[Xen-devel] [PATCH v3 01/20] net/xen-netback: xenvif_gop_frag_copy: move GSO check out of the loop

[Julien Grall <julien.grall@xxxxxxxxxx>]

The skb doesn't change within the function. Therefore it's only
necessary to check if we need GSO once at the beginning.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

---
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx

    Changes in v2:
        - Patch added
---
 drivers/net/xen-netback/netback.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index 8293374..66f1780 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -277,6 +277,13 @@ static void xenvif_gop_frag_copy(struct xenvif_queue 
*queue, struct sk_buff *skb
        unsigned long bytes;
        int gso_type = XEN_NETIF_GSO_TYPE_NONE;
 
+       if (skb_is_gso(skb)) {
+               if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
+                       gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
+               else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+                       gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
+       }
+
        /* Data must not cross a page boundary. */
        BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
 
@@ -336,13 +343,6 @@ static void xenvif_gop_frag_copy(struct xenvif_queue 
*queue, struct sk_buff *skb
                }
 
                /* Leave a gap for the GSO descriptor. */
-               if (skb_is_gso(skb)) {
-                       if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
-                               gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
-                       else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
-                               gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
-               }
-
                if (*head && ((1 << gso_type) & queue->vif->gso_mask))
                        queue->rx.req_cons++;
 
-- 
2.1.4


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