[reactos] 01/01: [MOUNTMGR] Fix invalid WorkerReferences check in QueueWorkItem()

[Pierre Schweitzer]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=457612702b615b45436f0…

commit 457612702b615b45436f02bb8c7eda9be4d0c47c
Author:     Pierre Schweitzer <pierre(a)reactos.org>
AuthorDate: Tue Oct 22 21:51:04 2019 +0200
Commit:     Pierre Schweitzer <pierre(a)reactos.org>
CommitDate: Tue Oct 22 21:53:48 2019 +0200

    [MOUNTMGR] Fix invalid WorkerReferences check in QueueWorkItem()
    
    This fixes shutting down ReactOS under certain circumstances, where
    the references were incremented, but no worker thread started.
    Also, took the opportunity to clarify the WorkerReferences comparisons
    where relevant.
    
    CORE-16446
---
 drivers/filters/mountmgr/database.c | 4 ++--
 drivers/filters/mountmgr/mountmgr.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/filters/mountmgr/database.c b/drivers/filters/mountmgr/database.c
index a025f7db3ec..1cde41a995f 100644
--- a/drivers/filters/mountmgr/database.c
+++ b/drivers/filters/mountmgr/database.c
@@ -1268,8 +1268,8 @@ QueueWorkItem(IN PDEVICE_EXTENSION DeviceExtension,
 
     /* When called, lock is already acquired */
 
-    /* If noone, start to work */
-    if (InterlockedIncrement(&(DeviceExtension->WorkerReferences)))
+    /* If noone (-1 as references), start to work */
+    if (InterlockedIncrement(&(DeviceExtension->WorkerReferences)) == 0)
     {
         IoQueueWorkItem(WorkItem->WorkItem, WorkerThread, DelayedWorkQueue,
DeviceExtension);
     }
diff --git a/drivers/filters/mountmgr/mountmgr.c b/drivers/filters/mountmgr/mountmgr.c
index 37c85874c97..aa152621b51 100644
--- a/drivers/filters/mountmgr/mountmgr.c
+++ b/drivers/filters/mountmgr/mountmgr.c
@@ -822,7 +822,7 @@ MountMgrUnload(IN struct _DRIVER_OBJECT *DriverObject)
     KeInitializeEvent(&UnloadEvent, NotificationEvent, FALSE);
 
     /* Wait for workers to finish */
-    if (InterlockedIncrement(&DeviceExtension->WorkerReferences))
+    if (InterlockedIncrement(&DeviceExtension->WorkerReferences) > 0)
     {
         KeReleaseSemaphore(&(DeviceExtension->WorkerSemaphore),
                            IO_NO_INCREMENT, 1, FALSE);
@@ -1770,7 +1770,7 @@ MountMgrShutdown(IN PDEVICE_OBJECT DeviceObject,
     KeInitializeEvent(&UnloadEvent, NotificationEvent, FALSE);
 
     /* Wait for workers */
-    if (InterlockedIncrement(&(DeviceExtension->WorkerReferences)))
+    if (InterlockedIncrement(&(DeviceExtension->WorkerReferences)) > 0)
     {
         KeReleaseSemaphore(&(DeviceExtension->WorkerSemaphore),
                            IO_NO_INCREMENT,