Commit 759e5d00 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

[UDP]: Clean up UDP-Lite receive checksum 



This patch eliminates some duplicate code for the verification of
receive checksums between UDP-Lite and UDP.  It does this by
introducing __skb_checksum_complete_head which is identical to
__skb_checksum_complete_head apart from the fact that it takes
a length parameter rather than computing the first skb->len bytes.

As a result UDP-Lite will be able to use hardware checksum offload
for packets which do not use partial coverage checksums.  It also
means that UDP-Lite loopback no longer does unnecessary checksum
verification.

If any NICs start support UDP-Lite this would also start working
automatically.

This patch removes the assumption that msg_flags has MSG_TRUNC clear
upon entry in recvmsg.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1ab6eb62

include/linux/skbuff.h

+1 −0
Original line number Diff line number Diff line
@@ -1372,6 +1372,7 @@ static inline void __net_timestamp(struct sk_buff *skb) 
}





extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);

extern __sum16 __skb_checksum_complete(struct sk_buff *skb);



/**

include/net/udp.h

+1 −4
Original line number Diff line number Diff line
@@ -72,10 +72,7 @@ struct sk_buff; 
 */

static inline __sum16 __udp_lib_checksum_complete(struct sk_buff *skb)

{

	if (! UDP_SKB_CB(skb)->partial_cov)

		return __skb_checksum_complete(skb);

	return csum_fold(skb_checksum(skb, 0, UDP_SKB_CB(skb)->cscov,

				      skb->csum));

	return __skb_checksum_complete_head(skb, UDP_SKB_CB(skb)->cscov);

}



static inline int udp_lib_checksum_complete(struct sk_buff *skb)

include/net/udplite.h

+6 −33
Original line number Diff line number Diff line
@@ -47,11 +47,10 @@ static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh) 
		return 1;

	}



        UDP_SKB_CB(skb)->partial_cov = 0;

	cscov = ntohs(uh->len);



	if (cscov == 0)		 /* Indicates that full coverage is required. */

		cscov = skb->len;

		;

	else if (cscov < 8  || cscov > skb->len) {

		/*

		 * Coverage length violates RFC 3828: log and discard silently.
@@ -60,40 +59,14 @@ static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh) 
			       cscov, skb->len);

		return 1;



	} else if (cscov < skb->len)

	} else if (cscov < skb->len) {

        	UDP_SKB_CB(skb)->partial_cov = 1;



		UDP_SKB_CB(skb)->cscov = cscov;



	/*

	 * There is no known NIC manufacturer supporting UDP-Lite yet,

	 * hence ip_summed is always (re-)set to CHECKSUM_NONE.

	 */

		if (skb->ip_summed == CHECKSUM_COMPLETE)

			skb->ip_summed = CHECKSUM_NONE;



	return 0;

        }



static __inline__ int udplite4_csum_init(struct sk_buff *skb, struct udphdr *uh)

{

	int rc = udplite_checksum_init(skb, uh);



	if (!rc)

		skb->csum = csum_tcpudp_nofold(skb->nh.iph->saddr,

					       skb->nh.iph->daddr,

					       skb->len, IPPROTO_UDPLITE, 0);

	return rc;

}



static __inline__ int udplite6_csum_init(struct sk_buff *skb, struct udphdr *uh)

{

	int rc = udplite_checksum_init(skb, uh);



	if (!rc)

		skb->csum = ~csum_unfold(csum_ipv6_magic(&skb->nh.ipv6h->saddr,

					     &skb->nh.ipv6h->daddr,

					     skb->len, IPPROTO_UDPLITE, 0));

	return rc;

	return 0;

}



static inline int udplite_sender_cscov(struct udp_sock *up, struct udphdr *uh)

net/core/datagram.c

+8 −2
Original line number Diff line number Diff line
@@ -411,11 +411,11 @@ fault: 
	return -EFAULT;

}



__sum16 __skb_checksum_complete(struct sk_buff *skb)

__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)

{

	__sum16 sum;



	sum = csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));

	sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));

	if (likely(!sum)) {

		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))

			netdev_rx_csum_fault(skb->dev);
@@ -423,6 +423,12 @@ __sum16 __skb_checksum_complete(struct sk_buff *skb) 
	}

	return sum;

