[PATCH 1/2] IRQ_NOPROBE helper functions

Ralf Baechle
2008-01-29T11:21:04Z

Probing non-ISA interrupts using the handle_percpu_irq as their handle_irq
method may crash the system because handle_percpu_irq does not check
IRQ_WAITING. This for example hits the MIPS Qemu configuration.

This patch provides two helper functions set_irq_noprobe and set_irq_probe
to set rsp. clear the IRQ_NOPROBE flag. The only current caller is MIPS
code but this really belongs into generic code.

As an aside, interrupt probing these days has become a mostly obsolete if
not dangerous art. I think Linux interrupts should be changed to default
to non-probing but that's subject of this patch.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

include/linux/irq.h | 3 +++
kernel/irq/chip.c | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+)

Index: linux-mips/include/linux/irq.h
===================================================================
--- linux-mips.orig/include/linux/irq.h
+++ linux-mips/include/linux/irq.h
@@ -367,6 +367,9 @@ set_irq_chained_handler(unsigned int irq
__set_irq_handler(irq, handle, 1, NULL);
}

+extern void set_irq_noprobe(unsigned int irq);
+extern void set_irq_probe(unsigned int irq);
+
/* Handle dynamic irq creation and destruction */
extern int create_irq(void);
extern void destroy_irq(unsigned int irq);
Index: linux-mips/kernel/irq/chip.c
===================================================================
--- linux-mips.orig/kernel/irq/chip.c
+++ linux-mips/kernel/irq/chip.c
@@ -589,3 +589,39 @@ set_irq_chip_and_handler_name(unsigned i
set_irq_chip(irq, chip);
__set_irq_handler(irq, handle, 0, name);
}
+
+void __init set_irq_noprobe(unsigned int irq)
+{
+ struct irq_desc *desc;
+ unsigned long flags;
+
+ if (irq >= NR_IRQS) {
+ printk(KERN_ERR "Trying to mark IRQ%d non-probeable\n", irq);
+
+ return;
+ }
+
+ desc = irq_desc + irq;
+
+ spin_lock_irqsave(&desc->lock, flags);
+ desc->status |= IRQ_NOPROBE;
+ spin_unlock_irqrestore(&desc->lock, flags);
+}
+
+void __init set_irq_probe(unsigned int irq)
+{
+ struct irq_desc *desc;
+ unsigned long flags;
+
+ if (irq >= NR_IRQS) {
+ printk(KERN_ERR "Trying to mark IRQ%d probeable\n", irq);
+
+ return;
+ }
+
+ desc = irq_desc + irq;
+
+ spin_lock_irqsave(&desc->lock, flags);
+ desc->status &= ~IRQ_NOPROBE;
+ spin_unlock_irqrestore(&desc->lock, flags);
+}