From f5ca06016dbf41ea21752f34a16d9202bb7aaa02 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?R=C3=A9mi=20Bernon?= Date: Mon, 15 Feb 2021 20:42:00 +0100 Subject: [PATCH] plugplay: Broadcast WM_DEVICECHANGE message asynchronously. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It may otherwise trigger a nasty race condition, where: 1) For explorer.exe to register the CLSID_ShellWindows classes, it needs RpcSS service to be started, 2) services.exe may start WinePlugPlay service group first, waiting for its startup to complete, 3) during startup and early device enumeration, hidclass.sys may call IoSetDeviceInterfaceState, which calls plugplay_send_event [1], 4) plugplay_send_event tries to broadcast a WM_DEVICECHANGE message with BSF_QUERY, waiting for the individual threads to reply, 5) which times-out because window threads are waiting on explorer.exe to create its desktop window and reply to the WM_NULL SendMessage. This happens more likely as there is threads with message queues being started, each waiting on the desktop window to reply. Usually explorer.exe is able to reply to some messages with the implicit message processing while creating its window, but not all of them. [1] Not completely sure how, it looks like some RPC too, but before RpcSs is started? Signed-off-by: Rémi Bernon Signed-off-by: Alexandre Julliard --- programs/plugplay/main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/programs/plugplay/main.c b/programs/plugplay/main.c index 19e02286312..1156cb9f036 100644 --- a/programs/plugplay/main.c +++ b/programs/plugplay/main.c @@ -142,8 +142,8 @@ void __cdecl plugplay_send_event( DWORD code, const BYTE *data, unsigned int siz struct listener *listener; struct event *event; - BroadcastSystemMessageW( BSF_FORCEIFHUNG | BSF_QUERY, NULL, WM_DEVICECHANGE, code, (LPARAM)data ); - BroadcastSystemMessageW( BSF_FORCEIFHUNG | BSF_QUERY, NULL, WM_DEVICECHANGE, DBT_DEVNODES_CHANGED, 0 ); + BroadcastSystemMessageW( 0, NULL, WM_DEVICECHANGE, code, (LPARAM)data ); + BroadcastSystemMessageW( 0, NULL, WM_DEVICECHANGE, DBT_DEVNODES_CHANGED, 0 ); EnterCriticalSection( &plugplay_cs );