Re: [PATCH v5 08/12] powerpc: Add support to mask perf interrupts and replay them

On Wednesday 04 January 2017 06:08 PM, Nicholas Piggin wrote:

On Wed,  4 Jan 2017 17:19:46 +0530
Madhavan Srinivasan [off-list ref] wrote:

quoted

@@ -134,7 +137,7 @@ static inline bool arch_irqs_disabled(void)
  	_was_enabled = local_paca->soft_enabled;	\
  	local_paca->soft_enabled = IRQ_DISABLE_MASK_LINUX;\
  	local_paca->irq_happened |= PACA_IRQ_HARD_DIS;	\
-	if (!(_was_enabled & IRQ_DISABLE_MASK_LINUX))	\
+	if (!(_was_enabled & IRQ_DISABLE_MASK_ALL))	\
  		trace_hardirqs_off();			\
  } while(0)

Hang on, maybe there's some confusion about this. trace_hardirqs_off() is
for Linux irqs (i.e., local_irq_disable()), so that should continue to
test just the LINUX mask I think. Otherwise this

     powerpc_local_pmu_disable();
     hard_irq_disable();

Currently we set both bits for pmu soft disable

                flags = soft_disabled_mask_or_return(IRQ_DISABLE_MASK_LINUX | \
IRQ_DISABLE_MASK_PMU);                  \

So yes in the above seq, we will miss the pmu bit. But since trace_hardirqs_off()
is for _LINUX, instead will it not be safer to OR it?

        local_paca->soft_disabled_mask |= IRQ_DISABLE_MASK_LINUX;\

Maddy

Will miss calling trace_hardirqs_off(). You don't have a function that
disables PMU irqs without Linux irqs, but one might exist.

What I was concerned about is actually setting the disable mask to ALL

   	local_paca->soft_enabled = IRQ_DISABLE_MASK_ALL;

No? Otherwise if you did

     powerpc_local_irq_pmu_disable();
     hard_irq_disable();

Then you would lose the PMU bit out of the mask.

Thanks,
Nick