On Fri, Dec 9, 2022 at 9:22 AM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > On Thu, Dec 08, 2022, Hao Peng wrote: > > From: Peng Hao <flyingpeng@xxxxxxxxxxx> > > > > kvm->irq_routing is protected by kvm->irq_srcu. > > > > Signed-off-by: Peng Hao <flyingpeng@xxxxxxxxxxx> > > --- > > virt/kvm/irqchip.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c > > index 1e567d1f6d3d..90f54f04e37c 100644 > > --- a/virt/kvm/irqchip.c > > +++ b/virt/kvm/irqchip.c > > @@ -216,7 +216,8 @@ int kvm_set_irq_routing(struct kvm *kvm, > > } > > > > mutex_lock(&kvm->irq_lock); > > - old = rcu_dereference_protected(kvm->irq_routing, 1); > > + old = srcu_dereference_check(kvm->irq_routing, &kvm->irq_srcu, > > + lockdep_is_held(&kvm->irq_lock)); > > Readers of irq_routing are protected via kvm->irq_srcu, but this writer is never > called with kvm->irq_srcu held. I do like the of replacing '1' with > lockdep_is_held(&kvm->irq_lock) to document the protection, so what about just > doing that? I.e. > Sorry for the long delay in replying. Although kvm->irq_srcu is not required to protect irq_routing here, this interface function srcu_dereference_check indicates that irq_routing is protected by kvm->irq_srcu in the kvm subsystem. Thanks. > diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c > index 1e567d1f6d3d..77a18b4dc103 100644 > --- a/virt/kvm/irqchip.c > +++ b/virt/kvm/irqchip.c > @@ -216,7 +216,8 @@ int kvm_set_irq_routing(struct kvm *kvm, > } > > mutex_lock(&kvm->irq_lock); > - old = rcu_dereference_protected(kvm->irq_routing, 1); > + old = rcu_dereference_protected(kvm->irq_routing, > + lockdep_is_held(&kvm->irq_lock)); > rcu_assign_pointer(kvm->irq_routing, new); > kvm_irq_routing_update(kvm); > kvm_arch_irq_routing_update(kvm); > > > > rcu_assign_pointer(kvm->irq_routing, new); > > kvm_irq_routing_update(kvm); > > kvm_arch_irq_routing_update(kvm); > > -- > > 2.27.0
