8354530: AIX: sporadic unexpected errno when calling setsockopt in Net.joinOrDrop

Backport-of: dc881ee36900bc12bea9616a6078a1f3266c183d

Author: ArnoZeller

src/java.base/unix/native/libnio/ch/Net.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -655,6 +655,16 @@ Java_sun_nio_ch_Net_joinOrDrop4(JNIEnv *env, jobject this, jboolean join, jobjec
         n = setsockopt(fdval(env,fdo), IPPROTO_IP, opt, optval, optlen);
     }
 #endif
+#ifdef _AIX
+    // workaround AIX bug where IP_ADD_MEMBERSHIP fails intermittently
+    if (n < 0 && errno == EAGAIN) {
+        int countdown = 3;
+        while (n < 0 && errno == EAGAIN && countdown > 0) {
+            n = setsockopt(fdval(env,fdo), IPPROTO_IP, opt, optval, optlen);
+            countdown--;
+        }
+    }
+#endif
 
     if (n < 0) {
         if (join && (errno == ENOPROTOOPT || errno == EOPNOTSUPP))