}

EXPORT_SYMBOL(__skb_checksum_complete_head);



__sum16 __skb_checksum_complete(struct sk_buff *skb)

{

	return __skb_checksum_complete_head(skb, skb->len);

}

EXPORT_SYMBOL(__skb_checksum_complete);



/**

net/ipv4/udp.c

+49 −47
Original line number Diff line number Diff line
@@ -810,7 +810,9 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 
	struct inet_sock *inet = inet_sk(sk);

	struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;

	struct sk_buff *skb;

	int copied, err, copy_only, is_udplite = IS_UDPLITE(sk);

	unsigned int ulen, copied;

	int err;

	int is_udplite = IS_UDPLITE(sk);



	/*

	 *	Check any passed addresses
@@ -826,28 +828,25 @@ try_again: 
	if (!skb)

		goto out;



	copied = skb->len - sizeof(struct udphdr);

	if (copied > len) {

	ulen = skb->len - sizeof(struct udphdr);

	copied = len;

	if (copied > ulen)

		copied = ulen;

	else if (copied < ulen)

		msg->msg_flags |= MSG_TRUNC;

	}



	/*

	 * 	Decide whether to checksum and/or copy data.

	 *

	 * 	UDP:      checksum may have been computed in HW,

	 * 	          (re-)compute it if message is truncated.

	 * 	UDP-Lite: always needs to checksum, no HW support.

	 * If checksum is needed at all, try to do it while copying the

	 * data.  If the data is truncated, or if we only want a partial

	 * coverage checksum (UDP-Lite), do it before the copy.

	 */

	copy_only = (skb->ip_summed==CHECKSUM_UNNECESSARY);



	if (is_udplite  ||  (!copy_only  &&  msg->msg_flags&MSG_TRUNC)) {

		if (__udp_lib_checksum_complete(skb))

	if (copied < ulen || UDP_SKB_CB(skb)->partial_cov) {

		if (udp_lib_checksum_complete(skb))

			goto csum_copy_err;

		copy_only = 1;

	}



	if (copy_only)

	if (skb->ip_summed == CHECKSUM_UNNECESSARY)

		err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr),

					      msg->msg_iov, copied       );

	else {
@@ -875,7 +874,7 @@ try_again: 


	err = copied;

	if (flags & MSG_TRUNC)

		err = skb->len - sizeof(struct udphdr);

		err = ulen;



out_free:

	skb_free_datagram(sk, skb);
@@ -1095,10 +1094,9 @@ int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb) 
		}

	}



	if (sk->sk_filter && skb->ip_summed != CHECKSUM_UNNECESSARY) {

		if (__udp_lib_checksum_complete(skb))

	if (sk->sk_filter) {

		if (udp_lib_checksum_complete(skb))

			goto drop;

		skb->ip_summed = CHECKSUM_UNNECESSARY;

	}



	if ((rc = sock_queue_rcv_skb(sk,skb)) < 0) {
@@ -1166,25 +1164,36 @@ static int __udp4_lib_mcast_deliver(struct sk_buff *skb, 
 * Otherwise, csum completion requires chacksumming packet body,

 * including udp header and folding it to skb->csum.

 */

static inline void udp4_csum_init(struct sk_buff *skb, struct udphdr *uh)

static inline int udp4_csum_init(struct sk_buff *skb, struct udphdr *uh,

				 int proto)

{

	int err;



	UDP_SKB_CB(skb)->partial_cov = 0;

	UDP_SKB_CB(skb)->cscov = skb->len;



	if (proto == IPPROTO_UDPLITE) {

		err = udplite_checksum_init(skb, uh);

		if (err)

			return err;

	}



	if (uh->check == 0) {

		skb->ip_summed = CHECKSUM_UNNECESSARY;

	} else if (skb->ip_summed == CHECKSUM_COMPLETE) {

	       if (!csum_tcpudp_magic(skb->nh.iph->saddr, skb->nh.iph->daddr,

				      skb->len, IPPROTO_UDP, skb->csum       ))

				      skb->len, proto, skb->csum))

			skb->ip_summed = CHECKSUM_UNNECESSARY;

	}

	if (skb->ip_summed != CHECKSUM_UNNECESSARY)

		skb->csum = csum_tcpudp_nofold(skb->nh.iph->saddr,

					       skb->nh.iph->daddr,

					       skb->len, IPPROTO_UDP, 0);

					       skb->len, proto, 0);

	/* Probably, we should checksum udp header (it should be in cache

	 * in any case) and data in tiny packets (< rx copybreak).

