8182672: Java 8u121 on Linux intermittently returns null for MAC address

Reviewed-by: chegar, clanger, msheppar, vtewari

jdk/src/java.base/unix/native/libnet/NetworkInterface.c

@@ -1244,7 +1244,7 @@ static int getMacAddress
   (JNIEnv *env, const char *ifname, const struct in_addr *addr,
    unsigned char *buf)
 {
-    static struct ifreq ifr;
+    struct ifreq ifr;
     int i, sock;
 
     if ((sock = openSocketWithFallback(env, ifname)) < 0) {

jdk/test/java/net/NetworkInterface/GetMacAddress.java

@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2017, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8182672
+ * @summary Java 8u121 on Linux intermittently returns null for MAC address
+ */
+
+import java.net.NetworkInterface;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.Phaser;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class GetMacAddress implements Callable<Exception> {
+    static final int NUM_THREADS = 5;
+    static final int NUM_ITERS = 100;
+    static volatile boolean failed; // false
+
+    final String threadName;
+    final NetworkInterface ni;
+    final Phaser startingGate;
+
+    public GetMacAddress(NetworkInterface ni, String name, Phaser phaser) {
+        this.ni = ni;
+        this.threadName = name;
+        this.startingGate = phaser;
+    }
+
+    @Override
+    public Exception call() {
+        int count = 0;
+        startingGate.arriveAndAwaitAdvance();
+        try {
+            for (int i = 0; i < NUM_ITERS; i++) {
+                ni.getMTU();
+                byte[] addr = ni.getHardwareAddress();
+                if (addr == null) {
+                    System.out.println(threadName + ". mac id is null");
+                    failed = true;
+                }
+                count = count + 1;
+                if (count % 100 == 0) {
+                    System.out.println(threadName + ". count is " + count);
+                }
+            }
+        } catch (Exception ex) {
+            System.out.println(threadName + ". Not expecting exception:" + ex.getMessage());
+            failed = true;
+            return ex;
+        }
+        return null;
+    }
+
+    static final Predicate<NetworkInterface> hasHardwareAddress = ni -> {
+        try {
+            if (ni.getHardwareAddress() == null) {
+                System.out.println("Not testing null addr: " + ni.getName());
+                return false;
+            }
+        } catch (Exception ex) {
+            System.out.println("Not testing: " + ni.getName() +
+                    " " + ex.getMessage());
+            return false;
+        }
+        return true;
+    };
+
+    public static Stream<NetworkInterface> getNetworkInterfacesAsStream() throws Exception {
+        // JDK 9 and later
+        return NetworkInterface.networkInterfaces();
+        // pre JDK 9
+        //return Collections.list(NetworkInterface.getNetworkInterfaces()).stream();
+    }
+
+    public static void main(String[] args) throws Exception {
+        List<NetworkInterface> toTest = getNetworkInterfacesAsStream()
+                        .filter(hasHardwareAddress)
+                        .collect(Collectors.toList());
+
+        ExecutorService executor = Executors.newFixedThreadPool(NUM_THREADS);
+
+        for (NetworkInterface ni : toTest) {
+            Phaser startingGate = new Phaser(NUM_THREADS);
+            System.out.println("Testing: " + ni.getName());
+            List<Callable<Exception>> list = new ArrayList<>();
+            for (int i = 0; i < NUM_THREADS; i++)
+                list.add(new GetMacAddress(ni, ni.getName() + "-Thread-" + i, startingGate));
+            List<Future<Exception>> futures = executor.invokeAll(list);
+            for (Future<Exception> f : futures) {
+                if (f.get() != null)
+                    f.get().printStackTrace(System.out);
+            }
+            if (failed)
+                break;
+        }
+        executor.shutdownNow();
+        if (!failed) {
+            System.out.println("PASSED - Finished all threads");
+        } else {
+            throw new RuntimeException("Failed");
+        }
+    }
+}