From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
When the primary handler of an interrupt which is marked IRQ_ONESHOT
does not wake the thread (e.g. due to a spurious interrupt) then
nothing ever unmasks the interrupt line again. Handle it gracefully.
Cc: stable-rt@xxxxxxxxxxxxxxx
Reported-by: Lothar Wassmann <lw@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
kernel/irq/chip.c | 25 +++++++++++++++++++++++--
1 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index dc5114b..3322a34 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -312,6 +312,24 @@ out_unlock:
}
EXPORT_SYMBOL_GPL(handle_simple_irq);
+/*
+ * Called unconditionally from handle_level_irq() and only for oneshot
+ * interrupts from handle_fasteoi_irq()
+ */
+static void cond_unmask_irq(struct irq_desc *desc)
+{
+ /*
+ * We need to unmask in the following cases:
+ * - Standard level irq (IRQF_ONESHOT is not set)
+ * - Oneshot irq which did not wake the thread (caused by a
+ * spurious interrupt or a primary handler handling it
+ * completely).
+ */
+ if (!irqd_irq_disabled(&desc->irq_data) &&
+ irqd_irq_masked(&desc->irq_data) && !desc->threads_oneshot)
+ unmask_irq(desc);
+}
+
/**
* handle_level_irq - Level type irq handler
* @irq: the interrupt number
@@ -344,8 +362,8 @@ handle_level_irq(unsigned int irq, struct irq_desc *desc)
handle_irq_event(desc);
- if (!irqd_irq_disabled(&desc->irq_data) && !(desc->istate & IRQS_ONESHOT))
- unmask_irq(desc);
+ cond_unmask_irq(desc);
+
out_unlock:
raw_spin_unlock(&desc->lock);
}
@@ -399,6 +417,9 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
preflow_handler(desc);
handle_irq_event(desc);
+ if (desc->istate & IRQS_ONESHOT)
+ cond_unmask_irq(desc);
+
out_eoi:
desc->irq_data.chip->irq_eoi(&desc->irq_data);
out_unlock:
--
1.7.8.3
--
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