igc: Introduce igc_rx_buffer_flip() helper

The igc driver implements the same page recycling scheme from other
Intel drivers which reuses the page by flipping the buffer. The code
to handle buffer flips is duplicated in many locations so introduce
the igc_rx_buffer_flip() helper and use it where applicable.

Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Signed-off-by: Vedang Patel <vedang.patel@intel.com>
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igc/igc_main.c

@@ -1499,6 +1499,16 @@ static struct igc_rx_buffer *igc_get_rx_buffer(struct igc_ring *rx_ring,
 	return rx_buffer;
 }
 
+static void igc_rx_buffer_flip(struct igc_rx_buffer *buffer,
+			       unsigned int truesize)
+{
+#if (PAGE_SIZE < 8192)
+	buffer->page_offset ^= truesize;
+#else
+	buffer->page_offset += truesize;
+#endif
+}
+
 /**
  * igc_add_rx_frag - Add contents of Rx buffer to sk_buff
  * @rx_ring: rx descriptor ring to transact packets on
@@ -1513,20 +1523,19 @@ static void igc_add_rx_frag(struct igc_ring *rx_ring,
 			    struct sk_buff *skb,
 			    unsigned int size)
 {
-#if (PAGE_SIZE < 8192)
-	unsigned int truesize = igc_rx_pg_size(rx_ring) / 2;
+	unsigned int truesize;
 
-	skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, rx_buffer->page,
-			rx_buffer->page_offset, size, truesize);
-	rx_buffer->page_offset ^= truesize;
+#if (PAGE_SIZE < 8192)
+	truesize = igc_rx_pg_size(rx_ring) / 2;
 #else
-	unsigned int truesize = ring_uses_build_skb(rx_ring) ?
-				SKB_DATA_ALIGN(IGC_SKB_PAD + size) :
-				SKB_DATA_ALIGN(size);
+	truesize = ring_uses_build_skb(rx_ring) ?
+		   SKB_DATA_ALIGN(IGC_SKB_PAD + size) :
+		   SKB_DATA_ALIGN(size);
+#endif
 	skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, rx_buffer->page,
 			rx_buffer->page_offset, size, truesize);
-	rx_buffer->page_offset += truesize;
-#endif
+
+	igc_rx_buffer_flip(rx_buffer, truesize);
 }
 
 static struct sk_buff *igc_build_skb(struct igc_ring *rx_ring,
@@ -1555,13 +1564,7 @@ static struct sk_buff *igc_build_skb(struct igc_ring *rx_ring,
 	skb_reserve(skb, IGC_SKB_PAD);
 	__skb_put(skb, size);
 
-	/* update buffer offset */
-#if (PAGE_SIZE < 8192)
-	rx_buffer->page_offset ^= truesize;
-#else
-	rx_buffer->page_offset += truesize;
-#endif
-
+	igc_rx_buffer_flip(rx_buffer, truesize);
 	return skb;
 }
 
@@ -1607,11 +1610,7 @@ static struct sk_buff *igc_construct_skb(struct igc_ring *rx_ring,
 		skb_add_rx_frag(skb, 0, rx_buffer->page,
 				(va + headlen) - page_address(rx_buffer->page),
 				size, truesize);
-#if (PAGE_SIZE < 8192)
-		rx_buffer->page_offset ^= truesize;
-#else
-		rx_buffer->page_offset += truesize;
-#endif
+		igc_rx_buffer_flip(rx_buffer, truesize);
 	} else {
 		rx_buffer->pagecnt_bias++;
 	}