tools: bpftool: use correct argument in cgroup errors

[ Upstream commit 6c6874f401e5a0caab3b6a0663169e1fb5e930bb ]

cgroup code tries to use argv[0] as the cgroup path,
but if it fails uses argv[1] to report errors.

Fixes: 5ccda64d ("bpftool: implement cgroup bpf operations")
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NQuentin Monnet <quentin.monnet@netronome.com>
Acked-by: NRoman Gushchin <guro@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

tools/bpf/bpftool/cgroup.c

@@ -164,7 +164,7 @@ static int do_show(int argc, char **argv)
 
 	cgroup_fd = open(argv[0], O_RDONLY);
 	if (cgroup_fd < 0) {
-		p_err("can't open cgroup %s", argv[1]);
+		p_err("can't open cgroup %s", argv[0]);
 		goto exit;
 	}
 
@@ -345,7 +345,7 @@ static int do_attach(int argc, char **argv)
 
 	cgroup_fd = open(argv[0], O_RDONLY);
 	if (cgroup_fd < 0) {
-		p_err("can't open cgroup %s", argv[1]);
+		p_err("can't open cgroup %s", argv[0]);
 		goto exit;
 	}
 
@@ -403,7 +403,7 @@ static int do_detach(int argc, char **argv)
 
 	cgroup_fd = open(argv[0], O_RDONLY);
 	if (cgroup_fd < 0) {
-		p_err("can't open cgroup %s", argv[1]);
+		p_err("can't open cgroup %s", argv[0]);
 		goto exit;
 	}