linux-kernel - [RFC patch 38/41] tracing: Make ftrace_trace

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Message-Id: <20190410103647.028742712@linutronix.de>
Date:   Wed, 10 Apr 2019 12:28:32 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexander Potapenko <glider@...gle.com>
Subject: [RFC patch 38/41] tracing: Make ftrace_trace_userstack() static and
 conditional

It's only used in trace.c and there is absolutely no point in compiling it
in when user space stack traces are not supported.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Steven Rostedt <rostedt@...dmis.org>
---
 kernel/trace/trace.c |   14 ++++++++------
 kernel/trace/trace.h |    8 --------
 2 files changed, 8 insertions(+), 14 deletions(-)

--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -159,6 +159,8 @@ static union trace_eval_map_item *trace_
 #endif /* CONFIG_TRACE_EVAL_MAP_FILE */
 
 static int tracing_set_tracer(struct trace_array *tr, const char *buf);
+static void ftrace_trace_userstack(struct ring_buffer *buffer,
+				   unsigned long flags, int pc);
 
 #define MAX_TRACER_SIZE		100
 static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
@@ -2905,9 +2907,10 @@ void trace_dump_stack(int skip)
 }
 EXPORT_SYMBOL_GPL(trace_dump_stack);
 
+#ifdef CONFIG_USER_STACKTRACE_SUPPORT
 static DEFINE_PER_CPU(int, user_stack_count);
 
-void
+static void
 ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
 {
 	struct trace_event_call *call = &event_user_stack;
@@ -2958,13 +2961,12 @@ ftrace_trace_userstack(struct ring_buffe
  out:
 	preempt_enable();
 }
-
-#ifdef UNUSED
-static void __trace_userstack(struct trace_array *tr, unsigned long flags)
+#else /* CONFIG_USER_STACKTRACE_SUPPORT */
+static void ftrace_trace_userstack(struct ring_buffer *buffer,
+				   unsigned long flags, int pc)
 {
-	ftrace_trace_userstack(tr, flags, preempt_count());
 }
-#endif /* UNUSED */
+#endif /* !CONFIG_USER_STACKTRACE_SUPPORT */
 
 #endif /* CONFIG_STACKTRACE */
 
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -782,17 +782,9 @@ void update_max_tr_single(struct trace_a
 #endif /* CONFIG_TRACER_MAX_TRACE */
 
 #ifdef CONFIG_STACKTRACE
-void ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags,
-			    int pc);
-
 void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
 		   int pc);
 #else
-static inline void ftrace_trace_userstack(struct ring_buffer *buffer,
-					  unsigned long flags, int pc)
-{
-}
-
 static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
 				 int skip, int pc)
 {