Fix server socket address already in use error even if close is called

Motivation:

when you submit a poll, io_uring still hold reference to it even if close is called
source io_uring mailing list(https://lore.kernel.org/io-uring/27657840-4E8E-422D-93BB-7F485F21341A@kernel.dk/T/#t)

Modification:

-To delete fd reference in io_uring, we use POLL_REMOVE to avoid a server socket address error
-Added a POLL_REMOVE test

Result:

server can be closed and restarted

transport-native-io_uring/src/main/java/io/netty/channel/uring/AbstractIOUringChannel.java

@@ -164,6 +164,7 @@ abstract class AbstractIOUringChannel extends AbstractChannel implements UnixCha
             }
         }
     }
+
     void readComplete(int localReadAmount) {
         boolean close = false;
         ByteBuf byteBuf = null;
@@ -275,6 +276,10 @@ abstract class AbstractIOUringChannel extends AbstractChannel implements UnixCha
     protected void doClose() throws Exception {
         if (parent() == null) {
             logger.trace("ServerSocket Close: {}", this.socket.intValue());
+            IOUringEventLoop ioUringEventLoop = (IOUringEventLoop) eventLoop();
+            IOUringSubmissionQueue submissionQueue = ioUringEventLoop.getRingBuffer().getIoUringSubmissionQueue();
+            submissionQueue.addPollRemove(socket.intValue());
+            submissionQueue.submit();
         }
         active = false;
         // Even if we allow half closed sockets we should give up on reading. Otherwise we may allow a read attempt on a

transport-native-io_uring/src/main/java/io/netty/channel/uring/AbstractIOUringServerChannel.java

@@ -28,10 +28,12 @@ abstract class AbstractIOUringServerChannel extends AbstractIOUringChannel imple
 
     AbstractIOUringServerChannel(int fd) {
         super(null, new LinuxSocket(fd));
+       System.out.println("Server Socket fd: " + fd);
     }
 
     AbstractIOUringServerChannel(LinuxSocket fd) {
         super(null, fd);
+        System.out.println("Server Socket fd: " + fd);
     }
 
     @Override

transport-native-io_uring/src/main/java/io/netty/channel/uring/IOUring.java

@@ -26,6 +26,7 @@ final class IOUring {
     static final int OP_ACCEPT = 13;
     static final int OP_READ = 22;
     static final int OP_WRITE = 23;
+    static final int OP_POLL_REMOVE = 7;
 
     static final int POLLMASK_LINK = 1;
     static final int POLLMASK_OUT = 4;

transport-native-io_uring/src/main/java/io/netty/channel/uring/IOUringCompletionQueue.java

@@ -74,6 +74,7 @@ final class IOUringCompletionQueue {
               int opMask = (int) udata;
               short op = (short) (opMask >> 16);
               short mask = (short) opMask;
+
               i++;
               if (!callback.handle(fd, res, flags, op, mask)) {
                   break;

transport-native-io_uring/src/main/java/io/netty/channel/uring/IOUringEventLoop.java

@@ -37,10 +37,12 @@ final class IOUringEventLoop extends SingleThreadEventLoop implements
 
     //Todo set config ring buffer size
     private final int ringSize = 32;
+    private final int ENOENT = -2;
 
     //just temporary -> Todo use ErrorsStaticallyReferencedJniMethods like in Epoll
-    private final int SOCKET_ERROR_EPIPE = -32;
-    private static long ETIME = -62;
+    private static final int SOCKET_ERROR_EPIPE = -32;
+    private static final long ETIME = -62;
+    static final long ECANCELED = -125;
 
     // events should be unique to identify which event type that was
     private long eventIdCounter;
@@ -175,6 +177,11 @@ final class IOUringEventLoop extends SingleThreadEventLoop implements
         IOUringSubmissionQueue submissionQueue = ringBuffer.getIoUringSubmissionQueue();
         switch (op) {
             case IOUring.OP_ACCEPT:
+                //Todo error handle the res
+                if (res == ECANCELED) {
+                    logger.trace("POLL_LINK canceled");
+                    break;
+                }
                 AbstractIOUringServerChannel acceptChannel = (AbstractIOUringServerChannel) channels.get(fd);
                 if (acceptChannel == null) {
                     break;
@@ -217,6 +224,11 @@ final class IOUringEventLoop extends SingleThreadEventLoop implements
 
                 break;
             case IOUring.IO_POLL:
+                //Todo error handle the res
+                if (res == ECANCELED) {
+                    logger.trace("POLL_LINK canceled");
+                    break;
+                }
                 if (eventfd.intValue() == fd) {
                     pendingWakeup = false;
                     // We need to consume the data as otherwise we would see another event
@@ -238,7 +250,12 @@ final class IOUringEventLoop extends SingleThreadEventLoop implements
                         break;
                     }
                 }
-
+            case IOUring.OP_POLL_REMOVE:
+                if (res == ENOENT) {
+                    logger.trace("POLL_REMOVE OPERATION not permitted");
+                } else if (res == 0) {
+                    logger.trace("POLL_REMOVE OPERATION successful");
+                }
                 break;
         }
         return true;

transport-native-io_uring/src/main/java/io/netty/channel/uring/IOUringSubmissionQueue.java

