ixgb and e1000: Use new function for copybreak tests

There appears to be an off-by-1 defect in the maximum packet size
copied when copybreak is speified in these modules.

The copybreak module params are specified as:
"Maximum size of packet that is copied to a new buffer on receive"

The tests are changed from "< copybreak" to "<= copybreak"
and moved into new static functions for readability.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 58 insertions, 41 deletions

diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index 5de738a6d0e6..ebdea0891665 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -3785,6 +3785,31 @@ next_desc:
         return cleaned;
 }
 
+/*
+ * this should improve performance for small packets with large amounts
+ * of reassembly being done in the stack
+ */
+static void e1000_check_copybreak(struct net_device *netdev,
+                                 struct e1000_buffer *buffer_info,
+                                 u32 length, struct sk_buff **skb)
+{
+        struct sk_buff *new_skb;
+
+        if (length > copybreak)
+                return;
+
+        new_skb = netdev_alloc_skb_ip_align(netdev, length);
+        if (!new_skb)
+                return;
+
+        skb_copy_to_linear_data_offset(new_skb, -NET_IP_ALIGN,
+                                       (*skb)->data - NET_IP_ALIGN,
+                                       length + NET_IP_ALIGN);
+        /* save the skb in buffer_info as good */
+        buffer_info->skb = *skb;
+        *skb = new_skb;
+}
+
 /**
  * e1000_clean_rx_irq - Send received data up the network stack; legacy
  * @adapter: board private structure
@@ -3883,26 +3908,8 @@ static bool e1000_clean_rx_irq(struct e1000_adapter *adapter,
                 total_rx_bytes += length;
                 total_rx_packets++;
 
-                /* code added for copybreak, this should improve
-                 * performance for small packets with large amounts
-                 * of reassembly being done in the stack */
-                if (length < copybreak) {
-                        struct sk_buff *new_skb =
-                            netdev_alloc_skb_ip_align(netdev, length);
-                        if (new_skb) {
-                                skb_copy_to_linear_data_offset(new_skb,
-                                                               -NET_IP_ALIGN,
-                                                               (skb->data -
-                                                                NET_IP_ALIGN),
-                                                               (length +
-                                                                NET_IP_ALIGN));
-                                /* save the skb in buffer_info as good */
-                                buffer_info->skb = skb;
-                                skb = new_skb;
-                        }
-                        /* else just continue with the old one */
-                }
-                /* end copybreak code */
+                e1000_check_copybreak(netdev, buffer_info, length, &skb);
+
                 skb_put(skb, length);
 
                 /* Receive Checksum Offload */
diff --git a/drivers/net/ixgb/ixgb_main.c b/drivers/net/ixgb/ixgb_main.c
index d58ca6b578cc..c6b75c83100c 100644
--- a/drivers/net/ixgb/ixgb_main.c
+++ b/drivers/net/ixgb/ixgb_main.c
@@ -1921,6 +1921,31 @@ ixgb_rx_checksum(struct ixgb_adapter *adapter,
         }
 }
 
+/*
+ * this should improve performance for small packets with large amounts
+ * of reassembly being done in the stack
+ */
+static void ixgb_check_copybreak(struct net_device *netdev,
+                                 struct ixgb_buffer *buffer_info,
+                                 u32 length, struct sk_buff **skb)
+{
+        struct sk_buff *new_skb;
+
+        if (length > copybreak)
+                return;
+
+        new_skb = netdev_alloc_skb_ip_align(netdev, length);
+        if (!new_skb)
+                return;
+
+        skb_copy_to_linear_data_offset(new_skb, -NET_IP_ALIGN,
+                                       (*skb)->data - NET_IP_ALIGN,
+                                       length + NET_IP_ALIGN);
+        /* save the skb in buffer_info as good */
+        buffer_info->skb = *skb;
+        *skb = new_skb;
+}
+
 /**
  * ixgb_clean_rx_irq - Send received data up the network stack,
  * @adapter: board private structure
@@ -1957,11 +1982,14 @@ ixgb_clean_rx_irq(struct ixgb_adapter *adapter, int *work_done, int work_to_do)
 
                 prefetch(skb->data - NET_IP_ALIGN);
 
-                if (++i == rx_ring->count) i = 0;
+                if (++i == rx_ring->count)
+                        i = 0;
                 next_rxd = IXGB_RX_DESC(*rx_ring, i);
                 prefetch(next_rxd);
 
-                if ((j = i + 1) == rx_ring->count) j = 0;
+                j = i + 1;
+                if (j == rx_ring->count)
+                        j = 0;
                 next2_buffer = &rx_ring->buffer_info[j];
                 prefetch(next2_buffer);
 
@@ -1997,25 +2025,7 @@ ixgb_clean_rx_irq(struct ixgb_adapter *adapter, int *work_done, int work_to_do)
                         goto rxdesc_done;
                 }
 
-                /* code added for copybreak, this should improve
-                 * performance for small packets with large amounts
-                 * of reassembly being done in the stack */
-                if (length < copybreak) {
-                        struct sk_buff *new_skb =
-                            netdev_alloc_skb_ip_align(netdev, length);
-                        if (new_skb) {
-                                skb_copy_to_linear_data_offset(new_skb,
-                                                               -NET_IP_ALIGN,
-                                                               (skb->data -
-                                                                NET_IP_ALIGN),
-                                                               (length +
-                                                                NET_IP_ALIGN));
-                                /* save the skb in buffer_info as good */
-                                buffer_info->skb = skb;
-                                skb = new_skb;
-                        }
-                }
-                /* end copybreak code */
+                ixgb_check_copybreak(netdev, buffer_info, length, &skb);
 
                 /* Good Receive */
                 skb_put(skb, length);