Re: [RFC PATCH] genirq: Avoid unnecessary low level irq function calls

[jeffy]

Hi Thomas,

thanx for your comments.
On 06/26/2017 04:20 PM, Thomas Gleixner wrote:
Jeffy,

On Mon, 26 Jun 2017, Jeffy Chen wrote:
  void irq_enable(struct irq_desc *desc)
  {
-       irq_state_clr_disabled(desc);
-       if (desc->irq_data.chip->irq_enable)
-               desc->irq_data.chip->irq_enable(&desc->irq_data);
-       else
-               desc->irq_data.chip->irq_unmask(&desc->irq_data);
-       irq_state_clr_masked(desc);
+       if (irqd_is_started(&desc->irq_data) &&
+           !irqd_irq_disabled(&desc->irq_data)) {
+               unmask_irq(desc);

I'm having a hard time to understand the logic here.

     if (started && !disabled)
        unmask()

That does not make any sense. If you need that to work around a state
inconsistency then it needs to be addressed there and not worked around
here.
right, we already set disabled state in desc_set_defaults, so the 
disabled state should be consistency here. so just
if(!disabled)
  unmask()
else
  enable()
?

and i saw we didn't set masked state in desc_set_defaults, i'll send a 
patch for that, and remove unmask_irq's started check too.

+       } else {
+               irq_state_clr_disabled(desc);
+               if (desc->irq_data.chip->irq_enable) {
+                       desc->irq_data.chip->irq_enable(&desc->irq_data);
+                       irq_state_clr_masked(desc);
+               } else {
+                       unmask_irq(desc);
+               }
+       }
  }

  static void __irq_disable(struct irq_desc *desc, bool mask)
  {
-       irq_state_set_disabled(desc);
-       if (desc->irq_data.chip->irq_disable) {
-               desc->irq_data.chip->irq_disable(&desc->irq_data);
-               irq_state_set_masked(desc);
-       } else if (mask) {
-               mask_irq(desc);
+       if (irqd_irq_disabled(&desc->irq_data)) {
+               if (mask)
+                       mask_irq(desc);
+       } else {
+               irq_state_set_disabled(desc);
+               if (desc->irq_data.chip->irq_disable) {
+                       desc->irq_data.chip->irq_disable(&desc->irq_data);
+                       irq_state_set_masked(desc);
+               } else if (mask) {
+                       mask_irq(desc);
+               }
        }
  }

@@ -311,18 +322,21 @@ void irq_percpu_disable(struct irq_desc *desc, unsigned 
int cpu)

  static inline void mask_ack_irq(struct irq_desc *desc)
  {
-       if (desc->irq_data.chip->irq_mask_ack)
+       if (desc->irq_data.chip->irq_mask_ack) {
                desc->irq_data.chip->irq_mask_ack(&desc->irq_data);
-       else {
-               desc->irq_data.chip->irq_mask(&desc->irq_data);
+               irq_state_set_masked(desc);
+       } else {
+               mask_irq(desc);
                if (desc->irq_data.chip->irq_ack)
                        desc->irq_data.chip->irq_ack(&desc->irq_data);
        }
-       irq_state_set_masked(desc);
  }

  void mask_irq(struct irq_desc *desc)
  {
+       if (irqd_irq_masked(&desc->irq_data))
+               return;
+
        if (desc->irq_data.chip->irq_mask) {
                desc->irq_data.chip->irq_mask(&desc->irq_data);
                irq_state_set_masked(desc);
@@ -331,6 +345,10 @@ void mask_irq(struct irq_desc *desc)

  void unmask_irq(struct irq_desc *desc)
  {
+       if (irqd_is_started(&desc->irq_data) &&
+           !irqd_irq_masked(&desc->irq_data))
+               return;

Ditto.

Thanks,

        tglx