kmod: introduce call_modprobe() helper

No functional changes.  Move the call_usermodehelper code from
__request_module() into the new simple helper, call_modprobe().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/kmod.c

@@ -60,6 +60,21 @@ static DECLARE_RWSEM(umhelper_sem);
 */
 char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
 
+static int call_modprobe(char *module_name, int wait)
+{
+	static char *envp[] = {
+		"HOME=/",
+		"TERM=linux",
+		"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
+		NULL
+	};
+
+	char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
+
+	return call_usermodehelper_fns(modprobe_path, argv, envp,
+					wait, NULL, NULL, NULL);
+}
+
 /**
  * __request_module - try to load a kernel module
  * @wait: wait (or not) for the operation to complete
@@ -81,11 +96,6 @@ int __request_module(bool wait, const char *fmt, ...)
 	char module_name[MODULE_NAME_LEN];
 	unsigned int max_modprobes;
 	int ret;
-	char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
-	static char *envp[] = { "HOME=/",
-				"TERM=linux",
-				"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
-				NULL };
 	static atomic_t kmod_concurrent = ATOMIC_INIT(0);
 #define MAX_KMOD_CONCURRENT 50	/* Completely arbitrary value - KAO */
 	static int kmod_loop_msg;
@@ -128,9 +138,7 @@ int __request_module(bool wait, const char *fmt, ...)
 
 	trace_module_request(module_name, wait, _RET_IP_);
 
-	ret = call_usermodehelper_fns(modprobe_path, argv, envp,
-			wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC,
-			NULL, NULL, NULL);
+	ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
 
 	atomic_dec(&kmod_concurrent);
 	return ret;