From 055edbb9f2cdf23160fa9be1d7f597ec9935c19c Mon Sep 17 00:00:00 2001
From: Zebediah Figura <z.figura12@gmail.com>
Date: Mon, 13 Aug 2018 21:35:06 -0500
Subject: [PATCH 79/83] ntdll, server: Revert to old implementation of hung
 queue detection.
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By manually notifying the server every time we enter and exit a message wait.

The hung queue logic keeps breaking. In the case of bug #9 it was breaking
because we were waiting for more than 5 seconds on our queue and then someone
sent us a message with SMTO_ABORTIFHUNG. Just stop fighting against the
server and try to coöperate with it instead. It takes two extra server calls,
but ideally the GUI thread isn't going to be in the same sort of performance-
critical code that this patchset was written for.
---
 dlls/ntdll/esync.c  | 53 ++++++++++++++++++++++++++++++++++-----------
 server/protocol.def |  6 ++++-
 server/queue.c      | 35 ++++++++++++++++++++++++------
 3 files changed, 73 insertions(+), 21 deletions(-)

diff --git a/dlls/ntdll/esync.c b/dlls/ntdll/esync.c
index b84b7b83c..501175c1d 100644
--- a/dlls/ntdll/esync.c
+++ b/dlls/ntdll/esync.c
@@ -831,8 +831,8 @@ static void update_grabbed_object( struct esync *obj )
 
 /* A value of STATUS_NOT_IMPLEMENTED returned from this function means that we
  * need to delegate to server_select(). */
-NTSTATUS esync_wait_objects( DWORD count, const HANDLE *handles, BOOLEAN wait_any,
-                             BOOLEAN alertable, const LARGE_INTEGER *timeout )
+static NTSTATUS __esync_wait_objects( DWORD count, const HANDLE *handles,
+    BOOLEAN wait_any, BOOLEAN alertable, const LARGE_INTEGER *timeout )
 {
     static const LARGE_INTEGER zero = {0};
 
@@ -895,22 +895,11 @@ NTSTATUS esync_wait_objects( DWORD count, const HANDLE *handles, BOOLEAN wait_an
 
     if (objs[count - 1] && objs[count - 1]->type == ESYNC_QUEUE)
     {
-        select_op_t select_op;
-
         /* Last object in the list is a queue, which means someone is using
          * MsgWaitForMultipleObjects(). We have to wait not only for the server
          * fd (signaled on send_message, etc.) but also the USER driver's fd
          * (signaled on e.g. X11 events.) */
         msgwait = TRUE;
-
-        /* We need to let the server know we are doing a message wait, for two
-         * reasons. First one is WaitForInputIdle(). Second one is checking for
-         * hung queues. Do it like this. */
-        select_op.wait.op = SELECT_WAIT;
-        select_op.wait.handles[0] = wine_server_obj_handle( handles[count - 1] );
-        ret = server_select( &select_op, offsetof( select_op_t, wait.handles[1] ), 0, &zero );
-        if (ret != STATUS_WAIT_0 && ret != STATUS_TIMEOUT)
-            ERR("Unexpected ret %#x\n", ret);
     }
 
     if (has_esync && has_server)
@@ -1282,6 +1271,44 @@ userapc:
     return ret;
 }
 
+/* We need to let the server know when we are doing a message wait, and when we
+ * are done with one, so that all of the code surrounding hung queues works.
+ * We also need this for WaitForInputIdle(). */
+static void server_set_msgwait( int in_msgwait )
+{
+    SERVER_START_REQ( esync_msgwait )
+    {
+        req->in_msgwait = in_msgwait;
+        wine_server_call( req );
+    }
+    SERVER_END_REQ;
+}
+
+/* This is a very thin wrapper around the proper implementation above. The
+ * purpose is to make sure the server knows when we are doing a message wait.
+ * This is separated into a wrapper function since there are at least a dozen
+ * exit paths from esync_wait_objects(). */
+NTSTATUS esync_wait_objects( DWORD count, const HANDLE *handles, BOOLEAN wait_any,
+                             BOOLEAN alertable, const LARGE_INTEGER *timeout )
+{
+    BOOL msgwait = FALSE;
+    struct esync *obj;
+    NTSTATUS ret;
+
+    if (!get_object( handles[count - 1], &obj ) && obj->type == ESYNC_QUEUE)
+    {
+        msgwait = TRUE;
+        server_set_msgwait( 1 );
+    }
+
+    ret = __esync_wait_objects( count, handles, wait_any, alertable, timeout );
+
+    if (msgwait)
+        server_set_msgwait( 0 );
+
+    return ret;
+}
+
 NTSTATUS esync_signal_and_wait( HANDLE signal, HANDLE wait, BOOLEAN alertable,
     const LARGE_INTEGER *timeout )
 {
diff --git a/server/protocol.def b/server/protocol.def
index dbb8770df..fb7f1ad1e 100644
--- a/server/protocol.def
+++ b/server/protocol.def
@@ -4078,7 +4078,11 @@ struct handle_info
 
