bpf/tests: Reduce memory footprint of test suite

The test suite used to call any fill_helper callbacks to generate eBPF
program data for all test cases at once. This caused ballooning memory
requirements as more extensive test cases were added. Now the each
fill_helper is called before the test is run and the allocated memory
released afterwards, before the next test case is processed.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210914091842.4186267-3-johan.almbladh@anyfinetworks.com

lib/test_bpf.c

@@ -8694,8 +8694,6 @@ static __init int find_test_index(const char *test_name)
 
 static __init int prepare_bpf_tests(void)
 {
-	int i;
-
 	if (test_id >= 0) {
 		/*
 		 * if a test_id was specified, use test_range to
@@ -8739,23 +8737,11 @@ static __init int prepare_bpf_tests(void)
 		}
 	}
 
-	for (i = 0; i < ARRAY_SIZE(tests); i++) {
-		if (tests[i].fill_helper &&
-		    tests[i].fill_helper(&tests[i]) < 0)
-			return -ENOMEM;
-	}
-
 	return 0;
 }
 
 static __init void destroy_bpf_tests(void)
 {
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(tests); i++) {
-		if (tests[i].fill_helper)
-			kfree(tests[i].u.ptr.insns);
-	}
 }
 
 static bool exclude_test(int test_id)
@@ -8960,7 +8946,19 @@ static __init int test_bpf(void)
 
 		pr_info("#%d %s ", i, tests[i].descr);
 
+		if (tests[i].fill_helper &&
+		    tests[i].fill_helper(&tests[i]) < 0) {
+			pr_cont("FAIL to prog_fill\n");
+			continue;
+		}
+
 		fp = generate_filter(i, &err);
+
+		if (tests[i].fill_helper) {
+			kfree(tests[i].u.ptr.insns);
+			tests[i].u.ptr.insns = NULL;
+		}
+
 		if (fp == NULL) {
 			if (err == 0) {
 				pass_cnt++;