On Sat, Sep 26, 2020 at 10:33:00PM +0200, Andrew Lunn wrote:

quoted

+static inline void dsa_tag_generic_flow_dissect(const struct sk_buff *skb,
+						__be16 *proto, int *offset)
+{
+#if IS_ENABLED(CONFIG_NET_DSA)
+	const struct dsa_device_ops *ops = skb->dev->dsa_ptr->tag_ops;
+	int tag_len = ops->overhead;
+
+	*offset = tag_len;
+	*proto = ((__be16 *)skb->data)[(tag_len / 2) - 1];
+#endif
+}
+

Do you actually need the IS_ENABLED()? There is only one caller of
this function, and it is already protected by
IS_ENABLED(CONFIG_NET_DSA). So i don't think it adds anything.

It doesn't matter how many callers it has, it doesn't compile when
NET_DSA=n:

./include/net/dsa.h: In function ‘dsa_tag_generic_flow_dissect’:
./include/net/dsa.h:732:47: error: ‘struct net_device’ has no member named ‘dsa_ptr’; did you mean ‘ip_ptr’?
  const struct dsa_device_ops *ops = skb->dev->dsa_ptr->tag_ops;
                                               ^~~~~~~
                                               ip_ptr