genirq: Prevent irq storm on migration
move_native_irq() masks and unmasks the interrupt line
unconditionally, but the interrupt line might be masked due to a
threaded oneshot handler in progress. Unmasking the line in that case
can lead to interrupt storms. Observed on PREEMPT_RT.
Originally-from: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org
diff --git a/kernel/irq/migration.c b/kernel/irq/migration.c
index 1d25419..441fd62 100644
--- a/kernel/irq/migration.c
+++ b/kernel/irq/migration.c
@@ -56,6 +56,7 @@
void move_native_irq(int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
+ bool masked;
if (likely(!(desc->status & IRQ_MOVE_PENDING)))
return;
@@ -63,8 +64,15 @@
if (unlikely(desc->status & IRQ_DISABLED))
return;
- desc->irq_data.chip->irq_mask(&desc->irq_data);
+ /*
+ * Be careful vs. already masked interrupts. If this is a
+ * threaded interrupt with ONESHOT set, we can end up with an
+ * interrupt storm.
+ */
+ masked = desc->status & IRQ_MASKED;
+ if (!masked)
+ desc->irq_data.chip->irq_mask(&desc->irq_data);
move_masked_irq(irq);
- desc->irq_data.chip->irq_unmask(&desc->irq_data);
+ if (!masked)
+ desc->irq_data.chip->irq_unmask(&desc->irq_data);
}
-
