From: Milan Landaverde <milan@mdaverde.com>
Date: Wed, 4 May 2022 12:13:32 -0400
Subject: bpftool: Output message if no helpers found in feature probing
Patch-mainline: v5.19-rc1
Git-commit: b06a92a18d4651c983c60d83935a76b2d47d85e0
References: jsc#PED-1377

Currently in libbpf, we have hardcoded program types that are not
supported for helper function probing (e.g. tracing, ext, lsm).
Due to this (and other legitimate failures), bpftool feature probe returns
empty for those program type helper functions.

Instead of implying to the user that there are no helper functions
available for a program type, we output a message to the user explaining
that helper function probing failed for that program type.

Signed-off-by: Milan Landaverde <milan@mdaverde.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220504161356.3497972-3-milan@mdaverde.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 tools/bpf/bpftool/feature.c |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -690,7 +690,7 @@ probe_helper_ifindex(enum bpf_func_id id
 	return res;
 }
 
-static void
+static bool
 probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
 			  const char *define_prefix, unsigned int id,
 			  const char *ptype_name, __u32 ifindex)
@@ -723,6 +723,8 @@ probe_helper_for_progtype(enum bpf_prog_
 		if (res)
 			printf("\n\t- %s", helper_name[id]);
 	}
+
+	return res;
 }
 
 static void
@@ -732,6 +734,7 @@ probe_helpers_for_progtype(enum bpf_prog
 	const char *ptype_name = prog_type_name[prog_type];
 	char feat_name[128];
 	unsigned int id;
+	bool probe_res = false;
 
 	if (ifindex)
 		/* Only test helpers for offload-able program types */
@@ -764,7 +767,7 @@ probe_helpers_for_progtype(enum bpf_prog
 				continue;
 			/* fallthrough */
 		default:
-			probe_helper_for_progtype(prog_type, supported_type,
+			probe_res |= probe_helper_for_progtype(prog_type, supported_type,
 						  define_prefix, id, ptype_name,
 						  ifindex);
 		}
@@ -772,8 +775,17 @@ probe_helpers_for_progtype(enum bpf_prog
 
 	if (json_output)
 		jsonw_end_array(json_wtr);
-	else if (!define_prefix)
+	else if (!define_prefix) {
 		printf("\n");
+		if (!probe_res) {
+			if (!supported_type)
+				printf("\tProgram type not supported\n");
+			else
+				printf("\tCould not determine which helpers are available\n");
+		}
+	}
+
+
 }
 
 static void