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Commit 662880f4 authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
Browse files

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: default avatarTom Herbert <therbert@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 77cffe23

include/linux/netdevice.h

+12 −14
Original line number Diff line number Diff line
@@ -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);

	}

}

net/core/dev.c

+16 −8
Original line number Diff line number Diff line
@@ -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;

net/ipv4/gre_offload.c

+2 −5
Original line number Diff line number Diff line
@@ -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 &&

	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;

net/ipv4/udp_offload.c

+3 −2
Original line number Diff line number Diff line
@@ -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);