PV multiconsole bug during resume.

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

So .. we used to have in the event.c a spin_lock to protect the
irq_mapping_update_lock, but with git commit  773659483685d652970583384a0294948e57f8b3
"xen/irq: Alter the locking to use a mutex instead of a spinlock."
I changed it to a mutex b/c we keept on getting WARNs.

But now I get this when I resume a PVHVM guest:

Grant tables using version 2 layout.
BUG: sleeping function called from invalid context at /home/konrad/ssd/linux/kernel/mutex.c:85
in_atomic(): 1, irqs_disabled(): 1, pid: 6, name: migration/0
Pid: 6, comm: migration/0 Tainted: G           O 3.4.0upstream-00113-g598ff45-dirty #1
Call Trace:
 [<ffffffff8109830a>] __might_sleep+0xda/0x100
 [<ffffffff815a47f7>] mutex_lock+0x27/0x50
 [<ffffffff81311ea6>] rebind_evtchn_irq+0x36/0x90
 [<ffffffff81341bfc>] xen_console_resume+0x5c/0x60
 [<ffffffff81313fea>] xen_suspend+0x8a/0xb0
 [<ffffffff810d42f3>] stop_machine_cpu_stop+0xa3/0xf0
 [<ffffffff810d4250>] ? stop_one_cpu_nowait+0x50/0x50
 [<ffffffff810d3f81>] cpu_stopper_thread+0xf1/0x1c0
 [<ffffffff815a5be6>] ? __schedule+0x3c6/0x760
 [<ffffffff815a6bb9>] ? _raw_spin_unlock_irqrestore+0x19/0x30
 [<ffffffff810d3e90>] ? res_counter_charge+0x150/0x150
 [<ffffffff8108e636>] kthread+0x96/0xa0
 [<ffffffff815aeb24>] kernel_thread_helper+0x4/0x10
 [<ffffffff815a7138>] ? retint_restore_args+0x5/0x6
 [<ffffffff815aeb20>] ? gs_change+0x13/0x13
PM: noirq restore of devices complete after 0.163 msecs


Any ideas?