On Mon, Nov 28, 2016 at 7:50 PM, Alexei Starovoitov
[off-list ref] wrote:

On Mon, Nov 28, 2016 at 02:52:42PM -0800, Sargun Dhillon wrote:

quoted

This patch modifies test_cgrp2_attach to use getopt so we can use standard
command line parsing.

It also adds an option to run the program in detach only mode. This does
not attach a new filter at the cgroup, but only runs the detach command.

Lastly, it changes the attach code to not detach and then attach. It relies
on the 'hotswap' behaviour of CGroup BPF programs to be able to change
in-place. If detach-then-attach behaviour needs to be tested, the example
can be run in detach only mode prior to attachment.

Signed-off-by: Sargun Dhillon <redacted>

looks fine to me.
I'd really prefer this example to become an automated test eventually.

I can do that. As far as test cases:

1. create /foo
2. enter foo
3. attach drop filter to foo
4. try to ping 127.0.0.1 (make sure it returns 0 replies)
5. create /foo/bar
6. enter /foo/bar
7. try to ping 127.0.0.1 (make sure it returns 0 replies)
8. attach passthrough filter to foo/bar
9. try to ping 127.0.0.1 (make sure it returns 1 replies)
10. Detach filter from foo/bar
11. try to ping 127.0.0.1 (make sure it returns 0 replies)
Reasonable?

Acked-by: Alexei Starovoitov <ast@kernel.org>