On pirq enable/disable we fully unregister/reregister with Xen. This

causes the underlying IRQ to be properly masked/unmasked, thus
avoiding deadlock scenarios if the IRQ is not EOIed.
Based on a patch by Chris Lalancette <clalance@redhat.com>
Signed-off-by: Keir Fraser <keir.fraser@eu.citrix.com>
linux-2.6.18-xen changeset:   313:51b2b0d0921c3aefb18e16a2eda68a5c3133e949
linux-2.6.18-xen date:        Wed Nov 21 09:41:11 2007 +0000

diff --git a/linux-2.6-xen-sparse/drivers/xen/core/evtchn.c b/linux-2.6-xen-sparse/drivers/xen/core/evtchn.c
index fda12a3f32ab8b2c526bac3d9f467966ef771de0..7661bbf1be820b1a44160ae0ebe0de5854c7fd67 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/core/evtchn.c
+++ b/linux-2.6-xen-sparse/drivers/xen/core/evtchn.c
@@ -778,20 +778,11 @@ static void shutdown_pirq(unsigned int irq)
 
 static void enable_pirq(unsigned int irq)
 {
-       int evtchn = evtchn_from_irq(irq);
-
-       if (VALID_EVTCHN(evtchn)) {
-               unmask_evtchn(evtchn);
-               pirq_unmask_notify(irq_to_pirq(irq));
-       }
+       startup_pirq(irq);
 }
 
 static void disable_pirq(unsigned int irq)
 {
-       int evtchn = evtchn_from_irq(irq);
-
-       if (VALID_EVTCHN(evtchn))
-               mask_evtchn(evtchn);
 }
 
 static void ack_pirq(unsigned int irq)
@@ -810,7 +801,10 @@ static void end_pirq(unsigned int irq)
 {
        int evtchn = evtchn_from_irq(irq);
 
-       if (VALID_EVTCHN(evtchn) && !(irq_desc[irq].status & IRQ_DISABLED)) {
+       if ((irq_desc[irq].status & (IRQ_DISABLED|IRQ_PENDING)) ==
+           (IRQ_DISABLED|IRQ_PENDING)) {
+               shutdown_pirq(irq);
+       } else if (VALID_EVTCHN(evtchn)) {
                unmask_evtchn(evtchn);
                pirq_unmask_notify(irq_to_pirq(irq));
        }