ftrace: add ftrace_vprintk

Impact: new helper function
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/ftrace.h

@@ -302,6 +302,9 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
 extern int
 __ftrace_printk(unsigned long ip, const char *fmt, ...)
 	__attribute__ ((format (printf, 2, 3)));
+# define ftrace_vprintk(fmt, ap) __ftrace_printk(_THIS_IP_, fmt, ap)
+extern int
+__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 extern void ftrace_dump(void);
 #else
 static inline void
@@ -317,6 +320,11 @@ ftrace_printk(const char *fmt, ...)
 {
 	return 0;
 }
+static inline int
+ftrace_vprintk(const char *fmt, va_list ap)
+{
+	return 0;
+}
 static inline void ftrace_dump(void) { }
 #endif
 

kernel/trace/trace.c

@@ -2951,6 +2951,15 @@ int __ftrace_printk(unsigned long ip, const char *fmt, ...)
 }
 EXPORT_SYMBOL_GPL(__ftrace_printk);
 
+int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap)
+{
+	if (!(trace_flags & TRACE_ITER_PRINTK))
+		return 0;
+
+	return trace_vprintk(ip, task_curr_ret_stack(current), fmt, ap);
+}
+EXPORT_SYMBOL_GPL(__ftrace_vprintk);
+
 static int trace_panic_handler(struct notifier_block *this,
 			       unsigned long event, void *unused)
 {