Re: [PATCH 2/4] ARM: add IPI tracepoints

[Steven Rostedt]

On Fri, 18 Jul 2014 16:55:42 -0400 (EDT)
Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> wrote:

> 
> Here's the patch I have at the head of the series now, with the above
> ugliness changed to an unconditional __tracepoint_string attribute.
> 

I was thinking of something like this. Feel free to add this to your
series.

-- Steve

From: Steven Rostedt <rostedt@xxxxxxxxxxx>
Subject: [PATCH] tracing: Do not do anything special with tracepoint_string when tracing is disabled

When CONFIG_TRACING is not enabled, there's no reason to save the trace
strings either by the linker or as a static variable that can be
referenced later. Simply pass back the string that is given to
tracepoint_string().

Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index cff3106..b296363 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -574,6 +574,7 @@ do {									\
 		__trace_printk(ip, fmt, ##args);			\
 } while (0)
 
+#ifdef CONFIG_TRACING
 /**
  * tracepoint_string - register constant persistent string to trace system
  * @str - a constant persistent string that will be referenced in tracepoints
@@ -607,6 +608,15 @@ do {									\
 		___tp_str;						\
 	})
 #define __tracepoint_string	__attribute__((section("__tracepoint_str")))
+#else
+/*
+ * tracepoint_string() is used to save the string address for userspace
+ * tracing tools. When tracing isn't configured, there's no need to save
+ * anything.
+ */
+# define tracepoint_string(str) str
+# define __tracepoint_string
+#endif
 
 #ifdef CONFIG_PERF_EVENTS
 struct perf_event;

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