From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751682AbeCOHUn (ORCPT ); Thu, 15 Mar 2018 03:20:43 -0400 Received: from mga18.intel.com ([134.134.136.126]:47720 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750950AbeCOHUm (ORCPT ); Thu, 15 Mar 2018 03:20:42 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,308,1517904000"; d="scan'208";a="208414772" From: ning.a.zhang@intel.com To: linux-kernel@vger.kernel.org Cc: Zhang Ning Subject: [PATCH] init: no need to wait device probe Date: Thu, 15 Mar 2018 15:20:29 +0800 Message-Id: <20180315072029.11441-1-ning.a.zhang@intel.com> X-Mailer: git-send-email 2.14.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zhang Ning 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 --- init/do_mounts.c | 9 --------- init/do_mounts_md.c | 2 -- 2 files changed, 11 deletions(-) diff --git a/init/do_mounts.c b/init/do_mounts.c index 7cf4f6dafd5f..a9fb2ad44964 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -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]) { diff --git a/init/do_mounts_md.c b/init/do_mounts_md.c index 3f733c760a8c..4aab3492e71d 100644 --- a/init/do_mounts_md.c +++ b/init/do_mounts_md.c @@ -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); -- 2.14.2