[PATCH v4 bpf-next 3/3] Improve stability of find_vma BPF test

[Mykola Lysenko <mykolal@fb.com>]

Remove unneeded spleep and increase length of dummy CPU
intensive computation to guarantee test process execution.
Also, complete aforemention computation as soon as
test success criteria is met

Signed-off-by: Mykola Lysenko <mykolal@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
 .../selftests/bpf/prog_tests/find_vma.c       | 28 +++++++++++++------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/find_vma.c b/tools/testing/selftests/bpf/prog_tests/find_vma.c
index 743a094c9510..5165b38f0e59 100644
--- a/tools/testing/selftests/bpf/prog_tests/find_vma.c
+++ b/tools/testing/selftests/bpf/prog_tests/find_vma.c
@@ -7,12 +7,14 @@
 #include "find_vma_fail1.skel.h"
 #include "find_vma_fail2.skel.h"
 
-static void test_and_reset_skel(struct find_vma *skel, int expected_find_zero_ret)
+static void test_and_reset_skel(struct find_vma *skel, int expected_find_zero_ret, bool need_test)
 {
-	ASSERT_EQ(skel->bss->found_vm_exec, 1, "found_vm_exec");
-	ASSERT_EQ(skel->data->find_addr_ret, 0, "find_addr_ret");
-	ASSERT_EQ(skel->data->find_zero_ret, expected_find_zero_ret, "find_zero_ret");
-	ASSERT_OK_PTR(strstr(skel->bss->d_iname, "test_progs"), "find_test_progs");
+	if (need_test) {
+		ASSERT_EQ(skel->bss->found_vm_exec, 1, "found_vm_exec");
+		ASSERT_EQ(skel->data->find_addr_ret, 0, "find_addr_ret");
+		ASSERT_EQ(skel->data->find_zero_ret, expected_find_zero_ret, "find_zero_ret");
+		ASSERT_OK_PTR(strstr(skel->bss->d_iname, "test_progs"), "find_test_progs");
+	}
 
 	skel->bss->found_vm_exec = 0;
 	skel->data->find_addr_ret = -1;
@@ -36,11 +38,20 @@ static int open_pe(void)
 	return pfd >= 0 ? pfd : -errno;
 }
 
+static bool find_vma_pe_condition(struct find_vma *skel)
+{
+	return skel->bss->found_vm_exec == 0 ||
+		skel->data->find_addr_ret != 0 ||
+		skel->data->find_zero_ret == -1 ||
+		strcmp(skel->bss->d_iname, "test_progs") != 0;
+}
+
 static void test_find_vma_pe(struct find_vma *skel)
 {
 	struct bpf_link *link = NULL;
 	volatile int j = 0;
 	int pfd, i;
+	const int one_bn = 1000000000;
 
 	pfd = open_pe();
 	if (pfd < 0) {
@@ -57,10 +68,10 @@ static void test_find_vma_pe(struct find_vma *skel)
 	if (!ASSERT_OK_PTR(link, "attach_perf_event"))
 		goto cleanup;
 
-	for (i = 0; i < 1000000; ++i)
+	for (i = 0; i < one_bn && find_vma_pe_condition(skel); ++i)
 		++j;
 
-	test_and_reset_skel(skel, -EBUSY /* in nmi, irq_work is busy */);
+	test_and_reset_skel(skel, -EBUSY /* in nmi, irq_work is busy */, i == one_bn);
 cleanup:
 	bpf_link__destroy(link);
 	close(pfd);
@@ -75,7 +86,7 @@ static void test_find_vma_kprobe(struct find_vma *skel)
 		return;
 
 	getpgid(skel->bss->target_pid);
-	test_and_reset_skel(skel, -ENOENT /* could not find vma for ptr 0 */);
+	test_and_reset_skel(skel, -ENOENT /* could not find vma for ptr 0 */, true);
 }
 
 static void test_illegal_write_vma(void)
@@ -108,7 +119,6 @@ void serial_test_find_vma(void)
 	skel->bss->addr = (__u64)(uintptr_t)test_find_vma_pe;
 
 	test_find_vma_pe(skel);
-	usleep(100000); /* allow the irq_work to finish */
 	test_find_vma_kprobe(skel);
 
 	find_vma__destroy(skel);
-- 
2.30.2