[Xen-devel] [PATCH v3] Clear IRQ_GUEST in irq_desc->status when setting action to NULL.

[Igor Mammedov <imammedo@xxxxxxxxxx>]

Looking more closely at usage of action field with relation to
IRQ_GUEST flag. It appears that set IRQ_GUEST implies that action
is not NULL. As result it is not safe to set action to NULL and
leave IRQ_GUEST set.

Hence IRQ_GUEST should be cleared in dynamic_irq_cleanup where
action is set to NULL.

An addition remove BUGON at __pirq_guest_unbind that appears to be
bogus and not needed anymore.

Thanks Paolo Bonzini for NACKing previous patch, and pointing at the
correct solution.

Please review.

Signed-off-by: Igor Mammedov <imammedo@xxxxxxxxxx>

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -192,6 +192,7 @@ static void dynamic_irq_cleanup(unsigned
 
     spin_lock_irqsave(&desc->lock, flags);
     desc->status  |= IRQ_DISABLED;
+    desc->status  &= ~IRQ_GUEST;
     desc->handler->shutdown(irq);
     action = desc->action;
     desc->action  = NULL;
@@ -1465,8 +1466,6 @@ static irq_guest_action_t *__pirq_guest_
     cpumask_t           cpu_eoi_map;
     int                 i;
 
-    BUG_ON(!(desc->status & IRQ_GUEST));
-
     action = (irq_guest_action_t *)desc->action;
     irq = desc - irq_desc;
 

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