Hello Paul Mackerras,
The patch 898b25b202f3: "KVM: PPC: Book3S HV: Simplify dynamic
micro-threading code" from Jun 22, 2017, leads to the following
static checker warning:
arch/powerpc/kvm/book3s_hv.c:3096 kvmppc_run_vcpu()
error: double lock 'spin_lock:&vc->lock'
arch/powerpc/kvm/book3s_hv.c:3183 kvmppc_run_vcpu()
error: double unlock 'spin_lock:&vc->lock'
arch/powerpc/kvm/book3s_hv.c
3062 static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
3063 {
3064 int n_ceded, i;
3065 struct kvmppc_vcore *vc;
3066 struct kvm_vcpu *v;
3067
3068 trace_kvmppc_run_vcpu_enter(vcpu);
3069
3070 kvm_run->exit_reason = 0;
3071 vcpu->arch.ret = RESUME_GUEST;
3072 vcpu->arch.trap = 0;
3073 kvmppc_update_vpas(vcpu);
3074
3075 /*
3076 * Synchronize with other threads in this virtual core
3077 */
3078 vc = vcpu->arch.vcore;
3079 spin_lock(&vc->lock);
^^^^^^^^^^^^^^^^^^^^
Lock
3080 vcpu->arch.ceded = 0;
3081 vcpu->arch.run_task = current;
3082 vcpu->arch.kvm_run = kvm_run;
3083 vcpu->arch.stolen_logged = vcore_stolen_time(vc, mftb());
3084 vcpu->arch.state = KVMPPC_VCPU_RUNNABLE;
3085 vcpu->arch.busy_preempt = TB_NIL;
3086 WRITE_ONCE(vc->runnable_threads[vcpu->arch.ptid], vcpu);
3087 ++vc->n_runnable;
3088
3089 /*
3090 * This happens the first time this is called for a vcpu.
3091 * If the vcore is already running, we may be able to start
3092 * this thread straight away and have it join in.
3093 */
3094 if (!signal_pending(current)) {
3095 if (vc->vcore_state == VCORE_PIGGYBACK) {
3096 if (spin_trylock(&vc->lock)) {
^^^^^^^^^^^^^^^^^^^^^^
Can't ever succeed?
3097 if (vc->vcore_state == VCORE_RUNNING &&
3098 !VCORE_IS_EXITING(vc)) {
3099 kvmppc_create_dtl_entry(vcpu, vc);
3100 kvmppc_start_thread(vcpu, vc);
3101 trace_kvm_guest_enter(vcpu);
3102 }
3103 spin_unlock(&vc->lock);
3104 }
3105 } else if (vc->vcore_state == VCORE_RUNNING &&
3106 !VCORE_IS_EXITING(vc)) {
regards,
dan carpenter
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