--- driver.c.orig	2004-06-17 02:00:00.000000000 +0200
+++ driver.c	2005-02-26 10:40:39.000000000 +0100
@@ -18,6 +18,16 @@
  * http://www.opensource.org/licenses/lgpl-license.html
  * 
  * Contact: AVM GmbH, Alt-Moabit 95, 10559 Berlin, Germany, email: info@avm.de
+ *
+ * Sunday Dec 07 18:10 2003
+ * Modified by Christian 'greeny' Heckhoff to improve locking
+ * based on modifications by Joerg Lehrke for Fritz!Card DSL
+ *
+ * Saturday Jul 24 2004, Oswin Horvath 
+ * small modifications to make the patch work for the Fritz!Card SL USB (03.11.94)
+ * 
+ * Saturday Feb 26 2005, Stefan Schweizer
+ * Fixed patch for rev 0.2.2
  */
 
 #include <asm/io.h>
@@ -54,6 +64,8 @@
 #include "devif.h"
 #include "driver.h"
 
+#undef SINGLE_LOCK
+
 #ifndef HZ
 # error HZ is not defined...
 #endif
@@ -84,7 +96,11 @@
 \*---------------------------------------------------------------------------*/
 card_p				capi_card		= NULL;
 lib_callback_t *		capi_lib		= NULL;
+#if defined (SINGLE_LOCK)
+# define stack_lock qt_lock
+#else
 spinlock_t			stack_lock		= SPIN_LOCK_UNLOCKED;
+#endif
 struct capi_ctr *		capi_controller[2]	= { NULL, NULL } ;
 int				card_config;
 
@@ -919,12 +935,17 @@ static inline int in_critical (void) {
 /*---------------------------------------------------------------------------*\
 \*---------------------------------------------------------------------------*/
 static inline void check (void) {
+	unsigned long flags;
 
         if (atomic_read (&rx_flag) > 0) {
+		spin_lock_irqsave (&stack_lock, flags);
 		rx_handler (capi_card);
+		spin_unlock_irqrestore (&stack_lock, flags);
 	}
 	if (atomic_read (&tx_flag) > 0) {
+		spin_lock_irqsave (&stack_lock, flags);
 		tx_handler (capi_card);
+		spin_unlock_irqrestore (&stack_lock, flags);
 	}
 } /* check */
 
@@ -1101,6 +1122,7 @@ static __attr void __stack scheduler_con
 /*-S-------------------------------------------------------------------------*\
 \*---------------------------------------------------------------------------*/
 static int scheduler (void * arg) {
+        unsigned long flags;
 
 	UNUSED_ARG (arg);
 	daemonize (TARGET);
@@ -1134,6 +1156,7 @@ static int scheduler (void * arg) {
 		}
 		
 		/* Body of thread, invoke scheduler */
+		local_irq_save(flags);
 		if (spin_trylock (&stack_lock)) {
 			info (!atomic_xchg (&in_scheduler, 1));
 			os_timer_poll ();
@@ -1146,6 +1169,7 @@ static int scheduler (void * arg) {
 #endif
 			spin_unlock (&stack_lock);
 		}
+		local_irq_restore(flags);
 	}
 	LOG("Scheduler thread stopped.\n");
 	up (&thread_sync);
@@ -1324,22 +1348,44 @@ static void rx_handler (card_p pdc) {
 /*---------------------------------------------------------------------------*\
 \*---------------------------------------------------------------------------*/ 
 static void tx_task (unsigned long data) {
-
+	unsigned long flags;
 	UNUSED_ARG (data);
-	if (!in_critical () && spin_trylock (&stack_lock)) {
-		tx_handler (capi_card);
-		spin_unlock (&stack_lock);
+
+	if (in_critical ()){
+		atomic_set (&tx_flag, 1);
+		kick_scheduler ();
+	} else {
+		local_irq_save(flags);
+		if (spin_trylock (&stack_lock)) {
+			tx_handler (capi_card);
+			spin_unlock (&stack_lock);
+		} else {
+			atomic_set (&tx_flag, 1);
+			kick_scheduler ();
+		}
+		local_irq_restore(flags);
 	}
 } /* tx_task */
 
 /*---------------------------------------------------------------------------*\
 \*---------------------------------------------------------------------------*/ 
 static void rx_task (unsigned long data) {
-
+	unsigned long flags;
 	UNUSED_ARG (data);
-	if (!in_critical () && spin_trylock (&stack_lock)) {
-		rx_handler (capi_card);
-		spin_unlock (&stack_lock);
+
+	if (in_critical ()){
+		atomic_set (&tx_flag, 1);
+		kick_scheduler ();
+	} else {
+		local_irq_save(flags);
+		if (spin_trylock (&stack_lock)) {
+			tx_handler (capi_card);
+			spin_unlock (&stack_lock);
+		} else {
+			atomic_set (&tx_flag, 1);
+			kick_scheduler ();
+		}
+		local_irq_restore(flags);
 	}
 } /* rx_task */