Drivers registering IRQ handlers with SA_SHIRQ really ought to be able
to handle an interrupt happening before request_irq() returns. They also
ought to be able to handle an interrupt happening during the start of
their call to free_irq(). Let's test that hypothesis....
Signed-off-by: David Woodhouse <[email protected]>
I'm not wonderfully happy with the faked pt_regs, but I think it ought
to be OK like that.
--- linux-2.6.14/lib//Kconfig.debug~ 2005-12-19 00:57:18.000000000 +0000
+++ linux-2.6.14/lib//Kconfig.debug 2005-12-22 11:37:27.000000000 +0000
@@ -176,6 +176,15 @@ config DEBUG_VM
If unsure, say N.
+config SHARE_ME_HARDER
+ bool "Debug shared IRQ handlers"
+ depends on GENERIC_HARDIRQS
+ help
+ Enable this to generate a spurious interrupt as soon as a shared interrupt
+ handler is registered, and just before one is deregistered. Drivers ought
+ to be able to handle interrupts coming in at those some; some don't and
+ need to be caught.
+
config FRAME_POINTER
bool "Compile the kernel with frame pointers"
depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML)
--- linux-2.6.14/kernel/irq/manage.c~ 2005-12-19 00:57:18.000000000 +0000
+++ linux-2.6.14/kernel/irq/manage.c 2005-12-22 11:24:40.000000000 +0000
@@ -238,6 +238,10 @@ int setup_irq(unsigned int irq, struct i
return 0;
}
+#ifdef CONFIG_SHARE_ME_HARDER
+static struct pt_regs shirq_fakeregs;
+#endif
+
/**
* free_irq - free an interrupt
* @irq: Interrupt line to free
@@ -257,6 +261,7 @@ void free_irq(unsigned int irq, void *de
struct irq_desc *desc;
struct irqaction **p;
unsigned long flags;
+ irqreturn_t (*handler)(int, void *, struct pt_regs *) = NULL;
if (irq >= NR_IRQS)
return;
@@ -295,6 +300,8 @@ void free_irq(unsigned int irq, void *de
/* Make sure it's not being used on another CPU */
synchronize_irq(irq);
+ if (action->flags & SA_SHIRQ)
+ handler = action->handler;
kfree(action);
return;
}
@@ -302,6 +309,15 @@ void free_irq(unsigned int irq, void *de
spin_unlock_irqrestore(&desc->lock,flags);
return;
}
+#ifdef CONFIG_SHARE_ME_HARDER
+ if (handler) {
+ /* It's a shared IRQ -- the driver ought to be prepared for it to happen
+ even now it's being freed, so let's make sure....
+ We do this after actually deregistering it, to make sure that a 'real'
+ IRQ doesn't run in parallel with our fake. */
+ handler(irq, dev_id, &shirq_fakeregs);
+ }
+#endif
}
EXPORT_SYMBOL(free_irq);
@@ -366,6 +382,16 @@ int request_irq(unsigned int irq,
action->next = NULL;
action->dev_id = dev_id;
+#ifdef CONFIG_SHARE_ME_HARDER
+ if (irqflags & SA_SHIRQ) {
+ /* It's a shared IRQ -- the driver ought to be prepared for it to happen
+ immediately, so let's make sure....
+ We do this before actually registering it, to make sure that a 'real'
+ IRQ doesn't run in parallel with our fake. */
+ handler(irq, dev_id, &shirq_fakeregs);
+ }
+#endif
+
retval = setup_irq(irq, action);
if (retval)
kfree(action);
--
dwmw2
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