[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>

2 files changed, 8 insertions, 6 deletions

diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
index 8f97e90f36c8..eb330d4f66d6 100644
--- a/net/sunrpc/socklib.c
+++ b/net/sunrpc/socklib.c
@@ -6,6 +6,9 @@
  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
  */
 
+#include <linux/compiler.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
 #include <linux/types.h>
 #include <linux/pagemap.h>
 #include <linux/udp.h>
@@ -165,6 +168,8 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
                 return -1;
         if ((unsigned short)csum_fold(desc.csum))
                 return -1;
+        if (unlikely(skb->ip_summed == CHECKSUM_HW))
+                netdev_rx_csum_fault(skb->dev);
         return 0;
 no_checksum:
         if (xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_bits) < 0)
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index f16e7cdd6150..e50e7cf43737 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -623,12 +623,9 @@ svc_udp_recvfrom(struct svc_rqst *rqstp)
                 /* we can use it in-place */
                 rqstp->rq_arg.head[0].iov_base = skb->data + sizeof(struct udphdr);
                 rqstp->rq_arg.head[0].iov_len = len;
-                if (skb->ip_summed != CHECKSUM_UNNECESSARY) {
-                        if ((unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum))) {
-                                skb_free_datagram(svsk->sk_sk, skb);
-                                return 0;
-                        }
-                        skb->ip_summed = CHECKSUM_UNNECESSARY;
+                if (skb_checksum_complete(skb)) {
+                        skb_free_datagram(svsk->sk_sk, skb);
+                        return 0;
                 }
                 rqstp->rq_skbuff = skb;
         }