[Xen-devel] [PATCH v4 3/3] xen/arm: don't try to re-register vcpu_info on cpu_hotplug.

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Call disable_percpu_irq on CPU_DYING and enable_percpu_irq when the cpu
is coming up.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

---

Changes in v4:
- use goto
- call disable_percpu_irq on CPU_DYING

Changes in v3:
- call disable_percpu_irq on CPU_DYING
- call enable_percpu_irq even when VCPUOP_register_vcpu_info has already
been called

Changes in v2:
- better comment
---
 arch/arm/xen/enlighten.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 6c09cc4..1efa22b 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -93,6 +93,14 @@ static void xen_percpu_init(void)
        int err;
        int cpu = get_cpu();
 
+       /* 
+        * VCPUOP_register_vcpu_info cannot be called twice for the same
+        * vcpu, so if vcpu_info is already registered, just get out. This
+        * can happen with cpu-hotplug.
+        */
+       if (per_cpu(xen_vcpu, cpu) != NULL)
+               goto after_register_vcpu_info;
+
        pr_info("Xen: initializing cpu%d\n", cpu);
        vcpup = per_cpu_ptr(xen_vcpu_info, cpu);
 
@@ -103,6 +111,7 @@ static void xen_percpu_init(void)
        BUG_ON(err);
        per_cpu(xen_vcpu, cpu) = vcpup;
 
+after_register_vcpu_info:
        enable_percpu_irq(xen_events_irq, 0);
        put_cpu();
 }
@@ -131,6 +140,9 @@ static int xen_cpu_notification(struct notifier_block *self,
        case CPU_STARTING:
                xen_percpu_init();
                break;
+       case CPU_DYING:
+               disable_percpu_irq(xen_events_irq);
+               break;
        default:
                break;
        }
-- 
1.7.10.4


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