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Message-ID: <alpine.DEB.2.02.1408251746540.4553@tomh.mtv.corp.google.com>
Date: Mon, 25 Aug 2014 17:56:05 -0700 (PDT)
From: Tom Herbert <therbert@...gle.com>
To: davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH net-next 2/8] 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@...gle.com>
---
include/linux/netdevice.h | 26 ++++++++++++--------------
net/core/dev.c | 24 ++++++++++++++++--------
net/ipv4/gre_offload.c | 7 ++-----
net/ipv4/udp_offload.c | 5 +++--
4 files changed, 33 insertions(+), 29 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index eb73444..4bb67c5 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1888,8 +1888,8 @@ struct napi_gro_cb {
/* 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;
@@ -2177,8 +2177,7 @@ static inline bool __skb_gro_checksum_validate_needed(struct sk_buff *skb,
__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));
}
@@ -2194,18 +2193,17 @@ static inline __sum16 __skb_gro_checksum_validate_complete(struct sk_buff *skb,
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);
}
}
diff --git a/net/core/dev.c b/net/core/dev.c
index b6a718e..40e57cf 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3963,13 +3963,6 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
gro_list_prepare(napi, skb);
- if (skb->ip_summed == CHECKSUM_COMPLETE) {
- NAPI_GRO_CB(skb)->csum = skb->csum;
- NAPI_GRO_CB(skb)->csum_valid = 1;
- } else {
- NAPI_GRO_CB(skb)->csum_valid = 0;
- }
-
rcu_read_lock();
list_for_each_entry_rcu(ptype, head, list) {
if (ptype->type != type || !ptype->callbacks.gro_receive)
@@ -3981,7 +3974,22 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
NAPI_GRO_CB(skb)->flush = 0;
NAPI_GRO_CB(skb)->free = 0;
NAPI_GRO_CB(skb)->udp_mark = 0;
- NAPI_GRO_CB(skb)->encapsulation = 0;
+
+ /* Setup for GRO checksum validation */
+ switch (skb->ip_summed) {
+ case CHECKSUM_COMPLETE:
+ NAPI_GRO_CB(skb)->csum = skb->csum;
+ NAPI_GRO_CB(skb)->csum_valid = 1;
+ NAPI_GRO_CB(skb)->csum_cnt = 0;
+ break;
+ case CHECKSUM_UNNECESSARY:
+ NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
+ NAPI_GRO_CB(skb)->csum_valid = 0;
+ break;
+ default:
+ NAPI_GRO_CB(skb)->csum_cnt = 0;
+ NAPI_GRO_CB(skb)->csum_valid = 0;
+ }
pp = ptype->callbacks.gro_receive(&napi->gro_list, skb);
break;
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index d1bd169..a4d7965 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -172,12 +172,9 @@ static struct sk_buff **gre_gro_receive(struct sk_buff **head,
}
/* Don't bother verifying checksum if we're going to flush anyway. */
- if (greh->flags & GRE_CSUM) {
- if (!NAPI_GRO_CB(skb)->flush &&
- skb_gro_checksum_simple_validate(skb))
+ if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush &&
+ skb_gro_checksum_simple_validate(skb))
goto out_unlock;
- NAPI_GRO_CB(skb)->encapsulation++;
- }
flush = 0;
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 8ed460e..a6adff9 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -238,12 +238,13 @@ struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
int flush = 1;
if (NAPI_GRO_CB(skb)->udp_mark ||
- (!skb->encapsulation && !NAPI_GRO_CB(skb)->csum_valid))
+ (skb->ip_summed != CHECKSUM_PARTIAL &&
+ NAPI_GRO_CB(skb)->csum_cnt == 0 &&
+ !NAPI_GRO_CB(skb)->csum_valid))
goto out;
/* mark that this skb passed once through the udp gro layer */
NAPI_GRO_CB(skb)->udp_mark = 1;
- NAPI_GRO_CB(skb)->encapsulation++;
rcu_read_lock();
uo_priv = rcu_dereference(udp_offload_base);
--
2.1.0.rc2.206.gedb03e5
--
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