On 5/22/19 4:20 PM, Roman Gushchin wrote:
> Enable all available cgroup v2 controllers when setting up
> the environment for the bpf kselftests. It's required to properly test
> the bpf prog auto-detach feature. Also it will generally increase
> the code coverage.
>
> Signed-off-by: Roman Gushchin <g...@fb.com>
Looks good to me. Ack with one nit below.
Acked-by: Yonghong Song <y...@fb.com>
> ---
> tools/testing/selftests/bpf/cgroup_helpers.c | 57 ++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c
> b/tools/testing/selftests/bpf/cgroup_helpers.c
> index 6692a40a6979..4efe57c171cd 100644
> --- a/tools/testing/selftests/bpf/cgroup_helpers.c
> +++ b/tools/testing/selftests/bpf/cgroup_helpers.c
> @@ -33,6 +33,60 @@
> snprintf(buf, sizeof(buf), "%s%s%s", CGROUP_MOUNT_PATH, \
> CGROUP_WORK_DIR, path)
>
> +/**
> + * enable_all_controllers() - Enable all available cgroup v2 controllers
> + *
> + * Enable all available cgroup v2 controllers in order to increase
> + * the code coverage.
> + *
> + * If successful, 0 is returned.
> + */
> +int enable_all_controllers(char *cgroup_path)
> +{
> + char path[PATH_MAX + 1];
> + char buf[PATH_MAX];
> + char *c, *c2;
> + int fd, cfd;
> + size_t len;
> +
> + snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path);
> + fd = open(path, O_RDONLY);
> + if (fd < 0) {
> + log_err("Opening cgroup.controllers: %s", path);
> + return -1;
It looks like either -1 or 1 could be returned to indicate an error
in this file. Maybe, at least for the consistency of this file,
always returning 1 is preferred as setup_cgroup_environment()
has the following comments:
* This function will print an error to stderr and return 1 if it is unable
* to setup the cgroup environment. If setup is successful, 0 is returned.
> + }
> +
> + len = read(fd, buf, sizeof(buf) - 1);
> + if (len < 0) {
> + close(fd);
> + log_err("Reading cgroup.controllers: %s", path);
> + return -1;
> + }
> + buf[len] = 0;
> + close(fd);
> +
> + /* No controllers available? We're probably on cgroup v1. */
> + if (len == 0)
> + return 0;
> +
> + snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
> + cfd = open(path, O_RDWR);
> + if (cfd < 0) {
> + log_err("Opening cgroup.subtree_control: %s", path);
> + return -1;
> + }
> +
> + for (c = strtok_r(buf, " ", &c2); c; c = strtok_r(NULL, " ", &c2)) {
> + if (dprintf(cfd, "+%s\n", c) <= 0) {
> + log_err("Enabling controller %s: %s", c, path);
> + close(cfd);
> + return -1;
> + }
> + }
> + close(cfd);
> + return 0;
> +}
> +
> /**
> * setup_cgroup_environment() - Setup the cgroup environment
> *
> @@ -71,6 +125,9 @@ int setup_cgroup_environment(void)
> return 1;
> }
>
> + if (enable_all_controllers(cgroup_workdir))
> + return 1;
> +
> return 0;
> }
>
>
