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| author | Carsten Otte <cotte@de.ibm.com> | 2008-05-21 13:37:44 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@qumranet.com> | 2008-06-06 21:08:26 +0300 |
| commit | e52b2af541bcb299212a63cfa3e3231618a415be (patch) | |
| tree | 745f8d30f645b052cb96909148f4dfe80d952361 /arch | |
| parent | 1f0d0f094df9a570dfc26d5eb825986b7e165e1d (diff) | |
| download | op-kernel-dev-e52b2af541bcb299212a63cfa3e3231618a415be.zip op-kernel-dev-e52b2af541bcb299212a63cfa3e3231618a415be.tar.gz | |
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.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index fcd1ed8..84a7fed 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) && |
