bpftool: mark orphaned programs during prog show

Commit ef01f4e25c17 ("bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD
and PERF_BPF_EVENT_PROG_UNLOAD") stopped removing program's id from
idr when the offloaded/bound netdev goes away. I was supposed to
take a look and check in [0], but apparently I did not.

Martin points out it might be useful to keep it that way for
observability sake, but we at least need to mark those programs as
unusable.

Mark those programs as 'orphaned' and keep printing the list when
we encounter ENODEV.

0: unspec tag 0000000000000000
xlated 0B not jited memlock 4096B orphaned

[0]: https://lore.kernel.org/all/[e-mail]/

v3:
* use two spaces for " orphaned" (Quentin)

Cc: [e-mail]
Fixes: ef01f4e25c17 ("bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD and PERF_BPF_EVENT_PROG_UNLOAD")
Signed-off-by: Stanislav Fomichev <[e-mail]>
Reviewed-by: Quentin Monnet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Martin KaFai Lau <[e-mail]>

tools/bpf/bpftool/prog.c

···
 		jsonw_uint_field(json_wtr, "recursion_misses", info->recursion_misses);
 }
 
-static void print_prog_json(struct bpf_prog_info *info, int fd)
+static void print_prog_json(struct bpf_prog_info *info, int fd, bool orphaned)
 {
 	char *memlock;
 
···
 		jsonw_uint_field(json_wtr, "uid", info->created_by_uid);
 	}
 
+	jsonw_bool_field(json_wtr, "orphaned", orphaned);
 	jsonw_uint_field(json_wtr, "bytes_xlated", info->xlated_prog_len);
 
 	if (info->jited_prog_len) {
···
 	printf("\n");
 }
 
-static void print_prog_plain(struct bpf_prog_info *info, int fd)
+static void print_prog_plain(struct bpf_prog_info *info, int fd, bool orphaned)
 {
 	char *memlock;
 
···
 	if (memlock)
 		printf("  memlock %sB", memlock);
 	free(memlock);
+
+	if (orphaned)
+		printf("  orphaned");
 
 	if (info->nr_map_ids)
 		show_prog_maps(fd, info->nr_map_ids);
···
 	int err;
 
 	err = bpf_prog_get_info_by_fd(fd, &info, &len);
-	if (err) {
+	if (err && err != -ENODEV) {
 		p_err("can't get prog info: %s", strerror(errno));
 		return -1;
 	}
 
 	if (json_output)
-		print_prog_json(&info, fd);
+		print_prog_json(&info, fd, err == -ENODEV);
 	else
-		print_prog_plain(&info, fd);
+		print_prog_plain(&info, fd, err == -ENODEV);
 
 	return 0;
 }