Re: [PATCH v4 05/17] irq & spin_lock: Add counted interrupt disabling/enabling

[Shrikanth Hegde <sshegde@linux.ibm.com>]

Hi Boqun,

> 
> Something as below? Going to send it to kernel build bot and see if it
> works for all configs.
> 
> ----------------->8
> diff --git a/include/linux/interrupt_rc.h b/include/linux/interrupt_rc.h
> index b9a7f05ecf42..39f30bc65548 100644
> --- a/include/linux/interrupt_rc.h
> +++ b/include/linux/interrupt_rc.h
> @@ -12,6 +12,7 @@
>    */
> 
>   #include <linux/irqflags.h>
> +#include <linux/debug_locks.h>
>   #include <linux/preempt.h>
>   #include <linux/processor.h>
>   #include <linux/smp.h>
> @@ -63,6 +64,12 @@ static inline void local_interrupt_disable(void)
> 
>          new_count = hardirq_disable_enter();
> 
> +       /* Is hardirq disable count overflow soon? */
> +       if (IS_ENABLED(CONFIG_DEBUG_PREEMPT))
> +               DEBUG_LOCKS_WARN_ON((new_count & HARDIRQ_DISABLE_MASK) +
> +                                   (10 << HARDIRQ_DISABLE_SHIFT) >
> +                                   HARDIRQ_DISABLE_MASK);
> +

This needs a return here right? Else we will see warning for 10 times
and then overflow happens and we will call _local_interrupt_disable. No?

Not sure, if below is any better? (Igore whitespace mangling)

if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) &&
     DEBUG_LOCKS_WARN_ON((preempt_count() & HARDIRQ_DISABLE_MASK) >=
			 HARDIRQ_DISABLE_MASK - (10 << HARDIRQ_DISABLE_SHIFT)))
	return;

>          /* Interrupts can happen here, but it's OK, see __irq_exit_rcu(). */
> 
>          if ((new_count & HARDIRQ_DISABLE_MASK) == HARDIRQ_DISABLE_OFFSET)
> @@ -73,6 +80,11 @@ static inline void local_interrupt_enable(void)
>   {
>          int new_count;
> 
> +       /* Unpaired local_interrupt_enable()? Warn and abort. */
> +       if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) &&
> +           DEBUG_LOCKS_WARN_ON((preempt_count() & HARDIRQ_DISABLE_MASK) == 0))
> +               return;
> +
>          new_count = hardirq_disable_exit();
> 
>          if ((new_count & HARDIRQ_DISABLE_MASK) == 0) >