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>

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index d11fac5..9e72ae6 100644 (file)
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -1693,6 +1693,89 @@ static bool ixgbe_add_rx_frag(struct ixgbe_ring *rx_ring,
        return true;
 }
 
+static struct sk_buff *ixgbe_fetch_rx_buffer(struct ixgbe_ring *rx_ring,
+                                            union ixgbe_adv_rx_desc *rx_desc)
+{
+       struct ixgbe_rx_buffer *rx_buffer;
+       struct sk_buff *skb;
+       struct page *page;
+
+       rx_buffer = &rx_ring->rx_buffer_info[rx_ring->next_to_clean];
+       page = rx_buffer->page;
+       prefetchw(page);
+
+       skb = rx_buffer->skb;
+
+       if (likely(!skb)) {
+               void *page_addr = page_address(page) +
+                                 rx_buffer->page_offset;
+
+               /* prefetch first cache line of first page */
+               prefetch(page_addr);
+#if L1_CACHE_BYTES < 128
+               prefetch(page_addr + L1_CACHE_BYTES);
+#endif
+
+               /* allocate a skb to store the frags */
+               skb = netdev_alloc_skb_ip_align(rx_ring->netdev,
+                                               IXGBE_RX_HDR_SIZE);
+               if (unlikely(!skb)) {
+                       rx_ring->rx_stats.alloc_rx_buff_failed++;
+                       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);
+
+               /*
+                * Delay unmapping of the first packet. It carries the
+                * header information, HW may still access the header
+                * after the writeback.  Only unmap it when EOP is
+                * reached
+                */
+               if (likely(ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_EOP)))
+                       goto dma_sync;
+
+               IXGBE_CB(skb)->dma = rx_buffer->dma;
+       } else {
+               if (ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_EOP))
+                       ixgbe_dma_sync_frag(rx_ring, skb);
+
+dma_sync:
+               /* we are reusing so sync this buffer for CPU use */
+               dma_sync_single_range_for_cpu(rx_ring->dev,
+                                             rx_buffer->dma,
+                                             rx_buffer->page_offset,
+                                             ixgbe_rx_bufsz(rx_ring),
+                                             DMA_FROM_DEVICE);
+       }
+
+       /* pull page into skb */
+       if (ixgbe_add_rx_frag(rx_ring, rx_buffer, rx_desc, skb)) {
+               /* hand second half of page back to the ring */
+               ixgbe_reuse_rx_page(rx_ring, rx_buffer);
+       } else if (IXGBE_CB(skb)->dma == rx_buffer->dma) {
+               /* the page has been released from the ring */
+               IXGBE_CB(skb)->page_released = true;
+       } else {
+               /* we are not reusing the buffer so unmap it */
+               dma_unmap_page(rx_ring->dev, rx_buffer->dma,
+                              ixgbe_rx_pg_size(rx_ring),
+                              DMA_FROM_DEVICE);
+       }
+
+       /* clear contents of buffer_info */
+       rx_buffer->skb = NULL;
+       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
@@ -1718,11 +1801,8 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
        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) {
@@ -1730,9 +1810,7 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
                        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];
+               rx_desc = IXGBE_RX_DESC(rx_ring, rx_ring->next_to_clean);
 
                if (!ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_DD))
                        break;
@@ -1744,78 +1822,12 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
                 */
                rmb();
 
-               page = rx_buffer->page;
-               prefetchw(page);
-
-               skb = rx_buffer->skb;
-
-               if (likely(!skb)) {
-                       void *page_addr = page_address(page) +
-                                         rx_buffer->page_offset;
-
-                       /* prefetch first cache line of first page */
-                       prefetch(page_addr);
-#if L1_CACHE_BYTES < 128
-                       prefetch(page_addr + L1_CACHE_BYTES);
-#endif
-
-                       /* allocate a skb to store the frags */
-                       skb = netdev_alloc_skb_ip_align(rx_ring->netdev,
-                                                       IXGBE_RX_HDR_SIZE);
-                       if (unlikely(!skb)) {
-                               rx_ring->rx_stats.alloc_rx_buff_failed++;
-                               break;
-                       }
-
-                       /*
-                        * 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);
-
-                       /*
-                        * Delay unmapping of the first packet. It carries the
-                        * header information, HW may still access the header
-                        * after the writeback.  Only unmap it when EOP is
-                        * reached
-                        */
-                       if (likely(ixgbe_test_staterr(rx_desc,
-                                                     IXGBE_RXD_STAT_EOP)))
-                               goto dma_sync;
+               /* retrieve a buffer from the ring */
+               skb = ixgbe_fetch_rx_buffer(rx_ring, rx_desc);
 
-                       IXGBE_CB(skb)->dma = rx_buffer->dma;
-               } else {
-                       if (ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_EOP))
-                               ixgbe_dma_sync_frag(rx_ring, skb);
-
-dma_sync:
-                       /* we are reusing so sync this buffer for CPU use */
-                       dma_sync_single_range_for_cpu(rx_ring->dev,
-                                                     rx_buffer->dma,
-                                                     rx_buffer->page_offset,
-                                                     ixgbe_rx_bufsz(rx_ring),
-                                                     DMA_FROM_DEVICE);
-               }
-
-               /* pull page into skb */
-               if (ixgbe_add_rx_frag(rx_ring, rx_buffer, rx_desc, skb)) {
-                       /* hand second half of page back to the ring */
-                       ixgbe_reuse_rx_page(rx_ring, rx_buffer);
-               } else if (IXGBE_CB(skb)->dma == rx_buffer->dma) {
-                       /* the page has been released from the ring */
-                       IXGBE_CB(skb)->page_released = true;
-               } else {
-                       /* we are not reusing the buffer so unmap it */
-                       dma_unmap_page(rx_ring->dev, rx_buffer->dma,
-                                      ixgbe_rx_pg_size(rx_ring),
-                                      DMA_FROM_DEVICE);
-               }
-
-               /* clear contents of buffer_info */
-               rx_buffer->skb = NULL;
-               rx_buffer->dma = 0;
-               rx_buffer->page = NULL;
+               /* exit if we failed to retrieve a buffer */
+               if (!skb)
+                       break;
 
                ixgbe_get_rsc_cnt(rx_ring, rx_desc, skb);