[pschweitzer] 69483: [MSFS] Fix a FIXME: properly reset timer when re-using a queued IRP for reading. Also fix a possible race condition between time out DPC and IRP re-use. Thanks to Thomas for hi...

Author: pschweitzer
Date: Sat Oct 10 12:50:33 2015
New Revision: 69483

URL: http://svn.reactos.org/svn/reactos?rev=69483&view=rev
Log:
[MSFS]
Fix a FIXME: properly reset timer when re-using a queued IRP for reading.
Also fix a possible race condition between time out DPC and IRP re-use.

Thanks to Thomas for his help with DPC & timers.

CORE-10245

Modified:
    trunk/reactos/drivers/filesystems/msfs/msfs.h
    trunk/reactos/drivers/filesystems/msfs/msfssup.c
    trunk/reactos/drivers/filesystems/msfs/rw.c

Modified: trunk/reactos/drivers/filesystems/msfs/msfs.h
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/drivers/filesystems/msfs/m…
==============================================================================
--- trunk/reactos/drivers/filesystems/msfs/msfs.h	[iso-8859-1] (original)
+++ trunk/reactos/drivers/filesystems/msfs/msfs.h	[iso-8859-1] Sat Oct 10 12:50:33 2015
@@ -46,6 +46,7 @@
     KTIMER Timer;
     KDPC Dpc;
     PIO_CSQ Csq;
+    KEVENT Event;
     IO_CSQ_IRP_CONTEXT CsqContext;
 } MSFS_DPC_CTX, *PMSFS_DPC_CTX;
 

Modified: trunk/reactos/drivers/filesystems/msfs/msfssup.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/drivers/filesystems/msfs/m…
==============================================================================
--- trunk/reactos/drivers/filesystems/msfs/msfssup.c	[iso-8859-1] (original)
+++ trunk/reactos/drivers/filesystems/msfs/msfssup.c	[iso-8859-1] Sat Oct 10 12:50:33
2015
@@ -117,14 +117,20 @@
 
     Context = (PMSFS_DPC_CTX)DeferredContext;
 
+    /* Try to get the IRP */
     Irp = IoCsqRemoveIrp(Context->Csq, &Context->CsqContext);
     if (Irp != NULL)
     {
+        /* It timed out, complete it (it's ours) and free context */
         Irp->IoStatus.Status = STATUS_IO_TIMEOUT;
         IoCompleteRequest(Irp, IO_NO_INCREMENT);
+        ExFreePoolWithTag(Context, 'NFsM');
     }
-
-    ExFreePool(Context);
+    else
+    {
+        /* We were racing with writing and failed, signal we're done */
+        KeSetEvent(&Context->Event, IO_NO_INCREMENT, FALSE);
+    }
 }
 
 /* EOF */

Modified: trunk/reactos/drivers/filesystems/msfs/rw.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/drivers/filesystems/msfs/r…
==============================================================================
--- trunk/reactos/drivers/filesystems/msfs/rw.c	[iso-8859-1] (original)
+++ trunk/reactos/drivers/filesystems/msfs/rw.c	[iso-8859-1] Sat Oct 10 12:50:33 2015
@@ -107,10 +107,12 @@
         return STATUS_INSUFFICIENT_RESOURCES;
     }
 
+    KeInitializeEvent(&Context->Event, SynchronizationEvent, FALSE);
     IoCsqInsertIrp(&Fcb->CancelSafeQueue, Irp, &Context->CsqContext);
     Timer = &Context->Timer;
     Dpc = &Context->Dpc;
     Context->Csq = &Fcb->CancelSafeQueue;
+    Irp->Tail.Overlay.DriverContext[0] = Context;
 
     /* No timer for INFINITY_WAIT */
     if (Timeout.QuadPart != -1)
@@ -139,6 +141,7 @@
     ULONG Length;
     PVOID Buffer;
     PIRP CsqIrp;
+    PMSFS_DPC_CTX Context;
 
     DPRINT("MsfsWrite(DeviceObject %p Irp %p)\n", DeviceObject, Irp);
 
@@ -193,7 +196,16 @@
     CsqIrp = IoCsqRemoveNextIrp(&Fcb->CancelSafeQueue, NULL);
     if (CsqIrp != NULL)
     {
-        /* FIXME: It is necessary to reset the timers. */
+        /* Get the context */
+        Context = CsqIrp->Tail.Overlay.DriverContext[0];
+        /* DPC was queued, wait for it to fail (IRP is ours) */
+        if (Fcb->TimeOut.QuadPart != -1 &&
!KeCancelTimer(&Context->Timer))
+        {
+            KeWaitForSingleObject(&Context->Event, Executive, KernelMode, FALSE,
NULL);
+        }
+
+        /* Free context & attempt read */
+        ExFreePoolWithTag(Context, 'NFsM');
         MsfsRead(DeviceObject, CsqIrp);
     }