xen: add new CONFIG_DEBUG_LOCKS option

Instead of enabling debugging for debug builds only add a dedicated
Kconfig option for that purpose which defaults to DEBUG.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/Kconfig.debug

@@ -51,6 +51,13 @@ config LOCK_PROFILE
 	  You can use serial console to print (and reset) using 'l' and 'L'
 	  respectively, or the 'xenlockprof' tool.
 
+config DEBUG_LOCKS
+	bool "Lock debugging"
+	default DEBUG
+	---help---
+	  Enable debugging features of lock handling.  Some additional
+	  checks will be performed when acquiring and releasing locks.
+
 config PERF_COUNTERS
 	bool "Performance Counters"
 	---help---

xen/common/spinlock.c

@@ -9,7 +9,7 @@
 #include <asm/processor.h>
 #include <asm/atomic.h>
 
-#ifndef NDEBUG
+#ifdef CONFIG_DEBUG_LOCKS
 
 static atomic_t spin_debug __read_mostly = ATOMIC_INIT(0);
 
@@ -99,7 +99,7 @@ void spin_debug_disable(void)
     atomic_dec(&spin_debug);
 }
 
-#else /* defined(NDEBUG) */
+#else /* CONFIG_DEBUG_LOCKS */
 
 #define check_lock(l) ((void)0)
 #define check_barrier(l) ((void)0)

xen/include/xen/spinlock.h

@@ -7,7 +7,7 @@
 
 #define SPINLOCK_CPU_BITS  12
 
-#ifndef NDEBUG
+#ifdef CONFIG_DEBUG_LOCKS
 union lock_debug {
     uint16_t val;
 #define LOCK_DEBUG_INITVAL 0xffff