[RFC]init:enable usermodehelper when we have a root filesystem

[wangyanqing <udknight@gmail.com>]

before we have a root filesystem , it is useless to enable usermodehelper,
and it may cause bug if we enable usermodehelper too early (see commit
d5767c53535ac79758084773418e0ad186aba4a2 for the reason why linus mv 
'usermodehelper_enable()' to the end of do_basic_setup, and commit 
b0f84374b6ab0dc9c47975df0b02d46165d558d4).This patch
enable usermodehelper when we have a root filesystem.

Signed-off-by: wang yanqing <udknight@gmail.com>
---
 init/do_mounts.c |    3 +++
 init/initramfs.c |    2 ++
 init/main.c      |    1 -
 3 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/init/do_mounts.c b/init/do_mounts.c
index c0851a8..9575bdd 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -490,4 +490,7 @@ out:
 	devtmpfs_mount("dev");
 	sys_mount(".", "/", NULL, MS_MOVE, NULL);
 	sys_chroot((const char __user __force *)".");
+#ifndef CONFIG_BLK_DEV_INITRD
+	usermodehelper_enable();
+#endif
 }
diff --git a/init/initramfs.c b/init/initramfs.c
index 2531811..881fc4b 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -581,6 +581,7 @@ static int __init populate_rootfs(void)
 		err = unpack_to_rootfs((char *)initrd_start,
 			initrd_end - initrd_start);
 		if (!err) {
+			usermodehelper_enable();
 			free_initrd();
 			return 0;
 		} else {
@@ -603,6 +604,7 @@ static int __init populate_rootfs(void)
 			initrd_end - initrd_start);
 		if (err)
 			printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
+		usermodehelper_enable();
 		free_initrd();
 #endif
 	}
diff --git a/init/main.c b/init/main.c
index 03b408d..2e232cb 100644
--- a/init/main.c
+++ b/init/main.c
@@ -730,7 +730,6 @@ static void __init do_basic_setup(void)
 	driver_init();
 	init_irq_proc();
 	do_ctors();
-	usermodehelper_enable();
 	do_initcalls();
 }
 
-- 
1.7.3.4