bpftool: mark orphaned programs during prog show

Commit ef01f4e ("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/CAKH8qBtyR20ZWAc11z1-6pGb3Hd47AQUTbE_cfoktG59TqaJ7Q@mail.gmail.com/

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

Cc: netdev@vger.kernel.org
Fixes: ef01f4e ("bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD and PERF_BPF_EVENT_PROG_UNLOAD")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/20231127182057.1081138-1-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

tools/bpf/bpftool/prog.c

@@ -442,7 +442,7 @@ static void print_prog_header_json(struct bpf_prog_info *info, int fd)
 		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;
 
@@ -461,6 +461,7 @@ static void print_prog_json(struct bpf_prog_info *info, int fd)
 		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) {
@@ -527,7 +528,7 @@ static void print_prog_header_plain(struct bpf_prog_info *info, int fd)
 	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;
 
@@ -554,6 +555,9 @@ static void print_prog_plain(struct bpf_prog_info *info, int fd)
 		printf("  memlock %sB", memlock);
 	free(memlock);
 
+	if (orphaned)
+		printf("  orphaned");
+
 	if (info->nr_map_ids)
 		show_prog_maps(fd, info->nr_map_ids);
 
@@ -581,15 +585,15 @@ static int show_prog(int fd)
 	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;
 }