linux-kernel - [PATCH] fix BUG using smp_processor_id() in preemptible thermal_throttle_add

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Date:	Fri, 20 Aug 2010 10:36:34 +0300
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	"Roedel, Joerg" <Joerg.Roedel@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] fix BUG using smp_processor_id() in preemptible
 thermal_throttle_add_dev

Fix: using smp_processor_id() in preemptible thermal_throttle_add_dev.
We know the cpu number when calling thermal_throttle_add_dev, so we can
remove smp_processor_id call in thermal_throttle_add_dev by supplying 
the cpu number as argument.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>

---

diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
index c2a8b26..bcd8499 100644
--- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
@@ -202,11 +202,12 @@ static int therm_throt_process(bool new_event, int event, int level)
 
 #ifdef CONFIG_SYSFS
 /* Add/Remove thermal_throttle interface for CPU device: */
-static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev)
+static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev,
+				unsigned int cpu)
 {
 	int err;
-	struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
-
+	struct cpuinfo_x86 *c = &cpu_data(cpu);
+	
 	err = sysfs_create_group(&sys_dev->kobj, &thermal_attr_group);
 	if (err)
 		return err;
@@ -251,7 +252,7 @@ thermal_throttle_cpu_callback(struct notifier_block *nfb,
 	case CPU_UP_PREPARE:
 	case CPU_UP_PREPARE_FROZEN:
 		mutex_lock(&therm_cpu_lock);
-		err = thermal_throttle_add_dev(sys_dev);
+		err = thermal_throttle_add_dev(sys_dev, cpu);
 		mutex_unlock(&therm_cpu_lock);
 		WARN_ON(err);
 		break;
@@ -287,7 +288,7 @@ static __init int thermal_throttle_init_device(void)
 #endif
 	/* connect live CPUs to sysfs */
 	for_each_online_cpu(cpu) {
-		err = thermal_throttle_add_dev(get_cpu_sysdev(cpu));
+		err = thermal_throttle_add_dev(get_cpu_sysdev(cpu), cpu);
 		WARN_ON(err);
 	}
 #ifdef CONFIG_HOTPLUG_CPU

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