* If no cookie has been set yet, generate a new cookie. Once
* generated, the socket cookie remains stable for the life of the
* socket. This helper can be useful for monitoring per socket
- * networking traffic statistics as it provides a unique socket
- * identifier per namespace.
+ * networking traffic statistics as it provides a global socket
+ * identifier that can be assumed unique.
* Return
* A 8-byte long non-decreasing number on success, or 0 if the
* socket field is missing inside *skb*.
* but this is only implemented for native XDP (with driver
* support) as of this writing).
*
- * All values for *flags* are reserved for future usage, and must
- * be left at zero.
+ * The lower two bits of *flags* are used as the return code if
+ * the map lookup fails. This is so that the return value can be
+ * one of the XDP program return codes up to XDP_TX, as chosen by
+ * the caller. Any higher bits in the *flags* argument must be
+ * unset.
*
* When used to redirect packets to net devices, this helper
* provides a high performance increase over **bpf_redirect**\ ().