[NET]: Detect hardware rx checksum faults correctly

Here is the patch that introduces the generic skb_checksum_complete
which also checks for hardware RX checksum faults.  If that happens,
it'll call netdev_rx_csum_fault which currently prints out a stack
trace with the device name.  In future it can turn off RX checksum.

I've converted every spot under net/ that does RX checksum checks to
use skb_checksum_complete or __skb_checksum_complete with the
exceptions of:

* Those places where checksums are done bit by bit.  These will call
netdev_rx_csum_fault directly.

* The following have not been completely checked/converted:

ipmr
ip_vs
netfilter
dccp

This patch is based on patches and suggestions from Stephen Hemminger
and David S. Miller.

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

1 files changed, 16 insertions, 26 deletions

diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 651c79b41eeb..8e9628f1c4c5 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -298,13 +298,10 @@ void rawv6_err(struct sock *sk, struct sk_buff *skb,
 static inline int rawv6_rcv_skb(struct sock * sk, struct sk_buff * skb)
 {
         if ((raw6_sk(sk)->checksum || sk->sk_filter) && 
-            skb->ip_summed != CHECKSUM_UNNECESSARY) {
-                if ((unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum))) {
-                        /* FIXME: increment a raw6 drops counter here */
-                        kfree_skb(skb);
-                        return 0;
-                }
-                skb->ip_summed = CHECKSUM_UNNECESSARY;
+            skb_checksum_complete(skb)) {
+                /* FIXME: increment a raw6 drops counter here */
+                kfree_skb(skb);
+                return 0;
         }
 
         /* Charge it to the socket. */
@@ -337,32 +334,25 @@ int rawv6_rcv(struct sock *sk, struct sk_buff *skb)
         if (!rp->checksum)
                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 
-        if (skb->ip_summed != CHECKSUM_UNNECESSARY) {
-                if (skb->ip_summed == CHECKSUM_HW) {
-                        skb_postpull_rcsum(skb, skb->nh.raw,
-                                           skb->h.raw - skb->nh.raw);
+        if (skb->ip_summed == CHECKSUM_HW) {
+                skb_postpull_rcsum(skb, skb->nh.raw,
+                                   skb->h.raw - skb->nh.raw);
+                if (!csum_ipv6_magic(&skb->nh.ipv6h->saddr,
+                                     &skb->nh.ipv6h->daddr,
+                                     skb->len, inet->num, skb->csum))
                         skb->ip_summed = CHECKSUM_UNNECESSARY;
-                        if (csum_ipv6_magic(&skb->nh.ipv6h->saddr,
-                                            &skb->nh.ipv6h->daddr,
-                                            skb->len, inet->num, skb->csum)) {
-                                LIMIT_NETDEBUG(KERN_DEBUG "raw v6 hw csum failure.\n");
-                                skb->ip_summed = CHECKSUM_NONE;
-                        }
-                }
-                if (skb->ip_summed == CHECKSUM_NONE)
-                        skb->csum = ~csum_ipv6_magic(&skb->nh.ipv6h->saddr,
-                                                     &skb->nh.ipv6h->daddr,
-                                                     skb->len, inet->num, 0);
         }
+        if (skb->ip_summed != CHECKSUM_UNNECESSARY)
+                skb->csum = ~csum_ipv6_magic(&skb->nh.ipv6h->saddr,
+                                             &skb->nh.ipv6h->daddr,
+                                             skb->len, inet->num, 0);
 
         if (inet->hdrincl) {
-                if (skb->ip_summed != CHECKSUM_UNNECESSARY &&
-                    (unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum))) {
+                if (skb_checksum_complete(skb)) {
                         /* FIXME: increment a raw6 drops counter here */
                         kfree_skb(skb);
                         return 0;
                 }
-                skb->ip_summed = CHECKSUM_UNNECESSARY;
         }
 
         rawv6_rcv_skb(sk, skb);
@@ -407,7 +397,7 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
         if (skb->ip_summed==CHECKSUM_UNNECESSARY) {
                 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
         } else if (msg->msg_flags&MSG_TRUNC) {
-                if ((unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum)))
+                if (__skb_checksum_complete(skb))
                         goto csum_copy_err;
                 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
         } else {