[PATCH v2 1/2] ntoskrnl.exe: Prevent blocking if timer is reset in DPC.

[Ivo Ivanov]

From: Ivo Ivanov

Fixes NaturalPoint's TrackIR5 app hanging indefinitely on exit,
while waiting synchronously on an IRP to complete. The blocking
happens in the app's npusbio_x64 driver, while it tries to reset
a timer in its DPC.
Probably fixes other drivers/apps in such situations.
---
 dlls/ntoskrnl.exe/sync.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/dlls/ntoskrnl.exe/sync.c b/dlls/ntoskrnl.exe/sync.c
index d9b5726b920..0b101158eb6 100644
--- a/dlls/ntoskrnl.exe/sync.c
+++ b/dlls/ntoskrnl.exe/sync.c
@@ -493,10 +493,14 @@ BOOLEAN WINAPI KeSetTimerEx( KTIMER *timer, LARGE_INTEGER duetime, LONG period,

EnterCriticalSection( &sync_cs );

-    if ((ret = timer->Header.Inserted))
-        KeCancelTimer(timer);
-
+    ret = timer->Header.Inserted;
     timer->Header.Inserted = TRUE;
+    timer->Header.SignalState = FALSE;
+    if (timer->Header.WaitListHead.Blink && !*((ULONG_PTR *)&timer->Header.WaitListHead.Flink))
+    {
+        CloseHandle(timer->Header.WaitListHead.Blink);
+        timer->Header.WaitListHead.Blink = NULL;
+    }

if (!timer->TimerListEntry.Blink)
         timer->TimerListEntry.Blink = (void *)CreateThreadpoolTimer(ke_timer_complete_proc, timer, NULL);