On Tue, 26 Sep 2017, Thomas Gleixner wrote:

On Mon, 25 Sep 2017, Thomas Gleixner wrote:

quoted

On Thu, 7 Sep 2017, Paul Burton wrote:

quoted

Up until now per_cpu_devid interrupts have not supported sharing. On
MIPS we have some percpu interrupts which are shared in many systems -
a single CPU interrupt line may be used to indicate a timer interrupt,
performance counter interrupt or fast debug channel interrupt. We have
up until now supported this with a series of hacks, wherein drivers call
each other's interrupt handlers & our MIPS GIC irqchip driver includes a
hack which configures the interrupt(s) for all CPUs. In order to allow
this mess to be cleaned up, this patch introduces support for shared
per_cpu_devid interrupts.

The major portion of this is supporting per_cpu_devid interrupts in
__handle_irq_event_percpu() and then making use of this, via
handle_irq_event_percpu(), from handler_percpu_devif_irq() to invoke the
handler for all actions associated with the shared interrupt. This does
have a few side effects worth noting:

 - per_cpu_devid interrupts will now add to the entropy pool via
   add_interrupt_randomness(), where they previously did not.

 - per_cpu_devid interrupts will record timings when IRQS_TIMINGS is
   set, via record_irq_time(), where they previously did not.

 - per_cpu_devid interrupts will handle an IRQ_WAKE_THREAD return from
   their handlers to wake a thread, where they previously did not.

That's broken because it lacks the magic synchronization which is described
in the comment in __irq_wake_thread().

Aside of that to make that work at all would require per cpu threads and
not a single systemwide thread.

also request_threaded_irq() will yell at you if you call it for a percpu
interrupt.

Care to rewrite the changelog and make that conditional:

 irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags)
 {
+	bool percpu = irq_settings_is_per_cpu_devid(desc);
 	irqreturn_t retval = IRQ_NONE;
 	unsigned int irq = desc->irq_data.irq;
 	struct irqaction *action;

@@ -142,9 +143,15 @@ irqreturn_t __handle_irq_event_percpu(st
 
 	for_each_action_of_desc(desc, action) {
 		irqreturn_t res;
+		void *dev_id;
+
+		if (!percpu))
+			dev_id = action->dev_id;
+		else
+			dev_id = raw_cpu_ptr(action->percpu_dev_id);
 

Thanks,

	tglx