[PATCH 6/6] kvm,powerpc: Serialize wq active checks in ops->vcpu_kick

From: Davidlohr Bueso
Date: Tue Sep 05 2017 - 15:01:26 EST


Particularly because kvmppc_fast_vcpu_kick_hv() is a callback,
ensure that we properly serialize wq active checks in order to
avoid potentially missing a wakeup due to racing with the waiter
side.

Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
---
arch/powerpc/kvm/book3s_hv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 359c79cdf0cc..7ffc757ef978 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -181,7 +181,7 @@ static void kvmppc_fast_vcpu_kick_hv(struct kvm_vcpu *vcpu)
struct swait_queue_head *wqp;

wqp = kvm_arch_vcpu_wq(vcpu);
- if (swait_active(wqp)) {
+ if (swq_has_sleeper(wqp)) {
swake_up(wqp);
++vcpu->stat.halt_wakeup;
}
--
2.12.0