--- vloopback.orig/webcamstudio.c	2010-11-04 21:59:27.000000000 +0200
+++ vloopback/webcamstudio.c	2011-02-05 23:52:30.134289481 +0200
@@ -241,7 +241,24 @@
  #include <linux/wrapper.h>
  #include <asm/io.h>
 #endif
+
+/* kernels <= 2.6.25 have asm only, 2.6.26 has both, and 2.6.27-rc2+ has linux only. */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 27)
+#   include <asm/semaphore.h>
+#else
+#   include <linux/semaphore.h>
+#endif
  
+#if (defined CONFIG_PREEMPT_RT && LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 31)) || LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 37)
+   #ifndef DECLARE_MUTEX
+      #define DECLARE_MUTEX(_m)  DEFINE_SEMAPHORE(_m)
+   #endif
+   #ifndef init_MUTEX
+      #define init_MUTEX(_m) sema_init(_m,1)
+   #endif
+#endif
+
+
 #define VIDIOCSINVALID    _IO('v',BASE_VIDIOCPRIVATE+1)
 
 #define verbose(format, arg...) if (printk_ratelimit()) \
@@ -1326,15 +1343,8 @@
     loops[nr]->vloopin->minor = minor_in;
 
     init_waitqueue_head(&loops[nr]->wait);
-#ifdef CONFIG_PREEMPT_RT
-    /* for RT kernels */
-#warning "******************************"
-#warning "* Using patch for RT Kernels *"
-#warning "******************************"
-    semaphore_init(&loops[nr]->lock); 
-#else
+    
     init_MUTEX(&loops[nr]->lock);
-#endif
 
     ret = video_register_device(loops[nr]->vloopin, VFL_TYPE_GRABBER, minor_in);