ixgbe: Make allocating skb and placing data in it a separate function

This patch creates a function named ixgbe_fetch_rx_buffer. The sole
purpose of this function is to retrieve a single buffer off of the ring and
to place it in an skb.

The advantage to doing this is that it helps improve the readability since
I can decrease the indentation and for the code in this section.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -1693,57 +1693,14 @@ static bool ixgbe_add_rx_frag(struct ixgbe_ring *rx_ring,
 	return true;
 }
 
-/**
- * ixgbe_clean_rx_irq - Clean completed descriptors from Rx ring - bounce buf
- * @q_vector: structure containing interrupt and ring information
- * @rx_ring: rx descriptor ring to transact packets on
- * @budget: Total limit on number of packets to process
- *
- * This function provides a "bounce buffer" approach to Rx interrupt
- * processing.  The advantage to this is that on systems that have
- * expensive overhead for IOMMU access this provides a means of avoiding
- * it by maintaining the mapping of the page to the syste.
- *
- * Returns true if all work is completed without reaching budget
- **/
-static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
-			       struct ixgbe_ring *rx_ring,
-			       int budget)
+static struct sk_buff *ixgbe_fetch_rx_buffer(struct ixgbe_ring *rx_ring,
+					     union ixgbe_adv_rx_desc *rx_desc)
 {
-	unsigned int total_rx_bytes = 0, total_rx_packets = 0;
-#ifdef IXGBE_FCOE
-	struct ixgbe_adapter *adapter = q_vector->adapter;
-	int ddp_bytes = 0;
-#endif /* IXGBE_FCOE */
-	u16 cleaned_count = ixgbe_desc_unused(rx_ring);
-
-	do {
 	struct ixgbe_rx_buffer *rx_buffer;
-		union ixgbe_adv_rx_desc *rx_desc;
 	struct sk_buff *skb;
 	struct page *page;
-		u16 ntc;
-
-		/* return some buffers to hardware, one at a time is too slow */
-		if (cleaned_count >= IXGBE_RX_BUFFER_WRITE) {
-			ixgbe_alloc_rx_buffers(rx_ring, cleaned_count);
-			cleaned_count = 0;
-		}
-
-		ntc = rx_ring->next_to_clean;
-		rx_desc = IXGBE_RX_DESC(rx_ring, ntc);
-		rx_buffer = &rx_ring->rx_buffer_info[ntc];
-
-		if (!ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_DD))
-			break;
-
-		/*
-		 * This memory barrier is needed to keep us from reading
-		 * any other fields out of the rx_desc until we know the
-		 * RXD_STAT_DD bit is set
-		 */
-		rmb();
 
+	rx_buffer = &rx_ring->rx_buffer_info[rx_ring->next_to_clean];
 	page = rx_buffer->page;
 	prefetchw(page);
 
@@ -1764,7 +1721,7 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
 						IXGBE_RX_HDR_SIZE);
 		if (unlikely(!skb)) {
 			rx_ring->rx_stats.alloc_rx_buff_failed++;
-				break;
+			return NULL;
 		}
 
 		/*
@@ -1780,8 +1737,7 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
 		 * after the writeback.  Only unmap it when EOP is
 		 * reached
 		 */
-			if (likely(ixgbe_test_staterr(rx_desc,
-						      IXGBE_RXD_STAT_EOP)))
+		if (likely(ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_EOP)))
 			goto dma_sync;
 
 		IXGBE_CB(skb)->dma = rx_buffer->dma;
@@ -1817,6 +1773,62 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
 	rx_buffer->dma = 0;
 	rx_buffer->page = NULL;
 
+	return skb;
+}
+
+/**
+ * ixgbe_clean_rx_irq - Clean completed descriptors from Rx ring - bounce buf
+ * @q_vector: structure containing interrupt and ring information
+ * @rx_ring: rx descriptor ring to transact packets on
+ * @budget: Total limit on number of packets to process
+ *
+ * This function provides a "bounce buffer" approach to Rx interrupt
+ * processing.  The advantage to this is that on systems that have
+ * expensive overhead for IOMMU access this provides a means of avoiding
+ * it by maintaining the mapping of the page to the syste.
+ *
+ * Returns true if all work is completed without reaching budget
+ **/
+static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
+			       struct ixgbe_ring *rx_ring,
+			       int budget)
+{
+	unsigned int total_rx_bytes = 0, total_rx_packets = 0;
+#ifdef IXGBE_FCOE
+	struct ixgbe_adapter *adapter = q_vector->adapter;
+	int ddp_bytes = 0;
+#endif /* IXGBE_FCOE */
+	u16 cleaned_count = ixgbe_desc_unused(rx_ring);
+
+	do {
+		union ixgbe_adv_rx_desc *rx_desc;
+		struct sk_buff *skb;
+
+		/* return some buffers to hardware, one at a time is too slow */
+		if (cleaned_count >= IXGBE_RX_BUFFER_WRITE) {
+			ixgbe_alloc_rx_buffers(rx_ring, cleaned_count);
+			cleaned_count = 0;
+		}
+
+		rx_desc = IXGBE_RX_DESC(rx_ring, rx_ring->next_to_clean);
+
+		if (!ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_DD))
+			break;
+
+		/*
+		 * This memory barrier is needed to keep us from reading
+		 * any other fields out of the rx_desc until we know the
+		 * RXD_STAT_DD bit is set
+		 */
+		rmb();
+
+		/* retrieve a buffer from the ring */
+		skb = ixgbe_fetch_rx_buffer(rx_ring, rx_desc);
+
+		/* exit if we failed to retrieve a buffer */
+		if (!skb)
+			break;
+
 		ixgbe_get_rsc_cnt(rx_ring, rx_desc, skb);
 
 		cleaned_count++;