| Message ID | 20190412132938.9044-3-quentin.monnet@netronome.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | None | expand |
diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c index 4b5c8da2a7c0..a81b34343eb8 100644 --- a/tools/bpf/bpftool/cgroup.c +++ b/tools/bpf/bpftool/cgroup.c @@ -248,6 +248,13 @@ static int do_show_tree_fn(const char *fpath, const struct stat *sb, for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) show_attached_bpf_progs(cgroup_fd, type, ftw->level); + if (errno == EINVAL) + /* Last attach type does not support query. + * Do not report an error for this, especially because batch + * mode would stop processing commands. + */ + errno = 0; + if (json_output) { jsonw_end_array(json_wtr); jsonw_end_object(json_wtr);
When trying to dump the tree of all cgroups under a given root node, bpftool attempts to query programs of all available attach types. Some of those attach types do not support queries, therefore several of the calls are actually expected to fail. Those calls set errno to EINVAL, which has no consequence for dumping the rest of the tree. It does have consequences however if errno is inspected at a later time. For example, bpftool batch mode relies on errno to determine whether a command has succeeded, and whether it should carry on with the next command. Setting errno to EINVAL when everything worked as expected would therefore make such command fail: # echo 'cgroup tree \n net show' | \ bpftool batch file - To improve this, reset errno when its value is EINVAL after attempting to show programs for all existing attach types in do_show_tree_fn(). Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com> Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com> --- tools/bpf/bpftool/cgroup.c | 7 +++++++ 1 file changed, 7 insertions(+)