On 03/19/2011 01:51 PM, Thomas Gleixner wrote:
On Fri, 18 Mar 2011, David Daney wrote:
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -178,6 +178,12 @@ static inline int irq_has_action(unsigned int irq)
return desc->action != NULL;
}
+/* Test to see if the irq is currently enabled */
+static inline int irq_desc_is_enabled(struct irq_desc *desc)
+{
+ return desc->depth == 0;
+}
That want's to go into kernel/irq/internal.h
I think I need to use this in my irq_chip.irq_unmask method.
Consider this:
CPU0 CPU1
handle_level_irq
lock
mask
handle_irq_event
unlock
.
. disable_irq
.
lock
unmask
unlock
I need to know in my .unmask method if the interrupt has been disabled.
If it has, I will not re-enable (unmask)it.
#ifndef CONFIG_GENERIC_HARDIRQS_NO_COMPAT
static inline int irq_balancing_disabled(unsigned int irq)
{
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index c9c0601..40736f7 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -689,3 +689,38 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
irq_put_desc_unlock(desc, flags);
}
+
+void irq_cpu_online(unsigned int irq)
Odd function name. It does not reflect that this is for per cpu
interrupts. So something like irq_xxx_per_cpu_irq(irq)
might be a bit more descriptive.
I am using it for per cpu interrupts, but I didn't want to impose that
policy on others.
+{
So that's called on the cpu which goes online, right?
Yes.
I wonder whether we can add any sanity check to verify this.
Though I would not worry too much about it. Calling that from a cpu
which is not going offline should have enough nasty side effects that
it's noticed during development. :)
+ unsigned long flags;
+ struct irq_chip *chip;
+ struct irq_desc *desc = irq_to_desc(irq);
Needs to check !desc
OK.
+ raw_spin_lock_irqsave(&desc->lock, flags);
+
+ chip = irq_data_get_irq_chip(&desc->irq_data);
+
+ if (chip&& chip->irq_cpu_online)
+ chip->irq_cpu_online(&desc->irq_data,
+ irq_desc_is_enabled(desc));
+
+ raw_spin_unlock_irqrestore(&desc->lock, flags);
+}
+
+void irq_cpu_offline(unsigned int irq)
+{
+ unsigned long flags;
+ struct irq_chip *chip;
+ struct irq_desc *desc = irq_to_desc(irq);
See above.
Style nit: I prefer ordering:
+ struct irq_desc *desc = irq_to_desc(irq);
+ struct irq_chip *chip;
+ unsigned long flags;
For some reason, probably because I'm used to it, that's easier to
parse. But don't worry about that, I'll turn it around before sticking
it into git. :)
Otherwise I'm fine with the approach itself.
Though one question remains: should we just iterate over the irq space
and call the online/offline callbacks when available instead of having
the arch code do the iteration.
That would be good I think, especially for sparse irqs.
In the case of the CPU going offline, the .irq_cpu_offline() may need to
adjust the affinity so that the irq no longer has affinity for the
off-lined CPU.
This is something needed even for non-per-cpu interrupts. Also I would
need a way to call irq_set_affinity() while holding the desc->lock.
David Daney
