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Fix preempt imbalance in kvm_timer_init()

PATCH In review Thomas Meyer 2 participants 2 messages Dec 9, 2010 – Dec 12, 2010

Subsystems (3)
x86 KVM KVM x86
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Thomas Meyer

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#0 lore raw

PATCH 1/1 Fix preempt imbalance in kvm_timer_init()

Signed-off-by Thomas Meyer <[email protected]>
---
 arch/x86/kvm/x86.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
arch/x86/kvm/x86.c +3 -2
index cdac9e5..2609c3d 100644
@@ -4561,7 +4561,7 @@ static struct notifier_block kvmclock_cpu_notifier_block = {
 
 static void kvm_timer_init(void)
 {
-	int cpu;
+	int cpu = get_cpu();
 
 	max_tsc_khz = tsc_khz;
 	register_hotcpu_notifier(&kvmclock_cpu_notifier_block);

@@ -4569,13 +4569,14 @@ static void kvm_timer_init(void)
 #ifdef CONFIG_CPU_FREQ
 		struct cpufreq_policy policy;
 		memset(&policy, 0, sizeof(policy));
-		cpufreq_get_policy(&policy, get_cpu());
+		cpufreq_get_policy(&policy, cpu);
 		if (policy.cpuinfo.max_freq)
 			max_tsc_khz = policy.cpuinfo.max_freq;
 #endif
 		cpufreq_register_notifier(&kvmclock_cpufreq_notifier_block,
 					  CPUFREQ_TRANSITION_NOTIFIER);
 	}
+	put_cpu();
 	pr_debug("kvm: max_tsc_khz = %ld\n", max_tsc_khz);
 	for_each_online_cpu(cpu)
 		smp_call_function_single(cpu, tsc_khz_changed, NULL, 1);
Signature · 1 line
1.7.3.3
#1 lore raw
Quoted 10 lines · Thomas Meyer
Signed-off-by Thomas Meyer<[email protected]>
---
  arch/x86/kvm/x86.c |    5 +++--
  1 files changed, 3 insertions(+), 2 deletions(-)
arch/x86/kvm/x86.c +0 -0
index cdac9e5..2609c3d 100644

arch/x86/kvm/x86.c static struct notifier_block kvmclock_cpu_notifier_block = { · line 4567

Quoted 8 lines
arch/x86/kvm/x86.c +1 -1
@@ -4561,7 +4561,7 @@ static struct notifier_block kvmclock_cpu_notifier_block = {
 
  static void kvm_timer_init(void)
  {
-	int cpu;
+	int cpu = get_cpu();
 
  	max_tsc_khz = tsc_khz;
  	register_hotcpu_notifier(&kvmclock_cpu_notifier_block);

This eventually takes a mutex (in cpu_maps_update_begin()), so it can't be called with preemption disabled.

Quoted 16 lines
arch/x86/kvm/x86.c +2 -1
@@ -4569,13 +4569,14 @@ static void kvm_timer_init(void)
  #ifdef CONFIG_CPU_FREQ
  		struct cpufreq_policy policy;
  		memset(&policy, 0, sizeof(policy));
-		cpufreq_get_policy(&policy, get_cpu());
+		cpufreq_get_policy(&policy, cpu);
  		if (policy.cpuinfo.max_freq)
  			max_tsc_khz = policy.cpuinfo.max_freq;
  #endif
  		cpufreq_register_notifier(&kvmclock_cpufreq_notifier_block,
  					  CPUFREQ_TRANSITION_NOTIFIER);
  	}
+	put_cpu();
  	pr_debug("kvm: max_tsc_khz = %ld\n", max_tsc_khz);
  	for_each_online_cpu(cpu)
  		smp_call_function_single(cpu, tsc_khz_changed, NULL, 1);
Signature · 1 line
error compiling committee.c: too many arguments to function