[NET]: Treat CHECKSUM_PARTIAL as CHECKSUM_UNNECESSARY

When a transmitted packet is looped back directly, CHECKSUM_PARTIAL
maps to the semantics of CHECKSUM_UNNECESSARY.  Therefore we should
treat it as such in the stack.

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

13 files changed, 29 insertions, 28 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 910560e85561..c413afbe0b9c 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -32,10 +32,11 @@
 #define HAVE_ALLOC_SKB          /* For the drivers to know */
 #define HAVE_ALIGNABLE_SKB      /* Ditto 8)                */
 
+/* Don't change this without changing skb_csum_unnecessary! */
 #define CHECKSUM_NONE 0
-#define CHECKSUM_PARTIAL 1
-#define CHECKSUM_UNNECESSARY 2
-#define CHECKSUM_COMPLETE 3
+#define CHECKSUM_UNNECESSARY 1
+#define CHECKSUM_COMPLETE 2
+#define CHECKSUM_PARTIAL 3
 
 #define SKB_DATA_ALIGN(X)       (((X) + (SMP_CACHE_BYTES - 1)) & \
                                  ~(SMP_CACHE_BYTES - 1))
@@ -1572,6 +1573,11 @@ 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);
 
+static inline int skb_csum_unnecessary(const struct sk_buff *skb)
+{
+        return skb->ip_summed & CHECKSUM_UNNECESSARY;
+}
+
 /**
  *      skb_checksum_complete - Calculate checksum of an entire packet
  *      @skb: packet to process
@@ -1590,8 +1596,8 @@ extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
  */
 static inline unsigned int skb_checksum_complete(struct sk_buff *skb)
 {
-        return skb->ip_summed != CHECKSUM_UNNECESSARY &&
-                __skb_checksum_complete(skb);
+        return skb_csum_unnecessary(skb) ?
+               0 : __skb_checksum_complete(skb);
 }
 
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index af9273204cfd..07f724e02f84 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -818,7 +818,7 @@ static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
 
 static inline int tcp_checksum_complete(struct sk_buff *skb)
 {
-        return skb->ip_summed != CHECKSUM_UNNECESSARY &&
+        return !skb_csum_unnecessary(skb) &&
                 __tcp_checksum_complete(skb);
 }
 
diff --git a/include/net/udp.h b/include/net/udp.h
index 4906ed7113e7..98755ebaf163 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -77,7 +77,7 @@ static inline __sum16 __udp_lib_checksum_complete(struct sk_buff *skb)
 
 static inline int udp_lib_checksum_complete(struct sk_buff *skb)
 {
-        return skb->ip_summed != CHECKSUM_UNNECESSARY &&
+        return !skb_csum_unnecessary(skb) &&
                 __udp_lib_checksum_complete(skb);
 }
 
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 1fb30c3528bc..b316435b0e2a 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -86,7 +86,7 @@ static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
 {
         __wsum psum;
 
-        if (uh->check == 0 || skb->ip_summed == CHECKSUM_UNNECESSARY)
+        if (uh->check == 0 || skb_csum_unnecessary(skb))
                 return 0;
 
         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
diff --git a/net/ipv4/ipvs/ip_vs_core.c b/net/ipv4/ipvs/ip_vs_core.c
index 62cfbed317bf..f005a2f929f4 100644
--- a/net/ipv4/ipvs/ip_vs_core.c
+++ b/net/ipv4/ipvs/ip_vs_core.c
@@ -681,8 +681,7 @@ static int ip_vs_out_icmp(struct sk_buff **pskb, int *related)
         }
 
         /* Ensure the checksum is correct */
-        if (skb->ip_summed != CHECKSUM_UNNECESSARY &&
-            ip_vs_checksum_complete(skb, ihl)) {
+        if (!skb_csum_unnecessary(skb) && ip_vs_checksum_complete(skb, ihl)) {
                 /* Failed checksum! */
                 IP_VS_DBG(1, "Forward ICMP: failed checksum from %d.%d.%d.%d!\n",
                           NIPQUAD(iph->saddr));
@@ -921,8 +920,7 @@ ip_vs_in_icmp(struct sk_buff **pskb, int *related, unsigned int hooknum)
         verdict = NF_DROP;
 
         /* Ensure the checksum is correct */
-        if (skb->ip_summed != CHECKSUM_UNNECESSARY &&
-            ip_vs_checksum_complete(skb, ihl)) {
+        if (!skb_csum_unnecessary(skb) && ip_vs_checksum_complete(skb, ihl)) {
                 /* Failed checksum! */
                 IP_VS_DBG(1, "Incoming ICMP: failed checksum from %d.%d.%d.%d!\n",
                           NIPQUAD(iph->saddr));
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9c3b4c7a50ad..d1604f59d77e 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4009,7 +4009,7 @@ static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen)
         int err;
 
         local_bh_enable();
-        if (skb->ip_summed==CHECKSUM_UNNECESSARY)
+        if (skb_csum_unnecessary(skb))
                 err = skb_copy_datagram_iovec(skb, hlen, tp->ucopy.iov, chunk);
         else
                 err = skb_copy_and_csum_datagram_iovec(skb, hlen,
@@ -4041,7 +4041,7 @@ static __sum16 __tcp_checksum_complete_user(struct sock *sk, struct sk_buff *skb
 
 static inline int tcp_checksum_complete_user(struct sock *sk, struct sk_buff *skb)
 {
-        return skb->ip_summed != CHECKSUM_UNNECESSARY &&
+        return !skb_csum_unnecessary(skb) &&
                 __tcp_checksum_complete_user(sk, skb);
 }
 
