Make the code reusable. If the timer was already pending, we shouldn't be waiting in a queue, so wake_up can be skipped, simplifying the path.
There is no 'reinject' case => the comment is removed. Current race behaves correctly. Signed-off-by: Radim Krčmář <[email protected]> --- Not sure about the FIXME, and it might motivate someone to redo the implicit checking as well :) arch/x86/kvm/lapic.c | 37 +++++++++++++++++++++---------------- 1 file changed, 21 insertions(+), 16 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index b8345dd..a3cf68b 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1034,6 +1034,26 @@ static void update_divide_count(struct kvm_lapic *apic) apic->divide_count); } +static void apic_timer_expired(struct kvm_lapic *apic) +{ + struct kvm_vcpu *vcpu = apic->vcpu; + wait_queue_head_t *q = &vcpu->wq; + + /* + * Note: KVM_REQ_PENDING_TIMER is implicitly checked in + * vcpu_enter_guest. + */ + if (atomic_read(&apic->lapic_timer.pending)) + return; + + atomic_inc(&apic->lapic_timer.pending); + /* FIXME: this code should not know anything about vcpus */ + kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu); + + if (waitqueue_active(q)) + wake_up_interruptible(q); +} + static void start_apic_timer(struct kvm_lapic *apic) { ktime_t now; @@ -1538,23 +1558,8 @@ static enum hrtimer_restart apic_timer_fn(struct hrtimer *data) { struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer); struct kvm_lapic *apic = container_of(ktimer, struct kvm_lapic, lapic_timer); - struct kvm_vcpu *vcpu = apic->vcpu; - wait_queue_head_t *q = &vcpu->wq; - /* - * There is a race window between reading and incrementing, but we do - * not care about potentially losing timer events in the !reinject - * case anyway. Note: KVM_REQ_PENDING_TIMER is implicitly checked - * in vcpu_enter_guest. - */ - if (!atomic_read(&ktimer->pending)) { - atomic_inc(&ktimer->pending); - /* FIXME: this code should not know anything about vcpus */ - kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu); - } - - if (waitqueue_active(q)) - wake_up_interruptible(q); + apic_timer_expired(apic); if (lapic_is_periodic(apic)) { hrtimer_add_expires_ns(&ktimer->timer, ktimer->period); -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
