linux-kernel - [PATCH] reboot: call syscore_shutdown() after disable_nonboot

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Message-Id: <1364981136-25629-1-git-send-email-chenhc@lemote.com>
Date:	Wed,  3 Apr 2013 17:25:36 +0800
From:	Huacai Chen <chenhc@...ote.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, Fuxin Zhang <zhangfx@...ote.com>,
	Huacai Chen <chenhc@...ote.com>, <stable@...r.kernel.org>
Subject: [PATCH] reboot: call syscore_shutdown() after disable_nonboot_cpus()

As commit 40dc166c (PM / Core: Introduce struct syscore_ops for core
subsystems PM) say, syscore_ops operations should be carried with one
CPU on-line and interrupts disabled. However, after commit f96972f2d
(kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()),
syscore_shutdown() is called before disable_nonboot_cpus(), so break
the rules. We have a MIPS machine with a 8259A PIC, and there is an
external timer (HPET) linked at 8259A. Since 8259A has been shutdown
too early (by syscore_shutdown()), disable_nonboot_cpus() runs without
timer interrupt, so it hangs and reboot fails. This patch call
syscore_shutdown() a little later (after disable_nonboot_cpus()) to
avoid reboot failure.

Signed-off-by: Huacai Chen <chenhc@...ote.com>
Cc: <stable@...r.kernel.org>
---
 kernel/sys.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index b0003db..f879033dd 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -320,7 +320,6 @@ void kernel_restart_prepare(char *cmd)
 	system_state = SYSTEM_RESTART;
 	usermodehelper_disable();
 	device_shutdown();
-	syscore_shutdown();
 }

 /**
@@ -366,6 +365,7 @@ void kernel_restart(char *cmd)
 {
 	kernel_restart_prepare(cmd);
 	disable_nonboot_cpus();
+	syscore_shutdown();
 	if (!cmd)
 		printk(KERN_EMERG "Restarting system.\n");
 	else
-- 
1.7.7.3

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