s390/debug: avoid function call for debug_sprintf_*

debug_sprintf_event/exception are called even for debug events
with a disabling debug level. All other functions already do
the check in a wrapper function. Lets do the same here.
Due to the var_args the compiler rejects to make this function
inline. So let's wrap this via a macro.
This patch saves around 80 ns on my z196 for a KVM round trip (we
have two debug statements for entry and exit) when KVM is build as
a module.
The savings for built-in drivers is smaller as we then avoid the
PLT overhead for a function call.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 31 insertions, 10 deletions

diff --git a/arch/s390/include/asm/debug.h b/arch/s390/include/asm/debug.h
index 530c15eb01e9..0206c8052328 100644
--- a/arch/s390/include/asm/debug.h
+++ b/arch/s390/include/asm/debug.h
@@ -151,9 +151,21 @@ debug_text_event(debug_info_t* id, int level, const char* txt)
  * stored in the s390dbf. See Documentation/s390/s390dbf.txt for more details!
  */
 extern debug_entry_t *
-debug_sprintf_event(debug_info_t* id,int level,char *string,...)
+__debug_sprintf_event(debug_info_t *id, int level, char *string, ...)
         __attribute__ ((format(printf, 3, 4)));
 
+#define debug_sprintf_event(_id, _level, _fmt, ...)                     \
+({                                                                      \
+        debug_entry_t *__ret;                                           \
+        debug_info_t *__id = _id;                                       \
+        int __level = _level;                                           \
+        if ((!__id) || (__level > __id->level))                         \
+                __ret = NULL;                                           \
+        else                                                            \
+                __ret = __debug_sprintf_event(__id, __level,            \
+                                              _fmt, ## __VA_ARGS__);    \
+        __ret;                                                          \
+})
 
 static inline debug_entry_t*
 debug_exception(debug_info_t* id, int level, void* data, int length)
@@ -194,9 +206,22 @@ debug_text_exception(debug_info_t* id, int level, const char* txt)
  * stored in the s390dbf. See Documentation/s390/s390dbf.txt for more details!
  */
 extern debug_entry_t *
-debug_sprintf_exception(debug_info_t* id,int level,char *string,...)
+__debug_sprintf_exception(debug_info_t *id, int level, char *string, ...)
         __attribute__ ((format(printf, 3, 4)));
 
+#define debug_sprintf_exception(_id, _level, _fmt, ...)                 \
+({                                                                      \
+        debug_entry_t *__ret;                                           \
+        debug_info_t *__id = _id;                                       \
+        int __level = _level;                                           \
+        if ((!__id) || (__level > __id->level))                         \
+                __ret = NULL;                                           \
+        else                                                            \
+                __ret = __debug_sprintf_exception(__id, __level,        \
+                                                  _fmt, ## __VA_ARGS__);\
+        __ret;                                                          \
+})
+
 int debug_register_view(debug_info_t* id, struct debug_view* view);
 int debug_unregister_view(debug_info_t* id, struct debug_view* view);
 
diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c
index ee8390da6ea7..c1f21aca76e7 100644
--- a/arch/s390/kernel/debug.c
+++ b/arch/s390/kernel/debug.c
@@ -1019,7 +1019,7 @@ debug_count_numargs(char *string)
  */
 
 debug_entry_t*
-debug_sprintf_event(debug_info_t* id, int level,char *string,...)
+__debug_sprintf_event(debug_info_t *id, int level, char *string, ...)
 {
         va_list   ap;
         int numargs,idx;
@@ -1027,8 +1027,6 @@ debug_sprintf_event(debug_info_t* id, int level,char *string,...)
         debug_sprintf_entry_t *curr_event;
         debug_entry_t *active;
 
-        if((!id) || (level > id->level))
-                return NULL;
         if (!debug_active || !id->areas)
                 return NULL;
         numargs=debug_count_numargs(string);
@@ -1050,14 +1048,14 @@ debug_sprintf_event(debug_info_t* id, int level,char *string,...)
 
         return active;
 }
-EXPORT_SYMBOL(debug_sprintf_event);
+EXPORT_SYMBOL(__debug_sprintf_event);
 
 /*
  * debug_sprintf_exception:
  */
 
 debug_entry_t*
-debug_sprintf_exception(debug_info_t* id, int level,char *string,...)
+__debug_sprintf_exception(debug_info_t *id, int level, char *string, ...)
 {
         va_list   ap;
         int numargs,idx;
@@ -1065,8 +1063,6 @@ debug_sprintf_exception(debug_info_t* id, int level,char *string,...)
         debug_sprintf_entry_t *curr_event;
         debug_entry_t *active;
 
-        if((!id) || (level > id->level))
-                return NULL;
         if (!debug_active || !id->areas)
                 return NULL;
 
@@ -1089,7 +1085,7 @@ debug_sprintf_exception(debug_info_t* id, int level,char *string,...)
 
         return active;
 }
-EXPORT_SYMBOL(debug_sprintf_exception);
+EXPORT_SYMBOL(__debug_sprintf_exception);
 
 /*
  * debug_register_view: