xen/events: Set irq_info->evtchn before binding the channel to CPU in __startup_pirq()

commit 16e6bd59 upstream.

.. because bind_evtchn_to_cpu(evtchn, cpu) will map evtchn to
'info' and pass 'info' down to xen_evtchn_port_bind_to_cpu().
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: Annie Li <annie.li@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
[lizf: Backported to 3.4: adjust filename and context]
Signed-off-by: Zefan Li <lizefan@huawei.com>

drivers/xen/events.c

@@ -563,8 +563,8 @@ static unsigned int __startup_pirq(unsigned int irq)
 	pirq_query_unmask(irq);
 
 	evtchn_to_irq[evtchn] = irq;
-	bind_evtchn_to_cpu(evtchn, 0);
 	info->evtchn = evtchn;
+	bind_evtchn_to_cpu(evtchn, 0);
 
 out:
 	unmask_evtchn(evtchn);