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[PATCH for-4.22 v2 3/4] xen/irq: handle IRQ being disabled while executing its handler
- To: xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
- Date: Mon, 29 Jun 2026 11:45:30 +0200
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- Cc: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>, Roger Pau Monne <roger.pau@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Teddy Astie <teddy.astie@xxxxxxxxxx>
- Delivery-date: Mon, 29 Jun 2026 09:46:46 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
It's possible for IRQ_DISABLED to be set while running the handler
execution loop in do_IRQ(). Such disabling can be done by the handler
itself, or from a remote CPU.
Check for IRQ_DISABLED not being set in the loop condition, as to not
execute the handler if the IRQ has been disabled.
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
I wanted to add a fixes tag, but this has been broken since forever, and
hence I should add:
Fixes: 4676bbf96dc8 ("bitkeeper revision 1.2 (3ddb79c9KusG02eh7i-uXkgY0IksKA)")
Which is pointless IMO.
---
xen/arch/x86/irq.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 739fc04bd16a..2082ad489d74 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -2088,7 +2088,9 @@ void do_IRQ(struct cpu_user_regs *regs)
desc->status |= IRQ_INPROGRESS;
action = desc->action;
- while ( desc->status & IRQ_PENDING )
+
+ /* Deal with IRQ_DISABLED being set while inside the loop body. */
+ while ( (desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING )
{
desc->status &= ~IRQ_PENDING;
spin_unlock_irq(&desc->lock);
--
2.53.0
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