[PATCH 2/2] dinput: Delay input thread start until the first device acquire.

[Rémi Bernon]

From: Rémi Bernon

Some applications create a IDirectInput and IDirectInputDevice instance
from their DllMain procedure, and starting the thread on the first user
creation and waiting for it to start will deadlock on the loader lock.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=54916
---
 dlls/dinput/dinput_main.c | 80 +++++++++++++++++++++------------------
 1 file changed, 44 insertions(+), 36 deletions(-)

diff --git a/dlls/dinput/dinput_main.c b/dlls/dinput/dinput_main.c
index 0d502821966..51e1a134023 100644
--- a/dlls/dinput/dinput_main.c
+++ b/dlls/dinput/dinput_main.c
@@ -89,28 +89,6 @@ static CRITICAL_SECTION dinput_hook_crit = { &dinput_critsect_debug, -1, 0, 0, 0

static struct list acquired_device_list = LIST_INIT( acquired_device_list );

-void dinput_hooks_acquire_device( IDirectInputDevice8W *iface )
-{
-    struct dinput_device *impl = impl_from_IDirectInputDevice8W( iface );
-
-    EnterCriticalSection( &dinput_hook_crit );
-    list_add_tail( &acquired_device_list, &impl->entry );
-    LeaveCriticalSection( &dinput_hook_crit );
-
-    SendMessageW( di_em_win, INPUT_THREAD_NOTIFY, NOTIFY_REFRESH_DEVICES, 0 );
-}
-
-void dinput_hooks_unacquire_device( IDirectInputDevice8W *iface )
-{
-    struct dinput_device *impl = impl_from_IDirectInputDevice8W( iface );
-
-    EnterCriticalSection( &dinput_hook_crit );
-    list_remove( &impl->entry );
-    LeaveCriticalSection( &dinput_hook_crit );
-
-    SendMessageW( di_em_win, INPUT_THREAD_NOTIFY, NOTIFY_REFRESH_DEVICES, 0 );
-}
-
 static void unhook_device_window_foreground_changes( struct dinput_device *device )
 {
     if (!device->cbt_hook) return;
@@ -429,37 +407,67 @@ static DWORD WINAPI dinput_thread_proc( void *params )
     return 0;
 }

-void input_thread_add_user(void)
+void input_thread_start(void)
 {
+    HANDLE start_event;
+
+    TRACE( "Starting input thread.\n" );
+
+    if (!(start_event = CreateEventW( NULL, FALSE, FALSE, NULL )))
+        ERR( "Failed to create start event, error %lu\n", GetLastError() );
+    else if (!(dinput_thread = CreateThread( NULL, 0, dinput_thread_proc, start_event, 0, NULL )))
+        ERR( "Failed to create internal thread, error %lu\n", GetLastError() );
+    else
+        WaitForSingleObject( start_event, INFINITE );
+
+    CloseHandle( start_event );
+}
+
+void dinput_hooks_acquire_device( IDirectInputDevice8W *iface )
+{
+    struct dinput_device *impl = impl_from_IDirectInputDevice8W( iface );
+
     EnterCriticalSection( &dinput_hook_crit );
-    if (!input_thread_user_count++)
-    {
-        HANDLE start_event;
+    /* start the input thread now if it wasn't started already */
+    if (!dinput_thread) input_thread_start();
+    list_add_tail( &acquired_device_list, &impl->entry );
+    LeaveCriticalSection( &dinput_hook_crit );

-        TRACE( "Starting input thread.\n" );
+    SendMessageW( di_em_win, INPUT_THREAD_NOTIFY, NOTIFY_REFRESH_DEVICES, 0 );
+}

-        if (!(start_event = CreateEventW( NULL, FALSE, FALSE, NULL )))
-            ERR( "Failed to create start event, error %lu\n", GetLastError() );
-        else if (!(dinput_thread = CreateThread( NULL, 0, dinput_thread_proc, start_event, 0, NULL )))
-            ERR( "Failed to create internal thread, error %lu\n", GetLastError() );
-        else
-            WaitForSingleObject( start_event, INFINITE );
+void dinput_hooks_unacquire_device( IDirectInputDevice8W *iface )
+{
+    struct dinput_device *impl = impl_from_IDirectInputDevice8W( iface );

-        CloseHandle( start_event );
-    }
+    EnterCriticalSection( &dinput_hook_crit );
+    list_remove( &impl->entry );
+    LeaveCriticalSection( &dinput_hook_crit );
+
+    SendMessageW( di_em_win, INPUT_THREAD_NOTIFY, NOTIFY_REFRESH_DEVICES, 0 );
+}
+
+void input_thread_add_user(void)
+{
+    /* we cannot start the input thread here because some games create dinput objects from their DllMain, and
+     * starting the thread will wait for it to initialize, which requires the loader lock to be released.
+     */
+    EnterCriticalSection( &dinput_hook_crit );
+    input_thread_user_count++;
     LeaveCriticalSection( &dinput_hook_crit );
 }

void input_thread_remove_user(void)
 {
     EnterCriticalSection( &dinput_hook_crit );
-    if (!--input_thread_user_count)
+    if (!--input_thread_user_count && dinput_thread)
     {
         TRACE( "Stopping input thread.\n" );

SendMessageW( di_em_win, INPUT_THREAD_NOTIFY, NOTIFY_THREAD_STOP, 0 );
         WaitForSingleObject( dinput_thread, INFINITE );
         CloseHandle( dinput_thread );
+        dinput_thread = NULL;
     }
     LeaveCriticalSection( &dinput_hook_crit );
 }