selftests/bpf: Add --no-error-summary to skip end-of-run error log dump

By default test_progs re-prints the aggregated error logs of all failed
tests at the end of the run (when not in verbose mode), starting with
"All error logs:".

With bpf-gcc the current failures and a couple runaway 1M fails cause a
huge print overhead/delay at the end.

Add a subtractive --no-error-summary flag, gated on a new
env.error_summary field which defaults to true, so the default behavior
is unchanged. Passing --no-error-summary suppresses the final
"All error logs:" dump.

Only the human readable output is elided. dump_test_log() also emits the
per-test and per-subtest entries of the --json-summary "results" array,
so it keeps being called (via a new @quiet argument) and the JSON report
is bit for bit what it was before.

Signed-off-by: Vineet Gupta <vineet.gupta@linux.dev>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20260807204434.1036279-3-vineet.gupta@linux.dev

tools/testing/selftests/bpf/test_progs.c

@@ -424,10 +424,12 @@ static void jsonw_write_log_message(json_writer_t *w, char *log_buf, size_t log_
 	}
 }
 
+/* @quiet elides the human readable output, the JSON report is unaffected */
 static void dump_test_log(const struct prog_test_def *test,
 			  const struct test_state *test_state,
 			  bool skip_ok_subtests,
 			  bool par_exec_result,
+			  bool quiet,
 			  json_writer_t *w)
 {
 	bool test_failed = test_state->error_cnt > 0;
@@ -449,7 +451,7 @@ static void dump_test_log(const struct prog_test_def *test,
 	if (verbose() && !par_exec_result)
 		return;
 
-	if (test_state->log_cnt && print_test)
+	if (test_state->log_cnt && print_test && !quiet)
 		print_test_log(test_state->log_buf, test_state->log_cnt);
 
 	if (w && print_test) {
@@ -471,15 +473,16 @@ static void dump_test_log(const struct prog_test_def *test,
 		if ((skip_ok_subtests && !subtest_failed) || subtest_filtered)
 			continue;
 
-		if (subtest_state->log_cnt && print_subtest) {
+		if (subtest_state->log_cnt && print_subtest && !quiet) {
 			print_test_log(subtest_state->log_buf,
 				       subtest_state->log_cnt);
 		}
 
-		print_subtest_name(test->test_num, i + 1,
-				   test->test_name, subtest_state->name,
-				   test_result(subtest_state->error_cnt,
-					       subtest_state->skipped));
+		if (!quiet)
+			print_subtest_name(test->test_num, i + 1,
+					   test->test_name, subtest_state->name,
+					   test_result(subtest_state->error_cnt,
+						       subtest_state->skipped));
 
 		if (w && print_subtest) {
 			jsonw_start_object(w);
@@ -496,7 +499,8 @@ static void dump_test_log(const struct prog_test_def *test,
 		jsonw_end_object(w);
 	}
 
-	print_test_result(test, test_state);
+	if (!quiet)
+		print_test_result(test, test_state);
 }
 
 /* A bunch of tests set custom affinity per-thread and/or per-process. Reset
@@ -899,6 +903,7 @@ enum ARG_KEYS {
 	ARG_JSON_SUMMARY = 'J',
 	ARG_TRAFFIC_MONITOR = 'm',
 	ARG_WATCHDOG_TIMEOUT = 'w',
+	ARG_NO_ERROR_SUMMARY = -2,
 };
 
 static const struct argp_option opts[] = {
@@ -931,6 +936,8 @@ static const struct argp_option opts[] = {
 #endif
 	{ "watchdog-timeout", ARG_WATCHDOG_TIMEOUT, "SECONDS", 0,
 	  "Kill the process if tests are not making progress for specified number of seconds." },
+	{ "no-error-summary", ARG_NO_ERROR_SUMMARY, NULL, 0,
+	  "Do not re-print the aggregated error logs of failed tests at the end of the run." },
 	{},
 };
 
@@ -1132,6 +1139,9 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 	case ARG_DEBUG:
 		env->debug = true;
 		break;
+	case ARG_NO_ERROR_SUMMARY:
+		env->error_summary = false;
+		break;
 	case ARG_JSON_SUMMARY:
 		env->json = fopen(arg, "w");
 		if (env->json == NULL) {
@@ -1304,7 +1314,7 @@ static void dump_crash_log(void)
 
 	if (env.test) {
 		env.test_state->error_cnt++;
-		dump_test_log(env.test, env.test_state, true, false, NULL);
+		dump_test_log(env.test, env.test_state, true, false, false, NULL);
 	}
 }
 
@@ -1462,7 +1472,7 @@ static void run_one_test(int test_num)
 
 	free(stop_libbpf_log_capture());
 
-	dump_test_log(test, state, false, false, NULL);
+	dump_test_log(test, state, false, false, false, NULL);
 }
 
 struct dispatch_data {
@@ -1623,7 +1633,7 @@ static void *dispatch_thread(void *ctx)
 		} while (false);
 
 		pthread_mutex_lock(&stdout_output_lock);
-		dump_test_log(test, state, false, true, NULL);
+		dump_test_log(test, state, false, true, false, NULL);
 		pthread_mutex_unlock(&stdout_output_lock);
 	} /* while (true) */
 error:
@@ -1686,9 +1696,14 @@ static void calculate_summary_and_print_errors(struct test_env *env)
 	 * We only print error logs summary when there are failed tests and
 	 * verbose mode is not enabled. Otherwise, results may be inconsistent.
 	 *
+	 * --no-error-summary elides the human readable dump. The walk still
+	 * happens when a JSON report was requested, so the JSON output keeps
+	 * its per-test results; with no JSON report there is nothing left to
+	 * do and the whole loop is skipped.
 	 */
-	if (!verbose() && fail_cnt) {
-		printf("\nAll error logs:\n");
+	if (!verbose() && fail_cnt && (env->error_summary || w)) {
+		if (env->error_summary)
+			printf("\nAll error logs:\n");
 
 		/* print error logs again */
 		for (i = 0; i < prog_test_cnt; i++) {
@@ -1698,7 +1713,8 @@ static void calculate_summary_and_print_errors(struct test_env *env)
 			if (!state->tested || !state->error_cnt)
 				continue;
 
-			dump_test_log(test, state, true, true, w);
+			dump_test_log(test, state, true, true,
+				      !env->error_summary, w);
 		}
 	}
 
@@ -2028,6 +2044,7 @@ int main(int argc, char **argv)
 
 	env.secs_till_notify = 10;
 	env.secs_till_kill = 120;
+	env.error_summary = true;
 	err = argp_parse(&argp, argc, argv, 0, NULL, &env);
 	if (err)
 		return err;

tools/testing/selftests/bpf/test_progs.h

@@ -105,6 +105,7 @@ struct test_env {
 	struct test_selector tmon_selector;
 	bool verifier_stats;
 	bool debug;
+	bool error_summary;
 	enum verbosity verbosity;
 
 	bool jit_enabled;