@@ -116,10 +116,14 @@ final class IOUringSubmissionQueue {
         PlatformDependent.putLong(sqe + SQE_ADDRESS_FIELD, bufferAddress);
         PlatformDependent.putInt(sqe + SQE_LEN_FIELD, length);
 
-        // Store the fd and event type in the user_data field
-        int opMask = (((short) op) << 16) | (((short) pollMask) & 0xFFFF);
-        long uData = (long) fd << 32 | opMask & 0xFFFFFFFFL;
+        //user_data should be same as POLL_LINK fd
+        if (op == IOUring.OP_POLL_REMOVE) {
+            PlatformDependent.putInt(sqe + SQE_FD_FIELD, -1);
+            long pollLinkuData = convertToUserData((byte) IOUring.IO_POLL, fd, IOUring.POLLMASK_LINK);
+            PlatformDependent.putLong(sqe + SQE_ADDRESS_FIELD, pollLinkuData);
+        }
 
+        long uData = convertToUserData(op, fd, pollMask);
         PlatformDependent.putLong(sqe + SQE_USER_DATA_FIELD, uData);
 
         //poll<link>read or accept operation
@@ -213,6 +217,17 @@ final class IOUringSubmissionQueue {
         return true;
     }
 
+    //fill the user_data which is associated with server poll link
+    public boolean addPollRemove(int fd) {
+        long sqe = getSqe();
+        if (sqe == 0) {
+            return false;
+        }
+        setData(sqe, (byte) IOUring.OP_POLL_REMOVE, 0, fd, 0, 0, 0);
+
+        return true;
+    }
+
     private int flushSqe() {
         long kTail = toUnsignedLong(PlatformDependent.getInt(kTailAddress));
         long kHead = toUnsignedLong(PlatformDependent.getIntVolatile(kHeadAddress));
@@ -270,6 +285,11 @@ final class IOUringSubmissionQueue {
         PlatformDependent.putLong(timeoutMemoryAddress + KERNEL_TIMESPEC_TV_NSEC_FIELD, nanoSeconds);
     }
 
+    private long convertToUserData(byte op, int fd, int pollMask) {
+        int opMask = (((short) op) << 16) | (((short) pollMask) & 0xFFFF);
+        return (long) fd << 32 | opMask & 0xFFFFFFFFL;
+    }
+
     //delete memory
     public void release() {
         Buffer.free(timeoutMemory);

transport-native-io_uring/src/test/java/io/netty/channel/uring/NativeTest.java

@@ -16,11 +16,17 @@
 package io.netty.channel.uring;
 
 import io.netty.channel.unix.FileDescriptor;
+import io.netty.channel.unix.Socket;
 import org.junit.Test;
+
+import java.io.File;
 import java.nio.charset.Charset;
+
 import io.netty.buffer.ByteBufAllocator;
 import io.netty.buffer.UnpooledByteBufAllocator;
+
 import static org.junit.Assert.*;
+
 import io.netty.buffer.ByteBuf;
 import org.junit.experimental.theories.suppliers.TestedOn;
 
@@ -196,4 +202,46 @@ public class NativeTest {
         RingBuffer ringBuffer = Native.createRingBuffer();
         ringBuffer.close();
     }
+
+    @Test
+    public void ioUringPollRemoveTest() throws InterruptedException {
+        RingBuffer ringBuffer = Native.createRingBuffer(32);
+        IOUringSubmissionQueue submissionQueue = ringBuffer.getIoUringSubmissionQueue();
+        final IOUringCompletionQueue completionQueue = ringBuffer.getIoUringCompletionQueue();
+
+        FileDescriptor eventFd = Native.newEventFd();
+        submissionQueue.addPollLink(eventFd.intValue());
+        submissionQueue.submit();
+
+        Thread.sleep(10);
+
+        submissionQueue.addPollRemove(eventFd.intValue());
+        submissionQueue.submit();
+
+        Thread waitingCqe = new Thread() {
+            @Override
+            public void run() {
+                assertTrue(completionQueue.ioUringWaitCqe());
+                assertEquals(1, completionQueue.process(new IOUringCompletionQueue.IOUringCompletionQueueCallback() {
+                    @Override
+                    public boolean handle(int fd, int res, long flags, int op, int mask) {
+                        assertEquals(IOUringEventLoop.ECANCELED, res);
+                        assertEquals(IOUring.IO_POLL, op);
+                        return true;
+                    }
+                }));
+                assertEquals(1, completionQueue.process(new IOUringCompletionQueue.IOUringCompletionQueueCallback() {
+                    @Override
+                    public boolean handle(int fd, int res, long flags, int op, int mask) {
+                        assertEquals(0, res);
+                        assertEquals(IOUring.OP_POLL_REMOVE, op);
+                        return true;
+                    }
+                }));
+            }
+        };
+        waitingCqe.start();
+
+        waitingCqe.join();
+    }
 }