linux-kernel - Re: [PATCH] lockdep: report broken irq restoration

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Date:   Thu, 17 Dec 2020 15:36:40 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juergen Gross <jgross@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] lockdep: report broken irq restoration

On Wed, Dec 09, 2020 at 06:33:37PM +0000, Mark Rutland wrote:
> This means that a seuence such as:

+q

> diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
> index 3ed4e8771b64..bca3c6fa8270 100644
> --- a/include/linux/irqflags.h
> +++ b/include/linux/irqflags.h
> @@ -220,10 +220,26 @@ do {						\
>  
>  #else /* !CONFIG_TRACE_IRQFLAGS */
>  
> +#ifdef CONFIG_DEBUG_IRQFLAGS
> +extern void warn_bogus_irq_restore(bool *warned);
> +#define check_bogus_irq_restore()				\
> +	do {							\
> +		static bool __section(".data.once") __warned;	\
> +		if (unlikely(!raw_irqs_disabled()))		\
> +			warn_bogus_irq_restore(&__warned);	\
> +	} while (0)
> +#else
> +#define check_bogus_irq_restore() do { } while (0)
> +#endif
> +
>  #define local_irq_enable()	do { raw_local_irq_enable(); } while (0)
>  #define local_irq_disable()	do { raw_local_irq_disable(); } while (0)
>  #define local_irq_save(flags)	do { raw_local_irq_save(flags); } while (0)
> -#define local_irq_restore(flags) do { raw_local_irq_restore(flags); } while (0)
> +#define local_irq_restore(flags)		\
> +	do {					\
> +		check_bogus_irq_restore();	\
> +		raw_local_irq_restore(flags);	\
> +	} while (0)

Shouldn't that be in raw_local_irq_restore() ?

>  #define safe_halt()		do { raw_safe_halt(); } while (0)
>  
>  #endif /* CONFIG_TRACE_IRQFLAGS */

--- a/include/linux/irqflags.h
+++ b/include/linux/irqflags.h
@@ -162,6 +162,7 @@ do {						\
 #define raw_local_irq_restore(flags)			\
 	do {						\
 		typecheck(unsigned long, flags);	\
+		check_bogus_irq_restore();		\
 		arch_local_irq_restore(flags);		\
 	} while (0)
 #define raw_local_save_flags(flags)			\
@@ -235,11 +236,7 @@ extern void warn_bogus_irq_restore(bool
 #define local_irq_enable()	do { raw_local_irq_enable(); } while (0)
 #define local_irq_disable()	do { raw_local_irq_disable(); } while (0)
 #define local_irq_save(flags)	do { raw_local_irq_save(flags); } while (0)
-#define local_irq_restore(flags)		\
-	do {					\
-		check_bogus_irq_restore();	\
-		raw_local_irq_restore(flags);	\
-	} while (0)
+#define local_irq_restore(flags) do { raw_local_irq_restore(flags); } while (0)
 #define safe_halt()		do { raw_safe_halt(); } while (0)
 
 #endif /* CONFIG_TRACE_IRQFLAGS */