ftrace: move sysctl_ftrace_enabled to ftrace.c

This moves ftrace_enabled to trace/ftrace.c.

We move sysctls to places where features actually belong to improve
the readability of the code and reduce the risk of code merge conflicts.
At the same time, the proc-sysctl maintainers do not want to know what
sysctl knobs you wish to add for your owner piece of code, we just care
about the core logic.

Signed-off-by: Wei Xiao <xiaowei66@huawei.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

Author: Wei Xiao

include/linux/ftrace.h

@@ -101,9 +101,6 @@ static inline int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *val
 #ifdef CONFIG_FUNCTION_TRACER
 
 extern int ftrace_enabled;
-extern int
-ftrace_enable_sysctl(struct ctl_table *table, int write,
-		     void *buffer, size_t *lenp, loff_t *ppos);
 
 #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
 

kernel/sysctl.c

@@ -1751,15 +1751,6 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
-#ifdef CONFIG_FUNCTION_TRACER
-	{
-		.procname	= "ftrace_enabled",
-		.data		= &ftrace_enabled,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= ftrace_enable_sysctl,
-	},
-#endif
 #ifdef CONFIG_STACK_TRACER
 	{
 		.procname	= "stack_tracer_enabled",

kernel/trace/ftrace.c

@@ -7921,7 +7921,8 @@ static bool is_permanent_ops_registered(void)
 	return false;
 }
 
-int
+#ifdef CONFIG_SYSCTL
+static int
 ftrace_enable_sysctl(struct ctl_table *table, int write,
 		     void *buffer, size_t *lenp, loff_t *ppos)
 {
@@ -7964,3 +7965,22 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
 	mutex_unlock(&ftrace_lock);
 	return ret;
 }
+
+static struct ctl_table ftrace_sysctls[] = {
+	{
+		.procname       = "ftrace_enabled",
+		.data           = &ftrace_enabled,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = ftrace_enable_sysctl,
+	},
+	{}
+};
+
+static int __init ftrace_sysctl_init(void)
+{
+	register_sysctl_init("kernel", ftrace_sysctls);
+	return 0;
+}
+late_initcall(ftrace_sysctl_init);
+#endif