xen/spinlock: Check against default value of -1 for IRQ line.

The default (uninitialized) value of the IRQ line is -1.
Check if we already have allocated an spinlock interrupt line
and if somebody is trying to do it again. Also set it to -1
when we offline the CPU.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index f7a080ef03543e190b2475be811dd601d8b7c53d..47ae032f8d9779df696835554343d39fdd21001a 100644 (file)
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -364,6 +364,9 @@ void __cpuinit xen_init_lock_cpu(int cpu)
        int irq;
        const char *name;
 
+       WARN(per_cpu(lock_kicker_irq, cpu) > 0, "spinlock on CPU%d exists on IRQ%d!\n",
+            cpu, per_cpu(lock_kicker_irq, cpu));
+
        name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
        irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
                                     cpu,
@@ -383,6 +386,7 @@ void __cpuinit xen_init_lock_cpu(int cpu)
 void xen_uninit_lock_cpu(int cpu)
 {
        unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
+       per_cpu(lock_kicker_irq, cpu) = -1;
 }
 
 void __init xen_init_spinlocks(void)