linux-kernel - [for-next][PATCH] ftrace: Move toplevel init out of ftrace_init

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Date:	Tue, 5 Jul 2016 17:33:08 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	Stephen Rothwell <sfr@...b.auug.org.au>
Subject: [for-next][PATCH] ftrace: Move toplevel init out of
 ftrace_init_tracefs()

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
for-next

Head SHA1: 501c2375253c0795048f48368e0b3e8b2f6646dc


Steven Rostedt (Red Hat) (1):
      ftrace: Move toplevel init out of ftrace_init_tracefs()

----
 kernel/trace/ftrace.c | 16 ++++++++++------
 kernel/trace/trace.c  |  1 +
 kernel/trace/trace.h  |  3 +++
 3 files changed, 14 insertions(+), 6 deletions(-)
---------------------------
commit 501c2375253c0795048f48368e0b3e8b2f6646dc
Author: Steven Rostedt (Red Hat) <rostedt@...dmis.org>
Date:   Tue Jul 5 10:04:34 2016 -0400

    ftrace: Move toplevel init out of ftrace_init_tracefs()
    
    Commit 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the bitmap like events
    do") placed ftrace_init_tracefs into the instance creation, and encapsulated
    the top level updating with an if conditional, as the top level only gets
    updated at boot up. Unfortunately, this triggers section mismatch errors as
    the init functions are called from a function that can be called later, and
    the section mismatch logic is unaware of the if conditional that would
    prevent it from happening at run time.
    
    To make everyone happy, create a separate ftrace_init_tracefs_toplevel()
    routine that only gets called by init functions, and this will be what calls
    other init functions for the toplevel directory.
    
    Link: http://lkml.kernel.org/r/20160704102139.19cbc0d9@gandalf.local.home
    
    Reported-by: kbuild test robot <fengguang.wu@...el.com>
    Reported-by: Arnd Bergmann <arnd@...db.de>
    Fixes: 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the bitmap like events do")
    Signed-off-by: Steven Rostedt <rostedt@...dmis.org>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 8b488f4dd8e8..84752c8e28b5 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5539,16 +5539,20 @@ static const struct file_operations ftrace_pid_fops = {
 
 void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 {
-	/* Only the top level directory has the dyn_tracefs and profile */
-	if (tr->flags & TRACE_ARRAY_FL_GLOBAL) {
-		ftrace_init_dyn_tracefs(d_tracer);
-		ftrace_profile_tracefs(d_tracer);
-	}
-
 	trace_create_file("set_ftrace_pid", 0644, d_tracer,
 			    tr, &ftrace_pid_fops);
 }
 
+void __init ftrace_init_tracefs_toplevel(struct trace_array *tr,
+					 struct dentry *d_tracer)
+{
+	/* Only the top level directory has the dyn_tracefs and profile */
+	WARN_ON(!(tr->flags & TRACE_ARRAY_FL_GLOBAL));
+
+	ftrace_init_dyn_tracefs(d_tracer);
+	ftrace_profile_tracefs(d_tracer);
+}
+
 /**
  * ftrace_kill - kill ftrace
  *
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3d9f31b576f3..5fd53a7847bc 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7369,6 +7369,7 @@ static __init int tracer_init_tracefs(void)
 		return 0;
 
 	init_tracer_tracefs(&global_trace, d_tracer);
+	ftrace_init_tracefs_toplevel(&global_trace, d_tracer);
 
 	trace_create_file("tracing_thresh", 0644, d_tracer,
 			&global_trace, &tracing_thresh_fops);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index eaee458755a4..c1de3f493cd3 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -857,6 +857,8 @@ void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func);
 void ftrace_reset_array_ops(struct trace_array *tr);
 int using_ftrace_ops_list_func(void);
 void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer);
+void ftrace_init_tracefs_toplevel(struct trace_array *tr,
+				  struct dentry *d_tracer);
 #else
 static inline int ftrace_trace_task(struct trace_array *tr)
 {
@@ -874,6 +876,7 @@ static inline __init void
 ftrace_init_global_array_ops(struct trace_array *tr) { }
 static inline void ftrace_reset_array_ops(struct trace_array *tr) { }
 static inline void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d) { }
+static inline void ftrace_init_tracefs_toplevel(struct trace_array *tr, struct dentry *d) { }
 /* ftace_func_t type is not defined, use macro instead of static inline */
 #define ftrace_init_array_ops(tr, func) do { } while (0)
 #endif /* CONFIG_FUNCTION_TRACER */