linux-kernel - Re: [PATCH] kernel/watchdog: fix Kconfig constraints for perf hardlockup watchdog

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Message-ID: <20170810135346.cwrbipkow5klm6ga@redhat.com>
Date:   Thu, 10 Aug 2017 09:53:46 -0400
From:   Don Zickus <dzickus@...hat.com>
To:     Nicholas Piggin <npiggin@...il.com>
Cc:     Babu Moger <babu.moger@...cle.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kernel/watchdog: fix Kconfig constraints for perf
 hardlockup watchdog

On Thu, Aug 10, 2017 at 09:44:52PM +1000, Nicholas Piggin wrote:
> Patch 05a4a9527931 ("kernel/watchdog: split up config options") lost
> the perf-based hardlockup detector's dependency on PERF_EVENTS, which
> can result in broken builds with some powerpc configurations.
> 
> Restore the dependency. Add it in for x86 too, despite x86 always
> selecting PERF_EVENTS it seems reasonable to make the dependency
> explicit.

This is because ppc has the unusual configuration of supporting HARDLOCKUP
through perf or directly through the arch, right?  The Kconfigs assumed an
arch went one way or the other.

I think this is a good workaround for now.

Acked-by: Don Zickus <dzickus@...hat.com>

> 
> Fixes: 05a4a9527931 ("kernel/watchdog: split up config options")
> Signed-off-by: Nicholas Piggin <npiggin@...il.com>
> ---
> 
>  arch/powerpc/Kconfig | 2 +-
>  arch/x86/Kconfig     | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 36f858c37ca7..81b0031f909f 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -199,7 +199,7 @@ config PPC
>  	select HAVE_OPTPROBES			if PPC64
>  	select HAVE_PERF_EVENTS
>  	select HAVE_PERF_EVENTS_NMI		if PPC64
> -	select HAVE_HARDLOCKUP_DETECTOR_PERF	if HAVE_PERF_EVENTS_NMI && !HAVE_HARDLOCKUP_DETECTOR_ARCH
> +	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !HAVE_HARDLOCKUP_DETECTOR_ARCH
>  	select HAVE_PERF_REGS
>  	select HAVE_PERF_USER_STACK_DUMP
>  	select HAVE_RCU_TABLE_FREE		if SMP
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 781521b7cf9e..29a1bf85e507 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -163,7 +163,7 @@ config X86
>  	select HAVE_PCSPKR_PLATFORM
>  	select HAVE_PERF_EVENTS
>  	select HAVE_PERF_EVENTS_NMI
> -	select HAVE_HARDLOCKUP_DETECTOR_PERF	if HAVE_PERF_EVENTS_NMI
> +	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
>  	select HAVE_PERF_REGS
>  	select HAVE_PERF_USER_STACK_DUMP
>  	select HAVE_REGS_AND_STACK_ACCESS_API
> -- 
> 2.13.3
>