init: no need to wait device probe

From: Zhang Ning <[email protected]>

there are 2 reasons for no need to wait device probe

reason 1:
mount root device is very late in kernel initial stage. all initcalls are finished. that means most of probe functions are returned.

and deferred probe are also finished by late_initcall. only async probe driver are possible in probing.

no block devices, device-mapper or nfs are use async probe. so no need to wait device probe.

reason 2:
let's check dd.c, probe_count is increased and decreased only in really_probe, and when really_probe returns, probe_count always be 0.

when someone really wants to wait device-B probe. but code looks like:

thread-1: thread-2:
probe device-A; wait_for_device_probe();
msleep(30);
probe device-B

when device-A probe finishes, thread-2 will be wakeup, but device-B is not probed.

wait_for_device_probe can't make sure the device you want is probed.

based on above 2 reasons, no need to wait for device probe.

Signed-off-by Zhang Ning <[email protected]>

---
 init/do_mounts.c    | 9 ---------
 init/do_mounts_md.c | 2 --
 2 files changed, 11 deletions(-)

init/do_mounts.c +0 -9

index 7cf4f6dafd5f..a9fb2ad44964 100644
@@ -555,15 +555,6 @@ void __init prepare_namespace(void)
 		ssleep(root_delay);
 	}
 
-	/*
-	 * wait for the known devices to complete their probing
-	 *
-	 * Note: this is a potential source of long boot delays.
-	 * For example, it is not atypical to wait 5 seconds here
-	 * for the touchpad of a laptop to initialize.
-	 */
-	wait_for_device_probe();
-
 	md_run_setup();
 
 	if (saved_root_name[0]) {

init/do_mounts_md.c +0 -2

index 3f733c760a8c..4aab3492e71d 100644
@@ -292,8 +292,6 @@ static void __init autodetect_raid(void)
 	printk(KERN_INFO "md: Waiting for all devices to be available before autodetect\n");
 	printk(KERN_INFO "md: If you don't use raid, use raid=noautodetect\n");
 
-	wait_for_device_probe();
-
 	fd = sys_open("/dev/md0", 0, 0);
 	if (fd >= 0) {
 		sys_ioctl(fd, RAID_AUTORUN, raid_autopart);

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