[PATCH v1 bpf] selftests/bpf: Add exponential backoff to map_update_retriable in test_maps

[Yucong Sun <fallentree@xxxxxx>]

Using a fixed delay of 1ms is proven flaky in slow CPU environment, eg.  github
action CI system. This patch adds exponential backoff with a cap of 50ms, to
reduce the flakyness of the test.

Signed-off-by: Yucong Sun <fallentree@xxxxxx>
---
 tools/testing/selftests/bpf/test_maps.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
index 14cea869235b..ed92d56c19cf 100644
--- a/tools/testing/selftests/bpf/test_maps.c
+++ b/tools/testing/selftests/bpf/test_maps.c
@@ -1400,11 +1400,16 @@ static void test_map_stress(void)
 static int map_update_retriable(int map_fd, const void *key, const void *value,
 				int flags, int attempts)
 {
+	int delay = 1;
+
 	while (bpf_map_update_elem(map_fd, key, value, flags)) {
 		if (!attempts || (errno != EAGAIN && errno != EBUSY))
 			return -errno;
 
-		usleep(1);
+		if (delay < 50)
+			delay *= 2;
+
+		usleep(delay);
 		attempts--;
 	}
 
-- 
2.30.2