kmod: move call_usermodehelper_fns() to .c file and unexport all it's helpers

If we move call_usermodehelper_fns() to kmod.c file and EXPORT_SYMBOL it
we can avoid exporting all it's helper functions:
call_usermodehelper_setup
call_usermodehelper_setfns
call_usermodehelper_exec
And make all of them static to kmod.c

Since the optimizer will see all these as a single call site it will
inline them inside call_usermodehelper_fns(). So we loose the call to
_fns but gain 3 calls to the helpers. (Not that it matters)

Signed-off-by: Boaz Harrosh <[e-mail]>
Cc: Oleg Nesterov <[e-mail]>
Cc: Tetsuo Handa <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/kmod.h

···
 	void *data;
 };
 
-/* Allocate a subprocess_info structure */
-struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
-						  char **envp, gfp_t gfp_mask);
-
-/* Set various pieces of state into the subprocess_info structure */
-void call_usermodehelper_setfns(struct subprocess_info *info,
-		    int (*init)(struct subprocess_info *info, struct cred *new),
-		    void (*cleanup)(struct subprocess_info *info),
-		    void *data);
-
-/* Actually execute the sub-process */
-int call_usermodehelper_exec(struct subprocess_info *info, int wait);
-
-static inline int
+extern int
 call_usermodehelper_fns(char *path, char **argv, char **envp, int wait,
 			int (*init)(struct subprocess_info *info, struct cred *new),
-			void (*cleanup)(struct subprocess_info *), void *data)
-{
-	struct subprocess_info *info;
-	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
-
-	info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
-
-	if (info == NULL)
-		return -ENOMEM;
-
-	call_usermodehelper_setfns(info, init, cleanup, data);
-
-	return call_usermodehelper_exec(info, wait);
-}
+			void (*cleanup)(struct subprocess_info *), void *data);
 
 static inline int
 call_usermodehelper(char *path, char **argv, char **envp, int wait)

kernel/kmod.c

···
  * structure.  This should be passed to call_usermodehelper_exec to
  * exec the process and free the structure.
  */
+static
 struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
 						  char **envp, gfp_t gfp_mask)
 {
···
   out:
 	return sub_info;
 }
-EXPORT_SYMBOL(call_usermodehelper_setup);
 
 /**
  * call_usermodehelper_setfns - set a cleanup/init function
···
  * Function must be runnable in either a process context or the
  * context in which call_usermodehelper_exec is called.
  */
+static
 void call_usermodehelper_setfns(struct subprocess_info *info,
 		    int (*init)(struct subprocess_info *info, struct cred *new),
 		    void (*cleanup)(struct subprocess_info *info),
···
 	info->init = init;
 	info->data = data;
 }
-EXPORT_SYMBOL(call_usermodehelper_setfns);
 
 /**
  * call_usermodehelper_exec - start a usermode application
···
  * asynchronously if wait is not set, and runs as a child of keventd.
  * (ie. it runs with full root capabilities).
  */
+static
 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
 {
 	DECLARE_COMPLETION_ONSTACK(done);
···
 	helper_unlock();
 	return retval;
 }
-EXPORT_SYMBOL(call_usermodehelper_exec);
+
+int call_usermodehelper_fns(
+	char *path, char **argv, char **envp, int wait,
+	int (*init)(struct subprocess_info *info, struct cred *new),
+	void (*cleanup)(struct subprocess_info *), void *data)
+{
+	struct subprocess_info *info;
+	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
+
+	info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
+
+	if (info == NULL)
+		return -ENOMEM;
+
+	call_usermodehelper_setfns(info, init, cleanup, data);
+
+	return call_usermodehelper_exec(info, wait);
+}
+EXPORT_SYMBOL(call_usermodehelper_fns);
 
 static int proc_cap_handler(struct ctl_table *table, int write,
 			 void __user *buffer, size_t *lenp, loff_t *ppos)