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

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Message-Id: <1365300854-3133-1-git-send-email-chenhc@lemote.com>
Date:	Sun,  7 Apr 2013 10:14:14 +0800
From:	Huacai Chen <chenhc@...ote.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Fuxin Zhang <zhangfx@...ote.com>,
	Huacai Chen <chenhc@...ote.com>, <stable@...r.kernel.org>
Subject: [PATCH] PM/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, this is the same way as poweroff does.

BTW, add disable_nonboot_cpus() in kernel_halt() for consistency.

Signed-off-by: Huacai Chen <chenhc@...ote.com>
Cc: <stable@...r.kernel.org>
---
 kernel/sys.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index 39c9c4a..0da73cf 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -324,7 +324,6 @@ void kernel_restart_prepare(char *cmd)
 	system_state = SYSTEM_RESTART;
 	usermodehelper_disable();
 	device_shutdown();
-	syscore_shutdown();
 }

 /**
@@ -370,6 +369,7 @@ void kernel_restart(char *cmd)
 {
 	kernel_restart_prepare(cmd);
 	disable_nonboot_cpus();
+	syscore_shutdown();
 	if (!cmd)
 		printk(KERN_EMERG "Restarting system.\n");
 	else
@@ -395,6 +395,7 @@ static void kernel_shutdown_prepare(enum system_states state)
 void kernel_halt(void)
 {
 	kernel_shutdown_prepare(SYSTEM_HALT);
+	disable_nonboot_cpus();
 	syscore_shutdown();
 	printk(KERN_EMERG "System halted.\n");
 	kmsg_dump(KMSG_DUMP_HALT);
-- 
1.7.7.3

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