net: avoid skb_warn_bad_offload false positives on UFO

skb_warn_bad_offload triggers a warning when an skb enters the GSO
stack at __skb_gso_segment that does not have CHECKSUM_PARTIAL
checksum offload set.

Commit b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise")
observed that SKB_GSO_DODGY producers can trigger the check and
that passing those packets through the GSO handlers will fix it
up. But, the software UFO handler will set ip_summed to
CHECKSUM_NONE.

When __skb_gso_segment is called from the receive path, this
triggers the warning again.

Make UFO set CHECKSUM_UNNECESSARY instead of CHECKSUM_NONE. On
Tx these two are equivalent. On Rx, this better matches the
skb state (checksum computed), as CHECKSUM_NONE here means no
checksum computed.

See also this thread for context:
http://patchwork.ozlabs.org/patch/799015/

Fixes: b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dev.c b/net/core/dev.c
index 8515f8fe0460ae08e08e269a47524e0738714626..ce15a06d5558af0292cc739b42a7dc3c1d89428d 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2739,7 +2739,7 @@ static inline bool skb_needs_check(struct sk_buff *skb, bool tx_path)
 {
        if (tx_path)
                return skb->ip_summed != CHECKSUM_PARTIAL &&
-                      skb->ip_summed != CHECKSUM_NONE;
+                      skb->ip_summed != CHECKSUM_UNNECESSARY;
 
        return skb->ip_summed == CHECKSUM_NONE;
 }

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 781250151d40ee4559f7b90d15dccad8ffaeafd0..0932c85b42af0bc868badd1771b5cb9353c969a9 100644 (file)
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -235,7 +235,7 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
        if (uh->check == 0)
                uh->check = CSUM_MANGLED_0;
 
-       skb->ip_summed = CHECKSUM_NONE;
+       skb->ip_summed = CHECKSUM_UNNECESSARY;
 
        /* If there is no outer header we can fake a checksum offload
         * due to the fact that we have already done the checksum in

diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index a2267f80febbb6f31459097f27bd89d51d0f2b11..e7d378c032cb6ebe80323db987ca201e5ae2d845 100644 (file)
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -72,7 +72,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
                if (uh->check == 0)
                        uh->check = CSUM_MANGLED_0;
 
-               skb->ip_summed = CHECKSUM_NONE;
+               skb->ip_summed = CHECKSUM_UNNECESSARY;
 
                /* If there is no outer header we can fake a checksum offload
                 * due to the fact that we have already done the checksum in