s390/s390dbf: add debug_level_enabled() function

Add the debug_level_enabled() function to check if debug events for
a particular level would be logged.  This might help to save cycles
for debug events that require additional information collection.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Documentation/s390/s390dbf.txt

@@ -157,6 +157,16 @@ Return Value:  none
 
 Description:   Sets new actual debug level if new_level is valid. 
 
+---------------------------------------------------------------------------
+bool debug_level_enabled (debug_info_t * id, int level);
+
+Parameter:    id:	  handle for debug log
+	      level:	  debug level
+
+Return Value: True if level is less or equal to the current debug level.
+
+Description:  Returns true if debug events for the specified level would be
+	      logged. Otherwise returns false.
 ---------------------------------------------------------------------------
 void debug_stop_all(void);
 

arch/s390/include/asm/debug.h

@@ -107,6 +107,11 @@ void debug_set_level(debug_info_t* id, int new_level);
 void debug_set_critical(void);
 void debug_stop_all(void);
 
+static inline bool debug_level_enabled(debug_info_t* id, int level)
+{
+	return level <= id->level;
+}
+
 static inline debug_entry_t*
 debug_event(debug_info_t* id, int level, void* data, int length)
 {