--- driver.c.orig	2004-05-14 02:00:00.000000000 +0200
+++ driver.c	2005-01-21 15:40:33.000000000 +0100
@@ -18,6 +18,10 @@
  * http://www.opensource.org/licenses/lgpl-license.html
  * 
  * Contact: AVM GmbH, Alt-Moabit 95, 10559 Berlin, Germany, email: info@avm.de
+ *
+ * Mon Oct 20 22:43:31 2003
+ * Modified by Joerg Lehrke to improve locking 
+ * Fixed for rev 0.4.1 by Stefan Schweizer
  */
 
 #include <asm/io.h>
@@ -57,6 +61,8 @@
 #include "dbgif.h"
 #endif
 
+#undef SINGLE_LOCK
+
 #define	KILOBYTE		1024
 #define	MEGABYTE		(1024*KILOBYTE)
 #define	DMA_BUFFER_SIZE		(9*KILOBYTE)
@@ -101,7 +107,11 @@
 static struct capi_ctr		capi_ctrl[2];
 static int			capi_ctrl_ix		= 0;
 static per_ctrl_t		ctrl_params[2];
+#if defined (SINGLE_LOCK)
+# define stack_lock qt_lock
+#else
 static spinlock_t		stack_lock		= SPIN_LOCK_UNLOCKED;
+#endif
 static atomic_t			rx_flag			= ATOMIC_INIT (0);
 static atomic_t			tx_flag			= ATOMIC_INIT (0);
 static atomic_t			thread_flag		= ATOMIC_INIT (0);
@@ -1142,7 +1152,7 @@
 } /* remove_ctrl */
 
 /*---------------------------------------------------------------------------*\
-\*-C-------------------------------------------------------------------------*/
+\*---------------------------------------------------------------------------*/
 static inline int in_critical (void) {
 	
 	return (0 < atomic_read (&crit_count));
@@ -1301,7 +1311,7 @@
 	capi_ctr_handle_message (ctrl, appl, skb);
 } /* msg2capi */
 
-/*-S-------------------------------------------------------------------------*\
+/*---------------------------------------------------------------------------*\
 \*---------------------------------------------------------------------------*/
 static __attr void __stack scheduler_control (unsigned ena) {
 	int	enabled = (int) ena;
@@ -1323,6 +1333,7 @@
 /*---------------------------------------------------------------------------*\
 \*---------------------------------------------------------------------------*/ 
 static int sched_thread (void * arg) {
+        unsigned long	flags;
 
 	UNUSED_ARG (arg);
 	daemonize (TARGET);
@@ -1356,6 +1367,7 @@
 		}
 
 		/* Body of thread, invoke scheduler */
+		local_irq_save(flags);
 		if (spin_trylock (&stack_lock)) {
 			os_timer_poll ();
 			assert (capi_lib->cm_schedule);
@@ -1364,6 +1376,7 @@
 			}
 			spin_unlock (&stack_lock);
 		}
+		local_irq_restore(flags);
 	}
 	LOG("Scheduler thread stopped.\n");
 	up (&hotplug);
@@ -1470,17 +1483,22 @@
 /*---------------------------------------------------------------------------*\
 \*---------------------------------------------------------------------------*/
 static void tx_task (unsigned long data) {
-	
+        unsigned long	flags;
+
 	UNUSED_ARG (data);
 	if (in_critical ()) {
 		atomic_set (&tx_flag, 1);
 		kick_scheduler ();
-	} else if (spin_trylock (&stack_lock)) {
-		tx_handler (capi_card);
-		spin_unlock (&stack_lock);
 	} else {
-		atomic_set (&tx_flag, 1);
-		kick_scheduler ();
+		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 */
 
@@ -1533,17 +1551,22 @@
 /*---------------------------------------------------------------------------*\
 \*---------------------------------------------------------------------------*/
 static void rx_task (unsigned long data) {
+        unsigned long	flags;
 	
 	UNUSED_ARG (data);
 	if (in_critical ()) {
 		atomic_set (&rx_flag, 1);
 		kick_scheduler ();
-	} else if (spin_trylock (&stack_lock)) {
-		rx_handler (capi_card);
-		spin_unlock (&stack_lock);
 	} else {
-		atomic_set (&rx_flag, 1);
-		kick_scheduler ();
+		local_irq_save(flags);
+		if (spin_trylock (&stack_lock)) {
+			rx_handler (capi_card);
+			spin_unlock (&stack_lock);
+		} else {
+			atomic_set (&rx_flag, 1);
+			kick_scheduler ();
+		}
+		local_irq_restore(flags);
 	}
 } /* rx_task */
 
@@ -1562,6 +1585,7 @@
 		return IRQ_NONE;
 	}
 	cp = (card_p) args;
+	spin_lock (&stack_lock);
 	while (0 != ((flags = PEEK (cp->io_base + INT_CTL)) & CARD_PCI_INT_ASSERT)) {
 		++count;
 		assert (count < 3);
@@ -1572,6 +1596,7 @@
 		assert ((PEEK (cp->io_base + INT_CTL) 
 				& ~(CARD_PCI_INT_ASSERT | CARD_PCI_INT_ISASSERTED)) != 0);
 		if (!atomic_read (&link_open)) {
+			spin_unlock (&stack_lock);
 			return IRQ_HANDLED;
 		}
 		tx_flag = PEEK (cp->io_base + XFER_TOTM_STATUS) == TM_READY;
@@ -1586,6 +1611,7 @@
 		}
 	}
 	info (0 == (PEEK (cp->io_base + INT_CTL) & CARD_PCI_INT_ASSERT));
+	spin_unlock (&stack_lock);
 	return IRQ_RETVAL(count > 0);
 } /* irq_handler */