[ Upstream commit 1162f844030ac1ac7321b5e8f6c9badc7a11428f ]
Currently, when bpftool cgroup show <path> has an error, no error
message is printed. This is confusing because the user may think the
result is empty.
Before the change:
$ bpftool cgroup show /sys/fs/cgroup
ID AttachType AttachFlags Name
$ echo $?
255
After the change:
$ ./bpftool cgroup show /sys/fs/cgroup
Error: can't query bpf programs attached to /sys/fs/cgroup: Operation
not permitted
v2: Rename check_query_cgroup_progs to cgroup_has_attached_progs
Signed-off-by: Hechao Li <hechaol@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191224011742.3714301-1-hechaol@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
4783bf08f8