[PATCH v2 net-next] net: hsr: Provide fix for HSRv1 supervisor frames decoding

[Lukasz Majewski]

Provide fix to decode correctly supervisory frames when HSRv1 version of
the HSR protocol is used.

Without this patch console is polluted with:
ksz-switch spi1.0 lan1: hsr_addr_subst_dest: Unknown node

as a result of destination node's A MAC address equals to:
00:00:00:00:00:00.

cat /sys/kernel/debug/hsr/hsr0/node_table
Node Table entries for (HSR) device
MAC-Address-A,    MAC-Address-B,    time_in[A], time_in[B], Address-B
00:00:00:00:00:00 00:10:a1:94:77:30      400bf,       399c,	        0

It was caused by wrong frames decoding in the hsr_handle_sup_frame().

As the supervisor frame is encapsulated in HSRv1 frame:

SKB_I100000000: 01 15 4e 00 01 2d 00 10 a1 94 77 30 89 2f 00 34
SKB_I100000010: 02 59 88 fb 00 01 84 15 17 06 00 10 a1 94 77 30
SKB_I100000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
SKB_I100000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
SKB_I100000040: 00 00

The code had to be adjusted accordingly and the MAC-Address-A now
has the proper address (the MAC-Address-B now has all 0's).

Fixes: eafaa88b3eb7 ("net: hsr: Add support for redbox supervision frames")'

Signed-off-by: Lukasz Majewski <lukma@xxxxxxx>
---
Changes for v2:
- Use the proper parsing code altered with eafaa88b3eb7f
---
 net/hsr/hsr_framereg.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
index b77f1189d19d..6d14d935ee82 100644
--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -288,13 +288,13 @@ void hsr_handle_sup_frame(struct hsr_frame_info *frame)
 
 	/* And leave the HSR tag. */
 	if (ethhdr->h_proto == htons(ETH_P_HSR)) {
-		pull_size = sizeof(struct ethhdr);
+		pull_size = sizeof(struct hsr_tag);
 		skb_pull(skb, pull_size);
 		total_pull_size += pull_size;
 	}
 
 	/* And leave the HSR sup tag. */
-	pull_size = sizeof(struct hsr_tag);
+	pull_size = sizeof(struct hsr_sup_tag);
 	skb_pull(skb, pull_size);
 	total_pull_size += pull_size;
 
-- 
2.20.1