selftests/bpf: Export map_update_retriable()

Export map_update_retriable() to make it usable for other map_test
cases. These cases may only need retry for specific errno, so add
a new callback parameter to let map_update_retriable() decide whether or
not the errno is retriable.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231101032455.3808547-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/test_maps.c

@@ -1396,13 +1396,18 @@ static void test_map_stress(void)
 #define MAX_DELAY_US 50000
 #define MIN_DELAY_RANGE_US 5000
 
-static int map_update_retriable(int map_fd, const void *key, const void *value,
-				int flags, int attempts)
+static bool retry_for_again_or_busy(int err)
+{
+	return (err == EAGAIN || err == EBUSY);
+}
+
+int map_update_retriable(int map_fd, const void *key, const void *value, int flags, int attempts,
+			 retry_for_error_fn need_retry)
 {
 	int delay = rand() % MIN_DELAY_RANGE_US;
 
 	while (bpf_map_update_elem(map_fd, key, value, flags)) {
-		if (!attempts || (errno != EAGAIN && errno != EBUSY))
+		if (!attempts || !need_retry(errno))
 			return -errno;
 
 		if (delay <= MAX_DELAY_US / 2)
@@ -1445,11 +1450,13 @@ static void test_update_delete(unsigned int fn, void *data)
 		key = value = i;
 
 		if (do_update) {
-			err = map_update_retriable(fd, &key, &value, BPF_NOEXIST, MAP_RETRIES);
+			err = map_update_retriable(fd, &key, &value, BPF_NOEXIST, MAP_RETRIES,
+						   retry_for_again_or_busy);
 			if (err)
 				printf("error %d %d\n", err, errno);
 			assert(err == 0);
-			err = map_update_retriable(fd, &key, &value, BPF_EXIST, MAP_RETRIES);
+			err = map_update_retriable(fd, &key, &value, BPF_EXIST, MAP_RETRIES,
+						   retry_for_again_or_busy);
 			if (err)
 				printf("error %d %d\n", err, errno);
 			assert(err == 0);

tools/testing/selftests/bpf/test_maps.h

@@ -4,6 +4,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdbool.h>
 
 #define CHECK(condition, tag, format...) ({				\
 	int __ret = !!(condition);					\
@@ -16,4 +17,8 @@
 
 extern int skips;
 
+typedef bool (*retry_for_error_fn)(int err);
+int map_update_retriable(int map_fd, const void *key, const void *value, int flags, int attempts,
+			 retry_for_error_fn need_retry);
+
 #endif