	 */



	/* UDP = UDP-Lite with a non-partial checksum coverage */

	UDP_SKB_CB(skb)->partial_cov = 0;

	return 0;

}



/*
@@ -1192,7 +1201,7 @@ static inline void udp4_csum_init(struct sk_buff *skb, struct udphdr *uh) 
 */



int __udp4_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[],

		   int is_udplite)

		   int proto)

{

	struct sock *sk;

	struct udphdr *uh = skb->h.uh;
@@ -1211,18 +1220,15 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[], 
	if (ulen > skb->len)

		goto short_packet;



	if(! is_udplite ) {		/* UDP validates ulen. */



	if (proto == IPPROTO_UDP) {

		/* UDP validates ulen. */

		if (ulen < sizeof(*uh) || pskb_trim_rcsum(skb, ulen))

			goto short_packet;

		uh = skb->h.uh;

	}



		udp4_csum_init(skb, uh);



	} else 	{			/* UDP-Lite validates cscov. */

		if (udplite4_csum_init(skb, uh))

	if (udp4_csum_init(skb, uh, proto))

		goto csum_error;

	}



	if(rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))

		return __udp4_lib_mcast_deliver(skb, uh, saddr, daddr, udptable);
@@ -1250,7 +1256,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[], 
	if (udp_lib_checksum_complete(skb))

		goto csum_error;



	UDP_INC_STATS_BH(UDP_MIB_NOPORTS, is_udplite);

	UDP_INC_STATS_BH(UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);

	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);



	/*
@@ -1262,7 +1268,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[], 


short_packet:

	LIMIT_NETDEBUG(KERN_DEBUG "UDP%s: short packet: From %u.%u.%u.%u:%u %d/%d to %u.%u.%u.%u:%u\n",

		       is_udplite? "-Lite" : "",

		       proto == IPPROTO_UDPLITE ? "-Lite" : "",

		       NIPQUAD(saddr),

		       ntohs(uh->source),

		       ulen,
@@ -1277,21 +1283,21 @@ csum_error: 
	 * the network is concerned, anyway) as per 4.1.3.4 (MUST).

	 */

	LIMIT_NETDEBUG(KERN_DEBUG "UDP%s: bad checksum. From %d.%d.%d.%d:%d to %d.%d.%d.%d:%d ulen %d\n",

		       is_udplite? "-Lite" : "",

		       proto == IPPROTO_UDPLITE ? "-Lite" : "",

		       NIPQUAD(saddr),

		       ntohs(uh->source),

		       NIPQUAD(daddr),

		       ntohs(uh->dest),

		       ulen);

drop:

	UDP_INC_STATS_BH(UDP_MIB_INERRORS, is_udplite);

	UDP_INC_STATS_BH(UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);

	kfree_skb(skb);

	return(0);

}



__inline__ int udp_rcv(struct sk_buff *skb)

{

	return __udp4_lib_rcv(skb, udp_hash, 0);

	return __udp4_lib_rcv(skb, udp_hash, IPPROTO_UDP);

}



int udp_destroy_sock(struct sock *sk)
@@ -1486,15 +1492,11 @@ unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait) 
		struct sk_buff *skb;



		spin_lock_bh(&rcvq->lock);

		while ((skb = skb_peek(rcvq)) != NULL) {

			if (udp_lib_checksum_complete(skb)) {

		while ((skb = skb_peek(rcvq)) != NULL &&

		       udp_lib_checksum_complete(skb)) {

			UDP_INC_STATS_BH(UDP_MIB_INERRORS, is_lite);

			__skb_unlink(skb, rcvq);

			kfree_skb(skb);

			} else {

				skb->ip_summed = CHECKSUM_UNNECESSARY;

				break;

			}

		}

		spin_unlock_bh(&rcvq->lock);

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