice_add_rx_frag(struct ice_rx_buf *rx_buf, struct sk_buff *skb,
+		unsigned int size)
 {
 #if (PAGE_SIZE < 8192)
 	unsigned int truesize = ICE_RXBUF_2048;
@@ -522,10 +522,6 @@ ice_add_rx_frag(struct ice_rx_buf *rx_buf, union ice_32b_rx_flex_desc *rx_desc,
 #endif /* PAGE_SIZE < 8192) */
 
 	struct page *page;
-	unsigned int size;
-
-	size = le16_to_cpu(rx_desc->wb.pkt_len) &
-		ICE_RX_FLX_DESC_PKT_LEN_M;
 
 	page = rx_buf->page;
 
@@ -603,10 +599,35 @@ ice_reuse_rx_page(struct ice_ring *rx_ring, struct ice_rx_buf *old_buf)
 	*new_buf = *old_buf;
 }
 
+/**
+ * ice_get_rx_buf - Fetch Rx buffer and synchronize data for use
+ * @rx_ring: Rx descriptor ring to transact packets on
+ * @size: size of buffer to add to skb
+ *
+ * This function will pull an Rx buffer from the ring and synchronize it
+ * for use by the CPU.
+ */
+static struct ice_rx_buf *
+ice_get_rx_buf(struct ice_ring *rx_ring, const unsigned int size)
+{
+	struct ice_rx_buf *rx_buf;
+
+	rx_buf = &rx_ring->rx_buf[rx_ring->next_to_clean];
+	prefetchw(rx_buf->page);
+
+	/* we are reusing so sync this buffer for CPU use */
+	dma_sync_single_range_for_cpu(rx_ring->dev, rx_buf->dma,
+				      rx_buf->page_offset, size,
+				      DMA_FROM_DEVICE);
+
+	return rx_buf;
+}
+
 /**
  * ice_fetch_rx_buf - Allocate skb and populate it
  * @rx_ring: Rx descriptor ring to transact packets on
- * @rx_desc: descriptor containing info written by hardware
+ * @rx_buf: Rx buffer to pull data from
+ * @size: the length of the packet
  *
  * This function allocates an skb on the fly, and populates it with the page
  * data from the current receive descriptor, taking care to set up the skb
@@ -614,20 +635,14 @@ ice_reuse_rx_page(struct ice_ring *rx_ring, struct ice_rx_buf *old_buf)
  * necessary.
  */
 static struct sk_buff *
-ice_fetch_rx_buf(struct ice_ring *rx_ring, union ice_32b_rx_flex_desc *rx_desc)
+ice_fetch_rx_buf(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf,
+		 unsigned int size)
 {
-	struct ice_rx_buf *rx_buf;
-	struct sk_buff *skb;
-	struct page *page;
-
-	rx_buf = &rx_ring->rx_buf[rx_ring->next_to_clean];
-	page = rx_buf->page;
-	prefetchw(page);
-
-	skb = rx_buf->skb;
+	struct sk_buff *skb = rx_buf->skb;
 
 	if (likely(!skb)) {
-		u8 *page_addr = page_address(page) + rx_buf->page_offset;
+		u8 *page_addr = page_address(rx_buf->page) +
+				rx_buf->page_offset;
 
 		/* prefetch first cache line of first page */
 		prefetch(page_addr);
@@ -644,25 +659,13 @@ ice_fetch_rx_buf(struct ice_ring *rx_ring, union ice_32b_rx_flex_desc *rx_desc)
 			return NULL;
 		}
 
-		/* we will be copying header into skb->data in
-		 * pskb_may_pull so it is in our interest to prefetch
-		 * it now to avoid a possible cache miss
-		 */
-		prefetchw(skb->data);
-
 		skb_record_rx_queue(skb, rx_ring->q_index);
 	} else {
-		/* we are reusing so sync this buffer for CPU use */
-		dma_sync_single_range_for_cpu(rx_ring->dev, rx_buf->dma,
-					      rx_buf->page_offset,
-					      ICE_RXBUF_2048,
-					      DMA_FROM_DEVICE);
-
 		rx_buf->skb = NULL;
 	}
 
 	/* pull page into skb */
-	if (ice_add_rx_frag(rx_buf, rx_desc, skb)) {
+	if (ice_add_rx_frag(rx_buf, skb, size)) {
 		/* hand second half of page back to the ring */
 		ice_reuse_rx_page(rx_ring, rx_buf);
 		rx_ring->rx_stats.page_reuse_count++;
@@ -963,7 +966,9 @@ static int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
 	/* start the loop to process RX packets bounded by 'budget' */
 	while (likely(total_rx_pkts < (unsigned int)budget)) {
 		union ice_32b_rx_flex_desc *rx_desc;
+		struct ice_rx_buf *rx_buf;
 		struct sk_buff *skb;
+		unsigned int size;
 		u16 stat_err_bits;
 		u16 vlan_tag = 0;
 		u8 rx_ptype;
@@ -993,8 +998,12 @@ static int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
 		 */
 		dma_rmb();
 
+		size = le16_to_cpu(rx_desc->wb.pkt_len) &
+			ICE_RX_FLX_DESC_PKT_LEN_M;
+
+		rx_buf = ice_get_rx_buf(rx_ring, size);
 		/* allocate (if needed) and populate skb */
-		skb = ice_fetch_rx_buf(rx_ring, rx_desc);
+		skb = ice_fetch_rx_buf(rx_ring, rx_buf, size);
 		if (!skb)
 			break;