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authorCarsten Otte <cotte@de.ibm.com>2008-05-21 13:37:44 +0200
committerAvi Kivity <avi@qumranet.com>2008-06-06 21:08:26 +0300
commite52b2af541bcb299212a63cfa3e3231618a415be (patch)
tree745f8d30f645b052cb96909148f4dfe80d952361 /arch
parent1f0d0f094df9a570dfc26d5eb825986b7e165e1d (diff)
KVM: s390: Fix race condition in kvm_s390_handle_wait
The call to add_timer was issued before local_int.lock was taken and before timer_due was set to 0. If the timer expires before the lock is being taken, the timer function will set timer_due to 1 and exit before the vcpu falls asleep. Depending on other external events, the vcpu might sleep forever. This fix pulls setting timer_due to the beginning of the function before add_timer, which ensures correct behavior. Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/s390/kvm/interrupt.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index fcd1ed8015c..84a7fed4cd4 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -339,6 +339,11 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
if (kvm_cpu_has_interrupt(vcpu))
return 0;
+ __set_cpu_idle(vcpu);
+ spin_lock_bh(&vcpu->arch.local_int.lock);
+ vcpu->arch.local_int.timer_due = 0;
+ spin_unlock_bh(&vcpu->arch.local_int.lock);
+
if (psw_interrupts_disabled(vcpu)) {
VCPU_EVENT(vcpu, 3, "%s", "disabled wait");
__unset_cpu_idle(vcpu);
@@ -366,8 +371,6 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
no_timer:
spin_lock_bh(&vcpu->arch.local_int.float_int->lock);
spin_lock_bh(&vcpu->arch.local_int.lock);
- __set_cpu_idle(vcpu);
- vcpu->arch.local_int.timer_due = 0;
add_wait_queue(&vcpu->arch.local_int.wq, &wait);
while (list_empty(&vcpu->arch.local_int.list) &&
list_empty(&vcpu->arch.local_int.float_int->list) &&