net: Allow GRO to use and set levels of checksum unnecessary
Allow GRO path to "consume" checksums provided in CHECKSUM_UNNECESSARY
and to report new checksums verfied for use in fallback to normal
path.
Change GRO checksum path to track csum_level using a csum_cnt field
in NAPI_GRO_CB. On GRO initialization, if ip_summed is
CHECKSUM_UNNECESSARY set NAPI_GRO_CB(skb)->csum_cnt to
skb->csum_level + 1. For each checksum verified, decrement
NAPI_GRO_CB(skb)->csum_cnt while its greater than zero. If a checksum
is verfied and NAPI_GRO_CB(skb)->csum_cnt == 0, we have verified a
deeper checksum than originally indicated in skbuf so increment
csum_level (or initialize to CHECKSUM_UNNECESSARY if ip_summed is
CHECKSUM_NONE or CHECKSUM_COMPLETE).
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index dfc1d8b..456eb1f 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1883,8 +1883,8 @@
/* GRO checksum is valid */
u8 csum_valid:1;
- /* Number encapsulation layers crossed */
- u8 encapsulation;
+ /* Number of checksums via CHECKSUM_UNNECESSARY */
+ u8 csum_cnt:3;
/* used to support CHECKSUM_COMPLETE for tunneling protocols */
__wsum csum;
@@ -2179,8 +2179,7 @@
__sum16 check)
{
return (skb->ip_summed != CHECKSUM_PARTIAL &&
- (skb->ip_summed != CHECKSUM_UNNECESSARY ||
- (NAPI_GRO_CB(skb)->encapsulation > skb->encapsulation)) &&
+ NAPI_GRO_CB(skb)->csum_cnt == 0 &&
(!zero_okay || check));
}
@@ -2196,18 +2195,17 @@
return __skb_gro_checksum_complete(skb);
}
-/* Update skb for CHECKSUM_UNNECESSARY when we verified a top level
- * checksum or an encapsulated one during GRO. This saves work
- * if we fallback to normal path with the packet.
- */
static inline void skb_gro_incr_csum_unnecessary(struct sk_buff *skb)
{
- if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
- if (NAPI_GRO_CB(skb)->encapsulation)
- skb->encapsulation = 1;
- } else if (skb->ip_summed != CHECKSUM_PARTIAL) {
- skb->ip_summed = CHECKSUM_UNNECESSARY;
- skb->encapsulation = 0;
+ if (NAPI_GRO_CB(skb)->csum_cnt > 0) {
+ /* Consume a checksum from CHECKSUM_UNNECESSARY */
+ NAPI_GRO_CB(skb)->csum_cnt--;
+ } else {
+ /* Update skb for CHECKSUM_UNNECESSARY and csum_level when we
+ * verified a new top level checksum or an encapsulated one
+ * during GRO. This saves work if we fallback to normal path.
+ */
+ __skb_incr_checksum_unnecessary(skb);
}
}