tools/resolve_btfids: Add --fatal-warnings option

Currently warnings emitted by resolve_btfids are buried in the build log
and are slipping into mainline frequently.
Add an option to elevate warnings to hard errors so the CI bots can
catch any new warnings.

Signed-off-by: Thomas Weißschuh <[email protected]>
Acked-by: Jiri Olsa <[email protected]>

tools/bpf/resolve_btfids/main.c

@@ -141,6 +141,7 @@ struct object {
 };
 
 static int verbose;
+static int warnings;
 
 static int eprintf(int level, int var, const char *fmt, ...)
 {
@@ -604,6 +605,7 @@ static int symbols_resolve(struct object *obj)
 			if (id->id) {
 				pr_info("WARN: multiple IDs found for '%s': %d, %d - using %d\n",
 					str, id->id, type_id, id->id);
+				warnings++;
 			} else {
 				id->id = type_id;
 				(*nr)--;
@@ -625,8 +627,10 @@ static int id_patch(struct object *obj, struct btf_id *id)
 	int i;
 
 	/* For set, set8, id->id may be 0 */
-	if (!id->id && !id->is_set && !id->is_set8)
+	if (!id->id && !id->is_set && !id->is_set8) {
 		pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name);
+		warnings++;
+	}
 
 	for (i = 0; i < id->addr_cnt; i++) {
 		unsigned long addr = id->addr[i];
@@ -782,13 +786,16 @@ int main(int argc, const char **argv)
 		.funcs    = RB_ROOT,
 		.sets     = RB_ROOT,
 	};
+	bool fatal_warnings = false;
 	struct option btfid_options[] = {
 		OPT_INCR('v', "verbose", &verbose,
 			 "be more verbose (show errors, etc)"),
 		OPT_STRING(0, "btf", &obj.btf, "BTF data",
 			   "BTF data"),
 		OPT_STRING('b', "btf_base", &obj.base_btf_path, "file",
 			   "path of file providing base BTF"),
+		OPT_BOOLEAN(0, "fatal-warnings", &fatal_warnings,
+			    "turn warnings into errors"),
 		OPT_END()
 	};
 	int err = -1;
@@ -823,7 +830,8 @@ int main(int argc, const char **argv)
 	if (symbols_patch(&obj))
 		goto out;
 
-	err = 0;
+	if (!(fatal_warnings && warnings))
+		err = 0;
 out:
 	if (obj.efile.elf) {
 		elf_end(obj.efile.elf);