On Fri, Aug 12, 2016 at 08:57:04AM -0700, Sargun Dhillon wrote:
> This test has a BPF program which writes the last known pid to call the
> sync syscall within a given cgroup to a map.
>
> The user mode program creates its own mount namespace, and mounts the
> cgroupsv2 hierarchy in there, as on all current test systems
> (Ubuntu 16.04, Debian), the cgroupsv2 vfs is unmounted by default.
> Once it does this, it proceeds to test.
>
> The test checks for positive and negative condition. It ensures that
> when it's part of a given cgroup, its pid is captured in the map,
> and that when it leaves the cgroup, this doesn't happen.
>
> It populate a cgroups arraymap prior to execution in userspace. This means
> that the program must be run in the same cgroups namespace as the programs
> that are being traced.
>
> Signed-off-by: Sargun Dhillon <[email protected]>
> Cc: Alexei Starovoitov <[email protected]>
> Cc: Daniel Borkmann <[email protected]>
> Cc: Tejun Heo <[email protected]>
I don't think there is much value explicitly adding 'cc:' to commit log.
> + if (join_cgroup("/mnt/my-cgroup")) {
> + log_err("Leaving target cgroup");
> + goto cleanup_cgroup_err;
> + }
> +
> + /*
> + * The installed helper program catched the sync call, and should
> + * write it to the map.
> + */
> +
> + sync();
> + bpf_lookup_elem(map_fd[1], &idx, &remote_pid);
> +
> + if (local_pid != remote_pid) {
> + fprintf(stderr,
> + "BPF Helper didn't write correct PID to map, but: %d\n",
> + remote_pid);
> + goto leave_cgroup_err;
> + }
> +
> + /* Verify the negative scenario; leave the cgroup */
> + if (join_cgroup(CGROUP_MOUNT_PATH))
> + goto leave_cgroup_err;
> +
> + remote_pid = 0;
> + bpf_update_elem(map_fd[1], &idx, &remote_pid, BPF_ANY);
> +
> + sync();
> + bpf_lookup_elem(map_fd[1], &idx, &remote_pid);
> +
> + if (local_pid == remote_pid) {
> + fprintf(stderr, "BPF cgroup negative test did not work\n");
> + goto cleanup_cgroup_err;
> + }
> +
> + rmdir(CGROUP_PATH);
> + return 0;
Nice test. Thanks
Acked-by: Alexei Starovoitov <[email protected]>
