[PATCH v4 net-next 12/17] net: dsa: sja1105: Make sja1105_is_link_local not match meta frames

[Vladimir Oltean <olteanv@gmail.com>]

Although meta frames are configured to be sent at SJA1105_META_DMAC
(01-80-C2-00-00-0E) which is a multicast MAC address that would also be
trapped by the switch to the CPU, were it to receive it on a front-panel
port, meta frames are conceptually not link-local frames, they only
carry their RX timestamps.

The choice of sending meta frames at a multicast DMAC is a pragmatic
one, to avoid installing an extra entry to the DSA master port's
multicast MAC filter.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
---
Changes in v4:

Since dropping the patch that moves sja1105_is_link_local to
include/linux from the previous series, this now applies over
net/dsa/tag_sja1105.c.

Changes in v3:

Split from previous 09/10 patch (no functional changes).

Changes in v2:

None.

 net/dsa/tag_sja1105.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/dsa/tag_sja1105.c b/net/dsa/tag_sja1105.c
index 0beb52518d56..094711ced5c0 100644
--- a/net/dsa/tag_sja1105.c
+++ b/net/dsa/tag_sja1105.c
@@ -13,6 +13,8 @@ static inline bool sja1105_is_link_local(const struct sk_buff *skb)
 	const struct ethhdr *hdr = eth_hdr(skb);
 	u64 dmac = ether_addr_to_u64(hdr->h_dest);
 
+	if (ntohs(hdr->h_proto) == ETH_P_SJA1105_META)
+		return false;
 	if ((dmac & SJA1105_LINKLOCAL_FILTER_A_MASK) ==
 		    SJA1105_LINKLOCAL_FILTER_A)
 		return true;
-- 
2.17.1