Re: [PATCH bpf-next 3/7] bpf: add netns cookie and enable it for bpf cgroup hooks

On Fri, Mar 27, 2020 at 04:58:52PM +0100, Daniel Borkmann wrote:

+ *
+ * u64 bpf_get_netns_cookie(void *ctx)
+ * 	Description
+ * 		Retrieve the cookie (generated by the kernel) of the network
+ * 		namespace the input *ctx* is associated with. The network
+ * 		namespace cookie remains stable for its lifetime and provides
+ * 		a global identifier that can be assumed unique. If *ctx* is
+ * 		NULL, then the helper returns the cookie for the initial
+ * 		network namespace. The cookie itself is very similar to that
+ * 		of bpf_get_socket_cookie() helper, but for network namespaces
+ * 		instead of sockets.

All new helpers in this patch and few others are missing 'flags' argument.
Yes. It's kinda hard right now to come up with a use case for the flags,
since all helpers look kinda trivial, simple, and single purpose.
But the same thing happened with bpf_send_signal(). It felt that there is no
way to extend it. Yet later we had to add bpf_send_signal_thread() which could
have been handled with flags if they were there. So please add flags to all new
helpers though it might seem redundant.