linux-kernel - Re: [patch 2/4] introduce the mechanism of disabling cpu hotplug control

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Message-ID: <20061107174024.B5401@unix-os.sc.intel.com>
Date:	Tue, 7 Nov 2006 17:40:25 -0800
From:	"Siddha, Suresh B" <suresh.b.siddha@...el.com>
To:	ak@...e.de, akpm@...l.org
Cc:	shaohua.li@...el.com, linux-kernel@...r.kernel.org,
	discuss@...-64.org, ashok.raj@...el.com, suresh.b.siddha@...el.com
Subject: Re: [patch 2/4] introduce the mechanism of disabling cpu hotplug control

Add 'cpu_hotplug_no_control' and when set, the hotplug control file("online")
will not be added under /sys/devices/system/cpu/cpuX/

Next patch doing PCI quirks will use this.

Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
---

diff --git a/arch/i386/kernel/topology.c b/arch/i386/kernel/topology.c
index 07d6da3..9b766e7 100644
--- a/arch/i386/kernel/topology.c
+++ b/arch/i386/kernel/topology.c
@@ -40,14 +40,22 @@ int arch_register_cpu(int num)
 	 * restrictions and assumptions in kernel. This basically
 	 * doesnt add a control file, one cannot attempt to offline
 	 * BSP.
+	 *
+	 * Also certain PCI quirks require to remove this control file
+	 * for all CPU's.
 	 */
+#ifdef CONFIG_HOTPLUG_CPU
+	if (!num || cpu_hotplug_no_control)
+#else
 	if (!num)
+#endif
 		cpu_devices[num].cpu.no_control = 1;
 
 	return register_cpu(&cpu_devices[num].cpu, num);
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
+int cpu_hotplug_no_control;
 
 void arch_unregister_cpu(int num) {
 	return unregister_cpu(&cpu_devices[num].cpu);
diff --git a/include/asm-i386/cpu.h b/include/asm-i386/cpu.h
index b1bc7b1..3c5da33 100644
--- a/include/asm-i386/cpu.h
+++ b/include/asm-i386/cpu.h
@@ -13,6 +13,7 @@ struct i386_cpu {
 extern int arch_register_cpu(int num);
 #ifdef CONFIG_HOTPLUG_CPU
 extern void arch_unregister_cpu(int);
+extern int cpu_hotplug_no_control;
 #endif
 
 DECLARE_PER_CPU(int, cpu_state);
-
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