linux-kernel - [PATCH] x86: make reboot task only run on the appropriate processor

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Date:	Tue,  5 Nov 2013 17:16:07 +0800
From:	Baoquan He <bhe@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, akpm@...ux-foundation.org, holt@....com,
	davej@...oraproject.org, rmk+kernel@....linux.org.uk,
	vgoyal@...hat.com, chaowang@...hat.com, mwhitehe@...hat.com,
	kexec@...ts.infradead.org, Baoquan He <bhe@...hat.com>
Subject: [PATCH] x86: make reboot task only run on the appropriate processor

Currently system always reboot after below message when execute "kexec -e".

[    0.572119] smpboot: Booting Node   0, Processors  #   1 OK

In commit 1b3a5d02ee070c8f9943333b9b6370f486601e0f, reboot= handling was
moved to kerne/reboot.c. However, the code to migrate current thread to
reboot cpu was removed. That cause this incorrect kexec behavior.

Now add that code block back.

Reported-by: Matthew Whitehead <mwhitehe@...hat.com>
Reported-by: Dave Young <dyoung@...hat.com>
Tested-by: WANG Chao <chaowang@...hat.com>
Signed-off-by: Baoquan He <bhe@...hat.com>
---
 arch/x86/kernel/reboot.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 7e920bf..3049de9 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -551,6 +551,21 @@ void native_machine_shutdown(void)
 {
 	/* Stop the cpus and apics */
 #ifdef CONFIG_SMP
+       /* The boot cpu is always logical cpu 0 */
+       int reboot_cpu_id = 0;
+
+       /* See if there has been given a command line override */
+       if ((reboot_cpu != -1) && (reboot_cpu < nr_cpu_ids) &&
+               cpu_online(reboot_cpu))
+               reboot_cpu_id = reboot_cpu;
+
+       /* Make certain the cpu I'm about to reboot on is online */
+       if (!cpu_online(reboot_cpu_id))
+               reboot_cpu_id = smp_processor_id();
+
+       /* Make certain I only run on the appropriate processor */
+       set_cpus_allowed_ptr(current, cpumask_of(reboot_cpu_id));
+
 	/*
 	 * Stop all of the others. Also disable the local irq to
 	 * not receive the per-cpu timer interrupt which may trigger
-- 
1.8.3.1

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