--- a/jdk/src/java.base/share/classes/java/io/CharArrayReader.java	Tue Dec 15 08:54:35 2015 -0800
+++ b/jdk/src/java.base/share/classes/java/io/CharArrayReader.java	Tue Dec 15 09:02:46 2015 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2015, 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
@@ -225,9 +225,12 @@
      * Closes the stream and releases any system resources associated with
      * it.  Once the stream has been closed, further read(), ready(),
      * mark(), reset(), or skip() invocations will throw an IOException.
-     * Closing a previously closed stream has no effect.
+     * Closing a previously closed stream has no effect. This method will block
+     * while there is another thread blocking on the reader.
      */
     public void close() {
-        buf = null;
+        synchronized (lock) {
+            buf = null;
+        }
     }
 }

--- a/jdk/src/java.base/share/classes/java/io/PushbackReader.java	Tue Dec 15 08:54:35 2015 -0800
+++ b/jdk/src/java.base/share/classes/java/io/PushbackReader.java	Tue Dec 15 09:02:46 2015 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2015, 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
@@ -241,13 +241,16 @@
      * Closes the stream and releases any system resources associated with
      * it. Once the stream has been closed, further read(),
      * unread(), ready(), or skip() invocations will throw an IOException.
-     * Closing a previously closed stream has no effect.
+     * Closing a previously closed stream has no effect. This method will block
+     * while there is another thread blocking on the reader.
      *
      * @exception  IOException  If an I/O error occurs
      */
     public void close() throws IOException {
-        super.close();
-        buf = null;
+        synchronized (lock) {
+            super.close();
+            buf = null;
+        }
     }
 
     /**

--- a/jdk/src/java.base/share/classes/java/io/StringReader.java	Tue Dec 15 08:54:35 2015 -0800
+++ b/jdk/src/java.base/share/classes/java/io/StringReader.java	Tue Dec 15 09:02:46 2015 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2015, 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
@@ -194,9 +194,12 @@
      * Closes the stream and releases any system resources associated with
      * it. Once the stream has been closed, further read(),
      * ready(), mark(), or reset() invocations will throw an IOException.
-     * Closing a previously closed stream has no effect.
+     * Closing a previously closed stream has no effect. This method will block
+     * while there is another thread blocking on the reader.
      */
     public void close() {
-        str = null;
+        synchronized (lock) {
+            str = null;
+        }
     }
 }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/io/PushbackReader/ReadCloseRaceNPE.java	Tue Dec 15 09:02:46 2015 -0800
@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2015, 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 8143394
+ * @summary Check for NullPointerException in race between read() and close().
+ */
+import java.io.CharArrayReader;
+import java.io.IOException;
+import java.io.PushbackReader;
+import java.io.Reader;
+import java.io.StringReader;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Supplier;
+
+public class ReadCloseRaceNPE {
+
+    private static final int BUF_SIZE = 1000;
+    private static final long TIMEOUT_MS = 3000;
+
+    private static final List<Exception> failures = new ArrayList<>();
+
+    private static void testReader(final Supplier<Reader> readerSupplier)
+            throws InterruptedException {
+        AtomicReference<Reader> readerRef =
+            new AtomicReference<>(readerSupplier.get());
+
+        AtomicBoolean isFinished = new AtomicBoolean();
+
+        Runnable readTask = () -> {
+            long startTime = System.currentTimeMillis();
+            while (System.currentTimeMillis() - startTime < TIMEOUT_MS) {
+                try {
+                    readerRef.get().read();
+                } catch (Exception e) {
+                    if (!(e instanceof IOException)) {
+                        failures.add(e);
+                        break;
+                    }
+                    readerRef.set(readerSupplier.get());
+                }
+            }
+            isFinished.set(true);
+        };
+
+        Runnable closeTask = () -> {
+            while (!isFinished.get()) {
+                try {
+                    readerRef.get().close();
+                } catch (Exception e) {
+                    if (!(e instanceof IOException)) {
+                        e.printStackTrace();
+                    }
+                }
+            }
+        };
+
+        Thread readThread = new Thread(readTask);
+        Thread closeThread = new Thread(closeTask);
+
+        readThread.start();
+        closeThread.start();
+        readThread.join();
+        closeThread.join();
+    }
+
+    public static void main(String[] args) throws Throwable {
+        final String s = "Two riders were approaching.\\n";
+
+        Supplier<Reader> charPushbackReaderSupplier = () -> {
+            char buf[] = new char[s.length()];
+            s.getChars(0, s.length(), buf, 0);
+            CharArrayReader in = new CharArrayReader(buf);
+            return new PushbackReader(in, BUF_SIZE);
+        };
+
+        testReader(charPushbackReaderSupplier);
+
+        Supplier<Reader> stringPushbackReaderSupplier = () -> {
+            StringReader in = new StringReader(s);
+            return new PushbackReader(in, BUF_SIZE);
+        };
+
+        testReader(stringPushbackReaderSupplier);
+
+        if (!failures.isEmpty()) {
+            failures.stream().forEach((x) -> ((Exception) x).printStackTrace());
+            throw new RuntimeException("PushbackReaderNPE failed");
+        }
+    }
+}