Don't rely on the finalizer to return blocks referenced by SocketInput

src/Microsoft.AspNetCore.Server.Kestrel/Filter/FilteredStreamAdapter.cs

@@ -48,10 +48,12 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Filter
         {
             if (copyAsyncTask.IsFaulted)
             {
+                SocketInput.AbortAwaiting();
                 _log.LogError(0, copyAsyncTask.Exception, "FilteredStreamAdapter.CopyToAsync");
             }
             else if (copyAsyncTask.IsCanceled)
             {
+                SocketInput.AbortAwaiting();
                 _log.LogError("FilteredStreamAdapter.CopyToAsync canceled.");
             }
 

src/Microsoft.AspNetCore.Server.Kestrel/Http/Connection.cs

@@ -123,6 +123,18 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Http
             }
         }
 
+        public void OnSocketClosed()
+        {
+            _rawSocketInput.Dispose();
+
+            // If a connection filter was applied there will be two SocketInputs.
+            // If a connection filter failed, SocketInput will be null.
+            if (SocketInput != null && SocketInput != _rawSocketInput)
+            {
+                SocketInput.Dispose();
+            }
+        }
+
         private void ApplyConnectionFilter()
         {
             if (_filterContext.Connection != _libuvStream)

src/Microsoft.AspNetCore.Server.Kestrel/Http/Frame.cs

@@ -334,7 +334,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Http
                 try
                 {
                     ConnectionControl.End(ProduceEndType.SocketDisconnect);
-                    SocketInput.AbortAwaiting();
                 }
                 catch (Exception ex)
                 {

src/Microsoft.AspNetCore.Server.Kestrel/Http/FrameOfT.cs

@@ -145,14 +145,20 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Http
                     // If _requestAborted is set, the connection has already been closed.
                     if (Volatile.Read(ref _requestAborted) == 0)
                     {
-                        // Inform client no more data will ever arrive
-                        ConnectionControl.End(ProduceEndType.SocketShutdownSend);
+                        try
+                        {
+                            // Inform client no more data will ever arrive
+                            ConnectionControl.End(ProduceEndType.SocketShutdownSend);
 
-                        // Wait for client to either disconnect or send unexpected data
-                        await SocketInput;
-
-                        // Dispose socket
-                        ConnectionControl.End(ProduceEndType.SocketDisconnect);
+                            // Wait for client to either disconnect or send unexpected data
+                            await SocketInput;
+                        }
+                        finally
+                        {
+                            // Ensure we *always* disconnect the socket.
+                            // Dispose socket
+                            ConnectionControl.End(ProduceEndType.SocketDisconnect);
+                        }
                     }
                 }
                 catch (Exception ex)

src/Microsoft.AspNetCore.Server.Kestrel/Http/SocketInput.cs

@@ -10,7 +10,7 @@ using Microsoft.AspNetCore.Server.Kestrel.Infrastructure;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Http
 {
-    public class SocketInput : ICriticalNotifyCompletion
+    public class SocketInput : ICriticalNotifyCompletion, IDisposable
     {
         private static readonly Action _awaitableIsCompleted = () => { };
         private static readonly Action _awaitableIsNotCompleted = () => { };
@@ -246,5 +246,23 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Http
                 throw new IOException(error.Message, error);
             }
         }
+
+        public void Dispose()
+        {
+            AbortAwaiting();
+
+            // Return all blocks
+            var block = _head;
+            while (block != null)
+            {
+                var returnBlock = block;
+                block = block.Next;
+
+                returnBlock.Pool.Return(returnBlock);
+            }
+
+            _head = null;
+            _tail = null;
+        }
     }
 }

src/Microsoft.AspNetCore.Server.Kestrel/Http/SocketOutput.cs

@@ -614,17 +614,18 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Http
             {
                 if (SocketDisconnect == false || Self._socket.IsClosed)
                 {
-                    CompleteOnUvThread();
+                    CompleteWithContextLock();
                     return;
                 }
 
                 Self._socket.Dispose();
+                Self._connection.OnSocketClosed();
                 Self.ReturnAllBlocks();
                 Self._log.ConnectionStop(Self._connectionId);
-                CompleteOnUvThread();
+                CompleteWithContextLock();
             }
 
-            public void CompleteOnUvThread()
+            public void CompleteWithContextLock()
             {
                 if (Monitor.TryEnter(Self._contextLock))
                 {