[NTOSKRNL]

Implement IopAllocateIrpMustSucceed() which is designed to *normally* always return an IRP.
Even in low memory situations (if you wait enough). 

svn path=/trunk/; revision=58243

reactos/ntoskrnl/include/internal/io.h

@@ -903,6 +903,12 @@ IopAbortInterruptedIrp(
     IN PIRP Irp
 );
 
+PIRP
+NTAPI
+IopAllocateIrpMustSucceed(
+    IN CCHAR StackSize
+);
+
 //
 // Shutdown routines
 //

reactos/ntoskrnl/io/iomgr/irp.c

@@ -625,6 +625,40 @@ IoAllocateIrp(IN CCHAR StackSize,
     return Irp;
 }
 
+/*
+ * @implemented
+ */
+PIRP
+NTAPI
+IopAllocateIrpMustSucceed(IN CCHAR StackSize)
+{
+    LONG i;
+    PIRP Irp;
+    LARGE_INTEGER Sleep;
+
+    /* Try to get an IRP */
+    Irp = IoAllocateIrp(StackSize, FALSE);
+    if (Irp)
+        return Irp;
+
+    /* If we fail, start looping till we may get one */
+    i = LONG_MAX;
+    do {
+        i--;
+
+        /* First, sleep for 10ms */
+        Sleep.QuadPart = -10 * 1000 * 10;;
+        KeDelayExecutionThread(KernelMode, FALSE, &Sleep);
+
+        /* Then, retry allocation */
+        Irp = IoAllocateIrp(StackSize, FALSE);
+        if (Irp)
+            return Irp;
+    } while (i > 0);
+
+    return Irp;
+}
+
 /*
  * @implemented
  */