1 files changed, 58 insertions, 0 deletions

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 7fa371898e3e..08bf5da86676 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -368,6 +368,64 @@ static inline char *pack_hex_byte(char *buf, u8 byte)
 #endif
 
 /*
+ * General tracing related utility functions - trace_printk(),
+ * tracing_start()/tracing_stop:
+ */
+#ifdef CONFIG_TRACING
+extern void tracing_start(void);
+extern void tracing_stop(void);
+extern void ftrace_off_permanent(void);
+
+extern void
+ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
+
+/**
+ * trace_printk - printf formatting in the ftrace buffer
+ * @fmt: the printf format for printing
+ *
+ * Note: __trace_printk is an internal function for trace_printk and
+ *       the @ip is passed in via the trace_printk macro.
+ *
+ * This function allows a kernel developer to debug fast path sections
+ * that printk is not appropriate for. By scattering in various
+ * printk like tracing in the code, a developer can quickly see
+ * where problems are occurring.
+ *
+ * This is intended as a debugging tool for the developer only.
+ * Please refrain from leaving trace_printks scattered around in
+ * your code.
+ */
+# define trace_printk(fmt...) __trace_printk(_THIS_IP_, fmt)
+extern int
+__trace_printk(unsigned long ip, const char *fmt, ...)
+        __attribute__ ((format (printf, 2, 3)));
+# define ftrace_vprintk(fmt, ap) __trace_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
+ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
+static inline int
+trace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
+
+static inline void tracing_start(void) { }
+static inline void tracing_stop(void) { }
+static inline void ftrace_off_permanent(void) { }
+static inline int
+trace_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
+
+/*
  *      Display an IP address in readable format.
  */