@@ -4059,7 +4059,7 @@ static int tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb, int hlen
         if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
                 tp->ucopy.dma_chan = get_softnet_dma();
 
-        if (tp->ucopy.dma_chan && skb->ip_summed == CHECKSUM_UNNECESSARY) {
+        if (tp->ucopy.dma_chan && skb_csum_unnecessary(skb)) {
 
                 dma_cookie = dma_skb_copy_datagram_iovec(tp->ucopy.dma_chan,
                         skb, hlen, tp->ucopy.iov, chunk, tp->ucopy.pinned_list);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a091a99ad263..5a3e7f839fc5 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1638,8 +1638,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
          * Packet length and doff are validated by header prediction,
          * provided case of th->doff==0 is eliminated.
          * So, we defer the checks. */
-        if ((skb->ip_summed != CHECKSUM_UNNECESSARY &&
-             tcp_v4_checksum_init(skb)))
+        if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
                 goto bad_packet;
 
         th = tcp_hdr(skb);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5ad7a26e3091..cec0f2cc49b7 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -848,7 +848,7 @@ try_again:
                         goto csum_copy_err;
         }
 
-        if (skb->ip_summed == CHECKSUM_UNNECESSARY)
+        if (skb_csum_unnecessary(skb))
                 err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr),
                                               msg->msg_iov, copied       );
         else {
@@ -1190,7 +1190,7 @@ static inline int udp4_csum_init(struct sk_buff *skb, struct udphdr *uh,
                                       proto, skb->csum))
                         skb->ip_summed = CHECKSUM_UNNECESSARY;
         }
-        if (skb->ip_summed != CHECKSUM_UNNECESSARY)
+        if (!skb_csum_unnecessary(skb))
                 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
                                                skb->len, proto, 0);
         /* Probably, we should checksum udp header (it should be in cache
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 2b3be68b70a7..f65fcd7704ca 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -368,7 +368,7 @@ int rawv6_rcv(struct sock *sk, struct sk_buff *skb)
                                      skb->len, inet->num, skb->csum))
                         skb->ip_summed = CHECKSUM_UNNECESSARY;
         }
-        if (skb->ip_summed != CHECKSUM_UNNECESSARY)
+        if (!skb_csum_unnecessary(skb))
                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
                                                          &ipv6_hdr(skb)->daddr,
                                                          skb->len,
@@ -421,7 +421,7 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
                 msg->msg_flags |= MSG_TRUNC;
         }
 
-        if (skb->ip_summed==CHECKSUM_UNNECESSARY) {
+        if (skb_csum_unnecessary(skb)) {
                 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
         } else if (msg->msg_flags&MSG_TRUNC) {
                 if (__skb_checksum_complete(skb))
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 7e824b97126d..2b668a6ae698 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1707,8 +1707,7 @@ static int tcp_v6_rcv(struct sk_buff **pskb)
         if (!pskb_may_pull(skb, th->doff*4))
                 goto discard_it;
 
-        if ((skb->ip_summed != CHECKSUM_UNNECESSARY &&
-             tcp_v6_checksum_init(skb)))
+        if (!skb_csum_unnecessary(skb) && tcp_v6_checksum_init(skb))
                 goto bad_packet;
 
         th = tcp_hdr(skb);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 1e3dfb20b1cf..b083c09e3d2d 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -153,7 +153,7 @@ try_again:
                         goto csum_copy_err;
         }
 
-        if (skb->ip_summed == CHECKSUM_UNNECESSARY)
+        if (skb_csum_unnecessary(skb))
                 err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr),
                                               msg->msg_iov, copied       );
         else {
@@ -397,7 +397,7 @@ static inline int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh,
                              skb->len, proto, skb->csum))
                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 
-        if (skb->ip_summed != CHECKSUM_UNNECESSARY)
+        if (!skb_csum_unnecessary(skb))
                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
                                                          &ipv6_hdr(skb)->daddr,
                                                          skb->len, proto, 0));
diff --git a/net/sctp/input.c b/net/sctp/input.c
index 18b97eedc1fa..885109fb3dda 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -140,8 +140,7 @@ int sctp_rcv(struct sk_buff *skb)
         __skb_pull(skb, skb_transport_offset(skb));
         if (skb->len < sizeof(struct sctphdr))
                 goto discard_it;
-        if ((skb->ip_summed != CHECKSUM_UNNECESSARY) &&
-            (sctp_rcv_checksum(skb) < 0))
+        if (!skb_csum_unnecessary(skb) && sctp_rcv_checksum(skb) < 0)
                 goto discard_it;
 
         skb_pull(skb, sizeof(struct sctphdr));
diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
index 634885b0c04d..1d377d1ab7f4 100644
--- a/net/sunrpc/socklib.c
+++ b/net/sunrpc/socklib.c
@@ -154,7 +154,7 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
         desc.offset = sizeof(struct udphdr);
         desc.count = skb->len - desc.offset;
 
-        if (skb->ip_summed == CHECKSUM_UNNECESSARY)
+        if (skb_csum_unnecessary(skb))
                 goto no_checksum;
 
         desc.csum = csum_partial(skb->data, desc.offset, skb->csum);