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Date: Fri, 20 Feb 2015 21:18:45 -0800
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Paul Clarke <pc@us.ibm.com>
Cc: "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] powerpc: re-enable dynticks
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On Fri, Feb 20, 2015 at 11:13:33AM -0600, Paul Clarke wrote:
> 
> implement arch_irq_work_has_interrupt() for powerpc
> 
> (resending because I messed up the e-mail addresses)
> 
> Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
> full dynamic ticks to be enabled, by expecting architectures to
> implement a suitable arch_irq_work_has_interrupt() routine.
> 
> Several arches have implemented this routine, including x86
> (3010279f) and arm (09f6edd4), but powerpc was omitted.
> 
> This patch implements this routine for powerpc.
> 
> The symptom, at boot (on powerpc arch systems) with "nohz_full=<CPU
> list>" is displayed:
>     NO_HZ: Can't run full dynticks because arch doesn't support irq
> work self-IPIs
> 
> after this patch:
>     NO_HZ: Full dynticks CPUs: <CPU list>.
> 
> Tested against 3.19.
> 
> v2: changed "return 1" to "return true", per Michael Ellerman
> 
> CC: Frederic Weisbecker <fweisbec@gmail.com>
> CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Signed-off-by: Paul A. Clarke <pc@us.ibm.com>

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> diff --git a/arch/powerpc/include/asm/irq_work.h
> b/arch/powerpc/include/asm/irq_work.h
> new file mode 100644
> index 0000000..99cc0aa
> --- /dev/null
> +++ b/arch/powerpc/include/asm/irq_work.h
> @@ -0,0 +1,11 @@
> +#ifndef _ASM_IRQ_WORK_H
> +#define _ASM_IRQ_WORK_H
> +
> +#include <asm/processor.h>
> +
> +static inline bool arch_irq_work_has_interrupt(void)
> +{
> +    return true;
> +}
> +
> +#endif /* _ASM_IRQ_WORK_H */