Re: [PATCH] net: dsa: lan9303: handle hwaccel VLAN tags

Vladimir Oltean [off-list ref] writes:

On Tue, Feb 15, 2022 at 02:59:13PM +0000, Mans Rullgard wrote:

quoted

Check for a hwaccel VLAN tag on rx and use it if present.  Otherwise,
use __skb_vlan_pop() like the other tag parsers do.  This fixes the case
where the VLAN tag has already been consumed by the master.

Signed-off-by: Mans Rullgard <redacted>
---
 net/dsa/tag_lan9303.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/net/dsa/tag_lan9303.c b/net/dsa/tag_lan9303.c
index cb548188f813..7fe180941ac4 100644
--- a/net/dsa/tag_lan9303.c
+++ b/net/dsa/tag_lan9303.c

@@ -77,7 +77,6 @@ static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
 
 static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev)
 {
-	__be16 *lan9303_tag;
 	u16 lan9303_tag1;
 	unsigned int source_port;
 

@@ -87,14 +86,15 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev)
 		return NULL;
 	}
 
-	lan9303_tag = dsa_etype_header_pos_rx(skb);
-
-	if (lan9303_tag[0] != htons(ETH_P_8021Q)) {
-		dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n");
-		return NULL;
+	skb_push_rcsum(skb, ETH_HLEN);
+	if (skb_vlan_tag_present(skb)) {
+		lan9303_tag1 = skb_vlan_tag_get(skb);
+		__vlan_hwaccel_clear_tag(skb);
+	} else {
+		__skb_vlan_pop(skb, &lan9303_tag1);

Sorry for the bad example, there is no reason to call skb_push_rcsum()
and skb_pull_rcsum() if we go through the skb_vlan_tag_present() code
path, just the "else" branch.

I could have realised that myself, had I not simply blindly copied the
example.  Anyway, new patch sent.

-- 
Måns Rullgård