[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: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 30089ad..df229bd 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -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);
 
 /**

diff --git a/include/net/udp.h b/include/net/udp.h
index 1b921fa..4a9699f 100644 (file)
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -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)

diff --git a/include/net/udplite.h b/include/net/udplite.h
index 67ac514..d99df75 100644 (file)
--- a/include/net/udplite.h
+++ b/include/net/udplite.h
@@ -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.
@@ -60,42 +59,16 @@ 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.
-        */
-       skb->ip_summed = CHECKSUM_NONE;
+               UDP_SKB_CB(skb)->cscov = cscov;
+               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;
-}
-
 static inline int udplite_sender_cscov(struct udp_sock *up, struct udphdr *uh)
 {
        int cscov = up->len;

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 186212b..cb056f4 100644 (file)
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -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);
 
 /**

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index fc620a7..8636883 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -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) {
-               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;
@@ -1211,19 +1220,16 @@ 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))
-                       goto csum_error;
        }
 
+       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)) {
-                               UDP_INC_STATS_BH(UDP_MIB_INERRORS, is_lite);
-                               __skb_unlink(skb, rcvq);
-                               kfree_skb(skb);
-                       } else {
-                               skb->ip_summed = CHECKSUM_UNNECESSARY;
-                               break;
-                       }
+               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);
                }
                spin_unlock_bh(&rcvq->lock);
 

diff --git a/net/ipv4/udplite.c b/net/ipv4/udplite.c
index b28fe1e..f34fd68 100644 (file)
--- a/net/ipv4/udplite.c
+++ b/net/ipv4/udplite.c
@@ -31,7 +31,7 @@ static int udplite_v4_get_port(struct sock *sk, unsigned short snum)
 
 static int udplite_rcv(struct sk_buff *skb)
 {
-       return __udp4_lib_rcv(skb, udplite_hash, 1);
+       return __udp4_lib_rcv(skb, udplite_hash, IPPROTO_UDPLITE);
 }
 
 static void udplite_err(struct sk_buff *skb, u32 info)

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 3413fc2..7333716 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -120,8 +120,9 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct inet_sock *inet = inet_sk(sk);
        struct sk_buff *skb;
-       size_t copied;
-       int err, copy_only, is_udplite = IS_UDPLITE(sk);
+       unsigned int ulen, copied;
+       int err;
+       int is_udplite = IS_UDPLITE(sk);
 
        if (addr_len)
                *addr_len=sizeof(struct sockaddr_in6);
@@ -134,24 +135,25 @@ try_again:
        if (!skb)
                goto out;
 
-       copied = skb->len - sizeof(struct udphdr);
-       if (copied > len) {
-               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.
+        * 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 {
@@ -194,7 +196,7 @@ try_again:
 
        err = copied;
        if (flags & MSG_TRUNC)
-               err = skb->len - sizeof(struct udphdr);
+               err = ulen;
 
 out_free:
        skb_free_datagram(sk, skb);
@@ -368,9 +370,20 @@ out:
        return 0;
 }
 
-static inline int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh)
-
+static inline int udp6_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) {
                /* RFC 2460 section 8.1 says that we SHOULD log
                   this error. Well, it is reasonable.
@@ -380,20 +393,19 @@ static inline int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh)
        }
        if (skb->ip_summed == CHECKSUM_COMPLETE &&
            !csum_ipv6_magic(&skb->nh.ipv6h->saddr, &skb->nh.ipv6h->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_unfold(csum_ipv6_magic(&skb->nh.ipv6h->saddr,
                                                         &skb->nh.ipv6h->daddr,
-                                                        skb->len, IPPROTO_UDP,
-                                                        0));
+                                                        skb->len, proto, 0));
 
-       return (UDP_SKB_CB(skb)->partial_cov = 0);
+       return 0;
 }
 
 int __udp6_lib_rcv(struct sk_buff **pskb, struct hlist_head udptable[],
-                  int is_udplite)
+                  int proto)
 {
        struct sk_buff *skb = *pskb;
        struct sock *sk;
@@ -413,7 +425,8 @@ int __udp6_lib_rcv(struct sk_buff **pskb, struct hlist_head udptable[],
        if (ulen > skb->len)
                goto short_packet;
 
-       if(! is_udplite ) {             /* UDP validates ulen. */
+       if (proto == IPPROTO_UDP) {
+               /* UDP validates ulen. */
 
                /* Check for jumbo payload */
                if (ulen == 0)
@@ -429,15 +442,11 @@ int __udp6_lib_rcv(struct sk_buff **pskb, struct hlist_head udptable[],
                        daddr = &skb->nh.ipv6h->daddr;
                        uh = skb->h.uh;
                }
-
-               if (udp6_csum_init(skb, uh))
-                       goto discard;
-
-       } else  {                       /* UDP-Lite validates cscov. */
-               if (udplite6_csum_init(skb, uh))
-                       goto discard;
        }
 
+       if (udp6_csum_init(skb, uh, proto))
+               goto discard;
+
        /*
         *      Multicast receive code
         */
@@ -459,7 +468,7 @@ int __udp6_lib_rcv(struct sk_buff **pskb, struct hlist_head udptable[],
 
                if (udp_lib_checksum_complete(skb))
                        goto discard;
-               UDP6_INC_STATS_BH(UDP_MIB_NOPORTS, is_udplite);
+               UDP6_INC_STATS_BH(UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
 
                icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0, dev);
 
@@ -475,17 +484,18 @@ int __udp6_lib_rcv(struct sk_buff **pskb, struct hlist_head udptable[],
 
 short_packet:
        LIMIT_NETDEBUG(KERN_DEBUG "UDP%sv6: short packet: %d/%u\n",
-                      is_udplite? "-Lite" : "",  ulen, skb->len);
+                      proto == IPPROTO_UDPLITE ? "-Lite" : "",
+                      ulen, skb->len);
 
 discard:
-       UDP6_INC_STATS_BH(UDP_MIB_INERRORS, is_udplite);
+       UDP6_INC_STATS_BH(UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);
        kfree_skb(skb);
        return(0);
 }
 
 static __inline__ int udpv6_rcv(struct sk_buff **pskb)
 {
-       return __udp6_lib_rcv(pskb, udp_hash, 0);
+       return __udp6_lib_rcv(pskb, udp_hash, IPPROTO_UDP);
 }
 
 /*

diff --git a/net/ipv6/udplite.c b/net/ipv6/udplite.c
index 629f971..f54016a 100644 (file)
--- a/net/ipv6/udplite.c
+++ b/net/ipv6/udplite.c
@@ -19,7 +19,7 @@ DEFINE_SNMP_STAT(struct udp_mib, udplite_stats_in6) __read_mostly;
 
 static int udplitev6_rcv(struct sk_buff **pskb)
 {
-       return __udp6_lib_rcv(pskb, udplite_hash, 1);
+       return __udp6_lib_rcv(pskb, udplite_hash, IPPROTO_UDPLITE);
 }
 
 static void udplitev6_err(struct sk_buff *skb,