xen/evtchn: don't do unbind_from_irqhandler under spinlock
unbind_from_irqhandler can end up doing /proc operations, which can't
happen under a spinlock. So before removing the IRQ handler,
disable the irq under the port_user lock (masking the underlying event
channel and making sure the irq handler isn't running concurrently and
won't start running), then remove the handler without the lock.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index f79ac5c..6a3a129 100644
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -375,10 +375,12 @@
break;
}
- evtchn_unbind_from_user(u, unbind.port);
+ disable_irq(irq_from_evtchn(unbind.port));
spin_unlock_irq(&port_user_lock);
+ evtchn_unbind_from_user(u, unbind.port);
+
rc = 0;
break;
}
@@ -484,11 +486,18 @@
if (get_port_user(i) != u)
continue;
- evtchn_unbind_from_user(get_port_user(i), i);
+ disable_irq(irq_from_evtchn(i));
}
spin_unlock_irq(&port_user_lock);
+ for (i = 0; i < NR_EVENT_CHANNELS; i++) {
+ if (get_port_user(i) != u)
+ continue;
+
+ evtchn_unbind_from_user(get_port_user(i), i);
+ }
+
kfree(u->name);
kfree(u);