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net: Allow GRO to use and set levels of checksum unnecessary

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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>
This commit is contained in:
Tom Herbert 2014-08-27 21:26:56 -07:00 committed by David S. Miller
parent 77cffe23c1
commit 662880f442
4 changed files with 33 additions and 29 deletions
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26
include/linux/netdevice.h
View File

@ -1883,8 +1883,8 @@ 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;
@ -2179,8 +2179,7 @@ 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));
}
@ -2196,18 +2195,17 @@ 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);
}
}

24
net/core/dev.c
View File

@ -3962,13 +3962,6 @@ 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)
@ -3980,7 +3973,22 @@ 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;

7
net/ipv4/gre_offload.c
View File

@ -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;

5
net/ipv4/udp_offload.c
View File

@ -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);