From 4c0b4bc60f95de4741c89b41174760258343f091 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Wed, 13 Sep 2017 13:08:24 -0700 Subject: [PATCH] kvm,mips: Fix potential swait_active() races For example, the following could occur, making us miss a wakeup: CPU0 CPU1 kvm_vcpu_block kvm_mips_comparecount_func [L] swait_active(&vcpu->wq) [S] prepare_to_swait(&vcpu->wq) [L] if (!kvm_vcpu_has_pending_timer(vcpu)) schedule() [S] queue_timer_int(vcpu) Ensure that the swait_active() check is not hoisted over the interrupt. Signed-off-by: Davidlohr Bueso Signed-off-by: Paolo Bonzini --- arch/mips/kvm/mips.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c index bce2a6431430..d535edc01434 100644 --- a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -514,7 +514,7 @@ int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, dvcpu->arch.wait = 0; - if (swait_active(&dvcpu->wq)) + if (swq_has_sleeper(&dvcpu->wq)) swake_up(&dvcpu->wq); return 0; @@ -1179,7 +1179,7 @@ static void kvm_mips_comparecount_func(unsigned long data) kvm_mips_callbacks->queue_timer_int(vcpu); vcpu->arch.wait = 0; - if (swait_active(&vcpu->wq)) + if (swq_has_sleeper(&vcpu->wq)) swake_up(&vcpu->wq); }