 /* Retrieve the fd to wait on for user APCs. */
 @REQ(get_esync_apc_fd)
-@REPLY
+@END
+
+/* Notify the server that we are doing a message wait (or done with one). */
+@REQ(esync_msgwait)
+    int          in_msgwait;    /* are we in a message wait? */
 @END
 
 enum esync_type
diff --git a/server/queue.c b/server/queue.c
index 174a4ac09..56fa4d98c 100644
--- a/server/queue.c
+++ b/server/queue.c
@@ -126,6 +126,7 @@ struct msg_queue
     struct thread         *thread;          /* reference to the thread owning the queue */
     struct fd             *fd;              /* optional file descriptor to poll */
     int                    esync_fd;        /* esync file descriptor (signalled on message) */
+    int                    esync_in_msgwait; /* our thread is currently waiting on us */
     unsigned int           wake_bits;       /* wakeup bits */
     unsigned int           wake_mask;       /* wakeup mask */
     unsigned int           changed_bits;    /* changed wakeup bits */
@@ -975,7 +976,21 @@ static void cleanup_results( struct msg_queue *queue )
 /* check if the thread owning the queue is hung (not checking for messages) */
 static int is_queue_hung( struct msg_queue *queue )
 {
-    return (current_time - queue->last_get_msg > 5 * TICKS_PER_SEC);
+    struct wait_queue_entry *entry;
+
+    if (current_time - queue->last_get_msg <= 5 * TICKS_PER_SEC)
+        return 0;  /* less than 5 seconds since last get message -> not hung */
+
+    LIST_FOR_EACH_ENTRY( entry, &queue->obj.wait_queue, struct wait_queue_entry, entry )
+    {
+        if (get_wait_queue_thread(entry)->queue == queue)
+            return 0;  /* thread is waiting on queue -> not hung */
+    }
+
+    if (do_esync() && queue->esync_in_msgwait)
+        return 0;   /* thread is waiting on queue in absentia -> not hung */
+
+    return 1;
 }
 
 static int msg_queue_add_queue( struct object *obj, struct wait_queue_entry *entry )
@@ -991,12 +1006,6 @@ static int msg_queue_add_queue( struct object *obj, struct wait_queue_entry *ent
     }
     if (process->idle_event && !(queue->wake_mask & QS_SMRESULT)) set_event( process->idle_event );
 
-    /* On Windows, we are considered hung iff we have not somehow processed
-     * messages OR done a MsgWait call in the last 5 seconds. Note that in the
-     * latter case repeatedly waiting for 0 seconds is not hung, but waiting
-     * forever is hung, so this is correct. */
-    queue->last_get_msg = current_time;
-
     if (queue->fd && list_empty( &obj->wait_queue ))  /* first on the queue */
         set_fd_events( queue->fd, POLLIN );
     add_queue( obj, entry );
@@ -1688,6 +1697,7 @@ static int send_hook_ll_message( struct desktop *desktop, struct message *hardwa
 
     if (!(hook_thread = get_first_global_hook( id ))) return 0;
     if (!(queue = hook_thread->queue)) return 0;
+    if (is_queue_hung( queue )) return 0;
 
     if (!(msg = mem_alloc( sizeof(*msg) ))) return 0;
 
@@ -3289,3 +3299,14 @@ DECL_HANDLER(update_rawinput_devices)
     e = find_rawinput_device( 1, 6 );
     current->process->rawinput_kbd   = e ? &e->device : NULL;
 }
+
+DECL_HANDLER(esync_msgwait)
+{
+    struct msg_queue *queue = get_current_queue();
+
+    if (!queue) return;
+    queue->esync_in_msgwait = req->in_msgwait;
+
+    if (current->process->idle_event && !(queue->wake_mask & QS_SMRESULT))
+        set_event( current->process->idle_event );
+}
-- 
2.20.1

